NASASpaceFlight.com Forum

General Discussion => New Physics for Space Technology => Topic started by: colbourne on 06/23/2008 06:03 am

Title: Theoretical FTL
Post by: colbourne on 06/23/2008 06:03 am
Assumption 1
===========
I am assuming that anti-matter wil be affected by gravity in the reverse to normal matter.

Assumption 2
===========
Therefore if we can create an anti matter object we should be able to accelerate it up to FTL. This in itself should allow FTL communications.

Assumption 3
===========

We can currently contain anti-matter by magnetic means, so we should be able to contain normal matter by a similar means inside our anti-matter spacecraft.

I expect the new CERN accelrator will be able to answer my probably incorrect assumptions.
Title: Re: Theoretical FTL
Post by: Eraser on 06/23/2008 10:08 am
No, gravitation equally affects on a matter and an antimatter.
Title: Re: Theoretical FTL
Post by: whitewatcher on 06/23/2008 11:23 am
Yep, anti-matter and matter are made of the same thing: energy.

To observe a reverse gravitational effect, you would need something like anti-antimatter (composed of anti-energy).
Title: Re: Theoretical FTL
Post by: William Barton on 06/23/2008 12:16 pm
I forget who, but somebody one suggested the force of negative gravity be referred to as "levity."

It's probably not a good idea to try to prognosticate the enabling technologies of soft SF (unless you're a high-end theoretical cosmologist or something). FTL, teleportation, time-travel, etc. do for SF what magic wands and incantations do for fantasy. One of their hallmarks is, they enable secondary technologies that allow us to bypass the secondary (practical) limitations imposed by physics. For example, if you have teleportation, you instantly have fuelless rockets. You sink a transmitter in Jupiter's atmosphere, a receiver at the back end of your spaceship, and la voila! The ignored magic trick is the energy density required for something like teleportation to work. They are all effectively perpetual motion machines, and if you had the command of physics necessary to make them work, you wouldn't need them.

The issue with trying to get past the contraints imposed by physics as we know it is, first you have to get past the contraints imposed by practical engineering. Somebody comes up with a theory that allows FTL, and Step 1 turns out to be, "Accummulate 400 vigintillion tonnes of neutronium and shape it into a rotating torus 4cm in diameter..."

A brilliant example of the borderland of achievable technology was Arthur C. Clarke's black-hole rocket engine in "Imperial Earth."
Title: Re: Theoretical FTL
Post by: cpcjr on 06/23/2008 02:12 pm
Assumption 1
===========
I am assuming that anti-matter wil be affected by gravity in the reverse to normal matter.

This assumption is wrong anti-matter is affect by gravity the same way ordinary matter is. 

Quote
Assumption 2
===========
Therefore if we can create an anti matter object we should be able to accelerate it up to FTL. This in itself should allow FTL communications.

Wrong even if assumption 1 were correct, which it is not.
1. The Gravity of the sun would only accelerate it to at most 617.5 Km/s
2. Anti-mater would still be limited by relativity to the speed light.

Quote
Assumption 3
===========

We can currently contain anti-matter by magnetic means, so we should be able to contain normal matter by a similar means inside our anti-matter spacecraft.

This does work but getting enough anti-matter for even the most basic anti-matter rocket would be exreamly expensive: over a $100,000,000.00 / ounce.
Title: Re: Theoretical FTL
Post by: scienceguy on 06/23/2008 08:13 pm
According to this paper

A `warp drive' with more reasonable total energy requirements
Chris Van Den Broeck
Class. Quantum Grav. 16 No 12 (December 1999) 3973-3979

Even if antimatter responded to gravity in an opposite way to matter, you would still need -10^30 kg of it for a warp drive.
Title: Re: Theoretical FTL
Post by: Martin FL on 06/23/2008 09:34 pm
Here's a curveball, but this area of science is all theory, what is there are gaps in the facts and FTL is possible?

Possible, no chance, I should go back to reading about shuttles? ;)
Title: Re: Theoretical FTL
Post by: scienceguy on 06/23/2008 11:34 pm
Miguel Alcubierrre (1994) published a paper that showed that a warp drive is at least mathematically possible, although it would require huge amounts of negative energy. Pfenning and Ford (1997) showed that a warp bubble wall as proposed by Alcubierre would have to be impossibly thin in order to work. Low (1999) showed that a warp in spacetime could travel no faster than the speed of light and that such a warp would require exotic matter (negative energy). Natario (2002) had a little more positive result: he showed that warp drives could be possible in that they wouldn’t need to compress spacetime ahead of themselves and stretch it behind in order to move. Lobo and Visser (2004) most recently published on this and they showed that in order for a warp drive to work, a couple of things need to happen:
1.   The spaceship can’t travel faster than light
2.   The amount of negative energy must be a significant fraction of the mass of the ship.
As I understand it, a spaceship using a warp drive can’t travel faster than light because gravity only travels at the speed of light, and such a ship would be relying on a negative gravitational force generated by the negative energy it is carrying along in its warp of spacetime.

References

The warp drive: hyper-fast travel within general relativity
Miguel Alcubierre
Class. Quantum Grav. 11 No 5 (May 1994) L73-L77

Fundamental limitations on 'warp drive' spacetimes
Francisco S N Lobo and Matt Visser
Class. Quantum Grav. 21 No 24 (21 December 2004) 5871-5892

Speed limits in general relativity
Robert J Low
Class. Quantum Grav. 16 No 2 (February 1999) 543-549

Warp drive with zero expansion
J Natario
Class. Quantum Grav. 19 No 6 (21 March 2002) 1157-1165

The unphysical nature of `warp drive'
M J Pfenning and L H Ford
Class. Quantum Grav. 14 No 7 (July 1997) 1743-1751
Title: Re: Theoretical FTL
Post by: hop on 06/24/2008 12:29 am
No, gravitation equally affects on a matter and an antimatter.
AFAIK, this is current strong consensus of people in the field, but hasn't been verified experimentally yet.

edit:
Not that FTL or antigravity would necessarily follow even if some difference was detected.
Title: Re: Theoretical FTL
Post by: khallow on 06/24/2008 04:14 am
My take is that if FTL was possible, we'd probably have seen it by now in particle accelerator experiments and supernova observations. High energy events cover a lot of theoretical possibilities. If there were FTL possibilities, one would need to explain why those possibilities aren't been seen in the trillions of recorded collisions by particle accelerators and why we don't see anything precede the neutrino (and sometimes gamma ray) burst from a supernova.

A technology that might be feasible is the wormhole. Mathematically, it's a "handle" or hole in space-time, that provides an alternate path to a destination that isn't equivalent to the usual way of going between two points. In particular, at no time is anything traveling faster than the speed of light. This changes the topology of space which may or may not be possible.

Optimistically, this new path is considerably shorter than the usual one. For example, Alpha Centauri is 4+ light years away from Earth. A wormhole might provide an alternate path that is say 20 AU long instead. That might be useful merely for communication (under six hours round trip communication time) or even for travel if the hole can be made wide enough (and the environment inside the wormhole is survivable for a vehicle).

As I understand it, the two ends of the wormhole would be created next to one another. Each end would go to an appropriate destination. I have no idea how you'd move it around, keep it from pinching shut, or change its length.
Title: Re: Theoretical FTL
Post by: TyMoore on 06/24/2008 03:43 pm
Miguel Alcubierre's "Warp Metric" relies on the bizarre behavior that a negative energy mass and a positive energy mass will have for each other: the positive mass attracts the negative mass, but the negative mass repels the positive mass. Or more correctly, the positive mass has the usual gravity field, but the negative mass has a gravity field with a negative sense (as felt by the positive mass.) So a system composed of two equal magnitude but opposite sensed masses (total energy of system: zero) will accelerate in the direction of the positive mass.

Miguel Alcubierre took the idea to the extreme by positing large masses: neutronium density or more. Further he used a nifty little gravitational trick: the gravity field inside a spherically symmetric shell of mass is zero--in general relativity terms, the spacetime inside a spherical shell is approximately flat. So putting the two ideas together you get a spherical shell with the forward end composed of positive energy matter, the aft half is composed of negative energy matter, and the 'vessel' or transport is at the center of the shell in the flat spacetime 'island' in the middle. Increase the density of the shell until it comes close to the density of neutronium, and voila you have massive acceleration that the occupants inside won't feel (they're in free fall.)

The system does not appear to violate conservation of energy as long as the spherical shell has a net-zero energy (sum of the positive energy mass and negative energy mass is zero;) the vessel inside does not possess any more or less kinetic energy than what it started out with since the 'spacelike' FTL movement is similar in some regards to expansion of the early universe.

This is what I got out of Mr. Alcubierre's paper (without being able to do the General Relativistic Tensor mathematics involved in the transforms!)
Title: Re: Theoretical FTL
Post by: gospacex on 06/24/2008 04:21 pm
Further he used a nifty little gravitational trick: the gravity field inside a spherically symmetric shell of mass is zero--in general relativity terms, the spacetime inside a spherical shell is approximately flat. So putting the two ideas together you get a spherical shell with the forward end composed of positive energy matter, the aft half is composed of negative energy matter,

Well, spherical shell's interior has zero gravity field _only if_ the density and thickness of the shell is the same eveywhere. The above description seems to violate that.
Title: Re: Theoretical FTL
Post by: colbourne on 06/26/2008 02:18 am
If anti-matter did respond to gravity differently to normal matter one of the results might have been after the big bang all the anti-matter would have quickly accelerated away at faster than light speed which may explain why there appears to be an absence/shortage of anti-matter in the universe.

This space craft seems expensive but as with everything you get what you pay for. I would say it is a bargain if it really could be built !!!

Initially once we get some results proving how gravity and anti-matter are linked , it might be a useful study for the SETI people.

If my assumptions were correct could we build a communications device that would work ?
Title: Re: Theoretical FTL
Post by: hop on 06/26/2008 02:56 am
If anti-matter did respond to gravity differently to normal matter one of the results might have been after the big bang all the anti-matter would have quickly accelerated away at faster than light speed which may explain why there appears to be an absence/shortage of anti-matter in the universe.
No, as previously pointed out, even if antimatter doesn't respond as we expect to gravity (which itself would be a huge surprise) that doesn't imply FTL.
Title: Re: Theoretical FTL
Post by: Suzy on 06/26/2008 06:11 am
As I understand it (not being a physicist!), you can't go Faster-than-light at all, but there are ways around this (in science fiction, at least!). One as mentioned is to use a wormhole. Two points in space are brought together and a hole is poked through spacetime, and the starship just pops through without traversing any distance in real space. (If anyone saw the movie Event Horizon there is a scene where Sam Neil explains this with a piece of paper and a pencil). A wormhole is a hole, not a tunnel (as incorrectly depicted in some sci-fi films).

A similar concept is folding space - I am not sure if it is the same as a wormhole - where a starship pulls or warps space toward it until it reaches the place it wants to be (without actually moving itself physically).

My take is that if FTL was possible, we'd probably have seen it by now in particle accelerator experiments and supernova observations. High energy events cover a lot of theoretical possibilities. If there were FTL possibilities, one would need to explain why those possibilities aren't been seen in the trillions of recorded collisions by particle accelerators and why we don't see anything precede the neutrino (and sometimes gamma ray) burst from a supernova.

A technology that might be feasible is the wormhole. Mathematically, it's a "handle" or hole in space-time, that provides an alternate path to a destination that isn't equivalent to the usual way of going between two points. In particular, at no time is anything traveling faster than the speed of light. This changes the topology of space which may or may not be possible.

Optimistically, this new path is considerably shorter than the usual one. For example, Alpha Centauri is 4+ light years away from Earth. A wormhole might provide an alternate path that is say 20 AU long instead. That might be useful merely for communication (under six hours round trip communication time) or even for travel if the hole can be made wide enough (and the environment inside the wormhole is survivable for a vehicle).

As I understand it, the two ends of the wormhole would be created next to one another. Each end would go to an appropriate destination. I have no idea how you'd move it around, keep it from pinching shut, or change its length.

Title: Re: Theoretical FTL
Post by: Lampyridae on 06/26/2008 06:37 am
I forget who, but somebody one suggested the force of negative gravity be referred to as "levity."

It's probably not a good idea to try to prognosticate the enabling technologies of soft SF (unless you're a high-end theoretical cosmologist or something). FTL, teleportation, time-travel, etc. do for SF what magic wands and incantations do for fantasy. One of their hallmarks is, they enable secondary technologies that allow us to bypass the secondary (practical) limitations imposed by physics. For example, if you have teleportation, you instantly have fuelless rockets. You sink a transmitter in Jupiter's atmosphere, a receiver at the back end of your spaceship, and la voila! The ignored magic trick is the energy density required for something like teleportation to work. They are all effectively perpetual motion machines, and if you had the command of physics necessary to make them work, you wouldn't need them.

The issue with trying to get past the contraints imposed by physics as we know it is, first you have to get past the contraints imposed by practical engineering. Somebody comes up with a theory that allows FTL, and Step 1 turns out to be, "Accummulate 400 vigintillion tonnes of neutronium and shape it into a rotating torus 4cm in diameter..."

A brilliant example of the borderland of achievable technology was Arthur C. Clarke's black-hole rocket engine in "Imperial Earth."

A classic thought experiment exists on the teleportation idea. Drill a hole through the Earth (yes, yes, I know...), evacuate it and drop an object down it. It will travel down, pop up in Australia or wherever the exit is, allowing you to catch it. Zero energy is required (apart from the catch) so in effect you have teleportation for nothing (after drilling the hole through Earth...).

It's a way of using potential energy to move something, and not actually pay the gazillion dollar energy bill. So it may therefore be possible to use potential energies such as casimir effect (which theoretically can only be tapped once, like dropping a ball is for gravitational potential) and using it for whatever purpose. I don't believe we will manipulate gazillion tonnes of neutronium anytime soon but the ability to manipulate if not harvest quantum effects might give you would give you options into these FTL options.

As for FTL itself, nothing prevents you travelling faster than light (in special relativity), it just prevents you from accelerating past the lightspeed barrier. Decelerating from FTL is also bad; you re-enter normal space as a blinding cascade of Cherenkov radiation... but then again wasn't it Stephen Hawking who made that bet about "information never being able to leave a black hole?"

A lot of basic assumptions have been spectacularly demolished over recent years, and have been replaced by "erm, we don't know." Case in point, the inflationary universe. So our standard physics models may be due for updates soon. It's the nature of science.
Title: Re: Theoretical FTL
Post by: scienceguy on 06/27/2008 07:48 pm
Let's say antimatter responds to gravity in an opposite manner to matter. Would it be cheaper to harvest it from Jupiter's radiation belts or dedicate a single particle accelerator to make it?
Title: Re: Theoretical FTL
Post by: khallow on 06/29/2008 07:48 am
Probably neither. It'd probably be easier to build a large scale solar powered plant in close orbit around the Sun (say a few million kilometers out or less) and farm the solar wind.
Title: Re: Theoretical FTL
Post by: Suzy on 07/08/2008 08:28 am
...A brilliant example of the borderland of achievable technology was Arthur C. Clarke's black-hole rocket engine in "Imperial Earth."

An explanation of the Asymptotic Drive (from here (http://www.almostsmart.com/forums/showthread.php?t=16669)):

The main character takes a trip from the Saturnian moon of Titan to Earth in a vessel powered by the “Asymptotic Drive” which is basically a small mass black hole (in the book it was one with “one or two thousand tons mass” – something which would be proton-sized or thereabouts) suspended in a very powerful magnetic field. The way it works is like this: The black hole “eats” matter as we all know, but it can only consume matter at a set rate depending on its mass and the size of the Event Horizon which surrounds the singularity. Now, (as Clarke visualizes) you dump a few grams per second of plain hydrogen onto the black hole which attempts to consume all of the hydrogen but can’t so the remaining hydrogen compresses against itself and the event horizon to the point that it gets hot.

Very hot.

Hot enough to fuse.

Now the singularity is suspended via powerful magnetic fields at the end of a tube open at one end to space and the superheated hydrogen jets out of the open end of the tube. This superhot gas is plasma which means it is electrically active and also means it can be shaped, focussed and directed by magnetic fields. The result is one has a fusion powered rocket which creates thrust with a nozzle velocity far in excess of anything a chemically powered rocket could produce, and do it for weeks on end. In the book, the billion-mile trip from Titan to Earth took 20 days with 10 days accelerating and 10 days decelerating.

You're still stuck going through normal space, though.

In the Event Horizon (http://en.wikipedia.org/wiki/Event_Horizon_%28movie%29) movie a "black hole drive" was used to somehow fold space so the ship could jump instantly from one point in space to another. Any idea of the details of how that could work?
Title: Re: Theoretical FTL
Post by: Eerie on 07/08/2008 01:18 pm
Suzy, you could just use a fusion rocket, without messing with a HEAVY black hole.

And antimatter rocket would be better anyway.
Title: Re: Theoretical FTL
Post by: Suzy on 07/08/2008 08:42 pm
Suzy, you could just use a fusion rocket, without messing with a HEAVY black hole.

And antimatter rocket would be better anyway.

But black holes are cooler!  ;D
Title: Re: Theoretical FTL
Post by: josh_simonson on 07/08/2008 11:22 pm
For conservation of energy to maintained, a wormhole or similar conveyance would require a minimum energy input of the difference in potential and kinetic energy between one and and the other in order to work, or perhaps it'd only be possible to fold space to a point of equal energy.   

Traveling at the speed of light is instantaneous to the traveler, so I suspect that c is effectively infinite speed, and it's just simply a matter of the ways we perceive and measure time and space don't work well at such extremes.  Looking out across the universe, a star 1 light year away is seen as it was one year ago - so the x,y and z coordinates can be viewed as distances in time.  Then c is 1s/s, or just 1 without units and you can't travel faster than 1.  There, now that sounds better than you can't travel faster than ~3e8m/s.
Title: Re: Theoretical FTL
Post by: gospacex on 07/09/2008 08:09 am
For conservation of energy to maintained, a wormhole or similar conveyance would require a minimum energy input of the difference in potential and kinetic energy between one and and the other in order to work

Global conservation of energy is not enforced by General Relativity, only local. It is possible to construct a setup where energy is not only not conserved, but where it is impossible to define a notion of "energy" globally.

Quote
Traveling at the speed of light is instantaneous to the traveler, so I suspect that c is effectively infinite speed, and it's just simply a matter of the ways we perceive and measure time and space don't work well at such extremes.  Looking out across the universe, a star 1 light year away is seen as it was one year ago - so the x,y and z coordinates can be viewed as distances in time.  Then c is 1s/s, or just 1 without units and you can't travel faster than 1.  There, now that sounds better than you can't travel faster than ~3e8m/s.

It sounds not better, but bizarre. Reading more on subject of Special Relativity might help you to get a firmer grasp on what's going on. Wikipedia article is not a bad start.

Can't agree on "c is instantaneous", why radar bounces off planets come back with delay?

Time and space are definitely different dimensions, since they enter into equations with opposite signs, like in ds^2 = dt^2 - dx^2 - dy^2 - dz^2.
Title: Re: Theoretical FTL
Post by: Eerie on 07/09/2008 01:59 pm
Can't agree on "c is instantaneous", why radar bounces off planets come back with delay?

C is instantaneous from POV of the traveller. But you will have to be massless.
Title: Re: Theoretical FTL
Post by: Suzy on 07/29/2008 05:39 am
Discovery.com article, 28/7: "Warp Drive Engine Would Travel Faster Than Light (http://dsc.discovery.com/news/2008/07/28/warp-speed-engine.html)".
Title: Re: Theoretical FTL
Post by: TyMoore on 07/29/2008 03:48 pm
With regards to using blackholes as power sources. A 1000 metric ton black hole will evaporate by Hawking Radiation in less than a microsecond. You'd get a very big bang, but little propulsion!

If you go smaller, much smaller: milligram mass blackholes, and you make them dozens of times a second, then the emissions should be predominantly gamma-rays, and electron/positron pairs, which will annhilate to gamma-rays. Use the gamma-rays to impinge on something dense, like tungsten balls in a pressure vessel and nozzle: you have something akin to a nuclear thermal rocket. Or you could use a closed Brayton cycle and use the electricity to power conventional ion thrusters.

