Author Topic: Theoretical FTL  (Read 31882 times)

Offline colbourne

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Theoretical FTL
« 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.

Offline Eraser

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Re: Theoretical FTL
« Reply #1 on: 06/23/2008 10:08 AM »
No, gravitation equally affects on a matter and an antimatter.

Offline whitewatcher

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Re: Theoretical FTL
« Reply #2 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).
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Offline William Barton

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Re: Theoretical FTL
« Reply #3 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."

Offline cpcjr

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Re: Theoretical FTL
« Reply #4 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.

Offline scienceguy

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Re: Theoretical FTL
« Reply #5 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.
e^(pi)i = -1

Offline Martin FL

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Re: Theoretical FTL
« Reply #6 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? ;)
« Last Edit: 06/23/2008 09:34 PM by Martin FL »

Offline scienceguy

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Re: Theoretical FTL
« Reply #7 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
e^(pi)i = -1

Online hop

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Re: Theoretical FTL
« Reply #8 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.
« Last Edit: 06/24/2008 12:30 AM by hop »

Offline khallow

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Re: Theoretical FTL
« Reply #9 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.
Karl Hallowell

Offline TyMoore

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Re: Theoretical FTL
« Reply #10 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!)

Offline gospacex

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Re: Theoretical FTL
« Reply #11 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.

Offline colbourne

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Re: Theoretical FTL
« Reply #12 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 ?

Online hop

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Re: Theoretical FTL
« Reply #13 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.

Offline Suzy

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Re: Theoretical FTL
« Reply #14 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.

« Last Edit: 06/26/2008 06:13 AM by Suzy »

Offline Lampyridae

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Re: Theoretical FTL
« Reply #15 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.
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Offline scienceguy

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Re: Theoretical FTL
« Reply #16 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?
e^(pi)i = -1

Offline khallow

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Re: Theoretical FTL
« Reply #17 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.
Karl Hallowell

Offline Suzy

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Re: Theoretical FTL
« Reply #18 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):

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 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?

Offline Eerie

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Re: Theoretical FTL
« Reply #19 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.

Offline Suzy

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Re: Theoretical FTL
« Reply #20 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

Offline josh_simonson

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Re: Theoretical FTL
« Reply #21 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.

Offline gospacex

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Re: Theoretical FTL
« Reply #22 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.

Offline Eerie

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Re: Theoretical FTL
« Reply #23 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.

Offline Suzy

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Re: Theoretical FTL
« Reply #24 on: 07/29/2008 05:39 AM »
Discovery.com article, 28/7: "Warp Drive Engine Would Travel Faster Than Light".

Offline TyMoore

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Re: Theoretical FTL
« Reply #25 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!
« Last Edit: 07/29/2008 03:50 PM by TyMoore »

Offline ChevalierGuard

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Re: Theoretical FTL
« Reply #26 on: 07/29/2008 11:05 PM »
Kaluza Klein Theory...

CG

Offline khallow

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Re: Theoretical FTL
« Reply #27 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.
« Last Edit: 07/29/2008 11:46 PM by khallow »
Karl Hallowell

Offline ChevalierGuard

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Re: Theoretical FTL
« Reply #28 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






Offline colbourne

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Re: Theoretical FTL
« Reply #29 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.


Offline gospacex

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Re: Theoretical FTL
« Reply #30 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.

Offline khallow

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Re: Theoretical FTL
« Reply #31 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.
Karl Hallowell

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Re: Theoretical FTL
« Reply #32 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.
"You can't declare yourself the boss of a chicken farm when you've only got one egg."  - Chinese saying

Offline khallow

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Re: Theoretical FTL
« Reply #33 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).
« Last Edit: 08/02/2008 09:54 PM by khallow »
Karl Hallowell

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Re: Theoretical FTL
« Reply #34 on: 08/03/2008 01:33 AM »
Creation of Mini black holes?

and capturing virtual particles?

any thoughts, known papers, etc?

CG

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Re: Theoretical FTL
« Reply #35 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. 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.
« Last Edit: 08/03/2008 04:59 AM by khallow »
Karl Hallowell

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Re: Theoretical FTL
« Reply #36 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



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Re: Theoretical FTL
« Reply #37 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. 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.

