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.
No, gravitation equally affects on a matter and an antimatter.
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,
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.
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.
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 brilliant example of the borderland of achievable technology was Arthur C. Clarke's black-hole rocket engine in "Imperial Earth."
Suzy, you could just use a fusion rocket, without messing with a HEAVY black hole.And antimatter rocket would be better anyway.
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
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.
Can't agree on "c is instantaneous", why radar bounces off planets come back with delay?
Kaluza Klein Theory...
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.
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..
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.)
Creation of Mini black holes?
and capturing virtual particles?any thoughts, known papers, etc?
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.
Quote from: khallow on 08/03/2008 04:58 amany 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.
Quote from: gospacex on 08/04/2008 09:42 amQuote from: khallow on 08/03/2008 04:58 amany 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.
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.
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.
Quote from: colbourne on 06/23/2008 06:03 amAssumption 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 ?
Quote from: colbourne on 12/04/2011 08:29 pmHow 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
Even this business major knows that gravity is considered to be a function of mass, not of charge.
Quote from: Cherokee43v6 on 12/05/2011 08:37 pmEven 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".
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 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" ...
Quote from: RanulfC on 12/06/2011 06:07 pmI 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
Randy. Here. Take two of these and call me in the morning....
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-3a3d9a1e90-90223594Enormous 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.
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.
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.
Quote from: Spaniard on 04/05/2017 07:45 amAssuming 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.
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.
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.
...
Quote from: flux_capacitor on 07/12/2017 10:58 pm...Thanks flux. I had no idea they already had a working model of such a system.
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.
Quote from: flux_capacitor on 07/12/2017 10:40 pmBut 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).
Quote from: gospacex on 07/13/2017 11:19 amQuote from: flux_capacitor on 07/12/2017 10:40 pmBut 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.
Quote from: gospacex on 07/13/2017 11:51 amNegative 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 ρwith α > -1α 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.
Pressures and Energies in Magnetized Vacuum and in Casimir effectCERN Document ServerRojas, H P2004-01-01We 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.
Quote from: gospacex on 07/13/2017 11:51 amOf 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 ρc2What 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?!
Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.htmlhttp://cds.cern.ch/record/726991/files/0402213.pdfPressures and Energies in Magnetized Vacuum and in Casimir effectCERN Document ServerRojas, H P2004-01-01We 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.
Quote from: flux_capacitor on 07/14/2017 12:30 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.
{snip}If this is not a demonstration that p is also an energy per unit volume?!
Quote from: gospacex on 07/14/2017 03:58 pmQuote from: flux_capacitor on 07/14/2017 12:30 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
Quote from: flux_capacitor on 07/14/2017 01:21 amQuote from: gospacex on 07/13/2017 11:51 amNegative 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 ρwith α > -1α 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_energySome other forms of negative energy exist. One is gravitational energy which pulls things together. I was suspecting queezed light might be a way of helping push against the vacuum and seems integral to detecting gravitational waves. Squeezed light is also connected to negative energy. There are the virtual particles that seem to pop in and out of existence that also have connections to negative energy. also found this which may possibly be of relation or maybe not,Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.htmlhttp://cds.cern.ch/record/726991/files/0402213.pdfPressures and Energies in Magnetized Vacuum and in Casimir effectCERN Document ServerRojas, H P2004-01-01We 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.
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...
Quote from: dustinthewind on 07/14/2017 02:16 amQuote from: flux_capacitor on 07/14/2017 01:21 amQuote from: gospacex on 07/13/2017 11:51 amNegative 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 ρwith α > -1α 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_energySome other forms of negative energy exist. One is gravitational energy which pulls things together. I was suspecting queezed light might be a way of helping push against the vacuum and seems integral to detecting gravitational waves. Squeezed light is also connected to negative energy. There are the virtual particles that seem to pop in and out of existence that also have connections to negative energy. also found this which may possibly be of relation or maybe not,Quote from: https://worldwidescience.org/topicpages/c/casimir+energy+density.htmlhttp://cds.cern.ch/record/726991/files/0402213.pdfPressures and Energies in Magnetized Vacuum and in Casimir effectCERN Document ServerRojas, H P2004-01-01We 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 QuoteNegative 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.
Accelerating expansion must have _positive_ energy density of vacuum (then it has negative pressure).
• 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 negative mass matter is nothing but antimatter (PT-symmetry) as suggested by Richard Feynman in 1949
Quote from: flux_capacitor on 07/16/2017 04:56 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 gravitationThis 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 from: flux_capacitor on 07/16/2017 04:56 pmThis negative mass matter is nothing but antimatter (PT-symmetry) as suggested by Richard Feynman in 1949This 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.
Quote from: gospacex on 07/17/2017 12:52 pmQuote from: flux_capacitor on 07/16/2017 04:56 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 gravitationThis 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.