Or if you really want to go wild, why not use the intense gamma-rays to heat something else: like lunar regolith and use that as your working fluid! Who cares if its inefficient from Isp point of view: with enough gamma-rays the plasma will be at tens of millions of degrees anyway. And the drive flare should be visible all the way across the solar system. Cool!
Title: Re: Theoretical FTL
Post by: ChevalierGuard on 07/29/2008 11:05 pm
Kaluza Klein Theory...

CG
Title: Re: Theoretical FTL
Post by: khallow on 07/29/2008 11:43 pm
Kaluza Klein Theory...

What about Kaluza Klein theory? As far as I know, it's the idea that you can start with a higher dimension massless/pure geometry model and reduce by the extra dimensions to get a model with our observed spacetime and physical properties like mass/energy (including curvature and possibly a cosmological constant or "dark energy") or electric current flows.
Title: Re: Theoretical FTL
Post by: ChevalierGuard on 07/30/2008 10:23 pm
Kaluza klein theory...

Not exactly...as far as I know the equations don't show dark energy or matter..

However, there is a compactification.. but primarily it links gravity equations to EM... and vice versa.. 
I speaking of the 5D case of course.. the other stuff really is nonsense.
speaking of the 11 dimensions..

Not to bore with equations, here is a simple definition from wikpedia..

In physics, Kaluza–Klein theory (or KK theory, for short) is a model that seeks to unify the two fundamental forces of gravitation and electromagnetism. The theory was first published in 1921 and was discovered by the mathematician Theodor Kaluza who extended general relativity to a five-dimensional spacetime. The resulting equations can be separated out into further sets of equations, one of which is equivalent to Einstein field equations, another set equivalent to Maxwell's equations for the electromagnetic field and the final part an extra scalar field now termed the "radion".

This is part of the solution...

Nice chatting with you...

Wish NASA would give pic EM and Beamline and Klystron codes freely.  You could do alot with a small Linux cluster..

Nice chatting..

CG





Title: Re: Theoretical FTL
Post by: colbourne on 08/01/2008 07:28 am
This weeks New Scientist (1 August 2008) has an article about how antimatter particles sometimes bounce off normal matter.
This possibly supports my previous assumption about the possible anti-gravity that might occur with anti-matter.

http://www.newscientist.com/channel/fundamentals/mg19926674.600-antimatter-plus-matter-doesnt-always-equal-bang.html

The "Colbourne" drive still might work. I expect we will know soon.

Title: Re: Theoretical FTL
Post by: gospacex on 08/01/2008 10:35 am
This weeks New Scientist (1 August 2008) has an article about how antimatter particles sometimes bounce off normal matter.

I think proton/antiproton collision was never thought to 100% reliably result in annihilation, they may just scatter on each other.

Quote
This possibly supports my previous assumption about the possible anti-gravity that might occur with anti-matter.

Magnitude of gravitational interaction in proton-antiproton (or proton-proton) pair is on the order of 10^37 times weaker than electromagnetic. Likely not detectable.
Title: Re: Theoretical FTL
Post by: khallow on 08/01/2008 05:47 pm
Kaluza klein theory...

Not exactly...as far as I know the equations don't show dark energy or matter..

However, there is a compactification.. but primarily it links gravity equations to EM... and vice versa.. 
I speaking of the 5D case of course.. the other stuff really is nonsense.
speaking of the 11 dimensions..

If you instead contract (collapse the direction in question) a 5 dimensional space (4 spatial/1 time dimensions) along a radial direction rather than along a single spatial dimention, you can get de Siter and anti-de Siter spaces. The idea is to treat each ray coming from the origin as a point in a 4 dimensional space. If this were a regular 5 dimensional Euclidean space, the result is a sphere centered at the origin (each ray passes once through this sphere). With one timelike dimension, you end up with a hyperboloid sheet instead (again each ray passing once through the sheet). The cosmological constant shows up as the inverse of a "radius" of this sheet.

Also, given that we observe a strong and weak force, this encourages the consideration of higher dimensional models. They may have limited physical relevance, but it is a good way to generate potential models for the interaction of the four forces and the math might be applicable to a better model. That is, it might turn out that a "good" model has a 10, 11, 26, etc dimensional extension that simplifies the math of the original model. You just need to know how to go from the manipulations of the higher dimension space to the real world space.
Title: Re: Theoretical FTL
Post by: Capt. Nemo on 08/02/2008 07:35 am


Miguel Alcubierre took the idea to the extreme by positing large masses: neutronium density or more. Further he used a nifty little gravitational trick: the gravity field inside a spherically symmetric shell of mass is zero--in general relativity terms, the spacetime inside a spherical shell is approximately flat. So putting the two ideas together you get a spherical shell with the forward end composed of positive energy matter, the aft half is composed of negative energy matter, and the 'vessel' or transport is at the center of the shell in the flat spacetime 'island' in the middle. Increase the density of the shell until it comes close to the density of neutronium, and voila you have massive acceleration that the occupants inside won't feel (they're in free fall.)

I wonder if this 'shell' would also act as a 'deflector shield' and/or a 'cloaking device'.  seems to me that something as dense as 'nuetronium' would be damned tough to see thru, if it let any EM radiation thru at all.
Title: Re: Theoretical FTL
Post by: khallow on 08/02/2008 06:00 pm
OTOH, everyone who detects the neutronium would suspect you were hiding something. An analogy is a 50 pound lead brick. There are all sorts of tricks for hiding a brick and usually it's not that hard. It's not particularly big and very few people really care about where you go with a lead brick. But don't try to pass one through an airport X ray security system.

Due to the density of the lead brick, you can stick anything in the center and it won't be scannable by X ray machines. But what would be the point? Most circumstances where the shielding matters, the brick itself would raise suspicion. The biggest exception is when the hidden item generates a signal somehow (say because it is a kilogram of plutonium 239).
Title: Re: Theoretical FTL
Post by: ChevalierGuard on 08/03/2008 01:33 am
Creation of Mini black holes?

and capturing virtual particles?

any thoughts, known papers, etc?

CG
Title: Re: Theoretical FTL
Post by: khallow on 08/03/2008 04:58 am
Creation of Mini black holes?

Very small rotating black holes do appear to be promising. I wouldn't recommend doing it on a planet or near a star. But it does look a good way to store energy.

Quote
and capturing virtual particles?

any thoughts, known papers, etc?

My take on virtual particles is that they are artifacts of particular models. For example, quantum electrodynamics (or QED, a quantum field theory used to describe electromagnetism) requires "virtual photons" to adequately describe the interaction between charged particles. Normal photons have two vibration modes (usually called "degrees of freedom") while virtual photons have the full four modes of vibration (sound waves are an example of waves that have four vibration modes). If one uses the QED model and attempts to observe a virtual photon, a strange thing happens. The two modes that we see have the expected positive probability of being observed. But the other two modes have a negative probability of being observed. This leads to the convention that observable states are only the states with positive probability.

Still the talk of black holes and virtual particles does allow for the possibility of gravitational capture of hard to observe particles. For example, any sufficiently dense object (possibly a neutron star just a bit shy of unrestrained collapse) can have a photon sphere (http://en.wikipedia.org/wiki/Photon_sphere). That is, the object through it's deep gravity well can actually trap photons in orbit around the object. Anything moving slower than that will be trapped in higher orbits. One can then attempt to scatter observable stuff off of what is in the photon sphere.
Title: Re: Theoretical FTL
Post by: ChevalierGuard on 08/04/2008 03:02 am
Karl,

Thanks for the link Photon sphere link...  I knew of virtual particles (QED based stuff) thought you might have additional info..

Has anyone modeled collisions or merges of mini black holes? Cactus simulations?

I haven't modeled anything astronomical in years..  need to get a Linux cluster up and running...
Recently only working on beamline stuff... O and M devices..

I heard that
Physicists are actually trying to probe other spatial dimensions using particle physics experiments?
True? if so, papers?

thx

CG


Title: Re: Theoretical FTL
Post by: gospacex on 08/04/2008 09:42 am
any sufficiently dense object (possibly a neutron star just a bit shy of unrestrained collapse) can have a photon sphere (http://en.wikipedia.org/wiki/Photon_sphere). That is, the object through it's deep gravity well can actually trap photons in orbit around the object. Anything moving slower than that will be trapped in higher orbits. One can then attempt to scatter observable stuff off of what is in the photon sphere.

I don't think so. Photon sphere is not a stable orbit, you can't "accumulate" orbiting photons there. IIRC lowest stable orbit around non-rotating black hole has a radius of 3*Rs.
Title: Re: Theoretical FTL
Post by: khallow on 08/04/2008 10:35 pm
any sufficiently dense object (possibly a neutron star just a bit shy of unrestrained collapse) can have a photon sphere (http://en.wikipedia.org/wiki/Photon_sphere). That is, the object through it's deep gravity well can actually trap photons in orbit around the object. Anything moving slower than that will be trapped in higher orbits. One can then attempt to scatter observable stuff off of what is in the photon sphere.

I don't think so. Photon sphere is not a stable orbit, you can't "accumulate" orbiting photons there. IIRC lowest stable orbit around non-rotating black hole has a radius of 3*Rs.

I'm not sure I understand what you're saying. This would be an orbit, then you effectively have that photon trapped in this zone. It can still escape either by hitting other things or due to the quantum nature of the photon, tunneling either into the massive object or out of the system.
Title: Re: Theoretical FTL
Post by: ChevalierGuard on 08/05/2008 02:54 am
Gentlemen,

Using miniblack holes to capture virtual particles and hence using the miniblackhole as storage device may not be the trick...Remember, Stephen Hawking predicted that black holes eventually evaporate!

Darn that negative energy virtual particle..

CG
Title: Re: Theoretical FTL
Post by: gospacex on 08/05/2008 08:22 am
any sufficiently dense object (possibly a neutron star just a bit shy of unrestrained collapse) can have a photon sphere (http://en.wikipedia.org/wiki/Photon_sphere). That is, the object through it's deep gravity well can actually trap photons in orbit around the object. Anything moving slower than that will be trapped in higher orbits. One can then attempt to scatter observable stuff off of what is in the photon sphere.

I don't think so. Photon sphere is not a stable orbit, you can't "accumulate" orbiting photons there. IIRC lowest stable orbit around non-rotating black hole has a radius of 3*Rs.

I'm not sure I understand what you're saying. This would be an orbit, then you effectively have that photon trapped in this zone. It can still escape either by hitting other things or due to the quantum nature of the photon, tunneling either into the massive object or out of the system.

Stable orbit is an orbit where small perturbations result in small changes of orbit.

The "photon sphere" is not such an orbit, neither any other orbit closer than three Schwarzschild radii. Even though theoretically an object (or photon) with *exactly* the right kinetic energy and direction of flight can be put on these orbit, even tiniest error in speed or direction will change this orbit into a spiral trajectory either falling into the hole or going outward until the object is on orbit >= 3 Rs.

The closest such unstable orbit is at 3/2 Rs and it requires "objects" to have v=c. In other words, only photons can be put on this orbit. But "can be put" is not equal to "there are lots and lots of photons on this orbit". Actually, most of the time (read: always) this orbit is empty.
Title: Re: Theoretical FTL
Post by: sandrot on 08/13/2008 10:02 pm
Dark energy is the key:

http://www.space.com/businesstechnology/080813-tw-warp-speed.html
Title: Re: Theoretical FTL
Post by: colbourne on 12/04/2011 11:32 am
Have we discovered any more about the properties of anti-matter to answer the ideas raised in this thread yet ?


I think it is fair to say that we have more doubt now on the definite limits imposed by Einsteins theories and scientists are willing to speculate on the possibility of FTL.

This thread is also relevant :-

http://forum.nasaspaceflight.com/index.php?topic=24858.0
Title: Re: Theoretical FTL
Post by: JohnFornaro on 12/04/2011 02:55 pm
Why don't we prove the characteristics of anti-matter first?  It takes very little thought, and not that much more typing to come up with usefull applications for anti-gravity.
Title: Re: Theoretical FTL
Post by: Joris on 12/04/2011 08:19 pm
Assumption 1
===========
I am assuming that anti-matter wil be affected by gravity in the reverse to normal matter.

Assumption 2
===========
Therefore if we can create an anti matter object we should be able to accelerate it up to FTL. This in itself should allow FTL communications.

Assumption 3
===========

We can currently contain anti-matter by magnetic means, so we should be able to contain normal matter by a similar means inside our anti-matter spacecraft.

I expect the new CERN accelrator will be able to answer my probably incorrect assumptions.


Nope, basic knowledge will do.

First two are wrong.
Third is irrelevant.
Title: Re: Theoretical FTL
Post by: colbourne on 12/04/2011 08:29 pm
Assumption 1
===========
I am assuming that anti-matter wil be affected by gravity in the reverse to normal matter.

Assumption 2
===========
Therefore if we can create an anti matter object we should be able to accelerate it up to FTL. This in itself should allow FTL communications.

Assumption 3
===========

We can currently contain anti-matter by magnetic means, so we should be able to contain normal matter by a similar means inside our anti-matter spacecraft.

I expect the new CERN accelrator will be able to answer my probably incorrect assumptions.


Nope, basic knowledge will do.

First two are wrong.
Third is irrelevant.

How did you know that the first two were wrong ?
Title: Re: Theoretical FTL
Post by: Joris on 12/04/2011 08:37 pm
How did you know that the first two were wrong ?

Observed since the moment we discovered anti-particles.

An example:
An electron and a positron are antiparticles of each other.
They exhibit perfectly predictable behavior.

Can I ask:
How big is your understanding of physics, it is good to know before continouing this discussion?
Title: Re: Theoretical FTL
Post by: colbourne on 12/05/2011 01:15 pm
How did you know that the first two were wrong ?

Observed since the moment we discovered anti-particles.

An example:
An electron and a positron are antiparticles of each other.
They exhibit perfectly predictable behavior.

Can I ask:
How big is your understanding of physics, it is good to know before continouing this discussion?

I think you better let CERN and other research establishments know, as they are spending a fortune to confirm the properties of anti-matter. As far as I know the exact properties have not been confirmed yet.

I only have a BSc in Physics
Title: Re: Theoretical FTL
Post by: Tass on 12/05/2011 01:35 pm
I think you better let CERN and other research establishments know, as they are spending a fortune to confirm the properties of anti-matter. As far as I know the exact properties have not been confirmed yet.

I only have a BSc in Physics

Oh sure they do, but it is more to check much more subtle things that wether their mass is negative.

We know antimatters charge is reversed (positronium is bound for example), we thus know from electromagnetic effects on antimatter that its inertial mass is positive. We don't strictly know that the gravitational mass is positive, no one has meassured the gravitational mass of antimatter (it is very hard to do), but having positive energy and negative gravitational mass would be very hard to reconcile with general relativity.
Title: Re: Theoretical FTL
Post by: KelvinZero on 12/05/2011 06:07 pm
Here is a wiki link. Very strongly expected to have the usual gravity though not yet experimentally confirmed.
http://en.m.wikipedia.org/wiki/Gravitational_interaction_of_antimatter
Title: Re: Theoretical FTL
Post by: Joris on 12/05/2011 08:15 pm
Okay fine let us assume anti-matter induces anti-gravity.
This raises a few questions:

A photon is its own antiparticle, how does it act under gravity?

How will particle-antiparticle parirs act under gravity? (charmonium, for example.)

Will an object that has a left side made of antimatter accelarate to the right?

The first one is observed, albeit raises questions about whether gravity is a two component force. (Mass-gravity and energy-gravity.)

The second two are thought-experiments, untill tested, but make me doubt it.


(IMHO, I think that it is best to assume that antimatter acts as predictable as matter with respect to the Standardmodel. At least untill we have an explanation for gravity.)

On a side note: I'm interested what direction you went after getting your BSc in physics: business, research, education, something else?
Title: Re: Theoretical FTL
Post by: Cherokee43v6 on 12/05/2011 08:37 pm
Even this business major knows that gravity is considered to be a function of mass, not of charge.

There is no such thing (so far) as 'antimass'.
Title: Re: Theoretical FTL
Post by: colbourne on 12/05/2011 09:18 pm
I am just saying that we have no knowledge of how gravity affects anti-matter and there is thus a possibility that it will act differently to normal matter with gravity. If so it might explain the discrepancy between the amount of matter versus anti-matter in the observed universe (It has simply accelerated away from us and could explain the accelerating expansion of the universe, removing the requirement for dark matter).

I designed visual systems for Singer flight simulators after getting my BSc.
Title: Re: Theoretical FTL
Post by: Tass on 12/06/2011 08:18 am
Even this business major knows that gravity is considered to be a function of mass, not of charge.

That is hardly relevant. Antiparticles are not just charge reversed. They are apparently everything-but-mass reversed. Some people speculate that they may be mass reversed as well. You are right there is probably no anti-mass. It is very unlikely, but the premise of this thread is "what if". 
Title: Re: Theoretical FTL
Post by: KelvinZero on 12/06/2011 08:37 am
Even this business major knows that gravity is considered to be a function of mass, not of charge.

That is hardly relevant. Antiparticles are not just charge reversed. They are apparently everything-but-mass reversed. Some people speculate that they may be mass reversed as well. You are right there is probably no anti-mass. It is very unlikely, but the premise of this thread is "what if". 

Also many physicists are dedicating themselves to somehow unifying the concepts of gravity and charge. Im probably misusing the terms a bit but that is essentially what the search for the Grand Unified Theory is all about.
http://en.wikipedia.org/wiki/Grand_Unified_Theory
Title: Re: Theoretical FTL
Post by: JohnFornaro on 12/06/2011 12:53 pm
Quote from: Colbourne
I think you better let CERN and other research establishments know, as they are spending a fortune to confirm the properties of anti-matter. As far as I know the exact properties have not been confirmed yet.

It is true that all the properties of anti-m have not yet been discovered.  It is your first assumption, made without specific knowledge of the properties, that anti-m would also have anti-g properties.  Since some properties of anti-m are known, it is currently accepted that there is no such thing.  Like Kelvin said; "Very strongly expected to have the usual gravity though not yet experimentally confirmed".

But since, as Tass observes, "the premise of this thread is 'what if'", then one is free, more or less, to talk up the fantastic possibilities of FTL.  It is very easy to do.  Is that all you wish to do?
Title: Re: Theoretical FTL
Post by: Tass on 12/06/2011 03:46 pm
I will just note that anti-gravity would still not enable faster-than-light.

Negative gravitational and inertial mass would, however, allow you to accelerate without bound.
Title: Re: Theoretical FTL
Post by: scienceguy on 12/06/2011 05:33 pm
Wouldn't negative mass be both antigravity and negative inertia? I'm thinking of papers by Bondi (1957) and Forward (1990).

Bondi, H. (1957) Negative mass in general relativity. Reviews of Modern Physics 29(3):423-428

Forward, R. L. (1990) Negative matter propulsion. Journal of Propulsion and Power 6(1):28-37
Title: Re: Theoretical FTL
Post by: scienceguy on 12/06/2011 05:46 pm
Oops! I realize the authors in those papers distinguish between negative inertial mass and negative gravitational mass.
Title: Re: Theoretical FTL
Post by: RanulfC on 12/06/2011 06:07 pm
I recall a lot of "speculative-fiction" about anti-matter when it was first discovered/postulated, much of it dealing with the concepts and ideas of what-and-how "contra-terrene" (Cee-Tee was the "popular" name at the time) matter would "interact" with the "standard" universe.

Nothing in the theoretical or observered work indicates "anti-gravity" properties and other than the "mutual-anihilation" aspect antimatter was supposed to simply be a "negativily" charged analog to normal matter. However one rather "glaring" early assumption seems to be "missing" from observed anti-matter phenomon; we don't find mucn (if any) actual "anti-matter" in the universe around us.

The theory (and assumptions) have always been that IF antimatter exists in nature then it SHOULD behave similarly to normal matter in that it SHOULD aggrate together into particles, molecules, and solid representations of "anti-matter"... So the question is where IS the "anti-asteroids," "anti-planets," and "anti-suns" one would expect to find? (Of course one then needs to delve into the exact details of "how" you'd tell the difference barring the catastrophic method of verification :)

Now I'm pretty much expecting my memory is wrong but I seem to recall that a question that has been raised during work on the various things like the "Mach-Effect" and other "alternative" theories on the nature of the universe that struck me was; "We have always pretty much "assumed" that Mass generates gravity, the more mass the higher the gravity. An interesting question though is this: What if mass does NOT 'generate' gravity as we understand it but it is simply that normal matter "concentrates" gravity?"