Offline khallow

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Re: Theoretical FTL
« Reply #38 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. 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.
« Last Edit: 08/04/2008 10:35 PM by khallow »
Karl Hallowell

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Re: Theoretical FTL
« Reply #39 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

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Re: Theoretical FTL
« Reply #40 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. 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.
« Last Edit: 08/05/2008 08:23 AM by gospacex »

Offline sandrot

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Re: Theoretical FTL
« Reply #41 on: 08/13/2008 10:02 PM »
"Paper planes do fly much better than paper spacecrafts."

Offline colbourne

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Re: Theoretical FTL
« Reply #42 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

Offline JohnFornaro

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Re: Theoretical FTL
« Reply #43 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.
Sometimes I just flat out don't get it.

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Re: Theoretical FTL
« Reply #44 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.
JIMO would have been the first proper spaceship.

Offline colbourne

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Re: Theoretical FTL
« Reply #45 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 ?

Offline Joris

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Re: Theoretical FTL
« Reply #46 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?
JIMO would have been the first proper spaceship.

Offline colbourne

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Re: Theoretical FTL
« Reply #47 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

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Re: Theoretical FTL
« Reply #48 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.

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Re: Theoretical FTL
« Reply #49 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

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Re: Theoretical FTL
« Reply #50 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?
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Offline Cherokee43v6

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Re: Theoretical FTL
« Reply #51 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'.
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Re: Theoretical FTL
« Reply #52 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.

Offline Tass

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Re: Theoretical FTL
« Reply #53 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". 

Online KelvinZero

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Re: Theoretical FTL
« Reply #54 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

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Re: Theoretical FTL
« Reply #55 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?
Sometimes I just flat out don't get it.

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Re: Theoretical FTL
« Reply #56 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.

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Re: Theoretical FTL
« Reply #57 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
e^(pi)i = -1

Offline scienceguy

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Re: Theoretical FTL
« Reply #58 on: 12/06/2011 05:46 PM »
Oops! I realize the authors in those papers distinguish between negative inertial mass and negative gravitational mass.
e^(pi)i = -1

Offline RanulfC

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Re: Theoretical FTL
« Reply #59 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
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Offline alexw

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Re: Theoretical FTL
« Reply #60 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?
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Offline RanulfC

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Re: Theoretical FTL
« Reply #61 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

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Randy
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Offline JohnFornaro

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Re: Theoretical FTL
« Reply #62 on: 12/07/2011 02:01 PM »
Dang.  Foiled again!
Sometimes I just flat out don't get it.

Offline colbourne

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Re: Theoretical FTL
« Reply #63 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.

Offline Stormbringer

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Re: Theoretical FTL
« Reply #64 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.
When antigravity is outlawed only outlaws will have antigravity.

Offline colbourne

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Re: Theoretical FTL
« Reply #65 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.

Offline aceshigh

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Re: Theoretical FTL
« Reply #66 on: 03/23/2017 08:16 PM »

Online dustinthewind

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Re: Theoretical FTL
« Reply #67 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. 

Offline Spaniard

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Re: Theoretical FTL
« Reply #68 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.


Online dustinthewind

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Re: Theoretical FTL
« Reply #69 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. 

Offline MrHollifield

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Re: Theoretical FTL
« Reply #70 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.

Offline Bob012345

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Re: Theoretical FTL
« Reply #71 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


Offline flux_capacitor

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Re: Theoretical FTL
« Reply #72 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.

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #73 on: 07/12/2017 10:40 PM »
The problem of negative mass in cosmology

Physics is like a cake:



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.




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". JETP Letters. 5 (1): 24–26.

[2] 2017: 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". 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". 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". Reviews of Modern Physics. 29 (3): 423–428. doi:10.1103/RevModPhys.29.423.

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

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

[8] The Nobel prize in physics 2011
« Last Edit: 07/17/2017 10:12 AM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #74 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:





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



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". Astrophysics and Space Science. 354. doi:10.1007/s10509-014-2106-5.
« Last Edit: 07/17/2017 01:53 PM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #75 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:


                                            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:

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:

                                "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". 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". 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". Astrophysics and Space Science. 357 (67). doi:10.1007/s10509-015-2250-6.
« Last Edit: 07/15/2017 12:01 AM by flux_capacitor »

Online dustinthewind

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Re: Theoretical FTL
« Reply #76 on: 07/13/2017 12:32 AM »
...

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

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #77 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"?