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.
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.
4.3. p=0, Λ=0This 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 S̈ must be nonnegative, and then from (26) that k = -1. Integrating (25) with p = 0 and k = -1 we findS = α2 cosh2 ut + to = α2 (1/2 sinh 2u + u)where α and to are constants.
In this series of videos, astrophysicist and cosmologist Jean-Pierre Petit explains the Janus Cosmological Model.JCM is a bimetric theory of gravity based on general relativity with a system of two coupled field equations, involving the presence of positive and negative masses in cosmology.It describes the universe as an M4 manifold with two metrics. The first metric g(+) or "positive sector" refers to a family of geodesics with positive mass and positive energy particles, while the second metric g(-) or "negative sector" refers to another family of geodesics with negative mass and negative energy particles. Negative mass particles emit negative energy photons that follow null geodesics of the metric g(-) hence cannot be seen.The Newtonian approximation provides the interaction laws: particles whose masses own the same sign mutually attract through Newton's law, while particles whose masses have opposite signs mutually repel through anti-Newton's law. This solves the unmanageable Runaway paradox, which arises when one tries to include negative masses in Einstein's model.Like Andrei Sakharov's model, the second sector is a CPT symmetry of the first one, linked together by the Big Bang, and explains the apparent lack of primordial antimatter.Dynamical group theory demonstrates that the reversal of the arrow of time equals energy inversion, and provides the nature of negative species.The negative sector contributes to the gravitational field and negative pressure and replaces both dark matter and dark energy of the concordance model and its six free parameters, without ant ad hoc parameter. The model challenges dark matter as it explains the formation of galactic spiral structures, their confinement and their anomalous rotation curves. It also explains the formation of galaxy clusters and the large-scale structure of the universe, the giant voids and the Dipole Repeller effect. Mirage effects around galaxies and galaxy clusters are due to a negative gravitational lensing effect.The model challenges dark energy, giving an exact solution referring to the matter-dominated era, which exhibits an accelerating expansion process for positive species and fits very well with available observational data. During the radiation-dominated era, the universe undergoes a variable constants regime, with a variation of the speed of light (VSL) and of all the constants of physics, involved in a generalized gauge process. Then the horizon grows like the space scale factor. This explains the homogeneity and isotropy of the primitive universe with no need to resort to the inflation hypothesis and the inflaton field.The two sectors have different speeds of light and scale factors. If a space probe could achieve a mass inversion process and cruise at a relativistic velocity following geodesics of the negative sector, the travel duration could be three orders of magnitude shorter than a corresponding conventional relativistic trip in the positive sector. The model suggests that interstellar travel in a limited time inferior to human's lifespan becomes theoretically possible. The Janus model has been published in peer reviewed scientific journals.
https://phys.org/news/2018-12-universe-theory-percent-cosmos.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletterScientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.
Quote from: colbourne on 12/06/2018 05:16 amhttps://phys.org/news/2018-12-universe-theory-percent-cosmos.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletterScientists at the University of Oxford may have solved one of the biggest questions in modern physics, with a new paper unifying dark matter and dark energy into a single phenomenon: a fluid which possesses 'negative mass." If you were to push a negative mass, it would accelerate towards you. This astonishing new theory may also prove right a prediction that Einstein made 100 years ago.Sonny White will be pleased to hear this. :>
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 light2. 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.ReferencesThe warp drive: hyper-fast travel within general relativityMiguel AlcubierreClass. Quantum Grav. 11 No 5 (May 1994) L73-L77Fundamental limitations on 'warp drive' spacetimesFrancisco S N Lobo and Matt VisserClass. Quantum Grav. 21 No 24 (21 December 2004) 5871-5892Speed limits in general relativity Robert J LowClass. Quantum Grav. 16 No 2 (February 1999) 543-549Warp drive with zero expansionJ NatarioClass. Quantum Grav. 19 No 6 (21 March 2002) 1157-1165The unphysical nature of `warp drive' M J Pfenning and L H FordClass. Quantum Grav. 14 No 7 (July 1997) 1743-1751
This engineering model firmly establishes a viable solution to quantum gravity for engineers within the standard model of Quantum Electrodynamics.
It opens the door to new innovations that might permit artificial gravity or anti-gravity technologies to be invented. Through the use of stimulated emission, increased or reduced radiative damping, or by amplification of the resonant driving fields that inflate matter to higher ground state energies. Engineers now have a new set of old, familiar tools to work with when thinking about gravity and Metric Engineering [3].
What was presented herein puts gravity in the hands of engineers, who could potentially advance such technologies as; warp drive, artificial gravity and anti-gravity, from pure speculation, to achievable endeavors in our lifetime.
..."Also, to preempt a likely response to what I just said: As far as I can tell you just did a change of variables, without changing the underlying math. In this case (assuming no mistakes), your new formulation is automatically consistent with GR,..."