This leads to the thought that the lack of observed mass' of "anti-iron" etc, might be because anti-matter since it isn't "normal" matter might actually have the opposite effect? Note that this is NOT "anti-gravity" though it's possible it could produce a somewhat similar effect given enough of it, the problem would be since normal matter SEEMS to acumulate due to an increasing mass/increasing gravity in-falling effect, anti-matter would NOT act the same and in fact would be almost impossible for it to accumulate in the "normal" manner.

Thoughts?
(Ok, OTHER than the ones about me being "Crazy" and a "Freak-a-zoid-Nut-Case" Lets concentrate on the "concept" and not my already diagnosed mental issues :) )

Randy
Title: Re: Theoretical FTL
Post by: alexw on 12/07/2011 03:04 am
I recall a lot of "speculative-fiction" about anti-matter when it was first discovered/postulated, much of it dealing with the concepts and ideas of what-and-how "contra-terrene" ...
     You do? That was 1928-1932. How much speculative fiction was written at the time, and were you born circa 1910?
    -Alex
Title: Re: Theoretical FTL
Post by: RanulfC on 12/07/2011 01:04 pm
I recall a lot of "speculative-fiction" about anti-matter when it was first discovered/postulated, much of it dealing with the concepts and ideas of what-and-how "contra-terrene" ...
     You do? That was 1928-1932. How much speculative fiction was written at the time, and were you born circa 1910?
    -Alex
Why yes "I do" it's called a "small-town-library" and a good majority of the "Science Fiction" section dated from that period yes :)

But the majority of the stuff I'm thinking of was written around the mid-to-late 40s and beyond.
http://beamjockey.livejournal.com/73304.html

SeeTee-CT-ContraTerrene Matter :)

When was I born? ...
"I was born in an small village in Macidonia and fell in battle, but did not die... I have been called many names in my life, Lazerus, Mathusala and a thousand more you do not know...." ::::grin:::

Quote from: JohnFornaro
Randy.  Here.  Take two of these and call me in the morning....
Oh NO you don't! You folks are NOT getting me with that one again! Last time I woke up under the "care" of large hairy guy named "Phil" and one of those formal coats where the sleeves tie in the back! You are NOT fooling me again! ;)

Randy
Title: Re: Theoretical FTL
Post by: JohnFornaro on 12/07/2011 02:01 pm
Dang.  Foiled again!
Title: Re: Theoretical FTL
Post by: colbourne on 12/21/2016 02:55 am
http://www.cbc.ca/news/technology/scientists-measure-antimatter-atom-for-1st-time-1.3903268

"The next phase of the group's experiment, ALPHA-G, will study gravitational forces on antihydrogen, and is expected to take place at the end of 2017. Specifically, the researchers want to see if antihydrogen will "fall up," suggesting that the two repel each other. If it does — which Menary is somewhat skeptical about — it could mean that half the galaxies we see are antimatter galaxies.

The physicists hope that eventually their experiments will provide scientists with yet another piece in the puzzle as to how our universe came to be."

So we should find out whether this will work within a couple of years. As a means of transport I think it is unlikely to ever be of use but it may have potential for use in communications.
Title: Re: Theoretical FTL
Post by: Stormbringer on 12/21/2016 03:01 am
there is more articles today related to the above article topic. They have measured the emission spectra for the s1 to p something or the other transition of anti-hydrogen. it is pretty close to the measured spectra for regular hydrogen with the remainder probably down to measurement precision.
Title: Re: Theoretical FTL
Post by: colbourne on 02/02/2017 04:12 am
http://newatlas.com/dipole-repeller-void-pushing-milky-way/47648/?utm_source=Gizmag+Subscribers&utm_campaign=3a3d9a1e90-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-3a3d9a1e90-90223594


Enormous extragalactic void is pushing on the Milky Way. Astronomers have now discovered a huge extragalactic void, called the Dipole Repeller, that's pushing us away.
Title: Re: Theoretical FTL
Post by: aceshigh on 03/23/2017 08:16 pm
https://www.youtube.com/watch?v=HUMGc8hEkpc
Title: Re: Theoretical FTL
Post by: dustinthewind on 03/24/2017 12:30 am
http://newatlas.com/dipole-repeller-void-pushing-milky-way/47648/?utm_source=Gizmag+Subscribers&utm_campaign=3a3d9a1e90-UA-2235360-4&utm_medium=email&utm_term=0_65b67362bd-3a3d9a1e90-90223594


Enormous extragalactic void is pushing on the Milky Way. Astronomers have now discovered a huge extragalactic void, called the Dipole Repeller, that's pushing us away.

I think it might be possible that the dark voids are another universe where gravitational objects what pull in their space expel it out into our universe.  We experience the gravity of this other universe as negative gravity.  This universe may have an excess of anti-matter rather than matter.  Anti-matter possibly being negative energy matter but its time runs backwards.  Negative energy matter already behaves as if its time arrow is backward so reversing time for it makes it behave as if its time arrow runs forward. 

Gravity appears to contract space into it pulling in whats around it.  Think of it as a Lorentz contraction in an accelerating frame.  So if space flows in where does it go?  Into the other universe maybe.  How does their universe perceive our gravity.  As repulsive possibly or as space flowing out which is repulsive to the matter in the other universe as well.  So they perceive us as dark matter and maybe we perceive them as dark matter.  That is they expel space from their dimension into ours and also appear repulsive.  Dipole repulsers.  The only thing different in this universe is because of the dominance of anti-matter time generally runs in reverse but its not a problem because all the matter is negative energy matter so it just behaves like normal matter in reverse time. 

Anyways just some speculation on my part.  Thought you all might find it interesting. 
Title: Re: Theoretical FTL
Post by: Spaniard on 04/05/2017 07:45 am
Assuming that antimatter generates antigravity, I think that there is some bad concepts around it. It's not that antimatter was repealed by gravity. It was that antimatter would generate a negative space curvature.
So, the answers to your questions will be the same that the standard model.

It will change other things. For example, photons shouldn't generate space curvature/gravity (never tested as you need a enormous quantity of photons in a small place to "weight" something).
Antimatter would be generate negative curvature, so it will never form planets or stars. Most antimatter would be in intergalactic space. It would generate negative pressure on galaxies.

Title: Re: Theoretical FTL
Post by: dustinthewind on 04/10/2017 01:07 am
Assuming that antimatter generates antigravity, I think that there is some bad concepts around it. It's not that antimatter was repealed by gravity. It was that antimatter would generate a negative space curvature.
So, the answers to your questions will be the same that the standard model.

It will change other things. For example, photons shouldn't generate space curvature/gravity (never tested as you need a enormous quantity of photons in a small place to "weight" something).
Antimatter would be generate negative curvature, so it will never form planets or stars. Most antimatter would be in intergalactic space. It would generate negative pressure on galaxies.

No, it is believed anti-matter generates normal gravity as far as I know.  It also takes positive energy to make anti-matter.  What I was speculating is that anti-matter is negative energy in reverse time which makes it behave like normal matter but when it comes into contact with normal matter the time and then energy cancel out inducing a wave in the vacuum which carries the effective mass elsewhere.  This being why when an electron and positron annihilate their mass isn't lost.  It is carried off in the light which is the result of the annihilation. 

The negative gravity speculation was just that, but speculating that dark matter is actually matter in a parallel dimension much like our own.  In this other dimension time runs backward and most matter that exist is anti-matter.  My speculation tries to answer the question - "where did all the anti-matter go?"  You see when we create matter - particles we always create equal amounts of matter+anti-matter.  So where did all this matter come from and where is all the anti-matter.  My speculation indicates maybe it is in a parallel dimension where time is running in reverse and it is considered dark matter to our dimension where it expels space into our dimension. 
Title: Re: Theoretical FTL
Post by: MrHollifield on 05/04/2017 07:55 pm
I think it might be possible that the dark voids are another universe where gravitational objects what pull in their space expel it out into our universe.

...

Gravity appears to contract space into it pulling in whats around it.

AIUI, gravity is our experience of spacetime contracted by the creation of matter from energy. When the energy in that matter is released, say during fusion in a star, spacetime expands outward, reducing the gravitation of the star. In the dark voids, there are no stars releasing energy, so there could be no expansion generated in the voids. More likely, the spacetime expanding out of the luminous regions with many stars is pushing against these voids to expand the universe.
Title: Re: Theoretical FTL
Post by: Bob012345 on 05/08/2017 02:30 pm
Assuming that antimatter generates antigravity, I think that there is some bad concepts around it. It's not that antimatter was repealed by gravity. It was that antimatter would generate a negative space curvature.
So, the answers to your questions will be the same that the standard model.

It will change other things. For example, photons shouldn't generate space curvature/gravity (never tested as you need a enormous quantity of photons in a small place to "weight" something).
Antimatter would be generate negative curvature, so it will never form planets or stars. Most antimatter would be in intergalactic space. It would generate negative pressure on galaxies.

No, it is believed anti-matter generates normal gravity as far as I know.  It also takes positive energy to make anti-matter.  What I was speculating is that anti-matter is negative energy in reverse time which makes it behave like normal matter but when it comes into contact with normal matter the time and then energy cancel out inducing a wave in the vacuum which carries the effective mass elsewhere.  This being why when an electron and positron annihilate their mass isn't lost.  It is carried off in the light which is the result of the annihilation. 

The negative gravity speculation was just that, but speculating that dark matter is actually matter in a parallel dimension much like our own.  In this other dimension time runs backward and most matter that exist is anti-matter.  My speculation tries to answer the question - "where did all the anti-matter go?"  You see when we create matter - particles we always create equal amounts of matter+anti-matter.  So where did all this matter come from and where is all the anti-matter.  My speculation indicates maybe it is in a parallel dimension where time is running in reverse and it is considered dark matter to our dimension where it expels space into our dimension.


Some think that electrons actually are not affected by gravity. The paper below measures gravitational force as 0.09mg. The authors though interpret that there is an induced electromagnetic force in the apparatus that counters gravity but others disagree with that interpretation.

https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.19.1049

Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/12/2017 10:31 pm
The negative gravity speculation was just that, but speculating that dark matter is actually matter in a parallel dimension much like our own.  In this other dimension time runs backward and most matter that exist is anti-matter.  My speculation tries to answer the question - "where did all the anti-matter go?"  You see when we create matter - particles we always create equal amounts of matter+anti-matter.  So where did all this matter come from and where is all the anti-matter.  My speculation indicates maybe it is in a parallel dimension where time is running in reverse and it is considered dark matter to our dimension where it expels space into our dimension.

Good catch! In the next posts I will detail this idea of primordial antimatter lacking, parallel universes and negative gravity in cosmology. A cosmological model exists, exactly behaving how you said, and has been published though peer review with recent (2014-2015) progress.

In a first post I will talk of the basis of negative mass in group theory, general relativity and quantum field theory, and the problems it brings in the current formulations of those theories.

In a second post I will talk of the application of such negative mass to a cosmological model based on general relativity but without such paradox

In a third post I will talk about the apparent FTL travel such a cosmological model allows.

With links to PDF files of all references to back up the presentation.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/12/2017 10:40 pm
The problem of negative mass in cosmology

Physics is like a cake:

(http://ayuba.fr/images/physics_cake.png)

1st floor: observations, experiments
2nd floor: differential equations
3rd floor: geometry
4th floor: group theory

Groups rule geometry, which fathers differential equations. With differential equations we build things, which then are used to explain or predict what we call physical facts.

Dynamical groups show there are not only two types of matters (matter and antimatter) but 4 types, according to the direction of their arrow of time:

- positive mass particles (the matter we are made of)
- positive mass antiparticles, C-symmetry of our matter: this is the antimatter after Dirac
- negative mass particles, CPT-symmetry of our matter
- negative mass antiparticles, C×CPT = PT-symmetry of our matter: this is the antimatter conjectured by Feynman as a "(parity) mirrored particle going backwards in time"

The antimatter that is produced in lab will "fall down" like normal matter because it is made of antiparticles, i.e. positive mass matter after a charge conjugation transformation.

The baryon asymmetry of the universe, due to CP violation that occurred during baryogenesis, i.e. the lack of primordial antimatter in the universe, was addressed by Andrei Sakharov in 1967. Sakharov realized a complete CPT symmetry between two spacetimes with two opposite arrows of time, that originated from the same Big Bang singularity and where opposite CP violations occurred. [1]

Julian Barbour et al. (with gravity) and Sean Carroll et al. (with thermodynamics) have shown the same thing with simulations, that two universes with an opposite arrow of time would indeed originate from the same Big Bang singularity, the direction of the time arrow being identified with entropy. [2] [3]

Dynamical groups (coadjoint action of the Poincaré group on its moment map) proves that reversing the arrow of time of a particle (T symmetry) is the same thing as reversing its energy sign, and its mass if it owns one, due to Einstein's mass-energy equivalence principle E=mc2. See [4]

The "antichron" components of the Poincaré group, describing negative energy particles, is not used in physics, mainly because:
- General relativity does not seriously consider the reality of negative mass particles, mostly due to the preposterous runaway paradox. [5] [6]
- Quantum Field Theory prevents any negative energy, on the axiom that no state could exist with an energy less than the vacuum state, so that Weinberg even wrote "we are forced to conclude that T is antilinear and antiunitary". [7]

But this axiom was stated before the discovery of the accelerating expansion of the universe. [8] We are even now in a "dark-energy-dominated era". Since such an acceleration implies the action of a negative pressure, and since a pressure is a density of energy (per unit of volume), this question should be reconsidered. The Casimir effect also shows some negative energy state.

So if the T operator is considered as unitary and linear, then QFT enables the existence of negative energy states, time inversion being synonymous of energy inversion. This is already the case with dynamical group theory, build with real coefficients. [4]

What about the runaway paradox? It arises when both positive energy and negative energy particles are considered to be real in general relativity, and they meet each others. When such particles of opposite signs evolve along the same set of geodesics, produced by a metric, solution of Einstein's field equations, then the Newtonian approximation gives a weird runaway motion: the positive mass particle accelerates away, repelled by the negative one; but the negative mass particle, attracted by the positive mass, chases it.

(http://ayuba.fr/images/runaway_motion.png)


The couple then uniformly accelerate, while the energy is conserved.

William Bonnor wrote, about this runaway motion: [6]

Quote from: William Bonnor
I regard the runaway (or self-accelerating) motion […] so preposterous that I prefer to rule it out by supposing that inertial mass is all positive or all negative.

So, are negative masses discarded from general relativity and cosmology forever?





References

[1] Sakharov, A. D. (1967). "Violation of CP invariance, C asymmetry, and baryon asymmetry of the universe" (http://www.jetpletters.ac.ru/ps/1643/article_25089.pdf). JETP Letters. 5 (1): 24–26.

[2] 2017: Physicists Propose a Mirror Universe Where Time Moves in the Opposite Direction (http://bigthink.com/philip-perry/physicists-propose-a-mirror-universe-where-time-moves-in-the-opposite-direction)

[3] Barbour, J.; Koslowski, T.; Mercati, F. (2014). "Identification of a Gravitational Arrow of Time" (https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.113.181101). Physical Review Letters. 113, 181101. doi:10.1103/PhysRevLett.113.181101.

[4] Souriau, J.-M. (1997). "A mechanistic description of elementary particles: Inversions of space and time" (http://ayuba.fr/pdf/souriau1997-chapter14.pdf). Structure of Dynamical Systems. Boston: Birkhäuser. ISBN 978-1-4612-6692-1. doi:10.1007/978-1-4612-0281-3_14.

[5] Bondi, H. (1957). "Negative Mass in General Relativity" (http://ayuba.fr/pdf/bondi1957.pdf). Reviews of Modern Physics. 29 (3): 423–428. doi:10.1103/RevModPhys.29.423.

[6] Bonnor, W. B. (1989). "Negative mass in general relativity" (http://ayuba.fr/pdf/bonnor1989.pdf). General Relativity and Gravitation. 21 (11): 1143–1157. doi:10.1007/BF00763458.

[7] Weinberg, S. (2005): "Space Inversion and Time Reversal" (http://ayuba.fr/pdf/weinberg_negative_energy.pdf) p.76 in The Quantum Theory of Fields, Volume 1: Foundations, Cambridge University Press. ISBN 978-0521670531.

[8] The Nobel prize in physics 2011 (https://www.nobelprize.org/nobel_prizes/physics/laureates/2011/#)
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/12/2017 10:51 pm
A cosmological model with negative mass and no paradox

Things go very differently if the universe is described not by one set of geodesics, but two sets, each sector being the place where each species (positive or negative masses) belong. Those two sets of geodesics are described by two metrics g+ (positive sector) and g- (negative sector) solutions of two coupled field equations:

(https://wikimedia.org/api/rest_v1/media/math/render/svg/90bc8dc57c7c8652aef30c59774c74b955790040)

(https://wikimedia.org/api/rest_v1/media/math/render/svg/878dc52132335f54466704059ae5d0c6c2e17186)

The Newtonian approximation this time provides the following laws of motion:

- particles whose masses are of the same sign mutually attract according to Newton's law
  (negative mass attracts negative mass and positive mass attracts positive mass)

- particles of opposite masses mutually repel according to "anti" Newton's law
  (negative mass and positive mass repel each other)

The runaway paradox disappears. [9]

This is the same as the previous twin, shadow or mirror universes of Sakharov, Salam/Schwarz/Green, Foot/Volkas, Hossenfelder, Barbour/Koslowski/Mercati, Carroll/Chen/Guth… except for the first time integrating Souriau's idea that time reversal generates energy and mass inversion, hence involving a gravitational interaction between particles populating the two opposite sectors.

By the way, thanks to the introduction of negative mass in cosmology, the Janus Cosmological Model (JCM) naturally explains many observational facts, such as :
- the homogeneity of the primitive universe
- the small inhomogeneities in the CMB
- the lack of primordial antimatter
- the primordial dwarf galaxies and the age of the universe
- the accelerating expansion of the universe
- the galaxy rotation curves
- the very large structure
- the dipole repeller
- the various voids and supervoids

Adding negative energy in cosmology is a big paradigm shift. The addition of a second metric with two coupled field equations could be seen as a lack of parsimony according to Occam's razor, but let's consider the following:

Describing the universe, adding more than one metric to one M4 manifold may seem difficult to some cosmologists, but not at all for mathematicians and geometers. General relativity is geometric in nature.

JCM does not have to rely on had hoc parameters to fit with observational data, unlike the standard ΛCDM (lambda-cold dark matter) "concordance" model and its… six free parameters.

JCM does not need cosmic inflation and inflatons.

JCM does not need to rely on some dark energy to explain the expansion of the universe, unlike the ΛCDM model. The negative energy density of the particles populating the other sector gives and antigravitational effect globally pushing and accelerating the expansion of our positive sector forward.

JCM does not have to rely on invisible dark matter of unknown nature, unlike the ΛCDM model. The same effects are produced by the particles populating the negative sector, of known nature: those particles are the same as ours but with a negative mass, i.e. negative mass baryons and anti-baryons made of negative mass quarks and antiquarks.

JCM does not modifies Newton's law with distance, unlike MOND and subsequent emergent gravity theories.

JCM is plain-vanilla GR, unlike MiHsC for example, which relies on quantum Unruh waves and a hypothesis about a cosmic-scale Casimir effect.




About the apparent absence of the primordial antimatter and the true nature of the negative mass in the negative sector

(http://ayuba.fr/images/baryon_asymmetry.png)

BARYON ASYMMETRY OF THE UNIVERSE AFTER SAKHAROV
LEFT: positive energy species | RIGHT: negative energy species
A: Primitive universe, 4 components: positive energy quarks and antiquarks; and negative energy quarks and antiquarks.
B: They combine to give more positive mass matter (red) than positive mass antimatter (blue) due to CP violation in the 1st sector; and more negative mass antimatter (purple) than negative mass matter (green) due to opposite CP violation in the 2nd sector.
C: Positive energy quarks and antiquarks stop combining and positive mass matter and antimatter annihilate each other in the first sector. Same thing in the 2nd sector for negative mass matter and antimatter.
D: In the 1st sector, positive energy photons remain from positive mass matter-antimatter annihilation, leaving a remnant of positive mass matter and positive energy antiquarks. In the 2nd sector, negative energy photons remain from negative mass matter-antimatter annihilation, leaving a remnant of negative mass antimatter and negative mass quarks.