« Last Edit: 07/14/2017 10:32 PM by flux_capacitor »

Offline gospacex

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Re: Theoretical FTL
« Reply #78 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).

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #79 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.

Offline gospacex

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Re: Theoretical FTL
« Reply #80 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.
« Last Edit: 07/13/2017 11:51 AM by gospacex »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #81 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:



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 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.

- Radiation pressure of electromagnetic fields on a conductive surface has been similarly detailed by Rodal, as the cyclic time-average of the energy density.

etc.

Pressure is an energy density and vice versa, in all aspects of physics.
« Last Edit: 07/14/2017 12:37 AM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #82 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. doi:10.1103/PhysRevD.66.045026.

[14] 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.
« Last Edit: 07/14/2017 11:36 AM by flux_capacitor »

Online dustinthewind

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Re: Theoretical FTL
« Reply #83 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. doi:10.1103/PhysRevD.66.045026.

[14] 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,

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.
« Last Edit: 07/14/2017 02:18 AM by dustinthewind »

Offline gospacex

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Re: Theoretical FTL
« Reply #84 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:



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.

Offline gospacex

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Re: Theoretical FTL
« Reply #85 on: 07/14/2017 04:09 PM »

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.

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #86 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
and
The relationship between radiation PRESSURE and the POYNTING VECTOR
both posts by Dr Rodal in the EmDrive threads.
« Last Edit: 07/23/2017 11:57 PM by flux_capacitor »

Offline gospacex

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Re: Theoretical FTL
« Reply #87 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.

Online dustinthewind

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Re: Theoretical FTL
« Reply #88 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. doi:10.1103/PhysRevD.66.045026.

[14] 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,

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. 
« Last Edit: 07/16/2017 05:45 AM by dustinthewind »

Offline ChrisWilson68

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Re: Theoretical FTL
« Reply #89 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. doi:10.1103/PhysRevD.66.045026.

[14] 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,

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".

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #90 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) 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).

Offline gospacex

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Re: Theoretical FTL
« Reply #91 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.

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #92 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 :)
« Last Edit: 07/17/2017 04:16 PM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #93 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). So here it is again with more explanation about antimatter:



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.
« Last Edit: 07/17/2017 06:07 PM by flux_capacitor »

Offline gospacex

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Re: Theoretical FTL
« Reply #94 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.
« Last Edit: 07/18/2017 06:22 AM by gospacex »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #95 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"?
« Last Edit: 07/21/2017 11:04 AM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #96 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)


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:

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.
« Last Edit: 07/21/2017 11:21 AM by flux_capacitor »

Offline flux_capacitor

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Re: Theoretical FTL
« Reply #97 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 13 first ones rather talk about the history and evolution of astrophysics and cosmology through time, from antiquity to modern days. But the Janus model is only broached from video #14.

Currently, JANUS #16 #17 #18 #19 are subtitled in English. Here they are:

• JANUS 16: Why the cosmic expansion is accelerating
How the Janus Cosmological Model explains the accelerating cosmic expansion, challenging dark energy. The accelerating expansion is caused by the negative pressure of the invisible negative mass content of the universe. The nature of such negative energy constituents is described and incidentally identifies the nature of the mysterious dark matter and the missing primordial antimatter.




• JANUS 17: The only consistent interpretation of the Great Repeller
The Janus Cosmological Model provides the only consistent interpretation of the Dipole Repeller, accounts for flat rotation curves oaf galaxies, their confinement and their spiral structure, as well as mirage effects around them and galaxy clusters, due to a negative gravitational lensing effect.




• JANUS 18: Why the primitive universe is so homogeneous
The current standard model justifies such homogeneity with a cosmic inflation due to an inflaton field. We present another explanation, already published in Modern Physics Letters A in 1988 and in 1995 in Astrophysics and Space Science. 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.




• JANUS 19: The speed of light had to be infinite at the Big Bang
Sakharov's model can't be geometrized with a constant speed of light, which must be infinite at the Big Bang. The arrow of time becomes zero then reverses. The initial singularity is cancelled and replaced by a structure shown to have an elliptic geometry. The question of time near the Big Bang becomes meaningless and chronology is identified with entropy.



I will edit this post to post more of the previous Janus videos once they are subtitled.

From video #20 Dr Petit shall double each video: one French and one English spoken versions so nor more subtitles.
« Last Edit: 07/24/2017 11:35 PM by flux_capacitor »

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