Quote from: meberbs on 01/12/2019 06:50 pm..."Also, to preempt a likely response to what I just said: As far as I can tell you just did a change of variables, without changing the underlying math. In this case (assuming no mistakes), your new formulation is automatically consistent with GR,..." No offense intended. I chalk it up to life experiences. I've only ever met a handful of engineers who even attempted to understand the mathematics and nuances of GR, and of them, I'm the best, which isn't saying much. So yeah, "most" engineers I've conversed with are not at that level in my experience, and simply find the topic an interesting curiosity. If you're an engineer, and given your understanding of GR, that makes "2", you and Hal Puthoff are unique in my experience....
I am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.
"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."
There is a fantastic difference between something that is probably impossible (or merely not proven possible) within the laws of physics and something that merely needs a jupiters-mass-worth of energy.
Quote from: KelvinZero on 04/18/2021 09:56 amThere is a fantastic difference between something that is probably impossible (or merely not proven possible) within the laws of physics and something that merely needs a jupiters-mass-worth of energy.No, not really. Unless you mean as in a "fantasy". And it's 100s of times the mass of Jupiter.Using up a Jupiter to send 1 bit would be quite useless, it is absurd to suggest otherwise. There are plenty of things we know for sure we can do, but still don't find it practical. e.g. supersonic passenger liners.Saying that something would revolutionize physicists understanding of the Universe is fantastically different to saying it would make any difference to the person on the street.
Looks like it has hit the (almost) the mainstream
Quote from: KelvinZero on 04/21/2021 09:23 pmLooks like it has hit the (almost) the mainstream I'm still not seeing how a warp drive is anything more than a fancy box that's particularly heavy (has high, black-hole like mass/energy density) in specific places.
Quote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.
Quote from: Frogstar_Robot on 04/15/2021 09:42 amQuote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.Can you show a precise calculation of the latter claim of yours ? Radius of Starship is 4,5 meters.So how much less would that need...being 500 x smaller as the referred 100 m radius ship ?Apollo would have been just 2 415th of that behemoth.
Quote from: Oberonian on 04/23/2021 03:39 pmQuote from: Frogstar_Robot on 04/15/2021 09:42 amQuote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.Can you show a precise calculation of the latter claim of yours ? Radius of Starship is 4,5 meters.So how much less would that need...being 500 x smaller as the referred 100 m radius ship ?Apollo would have been just 2 415th of that behemoth.That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.
Quote from: rakaydos on 04/23/2021 05:38 pmQuote from: Oberonian on 04/23/2021 03:39 pmQuote from: Frogstar_Robot on 04/15/2021 09:42 amQuote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.Can you show a precise calculation of the latter claim of yours ? Radius of Starship is 4,5 meters.So how much less would that need...being 500 x smaller as the referred 100 m radius ship ?Apollo would have been just 2 415th of that behemoth.That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.What was....the Dr Lentz relativity calculation ?
Quote from: Oberonian on 04/23/2021 06:20 pmQuote from: rakaydos on 04/23/2021 05:38 pmQuote from: Oberonian on 04/23/2021 03:39 pmQuote from: Frogstar_Robot on 04/15/2021 09:42 amQuote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.Can you show a precise calculation of the latter claim of yours ? Radius of Starship is 4,5 meters.So how much less would that need...being 500 x smaller as the referred 100 m radius ship ?Apollo would have been just 2 415th of that behemoth.That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.What was....the Dr Lentz relativity calculation ?"Your latter claim", the trillion trillion trillion watts, 30 orders of magnatude bigger than modern fission reactors. reducing the power costs by 1000 only drops that to 26 orders of magnatude bigger than our largest nuclear plants. Reducing the power costs to a trillionth of what they are calculated to be, and you still need 1,000,000,000,000,000,000 big nuclear reactors running at once to power it.