This answers the question "where did the primordial antimatter go?"

The primordial negative mass antimatter (PT symmetry of our positive mass matter) is still "there" but being invisible, as it emits negative energy photons our telescopes cannot see, since such negative energy photons follow the null-geodesics of the metric g(-) of the negative sector.

But the density of this negative mass primordial antimatter completely leads the (accelerating) cosmic expansion process, as well as the formation and confinement of galaxies and galaxy clusters in our positive energy sector.




Those two posts about the Janus cosmological model has put the basis to talk about the possibility of FTL interstellar travel.




References

[9] Petit, J.-P.; d'Agostini, G. (2014). "Negative mass hypothesis in cosmology and the nature of dark energy" (http://ayuba.fr/pdf/janus_runaway.pdf). Astrophysics and Space Science. 354. doi:10.1007/s10509-014-2106-5.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/12/2017 10:58 pm
Apparent FTL interstellar travel

Finally, the model allows –apparent– FTL interstellar travel with limited time and energy, through a mass-inversion process. [10]

About how a spaceship could make a technological hyperspace transfer, I already briefly talked about such possibility in a post in the EmDrive thread 9:
https://forum.nasaspaceflight.com/index.php?topic=41732.msg1632005#msg1632005

After mass inversion of its constituting particles, the spaceship would follow the geodesics of the metric g(-) in the negative sector. Yet the negative sector has a speed of light c(-) higher and distances shorter than in the positive sector.

Indeed with two metrics instead of one, between two distinct points there are two different distances. It depends what metric you use to measure length:

(http://ayuba.fr/images/metrics.png)
                                            A 2D surface with two different scales


Due to such trick with spacetimes, distances to cover are shorter, while the limit of the speed of light is now higher. But we are still talking about great distances. How to accelerate? What kind of engine our spaceship could use in the negative sector?


The Gulliver effect

Icing on the cake: perhaps the craft would not even have to use an engine for such a trip. It would appear in the negative sector at a relativistic speed v where
c(+) < v < c(-) [11] ← See part 4: "Back to the Problem of Interstellar Travel" page 11–14 of this reference for the part about FTL travel.

The size of a particle, its spatial extension, can be represented by the Compton wavelength:
(http://ayuba.fr/images/compton_wavelength.png)
Compton wavelength associated to a mass, for example a proton.

But a positive particle, after a hyperspace transfer in the negative sector (which is a "smaller space" due to the difference in the two space scale factors a(−) < a(+)) will appear larger than similar negative species around:
(http://ayuba.fr/images/compton_gulliver.png)
                                "Gulliver effect"

This variation in size is the sign of some energy loss. Hyperspace transfer will maybe one day be mathematically modeled. More precisely, quantum physics should be involved besides general relativity. If we look at the Einstein field equationns (EFE) the divergenceless hypothesis is equivalent to the conservation of energy-matter. This conservation of energy can also be "read" in the EFE in the form of

S = c T

where S is the metric (geometric) tensor, c the speed of light, and T the stress-energy tensor.

Now, if we look at two coupled field equations:

S = c ( T - T* )    and    S* = c ( T* - T )

the divergenceless hypothesis corresponds to the conservation of energy-matter over the two sectors, even during and after hyperspace transfer. Then we could derive some idea from this concept of energy-matter conservation. How to transfer a particle towards a "smaller" sector (whose gauge factor R is smaller) preserving its energy-matter?

This is possible if the wavelength is shortened thanks to Lorentz contraction, i.e. if the particle materializes in the negative sector at a relativistic velocity.

How to give all particles of the craft (and its passengers) the same velocity vector? There is no known answer to this question. Maybe aligning the spins of all particles before the mass inversion process.

Otherwise, if particles of the ship and its passengers all appear in the negative fold at a relativistic velocity but with random velocity vector orientations, I let you imagine the trip will finish way sooner than expected…

After mass inversion, a craft would go so fast that it could not slow down. But, arriving at its destination, a new mass inversion towards the positive sector would give it again its former slower (non relativistic) kinetic parameters, without deceleration.

If this idea is valid, a spaceship could jump into the negative sector and appear there at a relativistic velocity, without any acceleration. The journey duration would not be zero, but possibly greatly shortened. Perhaps some stars and their planetary systems, 10 or 100 lightyears away, could be reached in less than a year.




References

[10] Petit, J.-P.; d'Agostini, G. (2015). "Cancellation of the singularity of the Schwarzschild solution with natural mass inversion process" (http://ayuba.fr/pdf/janus_schwarzschild.pdf). Modern Physics Letters A. 30 (9): 1550051. doi:10.1142/S0217732315500510.

[11] Petit, J.-P.; d'Agostini, G. (2014). "Cosmological bimetric model with interacting positive and negative masses and two different speeds of light, in agreement with the observed acceleration of the Universe" (http://ayuba.fr/pdf/janus_vsl.pdf). Modern Physics Letters A. 29 (34): 1450182. doi:10.1142/S021773231450182X.

[12] Petit, J.-P.; d'Agostini, G. (2015). "Lagrangian derivation of the two coupled field equations in the Janus cosmological model" (http://ayuba.fr/pdf/janus_lagrangian.pdf). Astrophysics and Space Science. 357 (67). doi:10.1007/s10509-015-2250-6.
Title: Re: Theoretical FTL
Post by: dustinthewind on 07/13/2017 12:32 am
...

Thanks flux.  I had no idea they already had a working model of such a system. 
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/13/2017 01:28 am
...

Thanks flux.  I had no idea they already had a working model of such a system.

The first basis of the model goes back as soon as 1977 (Newtonian dynamics at that time) so it is has been an ongoing work for forty years… Few papers published, but good progress has been made recently with group theory.

The author is a French physicist, that's why the model is never advertised in the US media, contrary to much weaker works, for example the thermodynamic T-symmetry model of Sean Carroll and Allan Guth that is not even published through peer review. Or the mirror universes with opposite arrow of time of Julian Barbour et al. which consist of a computer simulation of only 1,000 mass-points in two populations… that does not even interact! Yet the media publish attractive cover magazines with beautiful CGI pictures and clickbait titles online about such interesting but somewhat limited and crude ideas, labelling them as "a new revolution" every few couples of years. Sigh…

Petit seems also blacklisted from the French community of astrophysicists and cosmologists (he cannot give any seminar in any French scientific institution) and has also been blacklisted by the ArXiv exactly like Mike McCulloch with MiHsC, even for paper published in peer reviewed academic, respectable and non predatory access journals. Petit's and McCulloch's work are not the same at all, but they share an attempt to challenge the mainstream concordance model in cosmology, which seems to trigger almost hate amongst the upholders of the standard model.

Especially, the interstellar travel schema proposed by the Janus model has stunning underlying possibilities, far away from the current trendy impulse propellantless engines, distortion warp drives and wormholes proposals.

Imagine Dr Petit invited to a propellantless propulsion workshop in the USA. What will he ask the attending engineers and physicists there? To learn topology, group theory and symplectic geometry in order to understand his model? And to let their research on advanced propulsion go, as there is no need for any reactionless drive when one can leverage the potential energy between the two conjugated metrics for hyperspace travel without the need for an "engine"?

https://youtu.be/wmYPxFcIMLo
Title: Re: Theoretical FTL
Post by: gospacex on 07/13/2017 11:19 am
But this axiom was stated before the discovery of the accelerating expansion of the universe. [8] We are even now in a "dark-energy-dominated era". Since such an acceleration implies the action of a negative pressure, and since a pressure is a density of energy (per unit of volume), this question should be reconsidered.

This is wrong. Pressure is not a density of energy. Energy is the T00 component of stress-energy tensor; pressure is components T11, T22 and T33. Accelerating expansion must have _positive_ energy density of vacuum (then it has negative pressure).
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/13/2017 11:40 am
But this axiom was stated before the discovery of the accelerating expansion of the universe. [8] We are even now in a "dark-energy-dominated era". Since such an acceleration implies the action of a negative pressure, and since a pressure is a density of energy (per unit of volume), this question should be reconsidered.

This is wrong. Pressure is not a density of energy. Energy is the T00 component of stress-energy tensor; pressure is components T11, T22 and T33. Accelerating expansion must have _positive_ energy density of vacuum (then it has negative pressure).

I just usde the international System of Units (SI). We are in the habit of calculating a pressure in pascals, which are newtons per squared meter. But this is also similar to joules per cubic meter, a "volumetric" (i.e. per unit volume) energy density.

A pressure can be expressed as a force per unit surface, or an energy per unit volume, i.e. an energy density. They share the same physical units.
Title: Re: Theoretical FTL
Post by: gospacex on 07/13/2017 11:51 am
But this axiom was stated before the discovery of the accelerating expansion of the universe. [8] We are even now in a "dark-energy-dominated era". Since such an acceleration implies the action of a negative pressure, and since a pressure is a density of energy (per unit of volume), this question should be reconsidered.

This is wrong. Pressure is not a density of energy. Energy is the T00 component of stress-energy tensor; pressure is components T11, T22 and T33. Accelerating expansion must have _positive_ energy density of vacuum (then it has negative pressure).

I just usde the international System of Units (SI). We are in the habit of calculating a pressure in pascals, which are newtons per squared meter. But this is also similar to joules per cubic meter, a "volumetric" (i.e. per unit volume) energy density.

A pressure can be expressed as a force per unit surface, or an energy per unit volume, i.e. an energy density. They share the same physical units.

Of course all components of stress-energy tensor have the same units. This is not the issue.

The issue is that pressure is a flux of *momentum* through *spatial* coordinates x,y,z. Whereas energy is a flux through *time* coordinate. Different things. Negative pressure does not cause negative energy.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/14/2017 12:30 am
Of course all components of stress-energy tensor have the same units. This is not the issue.

The issue is that pressure is a flux of *momentum* through *spatial* coordinates x,y,z. Whereas energy is a flux through *time* coordinate. Different things.

You are referring to the stress-energy tensor:

(https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/StressEnergyTensor_contravariant.svg/500px-StressEnergyTensor_contravariant.svg.png)

We can express the energy density in the stress energy-tensor as ρc2

What is it? n is the "density number" (number of particles per cubic meter) multiplied by mc2, an energy. Thus this is an energy per unit volume, in joules (or newton-meter) per cubic meter.

The other terms of the stress-energy tensor are three times the pressure and they have exactly the same dimension.

So p is also expressed in joules per cubic meter: an energy density. All the terms of the tensor expressed here share the same dimension.

If this is not a demonstration that p is also an energy per unit volume?!

As a whole, the stress-energy tensor Tµv is expressed in J/m3


                       Force   ×   Length             Energy
Pressure  =   –––––––     ––––––––   =   ––––––––  =  Energy density
                       Area    ×   Length             Volume


and with respect to time, as the work done is basically Force × Length, it is a change in Energy.

Then:

dE = F dx = P dV

One must consider how the physics behaves in various aspects of reality.

Pressure and energy density are the same thing. In physics, the choice of joules per cubic meter even comes first, with respect to the more usual daily form in newtons per square meter.

- Pneumatic pressure as in a cylinder with a compressing piston is the work done over a volume of gas.

- Pressure as strain σ in a material expresses the elastic deformation in the volume of the material.

- Magnetic pressure (https://en.wikipedia.org/wiki/Magnetic_pressure) is also an energy density associated with a magnetic field.

- Coulomb pressure and electrostatic pressure are stresses defined in terms of energy density, as already detailed by Dr Rodal on theses NSF forums (https://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577).

- Radiation pressure of electromagnetic fields on a conductive surface has been similarly detailed by Rodal (https://forum.nasaspaceflight.com/index.php?topic=39214.msg1532199#msg1532199), as the cyclic time-average of the energy density.

etc.

Pressure is an energy density and vice versa, in all aspects of physics.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/14/2017 01:21 am
Negative pressure does not cause negative energy.

It is true dark energy has a positive energy density associated to a negative pressure in the concordance model.

Conversely, does negative energy have to cause positive pressure?

As for negative energy density states, an example is the Casimir effect. In between the attracted plates there is indeed a negative pressure. But it has been shown that the negative energy density can also be either positive or negative in that region of limited spatial extension, with respect to the ground state energy of the vacuum. [13]

So both a negative pressure and a negative energy density at the same time…

In a more general form the pressure components in the stress-energy tensor can be written in terms of mass density:

p = α ρ

with α > -1

α being a scalar quantity. [14]

This opens the possibility of negative pressures, but this has not to be the case for any scenarii, including positive or negative energies.

Except the particular case of the Casimir effect, the physical behavior of negative energy states is rather unknown, so no conclusions, based solely on the extrapolation after effects due to positive energy, can be made certain.

Especially as the two coupled field equations of the Janus cosmological model generate a different Newtonian approximation for the gravitational interaction of positive vs negative mass matter, when compared to the Newtonian approximation for those two species from a single metric in general relativity.

In the model, when the negative element dominates, both ρ and p are negative. Because the detected pressure in this case is not a "pressure of the quantum vacuum" but the effect of the invisible presence of negative matter of mass density ρ located in the negative sector, and acting on our positive sector.

As for the three minus signs in the stress-energy tensor, they come from the metric tensor because the metric signature is written as time-positive ( + - - - )

Not intuitive at all.



References

[13] Sopova, V.; Ford, L. H. (2002). "The Energy Density in the Casimir Effect". Physical Review D. 66: 045026. arXiv:quant-ph/0204125 (https://arxiv.org/abs/quant-ph/0204125). doi:10.1103/PhysRevD.66.045026.

[14] Stress-energy tensor: negative pressure revisited (http://www.physicspages.com/2014/05/31/stress-energy-tensor-negative-pressure-revisited/), from Moore, T. A. (2013). "A General Relativity Workbook", Chapter 20 "The Stress-Energy Tensor". University Science Books. ISBN 978-1-891389-82-5.
Title: Re: Theoretical FTL
Post by: dustinthewind on 07/14/2017 02:16 am
Negative pressure does not cause negative energy.

It is true dark energy has a positive energy density associated to a negative pressure in the concordance model.

Conversely, does negative energy always have to cause positive pressure?

As for negative energy density states, an example is the Casimir effect. In between the attracted plates there is indeed a negative pressure. But it has been shown that the negative energy density can also be either positive or negative in that region of limited spatial extension, with respect to the ground state energy of the vacuum. [13]

So both a negative pressure and a negative energy density at the same time…

In a more general form the pressure components in the stress-energy tensor can be written in terms of mass density:

p = α ρ

with α > -1

α being a scalar quantity. [14]

This opens the possibility of negative pressures, but this has not to be the case for any scenarii, including positive or negative energies.

Except the particular case of the Casimir effect, the physical behavior of negative energy states is still unknown, so no conclusions, based solely on the extrapolation after effects due to positive energy, can be made certain. Especially as the two coupled field equations of the Janus cosmological model generate a different Newtonian approximation for the gravitational interaction of positive vs negative mass matter, when compared to the Newtonian approximation for those two species from a single metric in general relativity.



References

[13] Sopova, V.; Ford, L. H. (2002). "The Energy Density in the Casimir Effect". Physical Review D. 66: 045026. arXiv:quant-ph/0204125 (https://arxiv.org/abs/quant-ph/0204125). doi:10.1103/PhysRevD.66.045026.

[14] Stress-energy tensor: negative pressure revisited (http://www.physicspages.com/2014/05/31/stress-energy-tensor-negative-pressure-revisited/), from Moore, T. A. (2013). "A General Relativity Workbook", Chapter 20 "The Stress-Energy Tensor". University Science Books. ISBN 978-1-891389-82-5.
https://en.wikipedia.org/wiki/Negative_energy
Some other forms of negative energy exist.  One is gravitational energy which pulls things together.  I was suspecting queezed light might be a way of helping push against the vacuum and seems integral to detecting gravitational waves.  Squeezed light is also connected to negative energy. 

There are the virtual particles that seem to pop in and out of existence that also have connections to negative energy. 

also found this which may possibly be of relation or maybe not,
Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.html
http://cds.cern.ch/record/726991/files/0402213.pdf

Pressures and Energies in Magnetized Vacuum and in Casimir effect

CERN Document Server

Rojas, H P

2004-01-01

We study vacuum pressures and energies for electron-positron vacuum zero point energy in a strong magnetic field $B$ and for photon vacuum in Casimir effect, by a common method. Vacuum becomes magnetized, and due to it, the pressure transversal to $B$ is negative, whereas along $B$ an usual positive pressure arises. Similarly, in addition to the usual negative Casimir pressure perpendicular to the plates, the existence of a positive pressure along the plates is predicted. Both vacua bear the property of leading to a negative energy-momentum tensor trace ${\\cal T}_{\\mu}^{\\mu}<0$, which may lead to a repulsive gravity typical of dark energy. By assuming a space distribution of magnetic and/or Casimir domains, cosmological implications are also discussed.
Title: Re: Theoretical FTL
Post by: gospacex on 07/14/2017 03:58 pm
Of course all components of stress-energy tensor have the same units. This is not the issue.

The issue is that pressure is a flux of *momentum* through *spatial* coordinates x,y,z. Whereas energy is a flux through *time* coordinate. Different things.

You are referring to the stress-energy tensor:

(https://upload.wikimedia.org/wikipedia/commons/thumb/f/fe/StressEnergyTensor_contravariant.svg/500px-StressEnergyTensor_contravariant.svg.png)

We can express the energy density in the stress energy-tensor as ρc2

What is it? n is the "density number" (number of particles per cubic meter) multiplied by mc2, an energy. Thus this is an energy per unit volume, in joules (or newton-meter) per cubic meter.

The other terms of the stress-energy tensor are three times the pressure and they have exactly the same dimension.

So p is also expressed in joules per cubic meter: an energy density. All the terms of the tensor expressed here share the same dimension.

If this is not a demonstration that p is also an energy per unit volume?!

No, it is not.
Energy is linked to *time*, and momentum to *space*. Pressure (say, of gas) on a surface is caused by momentum of gas particles crossing this spatial surface.
Title: Re: Theoretical FTL
Post by: gospacex on 07/14/2017 04:09 pm
Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.html
http://cds.cern.ch/record/726991/files/0402213.pdf

Pressures and Energies in Magnetized Vacuum and in Casimir effect

CERN Document Server

Rojas, H P

2004-01-01

We study vacuum pressures and energies for electron-positron vacuum zero point energy in a strong magnetic field $B$ and for photon vacuum in Casimir effect, by a common method. Vacuum becomes magnetized, and due to it, the pressure transversal to $B$ is negative, whereas along $B$ an usual positive pressure arises. Similarly, in addition to the usual negative Casimir pressure perpendicular to the plates, the existence of a positive pressure along the plates is predicted. Both vacua bear the property of leading to a negative energy-momentum tensor trace ${\\cal T}_{\\mu}^{\\mu}<0$, which may lead to a repulsive gravity typical of dark energy. By assuming a space distribution of magnetic and/or Casimir domains, cosmological implications are also discussed.

"Both vacua bear the property of leading to a negative energy-momentum tensor trace" means that tensor looks like T = diag(ρ, -ρ, -ρ, -ρ) and therefore its trace is -2ρ.

Any vacuum state must have energy-momentum tensor proportional to the metric, since vacuum is invariant under boosts. (This is markedly different from states with particles (i.e. "not vacuums"), which are not invariant under boost - if observer is moving with a different velocity, it sees all particles having different velocity too).

For the usual case of flat Minkovski space this means that vacuum's energy-momentum tensor must be proportional to diag(1, -1, -1, -1).

If it is diag(ρ, -ρ, -ρ, -ρ), then it has positive energy density and negative pressure.
If it is diag(-ρ, ρ, ρ, ρ), then it has negative energy density and positive pressure.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/14/2017 11:57 pm
{snip}
If this is not a demonstration that p is also an energy per unit volume?!

No, it is not.
Energy is linked to *time*, and momentum to *space*. Pressure (say, of gas) on a surface is caused by momentum of gas particles crossing this spatial surface.

You dont' articulate your sentence with the rest of my post that you didn't quote. Please explain to all readers here how pressures we experience in physics, aka the pneumatic pressure, the strain in materials, the magnetic pressure, the coulomb pressure, the electrostatic pressure, the radiation pressure, etc… cannot, according to you, be expressed in terms of energy densities, whereas this is how every engineer and physicist do it since time immemorial.

Again, please read and comment:
• The relationship between radiation PRESSURE, ENERGY DENSITY and LAGRANGIAN DENSITY (https://forum.nasaspaceflight.com/index.php?topic=39214.msg1526577#msg1526577)
and
• The relationship between radiation PRESSURE and the POYNTING VECTOR (https://forum.nasaspaceflight.com/index.php?topic=39214.msg1532199#msg1532199)
both posts by Dr Rodal in the EmDrive threads.
Title: Re: Theoretical FTL
Post by: gospacex on 07/15/2017 12:40 am
{snip}
If this is not a demonstration that p is also an energy per unit volume?!

No, it is not.
Energy is linked to *time*, and momentum to *space*. Pressure (say, of gas) on a surface is caused by momentum of gas particles crossing this spatial surface.

You dont' articulate your sentence with the rest of my post that you didn't quote. Please explain to all readers here how pressures we experience in physics, aka the pneumatic pressure, the strain in materials, the magnetic pressure, the coulomb pressure, the electrostatic pressure, the radiation pressure, etc… cannot, according to you, be expressed in terms of energy densities

No, that's not "according to me". I'm not saying that, it's you not understanding what I'm saying.
Title: Re: Theoretical FTL
Post by: dustinthewind on 07/16/2017 05:40 am
Negative pressure does not cause negative energy.

It is true dark energy has a positive energy density associated to a negative pressure in the concordance model.

Conversely, does negative energy always have to cause positive pressure?

As for negative energy density states, an example is the Casimir effect. In between the attracted plates there is indeed a negative pressure. But it has been shown that the negative energy density can also be either positive or negative in that region of limited spatial extension, with respect to the ground state energy of the vacuum. [13]

So both a negative pressure and a negative energy density at the same time…

In a more general form the pressure components in the stress-energy tensor can be written in terms of mass density:

p = α ρ

with α > -1

α being a scalar quantity. [14]

This opens the possibility of negative pressures, but this has not to be the case for any scenarii, including positive or negative energies.

Except the particular case of the Casimir effect, the physical behavior of negative energy states is still unknown, so no conclusions, based solely on the extrapolation after effects due to positive energy, can be made certain. Especially as the two coupled field equations of the Janus cosmological model generate a different Newtonian approximation for the gravitational interaction of positive vs negative mass matter, when compared to the Newtonian approximation for those two species from a single metric in general relativity.



References

[13] Sopova, V.; Ford, L. H. (2002). "The Energy Density in the Casimir Effect". Physical Review D. 66: 045026. arXiv:quant-ph/0204125 (https://arxiv.org/abs/quant-ph/0204125). doi:10.1103/PhysRevD.66.045026.

[14] Stress-energy tensor: negative pressure revisited (http://www.physicspages.com/2014/05/31/stress-energy-tensor-negative-pressure-revisited/), from Moore, T. A. (2013). "A General Relativity Workbook", Chapter 20 "The Stress-Energy Tensor". University Science Books. ISBN 978-1-891389-82-5.
https://en.wikipedia.org/wiki/Negative_energy
Some other forms of negative energy exist.  One is gravitational energy which pulls things together.  I was suspecting queezed light might be a way of helping push against the vacuum and seems integral to detecting gravitational waves.  Squeezed light is also connected to negative energy. 

There are the virtual particles that seem to pop in and out of existence that also have connections to negative energy. 

also found this which may possibly be of relation or maybe not,
Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.html
http://cds.cern.ch/record/726991/files/0402213.pdf

Pressures and Energies in Magnetized Vacuum and in Casimir effect

CERN Document Server

Rojas, H P

2004-01-01

We study vacuum pressures and energies for electron-positron vacuum zero point energy in a strong magnetic field $B$ and for photon vacuum in Casimir effect, by a common method. Vacuum becomes magnetized, and due to it, the pressure transversal to $B$ is negative, whereas along $B$ an usual positive pressure arises. Similarly, in addition to the usual negative Casimir pressure perpendicular to the plates, the existence of a positive pressure along the plates is predicted. Both vacua bear the property of leading to a negative energy-momentum tensor trace ${\\cal T}_{\\mu}^{\\mu}<0$, which may lead to a repulsive gravity typical of dark energy. By assuming a space distribution of magnetic and/or Casimir domains, cosmological implications are also discussed.

This quote from https://en.wikipedia.org/wiki/Woodward_effect
Quote
Negative bare mass of the electron[edit]
The mass of the electron is positive according to the mass–energy equivalence E = mc2 but this invariant mass is made from the bare mass of the electron "clothed" by a virtual photon cloud. According to quantum field theory, as those virtual particles have an energy more than twice the bare mass of the electron, mandatory for pair production in renormalization, the nonelectromagnetic bare mass of the "unclothed" electron has to be negative.[45]

Using the ADM formalism, Woodward proposes that the physical interpretation...

This rings a bell for me.  I was suspecting the anti-matter as having some means of cloaking its negative mass so as to appear positive till annihilation.  Now we see the electron surrounded by the vacuum negative energy seemingly polarized by its presence.  Probably the only thing holding it back would be other annihilated and repelled electrons bonded to their counter parts. 

If the electron has its mass effectively reduced by this effect then a bare proton may have its mass effectively increased if its attracting annihilated electrons from the vacuum. 

I suspect inertia is a property of the vacuum as do some others.  The reverse time retarded waves would be the anti-matter positron fluctuations and the forward time waves are the vacuum annihilated electron waves.  These waves appear as photons or polarization of the vacuum (forward and reverse time simultaneously) such that an electric field can travel through space.  Its the local metric of this vacuum that determines what appears to be the constant speed of light while non-locally allowing it to change and why when annihilating a charge pair, light is made, while when reversing that light such that it converges in reverse time, we can get back those same two annihilated pairs. 

Gravity would be some gradient induced in the vacuum, initially by some unknown method of matters attraction of anti-matter out of the vacuum - particularly positrons - maybe by the outer electron cloud particularly.  This initial polarization of the vacuum is not caused by the gradient in time however, this cloud of negative energy or polarization of the vacuum (e-p phantom pairs) slows time time in a gravity well.  This gradient in time then causes attraction of other matter.  Well maybe, its just a hypothesis. 
Title: Re: Theoretical FTL
Post by: ChrisWilson68 on 07/16/2017 06:44 am
Negative pressure does not cause negative energy.

It is true dark energy has a positive energy density associated to a negative pressure in the concordance model.

Conversely, does negative energy always have to cause positive pressure?

As for negative energy density states, an example is the Casimir effect. In between the attracted plates there is indeed a negative pressure. But it has been shown that the negative energy density can also be either positive or negative in that region of limited spatial extension, with respect to the ground state energy of the vacuum. [13]

So both a negative pressure and a negative energy density at the same time…

In a more general form the pressure components in the stress-energy tensor can be written in terms of mass density:

p = α ρ

with α > -1

α being a scalar quantity. [14]

This opens the possibility of negative pressures, but this has not to be the case for any scenarii, including positive or negative energies.

Except the particular case of the Casimir effect, the physical behavior of negative energy states is still unknown, so no conclusions, based solely on the extrapolation after effects due to positive energy, can be made certain. Especially as the two coupled field equations of the Janus cosmological model generate a different Newtonian approximation for the gravitational interaction of positive vs negative mass matter, when compared to the Newtonian approximation for those two species from a single metric in general relativity.



References

[13] Sopova, V.; Ford, L. H. (2002). "The Energy Density in the Casimir Effect". Physical Review D. 66: 045026. arXiv:quant-ph/0204125 (https://arxiv.org/abs/quant-ph/0204125). doi:10.1103/PhysRevD.66.045026.

[14] Stress-energy tensor: negative pressure revisited (http://www.physicspages.com/2014/05/31/stress-energy-tensor-negative-pressure-revisited/), from Moore, T. A. (2013). "A General Relativity Workbook", Chapter 20 "The Stress-Energy Tensor". University Science Books. ISBN 978-1-891389-82-5.
https://en.wikipedia.org/wiki/Negative_energy
Some other forms of negative energy exist.  One is gravitational energy which pulls things together.  I was suspecting queezed light might be a way of helping push against the vacuum and seems integral to detecting gravitational waves.  Squeezed light is also connected to negative energy. 

There are the virtual particles that seem to pop in and out of existence that also have connections to negative energy. 

also found this which may possibly be of relation or maybe not,
Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.html
http://cds.cern.ch/record/726991/files/0402213.pdf

Pressures and Energies in Magnetized Vacuum and in Casimir effect

CERN Document Server

Rojas, H P

2004-01-01

We study vacuum pressures and energies for electron-positron vacuum zero point energy in a strong magnetic field $B$ and for photon vacuum in Casimir effect, by a common method. Vacuum becomes magnetized, and due to it, the pressure transversal to $B$ is negative, whereas along $B$ an usual positive pressure arises. Similarly, in addition to the usual negative Casimir pressure perpendicular to the plates, the existence of a positive pressure along the plates is predicted. Both vacua bear the property of leading to a negative energy-momentum tensor trace ${\\cal T}_{\\mu}^{\\mu}<0$, which may lead to a repulsive gravity typical of dark energy. By assuming a space distribution of magnetic and/or Casimir domains, cosmological implications are also discussed.

This quote from https://en.wikipedia.org/wiki/Woodward_effect
Quote
Negative bare mass of the electron[edit]
The mass of the electron is positive according to the mass–energy equivalence E = mc2 but this invariant mass is made from the bare mass of the electron "clothed" by a virtual photon cloud. According to quantum field theory, as those virtual particles have an energy more than twice the bare mass of the electron, mandatory for pair production in renormalization, the nonelectromagnetic bare mass of the "unclothed" electron has to be negative.[45]

Using the ADM formalism, Woodward proposes that the physical interpretation...

This rings a bell for me.  I was suspecting the anti-matter as having some means of cloaking its negative mass so as to appear positive till annihilation.  Now we see the electron surrounded by the vacuum negative energy seemingly polarized by its presence.  Probably the only thing holding it back would be other annihilated and repelled electrons bonded to their counter parts. 

If the electron has its mass effectively reduced by this effect then a bare proton may have its mass effectively increased if its attracting annihilated electrons from the vacuum. 

I suspect inertia is a property of the vacuum as do some others.  The reverse time retarded waves would be the anti-matter positron fluctuations and the forward time waves are the vacuum annihilated electron waves.  These waves appear as photons or polarization of the vacuum (forward and reverse time simultaneously) such that an electric field can travel through space.  Its the local metric of this vacuum that determines what appears to be the constant speed of light while non-locally allowing it to change and why when annihilating a charge pair, light is made, while when reversing that light such that it converges in reverse time, we can get back those same two annihilated pairs. 

Gravity would be some gradient induced in the vacuum, initially by some unknown method of matters attraction of anti-matter out of the vacuum - particularly positrons - maybe by the outer electron cloud particularly.  This initial polarization of the vacuum is not caused by the gradient in time however, this cloud of negative energy or polarization of the vacuum (e-p phantom pairs) slows time time in a gravity well.  This gradient in time then causes attraction of other matter.  Well maybe, its just a hypothesis.

It's actually not even a hypothesis.  Statements like "inertia is a property of the vacuum" are incoherent.  They're logically equivalent to "two is a property of green".
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/16/2017 04:56 pm
WHY NEGATIVE MASS GOES WITH NEGATIVE PRESSURE

In the standard ΛCDM model, the vacuum has a positive energy density and exerts a negative pressure, which drives the cosmic expansion.
Conversely, if the vacuum had a negative energy density, il would exert a positive pressure.
That's why when a model involving negative energies is presented, typical answers like this arise:

Accelerating expansion must have _positive_ energy density of vacuum (then it has negative pressure).
Negative pressure does not cause negative energy.

This puzzled me enough to email Dr Jean-Pierre Petit about his Janus model and how he relates a negative mass density to a negative pressure driving the cosmic expansion process.

Dr Petit was kind enough to write an answer, attached below as a PDF.

The misunderstanding comes from the vacuum being responsible for the accelerating expansion of the universe in the concordance model, whereas in the Janus cosmological model the acceleration of the cosmic expansion does not come from such "vacuum".

This document summarizes the basic relation, with general relativity and the standard equations of physics, between mass energy density and pressure, and it demonstrates why negative mass densities go with a negative pressure.

The main difference with the standard ΛCDM model, besides the two coupled field equations of the Janus model, is that:

• According to the ΛCDM model, the vacuum is "empty" (from a matter point of view: there are almost no real particles in a hard vacuum) but is "non-empty" from an energy point of view. It has a positive energy state. Invisible dark matter (of positive mass) may be there in space, but has nothing to do with the accelerating cosmic expansion, unlike the so-called "dark energy" and its associated negative pressure driving the expansion process. Two different things.

• According to the Janus model, where vacuum appears to be "empty" it is also really not. But don't be fooled, this is not according to some quantum notion of an "energy of the vacuum" and has all to do with the invisible presence of some mass. In our positive sector, the vacuum appears to be a rarefied medium full of photons with almost no mass particles. But in reality some mass, located in the negative sector, is "there" everywhere, especially in the voids of deep space, although being invisible. Such matter has a negative energy hence a negative mass. It interacts with positive mass matter in our positive sector through gravitation (challenging dark matter) and it also exerts a negative pressure (challenging dark energy) which drives the accelerating expansion of the universe. See the paper attached.

This negative mass matter is nothing but antimatter (PT-symmetry) as suggested by Richard Feynman in 1949; and later by Andrei Sakharov in 1967 (see 2nd part of this prior post (https://forum.nasaspaceflight.com/index.php?topic=13542.msg1701805#msg1701805)) who identified it with the lacking primordial antimatter; and nowadays by some other physicists like Julian Barbour who identifies some "mirror matter" populating a "mirror universe having an opposite arrow of time". In the Janus cosmological model: same thing, except that moreover this invisible primordial antimatter interacts through gravitation with our normal matter, as being of negative mass -m = -E/c2 simply because T symmetry goes with E inversion (Souriau 1970, see this prior post (https://forum.nasaspaceflight.com/index.php?topic=13542.msg1701803#msg1701803)).

EDIT — October 4, 2017: Broken links in the original attachement, updated version re-uploaded.
Title: Re: Theoretical FTL
Post by: gospacex on 07/17/2017 12:52 pm
• According to the Janus model, where vacuum appears to be "empty" it is also really not. But don't be fooled, this is not according to some quantum notion of an "energy of the vacuum" and has all to do with the invisible presence of some mass. In our positive sector, the vacuum appears to be a rarefied medium full of photons with almost no mass particles. But in reality some mass, located in the negative sector, is "there" everywhere, especially in the voids of deep space, although being invisible. Such matter has a negative energy hence a negative mass. It interacts with positive mass matter in our positive sector through gravitation

This means that this model predicts that properties of the vacuum change for observers moving with different velocities relative to each other. For vacuum to look the same to all such observers, it has to have energy-momentum tensor proportional to metric.

Quote
This negative mass matter is nothing but antimatter (PT-symmetry) as suggested by Richard Feynman in 1949

This contradicts the previous paragraph, where negative matter was said to be "invisible", i.e. undetectable except via gravity. We experimentally know that antimatter is not undetectable.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/17/2017 04:06 pm
• According to the Janus model, where vacuum appears to be "empty" it is also really not. But don't be fooled, this is not according to some quantum notion of an "energy of the vacuum" and has all to do with the invisible presence of some mass. In our positive sector, the vacuum appears to be a rarefied medium full of photons with almost no mass particles. But in reality some mass, located in the negative sector, is "there" everywhere, especially in the voids of deep space, although being invisible. Such matter has a negative energy hence a negative mass. It interacts with positive mass matter in our positive sector through gravitation

This means that this model predicts that properties of the vacuum change for observers moving with different velocities relative to each other. For vacuum to look the same to all such observers, it has to have energy-momentum tensor proportional to metric.

The nature of dark energy in the standard model cannot be explained otherwise as saying it is some peculiar attribute of the vacuum of space. Actually such "energy of the vacuum" profoundly involves a quantum notion and is a problem with quantum mechanics, not gravitational theories. The wedding between general relativity and quantum mechanics has not been done yet.

The Janus model does not use quantum notions. It stays carefully in a context of differential geometry, using plain-vanilla general relativity only. In the model, the "vacuum energy" does not exist. The space vacuum is just full of photons.

"Vacuum" would be a container. But there is only content.

As such modern "dark energy" of quantum origin is unmanageable in the ΛCDM model, for the lack of a grand unified theory or theory of everything, it is related to a "cosmological constant" as Einstein introduced in his field equations, originally for bad reasons (because he wanted his universe to be static); but such cosmological constant has again recently been took out of mothballs to explain the accelerating cosmic expansion. Thus the use of such cosmological constant which has a "negative pressure proportional to the metric".

The Repulsive Power of the Vacuum™ of the ΛCDM model simply becomes in the Janus model the repulsive power of the negative pressure due to the global negative mass density in the cosmos.

It seems it will take time before people understand that in the Janus model, there is no need for Λ gµν terms anymore in the EFE.

That said, the question about the spatial variation of mass densities due to the negative mass distribution in the Janus model is interesting.

If we're talking about the isotropy and homogeneity of the primitive universe at a very large scale, the Janus model is in accordance with such a cosmological principle.

As an aside: at smaller scales (< 250 million light-years) in the matter-dominated era, the universe is inhomogeneous. We have for example those giant voids with no matter within. By the way, how to explain classically the formation of such voids? As both matter and dark matter are of positive mass (attractive) in the concordance model, all the Jeans instability (the gravitational instability) can do is making lumps of matter, not giant void bubbles.

But any serious cosmological model considers the isotropy and homogeneity of the universe at a very large scale, and so does the Janus model. Although, like matter distribution in the universe at smaller scales, there are similarly local inhomogeneities in the negative mass distribution, there is also a statistical density of negative mass taken globally, at a very large scale. To my knowledge, such a very large scale statistical mass density has not been calculated yet in the model. Will suggest the author to do it :)
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/17/2017 04:06 pm
This negative mass matter is nothing but antimatter (PT-symmetry) as suggested by Richard Feynman in 1949

This contradicts the previous paragraph, where negative matter was said to be "invisible", i.e. undetectable except via gravity. We experimentally know that antimatter is not undetectable.

You didn't carefully read the diagram "baryon asymmetry of the universe after Sakharov" and the explanation underneath about the nature of particles in the model (the 2nd part of this prior post of mine (https://forum.nasaspaceflight.com/index.php?topic=13542.msg1701805#msg1701805)). So here it is again with more explanation about antimatter:

(http://ayuba.fr/images/baryon_asymmetry.png)

BARYON ASYMMETRY OF THE UNIVERSE AFTER SAKHAROV
LEFT: positive energy species | RIGHT: negative energy species
A: Primitive universe, 4 components: positive energy quarks and antiquarks; and negative energy quarks and antiquarks.
B: They combine to give more positive mass matter (red) than positive mass antimatter (blue) due to CP violation in the 1st sector; and more negative mass antimatter (purple) than negative mass matter (green) due to opposite CP violation in the 2nd sector.
C: Positive energy quarks and antiquarks stop combining and positive mass matter and antimatter annihilate each other in the first sector. Same thing in the 2nd sector for negative mass matter and antimatter.
D: In the 1st sector, positive energy photons remain from positive mass matter-antimatter annihilation, leaving a remnant of positive mass matter and positive energy antiquarks. In the 2nd sector, negative energy photons remain from negative mass matter-antimatter annihilation, leaving a remnant of negative mass antimatter and negative mass quarks.


So there are two kinds of matter:

positive energy matter : the normal matter we are made of.

negative energy matter : invisible matter located in the negative sector. CPT-symmetry with respect to our matter. T-symmetry is responsible for its invisibility and its opposite mass, from our point of view.


Then both have their own kind of antimatter (this addresses your question):

positive energy antimatter: C-symmetry wrt our matter (this is the antimatter after Dirac, in blue in the diagram). It has a positive mass and falls down in Earth's gravitational field. It has a positive arrow of time, hence is located in our positive sector and is visible to observational instruments. This is the antimatter created in lab.

negative energy antimatter: negative mass matter with a charge conjugation: C×CPT = PT-symmetry wrt our matter (this is the antimatter after Feynman, in violet in the diagram). It has a negative mass and "falls up" in Earth's gravitational field. It has an opposite arrow of time, hence is located in the negative sector and is invisible (T-symmetry is also why it appears as having a negative energy, and a negative mass, from our point of view).

NB: Positive mass antimatter is now absent from our universe due to CP violation during baryogenesis, and matter remains. Conversely in the negative sector, an opposite CP violation occurred and lead to a lack of negative mass matter, so the negative sector has been populated by negative mass antimatter. Taken globally, no violation occurred (Sakharov 1967).


There are also two kinds of photons (the photon is its own antiparticle):

positive energy photons: those photons follow null-geodesics of the metric g(+) (positive sector) and are seen by our eyes and instruments.

negative energy photons: those photons follow null-geodesics of the metric g(-) (negative sector) and cannot be seen by our eyes nor our instruments. This is why we can't optically detect negative mass antimatter (which is a candidate for dark matter) since it emits negative energy photons.


In fact this has been entirely geometrized with dynamical groups 20 years ago. If you like matrices you may read the four references below, which explain C, P, T, and E symmetries and relations. Please be aware those articles may content a few typos and some dated terminology sometimes ("momentum space" instead of "momentum map"; the "twin/shadow/ghost fold" now called the "negative sector" identified to the metric g(-), etc.) but the concepts presented there still hold and are at the heart of the Janus model:


Geometrization of matter and antimatter through coadjoint action of a group on its momentum map:

1: Charges as additional scalar components of the momentum of a group acting on a 10D-space. Geometrical definition of antimatter.

2: Geometrical description of Dirac's antimatter.

3: Geometrical description of Dirac's antimatter. A first geometrical interpretation of antimatter after Feynmann and so-called CPT-theorem.

4: The twin group. Geometrical description of Dirac's antimatter. Geometrical interpretation of antimatter after Feynmann and so-called CPT-theorem.


Documents attached below.
Title: Re: Theoretical FTL
Post by: gospacex on 07/18/2017 06:22 am
• According to the Janus model, where vacuum appears to be "empty" it is also really not. But don't be fooled, this is not according to some quantum notion of an "energy of the vacuum" and has all to do with the invisible presence of some mass. In our positive sector, the vacuum appears to be a rarefied medium full of photons with almost no mass particles. But in reality some mass, located in the negative sector, is "there" everywhere, especially in the voids of deep space, although being invisible. Such matter has a negative energy hence a negative mass. It interacts with positive mass matter in our positive sector through gravitation

This means that this model predicts that properties of the vacuum change for observers moving with different velocities relative to each other. For vacuum to look the same to all such observers, it has to have energy-momentum tensor proportional to metric.

The nature of dark energy in the standard model cannot be explained otherwise as saying it is some peculiar attribute of the vacuum of space. Actually such "energy of the vacuum" profoundly involves a quantum notion and is a problem with quantum mechanics, not gravitational theories. The wedding between general relativity and quantum mechanics has not been done yet.

The Janus model does not use quantum notions. It stays carefully in a context of differential geometry, using plain-vanilla general relativity only. In the model, the "vacuum energy" does not exist.

A model may postulate that expansion is done by fairies. By itself, this is not a crime.

What's important is that (a) a model should be mathematically consistent, and (b) its predictions should match experiments. If a model fails (a) or (b), it is in trouble.

By the looks of it, Janus model predicts that properties of the vacuum change for observers moving with different velocities relative to each other. This contradicts experiments.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/19/2017 10:47 am
By the looks of it, Janus model predicts that properties of the vacuum change for observers moving with different velocities relative to each other. This contradicts experiments.

I'm not quite sure what you are referring to. Can you please expand further with maths what does represent "isotropic properties of the vacuum" and point to some of the experiments your referred to, whose results showed such isotropic "properties of the vacuum"?
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/21/2017 12:53 am
What's important is that (a) a model should be mathematically consistent, and (b) its predictions should match experiments. If a model fails (a) or (b), it is in trouble.
I agree with you. You forgot (c) a model should also explain observations.
This is not exactly like point (b) which states a model can predict some physical behavior that can later be confirmed/disproved with experimental setups; while explaining observational data is the other way: popper falsifiability showing if a model can naturally fit, or if a model needs some tweaks to fit, or if a model can't fit at all new peculiar observations.

About this question of the cosmic expansion vs observations, here is the work done by Gilles d'Agostini (coworker of Dr Petit) about the Janus model and the acceleration of the cosmic expansion:

A new interpretation of the cosmic acceleration (paper attached below)
(http://ayuba.fr/images/deceleration_coefficient.png)

The work is structured on the comparison to the largest observational data available to date (740 high-z supernovae). The Janus bimetric model model (pink curve) challenges the ΛCDM concordance model (dotted black curve) quite well:
- in order for the concordance model to fit the curve, it has to include dark energy (non-zero cosmological constant added to the Einstein field equations) and adjust no less than 6 free parameters.
- Conversely, the exact solution of the Janus model fits naturally without resorting to a "vacuum dark energy": negative acceleration (i.e. deceleration) coefficient:
q0 = -0.087 ±0.015
is rather small, with no need to introduce a non-zero cosmological constant to fit the available data.

The exact solution of the Janus cosmological model for the evolution of the positive mass spacetime in the matter-dominated era is the same as Bonnor's parametric equation of the scale function S of a universe with negative mass and without a cosmological constant, given in the section 4.3 of ref. [6] in this prior post (https://forum.nasaspaceflight.com/index.php?topic=13542.msg1701803#msg1701803):

Quote from: William Bonnor

4.3. p=0, Λ=0

This case is actually included in the foregoing, but I mention it explicitly because it corresponds to the simplest Friedmann models of traditional cosmology. It follows from (27) that must be nonnegative, and then from (26) that k = -1. Integrating (25) with p = 0 and k = -1 we find

S = α2 cosh2 u
t + to = α2 (1/2 sinh 2u + u)

where α and to are constants.

It is worth noting that while the expansion of the positive mass universe is accelerating, conversely, the negative mass universe undergoes a decelerating expansion and follows one of the classical Friedmann models.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/21/2017 01:18 am
Dr Petit, 80 years old, is making a series of Youtube videos to popularize the Janus cosmological model and explain the basic concepts. There are 19 videos to date, but the 11 first ones rather talk about the history and evolution of astrophysics and cosmology through time, from antiquity to modern days. The foundations of the Janus model are broached from video #12.

Here is the Janus (English) YouTube playlist: https://goo.gl/MnGTHa

And its description:

Quote from: Jean-Pierre Petit
In this series of videos, astrophysicist and cosmologist Jean-Pierre Petit explains the Janus Cosmological Model.

JCM is a bimetric theory of gravity based on general relativity with a system of two coupled field equations, involving the presence of positive and negative masses in cosmology.

It describes the universe as an M4 manifold with two metrics. The first metric g(+) or "positive sector" refers to a family of geodesics with positive mass and positive energy particles, while the second metric g(-) or "negative sector" refers to another family of geodesics with negative mass and negative energy particles. Negative mass particles emit negative energy photons that follow null geodesics of the metric g(-) hence cannot be seen.

The Newtonian approximation provides the interaction laws: particles whose masses own the same sign mutually attract through Newton's law, while particles whose masses have opposite signs mutually repel through anti-Newton's law. This solves the unmanageable Runaway paradox, which arises when one tries to include negative masses in Einstein's model.

Like Andrei Sakharov's model, the second sector is a CPT symmetry of the first one, linked together by the Big Bang, and explains the apparent lack of primordial antimatter.

Dynamical group theory demonstrates that the reversal of the arrow of time equals energy inversion, and provides the nature of negative species.

The negative sector contributes to the gravitational field and negative pressure and replaces both dark matter and dark energy of the concordance model and its six free parameters, without ant ad hoc parameter.

The model challenges dark matter as it explains the formation of galactic spiral structures, their confinement and their anomalous rotation curves. It also explains the formation of galaxy clusters and the large-scale structure of the universe, the giant voids and the Dipole Repeller effect. Mirage effects around galaxies and galaxy clusters are due to a negative gravitational lensing effect.

The model challenges dark energy, giving an exact solution referring to the matter-dominated era, which exhibits an accelerating expansion process for positive species and fits very well with available observational data.

During the radiation-dominated era, the universe undergoes a variable constants regime, with a variation of the speed of light (VSL) and of all the constants of physics, involved in a generalized gauge process. Then the horizon grows like the space scale factor. This explains the homogeneity and isotropy of the primitive universe with no need to resort to the inflation hypothesis and the inflaton field.

The two sectors have different speeds of light and scale factors. If a space probe could achieve a mass inversion process and cruise at a relativistic velocity following geodesics of the negative sector, the travel duration could be three orders of magnitude shorter than a corresponding conventional relativistic trip in the positive sector. The model suggests that interstellar travel in a limited time inferior to human's lifespan becomes theoretically possible.

The Janus model has been published in peer reviewed scientific journals.
Title: Re: Theoretical FTL
Post by: flux_capacitor on 07/28/2017 11:09 am
Explaining the Janus model takes too much posts and I do not want to "hijack" a general thread like this one. So I created a dedicated topic about the model instead:
Janus Cosmological Model & FTL travel (https://forum.nasaspaceflight.com/index.php?topic=43501.0)

If you want to answer some of the things posted above, please write your answers in the new dedicated thread. Thank you.
Title: Re: Theoretical FTL
Post by: colbourne on 12/06/2018 05:16 am
https://phys.org/news/2018-12-universe-theory-percent-cosmos.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

Scientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.

Title: Re: Theoretical FTL
Post by: sghill on 12/06/2018 01:41 pm
https://phys.org/news/2018-12-universe-theory-percent-cosmos.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

Scientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.

Sonny White will be pleased to hear this. :>
Title: Re: Theoretical FTL
Post by: dustinthewind on 12/07/2018 12:13 am
https://phys.org/news/2018-12-universe-theory-percent-cosmos.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter

Scientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.

Sonny White will be pleased to hear this. :>
Kind of excited myself.  The vacuum seems responsible for superconductivity and I think superfluids.  Electron clouds seem super conductive.  Can be modeled as polarized vacuum osculation modes.  Superconductors also have electron pairing like orbitals.  Lowering their energy state seems key.  The vacuum also represents the lowest energy state. 

When electrons annihilate positrons they also go into the vacuum. I think as they annihilate that one reveals it self to the other as a form of negative energy.  Similar to the virtual particles in Feynman  diagrams that run backward in time.  As they annihilate their electric field stir the vacuum exciting it ensuring energy conservation.  Energy conservation seems inherent. For example in quantum tunneling the particle has a wave function that extends through a barrier. With vacuum noise the particle has a chance to exist on the other side of the barrier within its wavefunction, the noise also defines time I think as in radioactive decay. But when it does tunnel through it seems instantaneous.  This seems to be the case because the negative energy part that goes backward in time can go back and annihilate its previous position making the particle non unique. Similar to what you see Feynman diagrams with some stuff running backward in time.

I think that accelerating electrons while they are in their vacuum state similar to The Mach effect may enhance gravitational wave generation. Think electron pairing along with positrons makes quadrapoles - gravity waves are quadrapole. This suggests that maybe there might be something behind Podkletnov's gravity pulse generator. I think with enough gravitational wave generation, in the way a phased array works, putting them out in one direction, that the vacuum may become modifiable.  Maybe even allowing circumvention of the Lorentz contraction which I suspect is a result of the local vacuum.  Similar to  the Wormhole term in the Mach effect equation with the gravity waves being the rocket part of it - see wikipedia.  Similar to what carries off momentum of rapidly orbiting and orbit decaying black holes via gravity wave generation.

If so superluminal travel may not be impossible.
Title: Re: Theoretical FTL
Post by: RSE on 12/10/2018 01:44 pm
For modification of vacuum properties, review the research with Negative permeability/Negative permittivity experimentation, particularly those reaching zero Snell's laws experiments. 
Title: Re: Theoretical FTL
Post by: spaceman100 on 01/04/2019 04:05 pm
Miguel Alcubierrre (1994) published a paper that showed that a warp drive is at least mathematically possible, although it would require huge amounts of negative energy. Pfenning and Ford (1997) showed that a warp bubble wall as proposed by Alcubierre would have to be impossibly thin in order to work. Low (1999) showed that a warp in spacetime could travel no faster than the speed of light and that such a warp would require exotic matter (negative energy). Natario (2002) had a little more positive result: he showed that warp drives could be possible in that they wouldn’t need to compress spacetime ahead of themselves and stretch it behind in order to move. Lobo and Visser (2004) most recently published on this and they showed that in order for a warp drive to work, a couple of things need to happen:
1.   The spaceship can’t travel faster than light
2.   The amount of negative energy must be a significant fraction of the mass of the ship.
As I understand it, a spaceship using a warp drive can’t travel faster than light because gravity only travels at the speed of light, and such a ship would be relying on a negative gravitational force generated by the negative energy it is carrying along in its warp of spacetime.

References

The warp drive: hyper-fast travel within general relativity
Miguel Alcubierre
Class. Quantum Grav. 11 No 5 (May 1994) L73-L77

Fundamental limitations on 'warp drive' spacetimes
Francisco S N Lobo and Matt Visser
Class. Quantum Grav. 21 No 24 (21 December 2004) 5871-5892

Speed limits in general relativity
Robert J Low
Class. Quantum Grav. 16 No 2 (February 1999) 543-549

Warp drive with zero expansion
J Natario
Class. Quantum Grav. 19 No 6 (21 March 2002) 1157-1165

The unphysical nature of `warp drive'
M J Pfenning and L H Ford
Class. Quantum Grav. 14 No 7 (July 1997) 1743-1751

Yes I love this video; https://www.youtube.com/watch?v=5q_z8BjiYng
Title: Re: Theoretical FTL
Post by: WarpTech on 01/05/2019 03:33 pm
There is this;
The Electromagnetic Quantum Vacuum Warp Drive (see attached)

http://jbis.org.uk/paper.php?p=2015.68.347 (http://jbis.org.uk/paper.php?p=2015.68.347)

and this;
An Engineering Model of Quantum Gravity (see attached)

http://ssi.org/wp-content/uploads/2017/02/ssi_estes_park_proceedings_201609.pdf (http://ssi.org/wp-content/uploads/2017/02/ssi_estes_park_proceedings_201609.pdf)

Comments?



Title: Re: Theoretical FTL
Post by: meberbs on 01/12/2019 06:50 pm
I went through the "engineering model of quantum gravity" paper, and I see a few issues. I am quoting from the conclusion of the paper to provide a starting point for discussion:
Quote
This engineering model firmly establishes a viable solution to quantum gravity for engineers within the standard model of Quantum Electrodynamics.
First there are a couple issues with your claims of this being a theory of "quantum gravity." You make no predictions, and do not even discuss the realms where quantum gravity applies, for example: event horizons of black holes, Planck scale physics, and the potential existence of gravitons. Your only actual use of quantum mechanics is an extended justification of a change of variables in the GR equations. Performing this change of variables does not make it a quantum theory.

Assuming that the confusion caused by the way your theory is named is accidental, what you really sem to be discussing is "an engineering model of general relativity from an alternate perspective inspired by quantum mechanics.  The problem here being that you did not in fact "firmly establish a viable solution." At a minimum you should show how to use your modified theory for practical calculations of things such as the classical tests of GR. Gravitational redshift/time dilation is fairly trivial, so the precession of Mercury or bending of light rays around the sun would be good comparisons to see if your model really makes practical calculations easier. An example with gravitational waves would be a good follow on as well.

Also, to preempt a likely response to what I just said: As far as I can tell you just did a change of variables, without changing the underlying math. In this case (assuming no mistakes), your new formulation is automatically consistent with GR, but the only use for it is if it makes practical calculations easier. If I misunderstood, and you did in fact change the fundamentals of what the math means, that makes reconfirming that you fit the experimental data from tests of GR much more important.

Quote
It opens the door to new innovations that might permit artificial gravity or anti-gravity technologies to be invented. Through the use of stimulated emission, increased or reduced radiative damping, or by amplification of the resonant driving fields that inflate matter to higher ground state energies. Engineers now have a new set of old, familiar tools to work with when thinking about gravity and Metric Engineering [3].
No, it really doesn't open new doors. In the standard perspective GR is viewed from, to get things like warp drives from GR, you need a magic wand to create negative mass (or otherwise to directly curve space by magic) to create the interesting effects. In the perspective you introduce, you simply change this to magically changing fundamental constants such as those that determine the energy states of a hydrogen atom. This if anything seems further from reality, and as an engineer, I find picturing how to use this to create a warp drive less intuitive, than the concept of warping space-time.
 
Quote
What was presented herein puts gravity in the hands of engineers, who could potentially advance such technologies as; warp drive, artificial gravity and anti-gravity, from pure speculation, to achievable endeavors in our lifetime.
There is an implication here (hopefully unintended) that engineers aren't capable of understanding GR the way physicists do which I find a bit offensive. Besides that, as I said above, you did not actually provide a way for any of the things you claim to be done. Engineering is not magic.
Title: Re: Theoretical FTL
Post by: WarpTech on 01/12/2019 08:55 pm
...
"Also, to preempt a likely response to what I just said: As far as I can tell you just did a change of variables, without changing the underlying math. In this case (assuming no mistakes), your new formulation is automatically consistent with GR,..."

No offense intended. I chalk it up to life experiences. I've only ever met a handful of engineers who even attempted to understand the mathematics and nuances of GR, and of them, I'm the best, which isn't saying much. So yeah, "most" engineers I've conversed with are not at that level in my experience, and simply find the topic an interesting curiosity. If you're an engineer, and given your understanding of GR, that makes "2", you and Hal Puthoff are unique in my experience.

As far as tests of GR go, the radial solution is identical, therefore all of the tests that use that are identical. Hal Puthoff shows this in his papers. I have no need to reproduce his work. My point is to convey the difference in the "interpretation" of what we are observing, not that GR is in any way wrong. Just an alternative interpretation of the data.

As far as this engineering model being useful; I don't know how to engineer devices to make this work, but getting more engineers to think about this alternate interpretation is precisely how to get more minds working on that problem. How I understand it is, "Gravity" is the result of a loss of energy that causes matter to condense and oscillation frequencies to slow down. I attribute this to damping. Finding a means to increase damping would be the key to creating artificial gravity.

Alternatively, reducing damping and driving the oscillations with a source of energy would cause matter to inflate, and oscillation frequencies to speed up. This leads to volume increasing much faster than energy content, reducing the energy density of matter (like a hot air balloon). Which is mathematically equivalent to adding a "negative" energy density to positive energy density matter. This is the key to creating anti-gravity, warp drives and worm holes.

"How" to do it, I don't know, but when looking at the problem from this perspective, it puts it in the realm of the Standard Model where someday, someone, may come up with a means of doing these things. I'd just like to get more people to realize there is this alternate interpretation that puts things in a different perspective.
Title: Re: Theoretical FTL
Post by: meberbs on 01/14/2019 12:33 am
...
"Also, to preempt a likely response to what I just said: As far as I can tell you just did a change of variables, without changing the underlying math. In this case (assuming no mistakes), your new formulation is automatically consistent with GR,..."

No offense intended. I chalk it up to life experiences. I've only ever met a handful of engineers who even attempted to understand the mathematics and nuances of GR, and of them, I'm the best, which isn't saying much. So yeah, "most" engineers I've conversed with are not at that level in my experience, and simply find the topic an interesting curiosity. If you're an engineer, and given your understanding of GR, that makes "2", you and Hal Puthoff are unique in my experience.
...
No problem, I didn't think you intended any offense, but wanted to clarify.

I think for most engineers, the reason for the lack of understanding of GR is just that it is irrelevant for nearly any current engineering  job. Short of designing a gravitational wave detector, or extremely accurate interplanetary trajectories, it just doesn't come up. (As you mentioned, time dilation for navigation satellites is relatively trivial, and requires no deep understanding.) I do know of engineers who took GR in college (I took the relevant math in college, but have slowly been studying GR on my own.) So there are certainly other engineers out there who understand it better than me. (Although as far as I know, none of them actually make use of the GR they learned, they went in different directions for their careers.)

As to the purpose of your paper, while I would reword your conclusion, I don't think I have any disagreement with you on the technical issues based on your response. Personally I don't see anything in your version that particularly helps, but especially for an engineering model, it doesn't matter if it represents how things actually work, as long as it gets you correct answers. I have no complaints about alternate equivalent models, they often can be helpful. (Quantum mechanics is a good example, where there are multiple interpretations with no known difference between them, so you can use whichever one is easiest for you, or is easiest to comprehend for a specific problem.)

In the case of your model, while it doesn't help me personally, maybe it would be useful to someone else. As far as I am concerned, your model basically gives us a different perspective on a bolt we would like to turn. While that could be helpful, it doesn't do much to address the main problem: that we don't have a wrench capable of turning that bolt.
Title: Re: Theoretical FTL
Post by: WarpTech on 02/15/2019 03:24 am
This is pre-requisite for the warp drive paper I posted. This is the basis for the model, as presented by the master himself.

https://www.youtube.com/watch?v=12yjbyunRdM (https://www.youtube.com/watch?v=12yjbyunRdM)

Enjoy!
Title: Re: Theoretical FTL
Post by: colbourne on 03/18/2021 09:10 am
https://www.sciencealert.com/faster-than-light-travel-is-possible-within-einstein-s-physics-astrophysicist-shows?fbclid=IwAR0VP5VvwRMhfwG6WHXe447l9x3enbn5TT4yNRZTfrqt9MvKsiyTJfz_acA

Faster-Than-Light Travel Is Possible Within Einstein's Physics, Astrophysicist Shows
Title: Re: Theoretical FTL
Post by: clippie on 04/15/2021 12:16 am
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.
Title: Re: Theoretical FTL
Post by: Frogstar_Robot on 04/15/2021 09:42 am
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.
Title: Re: Theoretical FTL
Post by: edzieba on 04/15/2021 11:59 am
For further comparison:
- One Jupiter mass is ~1.7×10^44 joules
- The Sun outputs 3.8 x 10^26 Joules per second, so you would need to absorb the entire energy of the Sun for 14.2 billion years (i.e. more than 3 times longer than the Sun has existed) to power the drive
- The total energy output of a Type 1a supernova is estimated to be on the order of 10^44 jules, so you may be able to get away with merely absorbing the energy of an entire supernova to power your little ship.
Title: Re: Theoretical FTL
Post by: KelvinZero on 04/18/2021 09:56 am
There is a fantastic difference between something that is probably impossible (or merely not proven possible) within the laws of physics and something that merely needs a jupiters-mass-worth of energy.

I have no idea if that paper is valid but it would totally change physicists' perspective on the universe if true. And you don't need to move an entire ship either. It changes everything if you can move a single bit of information.

Look at the excitement caused by discovering a tiny anomaly in muon behaviour. Of course this would be significant.
Title: Re: Theoretical FTL
Post by: Frogstar_Robot on 04/18/2021 10:33 am
There is a fantastic difference between something that is probably impossible (or merely not proven possible) within the laws of physics and something that merely needs a jupiters-mass-worth of energy.

No, not really. Unless you mean as in a "fantasy". And it's 100s of times the mass of Jupiter.

Using up a Jupiter to send 1 bit would be quite useless, it is absurd to suggest otherwise. There are plenty of things we know for sure we can do, but still don't find it practical. e.g. supersonic passenger liners.

Saying that something would revolutionize physicists understanding of the Universe is fantastically different to saying it would make any difference to the person on the street.
Title: Re: Theoretical FTL
Post by: rakaydos on 04/19/2021 12:51 pm
There is a fantastic difference between something that is probably impossible (or merely not proven possible) within the laws of physics and something that merely needs a jupiters-mass-worth of energy.

No, not really. Unless you mean as in a "fantasy". And it's 100s of times the mass of Jupiter.

Using up a Jupiter to send 1 bit would be quite useless, it is absurd to suggest otherwise. There are plenty of things we know for sure we can do, but still don't find it practical. e.g. supersonic passenger liners.

Saying that something would revolutionize physicists understanding of the Universe is fantastically different to saying it would make any difference to the person on the street.
1 bit of information, at FTL, can test various time travel hypothosis implied by relativity.
Title: Re: Theoretical FTL
Post by: KelvinZero on 04/21/2021 09:23 pm
Looks like it has hit the (almost) the mainstream :)

https://www.youtube.com/watch?v=Vk5bxHetL4s
Title: Re: Theoretical FTL
Post by: RotoSequence on 04/22/2021 04:07 am
Looks like it has hit the (almost) the mainstream :)

I'm still not seeing how a warp drive is anything more than a fancy box that's particularly heavy (has high, black-hole like mass/energy density) in specific places.
Title: Re: Theoretical FTL
Post by: rakaydos on 04/22/2021 09:29 am
Looks like it has hit the (almost) the mainstream :)

I'm still not seeing how a warp drive is anything more than a fancy box that's particularly heavy (has high, black-hole like mass/energy density) in specific places.
My impression is that the "box" is made of spacetime, and thus can cheat relativity.

Though the quote predates the physics behind it, "Space is the thing that is moving!"
Title: Re: Theoretical FTL
Post by: Oberonian on 04/23/2021 03:39 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
Title: Re: Theoretical FTL
Post by: rakaydos on 04/23/2021 05:38 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.
Title: Re: Theoretical FTL
Post by: Oberonian on 04/23/2021 06:20 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.

What was....the Dr Lentz relativity calculation ?
Title: Re: Theoretical FTL
Post by: rakaydos on 04/24/2021 03:19 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.

What was....the Dr Lentz relativity calculation ?
"Your latter claim", the trillion trillion trillion watts, 30 orders of magnatude bigger than modern fission reactors. reducing the power costs by 1000 only drops that to 26 orders of magnatude bigger than our largest nuclear plants. Reducing the power costs to a trillionth of what they are calculated to be, and you still need 1,000,000,000,000,000,000 big nuclear reactors running at once to power it.
Title: Re: Theoretical FTL
Post by: KelvinZero on 04/24/2021 04:13 pm
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.
Title: Re: Theoretical FTL
Post by: Oberonian on 04/24/2021 04:19 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.

What was....the Dr Lentz relativity calculation ?
"Your latter claim", the trillion trillion trillion watts, 30 orders of magnatude bigger than modern fission reactors. reducing the power costs by 1000 only drops that to 26 orders of magnatude bigger than our largest nuclear plants. Reducing the power costs to a trillionth of what they are calculated to be, and you still need 1,000,000,000,000,000,000 big nuclear reactors running at once to power it.

 I found this about dr Lentz,


Erik Lentz:

“This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering,” Dr. Lentz said.

“The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today’s technologies, such as a large modern nuclear fission power plant. Then we can talk about building the first prototypes.”

“The energy required for this drive traveling at light speed encompassing a spacecraft of 100 m (328 feet) in radius is on the order of hundreds of times of the mass of Jupiter.”

“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”

“Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”

http://www.sci-news.com/physics/superluminal-travel-09448.html
Title: Re: Theoretical FTL
Post by: rakaydos on 04/24/2021 10:26 pm
I am really surprised that nobody is talking about this.
This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.

Because it would still require huge amounts of energy

Quote
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says.

"The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."

Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.

Can you show a precise calculation of the latter claim of yours ?

Radius of Starship is 4,5 meters.

So how much less would that need...being 500 x smaller as the referred 100 m radius ship  ?

Apollo would have been just 2 415th of that behemoth.
That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.

What was....the Dr Lentz relativity calculation ?
"Your latter claim", the trillion trillion trillion watts, 30 orders of magnatude bigger than modern fission reactors. reducing the power costs by 1000 only drops that to 26 orders of magnatude bigger than our largest nuclear plants. Reducing the power costs to a trillionth of what they are calculated to be, and you still need 1,000,000,000,000,000,000 big nuclear reactors running at once to power it.

 I found this about dr Lentz,


Erik Lentz:

“This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering,” Dr. Lentz said.

“The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today’s technologies, such as a large modern nuclear fission power plant. Then we can talk about building the first prototypes.”

“The energy required for this drive traveling at light speed encompassing a spacecraft of 100 m (328 feet) in radius is on the order of hundreds of times of the mass of Jupiter.”

“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”

“Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”

http://www.sci-news.com/physics/superluminal-travel-09448.html
you have those last two quotes in the wrong order. even after reducing by an unimaginable amount (serously, approaching an actual google, 10^100, down to 10^30), the energy costs are still comparable to the mass of jupiter
Title: Re: Theoretical FTL
Post by: Argonaut on 05/08/2021 02:45 pm
“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”

The quote order is correct

How are modern nuclear reactors producing energy comparable to mass of Jupiter?
Title: Re: Theoretical FTL
Post by: rakaydos on 05/10/2021 09:14 am
“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”

The quote order is correct

How are modern nuclear reactors producing energy comparable to mass of Jupiter?

The "quote order" I was referring to was these two:

Quote
“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”

“Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”

The way it was posted, it implied there was some discovery since the original quote that reduced the cost 30 orders of magnatude BELOW a fission plant, and that also seemed to be the posters (false) assumption.
Title: Re: Theoretical FTL
Post by: aceshigh on 05/11/2021 07:26 pm
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.

I don´t think it would make a difference at all.

It has been shown that even at sublight speeds, a civilization spreading from star to star, then building colonies at planets of that star, then spreading FROM that star after 100 years or more would still be able to colonize an entire galaxy in a timeline that is nothing compared to the age of the galaxy.

Even if it take 1000 years for a new colony to be able to send new colony ships around...  it doesn´t even mean you need to wait 1000 years for the second wave... the home planet can still send new colony ships further and further, every 100 years, while waiting for the already colonized star systems to build their own colony ships...
Title: Re: Theoretical FTL
Post by: gaballard on 05/18/2021 06:50 pm
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.

Too many political and economic factors working against a species ever accomplishing such a feat. Think about it - for all the billions of species on Earth, only one can go to space, and of that one species, a small percentage of its 7B population have the resources to create a space program, and of countries with space programs, the popular sentiment is against them in the long run (which is why the U.S., for instance, hasn't been out of LEO since Apollo got canceled). I don't think many possible solutions to the Fermi paradox account for a civilization that ventures into the stars, and then stops.
Title: Re: Theoretical FTL
Post by: dustinthewind on 05/18/2021 10:06 pm
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.

Once one masters manipulation of space timemaybe  it is possible to not only make FTL travel but FTL communications by manipulating the coordinate speed of light at which point it might be more desired to communicate that way rather than mainly use the electromagnetic spectrum and we aren't even using the proper radios, space time radios.  Maybe they have enemies and it isn't optimal to make ones presence known. Maybe they don't want their non space fairing colonists to know in the way startrek had their way of noninterference with nonspacefaring species but some would anyways im sure.

Maybe there is also pressure to find new species on the verge of becoming space faring and tweaking their DNA to be more like yours, if they have traits similar to yours and adaptations that would be beneficial to your species as allies or upgrades.  Imagine the pressure of a species that has existed that long to keep their species healthy with out the pressures of necessary evolution.  Sure we try and work around it but its a constant struggle I am guessing, eventually even for ourselves.  Genetic compatibility might not be possible with out tweaking though and might take some time.  Same as for genetic drift where eventually a species becomes 2 separate species but undoing that.  If they were, would they want them to know?  My imagination takes me to strange places some times

How sure are we that we can accurately detect for life on most earth sized planets on near by stars?
Title: Re: Theoretical FTL
Post by: raketa on 05/18/2021 10:25 pm
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.

Once one masters manipulation of space timemaybe  it is possible to not only make FTL travel but FTL communications by manipulating the coordinate speed of light at which point it might be more desired to communicate that way rather than mainly use the electromagnetic spectrum and we aren't even using the proper radios, space time radios.  Maybe they have enemies and it isn't optimal to make ones presence known. Maybe they don't want their non space fairing colonists to know in the way startrek had their way of noninterference with nonspacefaring species but some would anyways im sure.

Maybe there is also pressure to find new species on the verge of becoming space faring and tweaking their DNA to be more like yours, if they have traits similar to yours and adaptations that would be beneficial to your species as allies or upgrades.  Imagine the pressure of a species that has existed that long to keep their species healthy with out the pressures of necessary evolution.  Sure we try and work around it but its a constant struggle I am guessing, eventually even for ourselves.  Genetic compatibility might not be possible with out tweaking though and might take some time.  Same as for genetic drift where eventually a species becomes 2 separate species but undoing that.  If they were, would they want them to know?  My imagination takes me to strange places some times
automatic docking just Soyuz and Dragon 2,  Orbital don't have that expertise, Boing  has to show it with Starliner.
Title: Re: Theoretical FTL
Post by: KelvinZero on 05/19/2021 09:42 am
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.

I don´t think it would make a difference at all.
It would make an incredible difference.
Sure.. if interstellar races are as common as one every few galaxies, we should have seen many populated galaxies by now with dyson swarms or managed supernovae or whatever, and FTL would make no difference to the question of if life is out there because we would already have seen it.

We are in universe B though, without that confirmation. If FTL exists I would say that is an argument that there has been no moderately successful interstellar species not just within the observable universe but also in a probably much larger volume outside the observable universe, depending how many times faster than light our hypothetical FTL is.

By moderately successful, I just mean R-value slightly above 1, just like a moderately successful pandemic.

Even if it take 1000 years for a new colony to be able to send new colony ships around...  it doesn´t even mean you need to wait 1000 years for the second wave... the home planet can still send new colony ships further and further, every 100 years, while waiting for the already colonized star systems to build their own colony ships...
There is a decent chance you are quoting me there. I have made that point a number of times here before. In fact if we ever spot life in the universe I expect something like an expanding sphere of colonised systems, possibly as obvious as dismantled or obscured stars. That sphere could be expanding at a decent fraction of the speed of light, the fastest practicable within the laws of this universe, because the rim would be it's own niche ecology where natural selection always selects the faster variant. Also a simple optical illusion would mean that if the fastest practicable speed of colonisation is 99% the speed of light, then we will see the wall of colonisation approach us as if at 100x the speed of light. If we first spot it 10,000 lightyears away, a century later it will arrive at our doorstep.
Title: Re: Theoretical FTL
Post by: rakaydos on 05/19/2021 12:01 pm
if we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.

There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.

And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.
Title: Re: Theoretical FTL
Post by: rsdavis9 on 05/19/2021 01:13 pm
if we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.

There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.

And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.

I personally like (in addition to your points) the idea of the fact the moon is the same angular size as the sun we have had these rare things called total eclipses of the sun. This stimulated math and science development because of the apocalyptic nature of them and the ability to predict them went hand and hand.
Title: Re: Theoretical FTL
Post by: sghill on 05/19/2021 02:00 pm
OK. I'll bite.

A few great points have been brought up about why we haven't seen signatures of FTL-capable civilizations.

I'll through in three points of my own (plus a bonus fourth point):

1) I brought up a point in a different thread that we may be looking right at those signatures an have not recognized them for what they are.  https://forum.nasaspaceflight.com/index.php?topic=19421.msg2184874#msg2184874 For example, we may have over a century of photographic evidence capturing the space-time wake a functioning Alcubierre drive leaves behind it, and we simply haven't looked (see simulated bottom photo below of what a wake would look like against a background starfield). An AI could easily look for this pattern on millions of old digitized plates if someone took the time to setup a project. Similarly, a star that vanishes without a trace (and there are a few) could be a civilization at work absorbing the star or creating a Dyson sphere. But the odds of us seeing the before and after moments such a civilization does such a feat are preposterously low, IMHO, unless Type II and Type III civilizations are both common and wide-spread.

2) Any species is going to be limited by its tolerances to its environment. I've always had a problem with the Kardashev scale because it doesn't account for the frailty of the species' harnessing energy on solar and galactic scales.  In other words: What the f-ck would they do with all that energy?!? Other than travelling with Alcubierre drives, there isn't much a species could do out there with stellar levels of power harnessing that wouldn't also kill themselves. War? OK, I guess, but we'd see other signs of an interstellar war releasing stellar or galactic levels of energy.

3) We got quieter within moments of broadcasting our existence into space. Detection of other species may be limited to passive observation. Personally, I think this is the most likely explanation of the Fermi Paradox. Space is big and space faring species are rare even if they make it through the Great Filters all the way up to becoming multi-solar (at least within 80 light years from Earth). https://waitbutwhy.com/2014/05/fermi-paradox.html Our problem is that with a sample size of one, we don't know which side of the Great Filter we are on.

4) I've seen postulated that in a "Prisoner's Dilemma" universe of colonizing and competing species, the only way to survive is to colonize at ever increasing speeds. The preposterous conclusion therefore is that super-survivor (or super-predator depending on your perspective) multi-solar species will eventually encounter each other and expand their civilizations at nearly the speed of light in order to not be overtaken by the other species, and we on Earth would be completely unaware they even exist until colonization overtakes our solar system. This concept may have been mentioned by David Brin in his novel "Existence" (Which is in my mind one of the finest science fiction novels ever written. Do yourselves a favor and read it because it is entirely about the Fermi Paradox). I'll also mention that Brin is a member and occasional poster on NSF! https://www.amazon.com/Existence-David-Brin-ebook/dp/B0079XPMQS/ref=sr_1_12?dchild=1&keywords=david+brin&qid=1621432438&sr=8-12
Title: Re: Theoretical FTL
Post by: Frogstar_Robot on 05/19/2021 02:07 pm
if we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.

There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.

And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.

I personally like (in addition to your points) the idea of the fact the moon is the same angular size as the sun we have had these rare things called total eclipses of the sun. This stimulated math and science development because of the apocalyptic nature of them and the ability to predict them went hand and hand.

Solar eclipses were not predictable until Newton's laws, and Halley first predicted the eclipse in 1715. That's well after a lot of math and science and development and well after solar eclipses were regarded as "apocalyptic" portents.

However, I think it is true to say that the desire to predict phases of the Moon, and more generally events such as tides, solstice, equinox, etc, did spur math and scientific inquiry. The Moon has an intriguing role in our civilization development, but it's hard to say it was a necessary requirement. There is plenty of astronomical stuff to study, and I think such development would take place even without a large moon.

I have a hunch our large moon has played an important role in stabilizing the rotation of the Earth, and maybe tides have played an important role in evolution. With a sample of one, it's hard to tell.
Title: Re: Theoretical FTL
Post by: rsdavis9 on 05/19/2021 02:19 pm


Solar eclipses were not predictable until Newton's laws, and Halley first predicted the eclipse in 1715. That's well after a lot of math and science and development and well after solar eclipses were regarded as "apocalyptic" portents.

However, I think it is true to say that the desire to predict phases of the Moon, and more generally events such as tides, solstice, equinox, etc, did spur math and scientific inquiry. The Moon has an intriguing role in our civilization development, but it's hard to say it was a necessary requirement. There is plenty of astronomical stuff to study, and I think such development would take place even without a large moon.

I have a hunch our large moon has played an important role in stabilizing the rotation of the Earth, and maybe tides have played an important role in evolution. With a sample of one, it's hard to tell.

Saros cycle is pretty good at predicting them approximately. Isn't there evidence that the Mayans could do it?
Title: Re: Theoretical FTL
Post by: sanman on 12/06/2021 05:18 am
OK. I'll bite.

A few great points have been brought up about why we haven't seen signatures of FTL-capable civilizations.

I'll through in three points of my own (plus a bonus fourth point):

1) I brought up a point in a different thread that we may be looking right at those signatures an have not recognized them for what they are.  https://forum.nasaspaceflight.com/index.php?topic=19421.msg2184874#msg2184874 For example, we may have over a century of photographic evidence capturing the space-time wake a functioning Alcubierre drive leaves behind it, and we simply haven't looked (see simulated bottom photo below of what a wake would look like against a background starfield). An AI could easily look for this pattern on millions of old digitized plates if someone took the time to setup a project. Similarly, a star that vanishes without a trace (and there are a few) could be a civilization at work absorbing the star or creating a Dyson sphere. But the odds of us seeing the before and after moments such a civilization does such a feat are preposterously low, IMHO, unless Type II and Type III civilizations are both common and wide-spread.

Civilizations exist across a span of space and of time. Even if we were to use AI to diligently scan the heavens, we'd only be limited to scanning the light cone for events within a proximity radius that made them observable to us.

Quote
2) Any species is going to be limited by its tolerances to its environment. I've always had a problem with the Kardashev scale because it doesn't account for the frailty of the species' harnessing energy on solar and galactic scales.  In other words: What the f-ck would they do with all that energy?!? Other than travelling with Alcubierre drives, there isn't much a species could do out there with stellar levels of power harnessing that wouldn't also kill themselves. War? OK, I guess, but we'd see other signs of an interstellar war releasing stellar or galactic levels of energy.

This sounds more like an aspect of the Great Filter. At some point, a civilization's technical capabilities may become powerful enough to result in their destruction, and may even make it inevitable. We may have already reached that level with the advent of nuclear weapons.


Quote
3) We got quieter within moments of broadcasting our existence into space. Detection of other species may be limited to passive observation. Personally, I think this is the most likely explanation of the Fermi Paradox. Space is big and space faring species are rare even if they make it through the Great Filters all the way up to becoming multi-solar (at least within 80 light years from Earth). https://waitbutwhy.com/2014/05/fermi-paradox.html Our problem is that with a sample size of one, we don't know which side of the Great Filter we are on.

Which probably argues for the dispersal of humanity across as many self-sustaining habitats as possible, in order to maximize the chances of survival.

Quote
4) I've seen postulated that in a "Prisoner's Dilemma" universe of colonizing and competing species, the only way to survive is to colonize at ever increasing speeds. The preposterous conclusion therefore is that super-survivor (or super-predator depending on your perspective) multi-solar species will eventually encounter each other and expand their civilizations at nearly the speed of light in order to not be overtaken by the other species, and we on Earth would be completely unaware they even exist until colonization overtakes our solar system. This concept may have been mentioned by David Brin in his novel "Existence" (Which is in my mind one of the finest science fiction novels ever written. Do yourselves a favor and read it because it is entirely about the Fermi Paradox). I'll also mention that Brin is a member and occasional poster on NSF! https://www.amazon.com/Existence-David-Brin-ebook/dp/B0079XPMQS/ref=sr_1_12?dchild=1&keywords=david+brin&qid=1621432438&sr=8-12

A Prisoner's Dilemma itself implies a rational deliberate decision-making process, while simple Darwinism compels a Survival of the Fittest regardless. Whether it's a civilization deliberately creating Von Neumann machines to keep swarming outwards, or whether it's said swarm of Von Neumann machines continuing on their own long after any guiding creators have perished, Nature Abhors a Vacuum.

Playing a board game like Risk with its simple rules always narrows the field of competition down to the biggest players. But in the more complex rules of real life, civilizations may themselves fracture and break up, etc.
Title: Re: Theoretical FTL
Post by: kkattula on 12/06/2021 06:17 am
if we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.

There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.

And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.

I personally like (in addition to your points) the idea of the fact the moon is the same angular size as the sun we have had these rare things called total eclipses of the sun. This stimulated math and science development because of the apocalyptic nature of them and the ability to predict them went hand and hand.


Or lots of clouds.

If an intelligent species lived on a planet with permanent cloud cover, maybe they'd never even conceptualize a broader universe. 1

That would also make even theorising Newtonian gravity & mechanics pretty difficult.

1. Douglas Adams, 1982
Title: Re: Theoretical FTL
Post by: JohnFornaro on 12/06/2021 12:31 pm
If an intelligent species lived on a planet with permanent cloud cover, maybe they'd never even conceptualize a broader universe.

There's an evo-bio argument that the Moon's existence and visibility caused human consciousness to evolve.

2L2L

[too lazy to link]
Title: Re: Theoretical FTL
Post by: sanman on 02/18/2024 07:10 am
Stephen Wolfram explains Time Dilation (in his own way):

https://www.youtube.com/watch?v=0-fT_el3SGE
Title: Re: Theoretical FTL
Post by: Alex_O on 03/06/2024 02:31 pm
Fast flows of matter.

Abstract
The sun can be a source of superluminal signals and people can look for some correlations in the archives right now.
If nature allows matter to move faster than the speed of light, then how is this possible? And how do you find out about this?

Let's say that there are a million developed civilizations in the universe, but only one (out of a million) civilization was able to reveal the secret of FTL flights. How did she do it? Obviously, they were lucky; local astronomers saw the FTL flow of matter. Or the propagation of a signal (wave) at superluminal speed. And all other civilizations were unlucky, given the limited lifespan of a civilization’s existence.

Is this a good hypothesis? We have a term probability! Go ahead

This is, of course, physics, and this physics occurs in the universe. But somehow rarely, for example, during cosmic catastrophes, supernova explosions, etc., when extreme releases of energy appear. These could be jets, and the term lucky means that a fast jet flew nearby, safe for civilization itself.

Here's a good example based on observations from the Hubble Telescope.
https://www.youtube.com/watch?v=1hMZz0XmPZI (https://www.youtube.com/watch?v=1hMZz0XmPZI)

Pulsar and nebula
Quote
This episode of the Hubblecast explores striking new Hubble observations of a variable star known as RS Puppis. This star is growing brighter and dimmer as it pulsates over a period of five weeks. These pulsations have created a stunning example of a phenomenon known as a light echo, where light appears to reverberate through the foggy environment around the star.
Description - https://hubblesite.org/contents/media/images/2013/51/3263-Image.html (https://hubblesite.org/contents/media/images/2013/51/3263-Image.html)
Observation - https://archive.stsci.edu/proposal_search.php?mission=hst&id=11715 (https://archive.stsci.edu/proposal_search.php?mission=hst&id=11715)
Observation epoch = 2010 from March 25 to April 29, 468 seconds, 3 times a day

We see a nebula, there is some probability that an ultra-fast flow of matter will fly through the nebula, and people will see a trace of a “black stripe”.
It will be a solid observational fact that supervelocity motions of matter are physically possible..

But what is the probability? And what can you come up with to increase the likelihood?

For example, 100 or 1000 years ago a supernova exploded near the nebula and there was a short superluminal jet and Hubble can see a black streak. Taking into account the distance from the earthly observer to the globule and supernova, nature provides an extremely small window for Hubble.

Hubble himself looked at the globule somehow poorly - the era of observations - in 2010 from March 25 to April 29, for 468 seconds, 3 times a day. Agree that this is very little, right? There just aren’t that many stars in the vicinity of the globule; you have to wait millions of years to catch a useful signal.

The second problem is that we can see a black stripe, but only after 100 or 1000 years will we learn about the supernova explosion and this is a very big problem.

What if the superluminal flow was somehow very fast? And a developed civilization - in order to catch superlight, must build a telescope with performance characteristics 15 orders of magnitude better than Hubble’s, and allocate resources for continuous observations for a million years? And only with such investments can one expect a useful result. I omitted the questions - what is a black bar. Such a band can appear from additional dimensions of the universe and Hubble is needed for a multidimensional universe. And it takes incredible luck to detect such an event; the life cycle of an advanced civilization may not be enough, right?

We have the term probability, we have the level of development of science, and we can discuss ideas on how to increase the probability.

Possible ideas for astronomers to record natural fast flows of matter. For example, superluminal events can occur during extreme manifestations of energy on a cosmological scale, such as during supernova explosions. And nature gives people the opportunity to observe these fast phenomena through the registration of certain superluminal “signals”. Superluminal phenomena can then be reproduced in the laboratory and in practical design.

Let's make a table. Source - detector.
 
DetectorSource
PulsarQuasar
PulsarSupernova
SunUniverse
CometsSun
Sensor on the planet   .Sun

Omitting the details, we can note that our civilization has a powerful source of energy - the Sun, on which there are solar flares and times of release of high energies.

You can come up with two sensors - a solar activity sensor and some kind of sensor like a glass with water and a Brownian particle. The video camera observes the track of the particle in the glass and there is a useful short time interval - from 8 minutes. We need to catch the correlation between the sensor on the shadow side and the sensor on the sunny side. To increase the probability, if a superluminal signal from the sun is somehow faster than the speed of light by many orders of magnitude, a sensor on the shadow side must measure the track of a Brownian particle at certain picosecond intervals. It is clear that a shadow sensor can be built on different physical principles. It's a good idea that both sensors should be very fast.

Another example.

Let's say that a conventional particle of matter can make superluminal motion. What can the observer see? For example, observing the aurora, the flow of solar wind in the atmosphere of the planet. It could be some kind of tracer. Like in this video.
https://www.youtube.com/watch?v=pN1g64ngGg0 (https://www.youtube.com/watch?v=pN1g64ngGg0)

There is a frequency of flashes and there is a track length of light and dark.

The sum of light lengths and times does not exceed the speed of light limit. I mean, if you count the timings according to the light part of the tracer path, then everything is fine. Superlight only due to the dark part, as the sum of the light and dark parts.

Is the idea clear? If the particle flies slowly, then the observer sees a continuous, bright track.

Another example is a basketball bouncing on a glass, transparent floor. The observer is below, under the glass. He sees the ball only at the moment it touches the floor. This is an example of some kind of multidimensional physics, where there is a multidimensional reality. While the ball is in the air, the observer may think that the ball has entered another dimension, another reality. But by studying the contact patch of the ball with the floor and timings, you can come up with an idea about the physical properties of reality in additional dimensions. The task comes down to studying the track - the marks of the ball on the glass/screen.

And the last example is that it is possible that the planet is not a very convenient place for observations. Perhaps we should put sensors on the Moon. And after a hundred/thousand years of continuous observations of various physical phenomena, at high frequencies, a reliable result can be obtained.

Summary.
People have the Sun, and if superluminal flows of matter are possible, then you can look for correlations in the archives of solar astronomy + other archives where there is data from fast sensors. And perhaps faster solar activity sensors are needed. Faster than known ones by 15 orders of magnitude.

This example is completely unsuitable.
The eruption of fire on the Sun was filmed by a Novosibirsk astrophotographer - look at extraterrestrial footage
 (https://ngs.ru/text/science/2023/10/06/72783821/)
(https://cdn.iportal.ru/preview/news/articles/3026c85cd5a870d2279a28e0e6c9812e0ab835b7_666_444_c.jpg.webp-portal)

Quote
It took him about an hour to create the footage.
It is clear that the exposure time should be approximately 15 orders of magnitude less.
Title: Re: Theoretical FTL
Post by: CoolScience on 03/06/2024 10:18 pm
Is this a good hypothesis?
No. A good hypothesis is falsifiable. Your hypothesis boils down to "maybe some FTL stuff already exists and is moving around." This is simply too broad and poorly defined to be a scientific hypothesis.

The rest of what you said before this is just wild assumptions as a pseudo-justification for the hypothesis, they don't add anything.

The rest of your post after this is a combination of irrelevant nonsense, and demonstrations that you have never bothered to do basic research on the topic of what FTL means in the context of special relativity, and other basic relevant topics.

FTL means literal time travel. you seem unaware of this, and make a bunch of arguments that make no sense as a result. a particle travelling backwards in time from a distance would like like it is just travelling backwards no "faster camera" would detect this as interesting, it would just look like something moving in the opposite direction, you would need to have something tell you about the illogical reversal of causality, which a line moving through a nebula wouldn't.

Also, it is trivial for a particle beam (such as that from a pulsar) to "appear" to be moving FTL, but this is just like motion of a shadow, the pulsar is rotating, and the fact that tracking that motion along a surface many lightyears away is FTL along that surface is simply meaningless, it just means that each particle was travelling below the speed of light, but in different directions for many years.
Title: Re: Theoretical FTL
Post by: Alex_O on 03/07/2024 04:50 am
Is this a good hypothesis?
No. A good hypothesis is falsifiable. Your hypothesis boils down to "maybe some FTL stuff already exists and is moving around." This is simply too broad and poorly defined to be a scientific hypothesis.
Yes. My idea is based on solid physics and solid observational facts.

1st observational fact. There is a developed civilization on planet Earth that has scientific knowledge. And the known civilization is a new version.

2nd observational fact. From the history of science it is known that all modern knowledge was created based on the results of astronomical observations.

3rd observational fact. The mystery of fast, applied space logistics, travel faster than the speed of light, has not yet been revealed.

4th observational fact. Prominent theories report that engines for moving matter at superluminal speeds, in practical designs, require the use of very high energies, equivalent to stellar masses.

I made a bold generalization and justified the research program. This is a proposal for falsification.

From the first observational fact it follows that in the universe there are many developed civilizations.

From the history of the development of civilizations on planet Earth, a strict observational fact follows that any civilization has a life cycle duration.

From astronomical observations there are many observational facts about the manifestation of extreme energy flows.
I add 2+2 and get the conclusion that we all need a lot of luck. That the universe is large, the lifespan of civilizations is short - and there is a theory of probability. That someone will simply be unlucky to discover the secret, since the stars are poorly positioned in the sky.

  And then, I'm just trying to increase the probability. Recently, people have expanded their horizons of knowledge by observing pulsars in the light of relic gravitational waves.

This is an observational fact, and I boldly discuss the cosmological list of natural Sources and Detectors of superluminal flows of matter (or signals) and unexpectedly, but extremely logically, I find our Sun in this list.

And everything becomes extremely simple - there are extremely high manifestations of energy on the Sun and the earthly observer has exactly 8 minutes. Not 100 or 1000 years, as in the case of the black stripe against the background of the light echo in the nebula, but 8 wonderful minutes. And you just need to build two types of sensors, but they must be very fast sensors.

And you need to choose a good place to locate the sensors, because a superluminal signal from a Solar flare can simply fly past the Earth, for example, perpendicular to the Earth-Sun vector. The moon is a good place for a sensor, especially this one - https://en.wikipedia.org/wiki/524522_Zoozve

Zoozve! The very good place for FTL sensor.

The rest of what you said before this is just wild assumptions as a pseudo-justification for the hypothesis, they don't add anything.
The rest of your post after this is a combination of irrelevant nonsense, and demonstrations that you have never bothered to do basic research on the topic of what FTL means in the context of special relativity, and other basic relevant topics.
==
There are some very good messages here in this thread from flux_capacitor starting from the post
https://forum.nasaspaceflight.com/index.php?topic=13542.msg1701797#msg1701797

The negative gravity speculation was just that, but speculating that dark matter
  ...
Good catch! In the next posts I will detail this idea of primordial antimatter lacking, parallel universes and negative gravity in cosmology. A cosmological model exists, exactly behaving how you said, and has been published though peer review with recent (2014-2015) progress.

In these posts, flux_capacitor actually described the history of the development of science that is trying to uncover the mystery of superluminal fast flights.

FTL means literal time travel. you seem unaware of this, and make a bunch of arguments that make no sense as a result. a particle travelling backwards in time from a distance would like like it is just travelling backwards no "faster camera" would detect this as interesting, it would just look like something moving in the opposite direction, you would need to have something tell you about the illogical reversal of causality, which a line moving through a nebula wouldn't.

I'm not trying to discuss time travel. But I can show the idea of a sensor for recording time waves that can transmit impulse from the future to the past. But this will be offtopic.

Also, it is trivial for a particle beam (such as that from a pulsar) to "appear" to be moving FTL, but this is just like motion of a shadow, the pulsar is rotating, and the fact that tracking that motion along a surface many lightyears away is FTL along that surface is simply meaningless, it just means that each particle was travelling below the speed of light, but in different directions for many years.

Revisiting a Core–Jet Laboratory at High Redshift: Analysis of the Radio Jet in the Quasar PKS 2215+020 at z = 3.572
https://www.mdpi.com/2218-1997/10/2/97
Quote
Here, we analyse archival multi-epoch VLBI imaging data at five frequency bands from 1.7
 to 15.4  GHz covering a period of more than 25 years from 1995 to 2020. We constrain apparent proper motions of jet components in PKS 2215+020 for the first time. Brightness distribution modeling at 8 GHz reveals a nearly 0.02 mas yr−1 proper motion (moderately superluminal with apparently two times the speed of light)...


Are you talking about this? The apparent motion in the image at the telescope's focus (or the phase velocity of the EM wave) can be faster than the speed of light, and as the article showed, there is valuable information in this data.

Title: Re: Theoretical FTL
Post by: CoolScience on 03/07/2024 07:50 pm
Is this a good hypothesis?
No. A good hypothesis is falsifiable. Your hypothesis boils down to "maybe some FTL stuff already exists and is moving around." This is simply too broad and poorly defined to be a scientific hypothesis.
Yes. My idea is based on solid physics and solid observational facts.
As I show below this is false, it is not based on facts, and even if this wasn't false, it still remains unfalsifiable.

1st observational fact. There is a developed civilization on planet Earth that has scientific knowledge. And the known civilization is a new version.
...
From the first observational fact it follows that in the universe there are many developed civilizations.
The first fact would be true but irrelevant, the following statement later is false. This does not logically follow. It does remain irrelevant.

2nd observational fact. From the history of science it is known that all modern knowledge was created based on the results of astronomical observations.
False. The vast majority of knowledge is not from astronomical observations, and of particular relevance to the topic of this thread, special relativity was developed from, and has been thoroughly tested by purely ground based experiments. (astronomical observations confirming it also exist, but are not what got the theory started.)

3rd observational fact. The mystery of fast, applied space logistics, travel faster than the speed of light, has not yet been revealed.
This is false because it implies the false claim that FTL is possible. It is not, it cannot be "revealed" because it does not and cannot logically exist/

4th observational fact. Prominent theories report that engines for moving matter at superluminal speeds, in practical designs, require the use of very high energies, equivalent to stellar masses.
Also false, actual physics theories say that FTL is impossible, creates logical contradictions due to time travel, and no amount of energy can ever make it possible.

I made a bold generalization and justified the research program. This is a proposal for falsification.
No, you said a bunch of nonsense, and suggested an experiment that is not possible to perform, would not provide positive evidence if the observation you were looking for was seen, because the observation can be more easily explained without FTL, and there is no way to ever get negative proof, just infinite "it is random so just keep looking." This is what not falsifiable means, you cannot prove a negative, so there is no way to prove your claim wrong by your claimed experiment. (It is instead wrong by being nonsense and inconsistent.)

  And then, I'm just trying to increase the probability. Recently, people have expanded their horizons of knowledge by observing pulsars in the light of relic gravitational waves.
The probability is zero. You are begging people to waste time doing research that is fundamentally illogical and inconsistent, and cannot produce the result you wish for.

In these posts, flux_capacitor actually described the history of the development of science that is trying to uncover the mystery of superluminal fast flights.
Complete misrepresentation. further posts down pointed out misunderstandings flux_capacitor had. Again you are staring by assuming FTL exists. This is False.

FTL means literal time travel. you seem unaware of this, and make a bunch of arguments that make no sense as a result. a particle travelling backwards in time from a distance would like like it is just travelling backwards no "faster camera" would detect this as interesting, it would just look like something moving in the opposite direction, you would need to have something tell you about the illogical reversal of causality, which a line moving through a nebula wouldn't.

I'm not trying to discuss time travel. But I can show the idea of a sensor for recording time waves that can transmit impulse from the future to the past. But this will be offtopic.
What about the bolded statement above is unclear? If you are discussing FTL, you are discussing time travel. Ignoring this fact, just means that you refuse to have a logical discussion. The details on why FTL is time travel can be easily found through your favorite search engine.

Revisiting a Core–Jet Laboratory at High Redshift: Analysis of the Radio Jet in the Quasar PKS 2215+020 at z = 3.572
https://www.mdpi.com/2218-1997/10/2/97
Quote
Here, we analyse archival multi-epoch VLBI imaging data at five frequency bands from 1.7
 to 15.4  GHz covering a period of more than 25 years from 1995 to 2020. We constrain apparent proper motions of jet components in PKS 2215+020 for the first time. Brightness distribution modeling at 8 GHz reveals a nearly 0.02 mas yr−1 proper motion (moderately superluminal with apparently two times the speed of light)...


Are you talking about this? The apparent motion in the image at the telescope's focus (or the phase velocity of the EM wave) can be faster than the speed of light, and as the article showed, there is valuable information in this data.
Without clicking through, this seems to be referring to the type of effect that I was. Things that are very much NOT FTL can produce effects that would appear to be FTL if you do a naïve calculation. Even if you had a super camera happen to detect an "FTL" thing, it only means it is some effect like this, and would not demonstrate the actual existence of FTL.

edit: fixed missing "not"