Quote from: rakaydos on 04/24/2021 03:19 pmQuote from: Oberonian on 04/23/2021 06:20 pmQuote from: rakaydos on 04/23/2021 05:38 pmQuote from: Oberonian on 04/23/2021 03:39 pmQuote from: Frogstar_Robot on 04/15/2021 09:42 amQuote from: clippie on 04/15/2021 12:16 amI am really surprised that nobody is talking about this.This would seem to me (non engineer, lurker, medical professional) to move FTL into a less hand waveable contex.Because it would still require huge amounts of energyQuote"The energy required for this drive traveling at light speed encompassing a spacecraft of 100 meters in radius is on the order of hundreds of times of the mass of the planet Jupiter," Lentz says."The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors."Or, 10000000000000000000000000000 times more than a nuclear reactor. About a trillion trillion trillion Watts. When a scientist says 30 orders of magnitude, it is a practical impossibility.Can you show a precise calculation of the latter claim of yours ? Radius of Starship is 4,5 meters.So how much less would that need...being 500 x smaller as the referred 100 m radius ship ?Apollo would have been just 2 415th of that behemoth.That WAS the precice calculation. 500x smaller only chops off 3-4 zeroes off his number.What was....the Dr Lentz relativity calculation ?"Your latter claim", the trillion trillion trillion watts, 30 orders of magnatude bigger than modern fission reactors. reducing the power costs by 1000 only drops that to 26 orders of magnatude bigger than our largest nuclear plants. Reducing the power costs to a trillionth of what they are calculated to be, and you still need 1,000,000,000,000,000,000 big nuclear reactors running at once to power it. I found this about dr Lentz,Erik Lentz:“This work has moved the problem of faster-than-light travel one step away from theoretical research in fundamental physics and closer to engineering,” Dr. Lentz said.“The next step is to figure out how to bring down the astronomical amount of energy needed to within the range of today’s technologies, such as a large modern nuclear fission power plant. Then we can talk about building the first prototypes.”“The energy required for this drive traveling at light speed encompassing a spacecraft of 100 m (328 feet) in radius is on the order of hundreds of times of the mass of Jupiter.”“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”“Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”http://www.sci-news.com/physics/superluminal-travel-09448.html
“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”The quote order is correctHow are modern nuclear reactors producing energy comparable to mass of Jupiter?
“The energy savings would need to be drastic, of approximately 30 orders of magnitude to be in range of modern nuclear fission reactors.”“Fortunately, several energy-saving mechanisms have been proposed in earlier research that can potentially lower the energy required by nearly 60 orders of magnitude.”
If nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.
Quote from: KelvinZero on 04/24/2021 04:13 pmIf nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.Once one masters manipulation of space timemaybe it is possible to not only make FTL travel but FTL communications by manipulating the coordinate speed of light at which point it might be more desired to communicate that way rather than mainly use the electromagnetic spectrum and we aren't even using the proper radios, space time radios. Maybe they have enemies and it isn't optimal to make ones presence known. Maybe they don't want their non space fairing colonists to know in the way startrek had their way of noninterference with nonspacefaring species but some would anyways im sure.Maybe there is also pressure to find new species on the verge of becoming space faring and tweaking their DNA to be more like yours, if they have traits similar to yours and adaptations that would be beneficial to your species as allies or upgrades. Imagine the pressure of a species that has existed that long to keep their species healthy with out the pressures of necessary evolution. Sure we try and work around it but its a constant struggle I am guessing, eventually even for ourselves. Genetic compatibility might not be possible with out tweaking though and might take some time. Same as for genetic drift where eventually a species becomes 2 separate species but undoing that. If they were, would they want them to know? My imagination takes me to strange places some times
Quote from: KelvinZero on 04/24/2021 04:13 pmIf nothing else, apart from exciting the physics world, theoretically possible FTL would add another huge questionmark to the Fermi paradox. We haven't noticed any stellar scale engineering in our own galaxy. We haven't noticed any galactic scale engineering in the observable universe. Any settled part of the universe should surely have a different spectra from dead matter just as earth does. There could easily be interstellar civilisations in the observable universe we just haven't noticed though. They could be expanding in a colonising wave at almost the speed of light and still not made sufficient dent for us to notice. If FTL is possible to any species even a billion more years advanced than us then it appears there has been no true open ended success not only in our observable universe but also in the bubble far outside it that FTL makes accessible. If speed was not an issue then exponential growth would let a species colonise the observable universe in merely several thousand years.I don´t think it would make a difference at all.
Even if it take 1000 years for a new colony to be able to send new colony ships around... it doesn´t even mean you need to wait 1000 years for the second wave... the home planet can still send new colony ships further and further, every 100 years, while waiting for the already colonized star systems to build their own colony ships...
if we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.
Quote from: rakaydos on 05/19/2021 12:01 pmif we're talking the Fermi paradox, my pet theory is that there is only a narrow range of planet sizes where life is possible (life is easier to develop on worlds slightly larger than earth) AND where rocket science isnt an immediate dead proposition, requiring saturn 5 class rockets to put individual satelites into orbit- a "poison pill" that prevents a civilization that achieves industrialization from ever becoming spacefaring, and from there starfaring.There's also the question of motivation. even on our relatively small habitable planet, it took having a relatively close and highly visible destination, which political leaders could have a pissing match over, to jump start our space technoligy. And once that technoligy was developed and integrated through our society, it's taking a rich and driven polymath to refine it to the point where other destinations may soon be viable for humans. Take away the astronomical coincidence of the moon, and we may never have gone beyond LEO.And that's not even getting into the ticking time bomb that is Industrial Revolution-caused climate change, which seems to me like it could well be a universal problem. Because of this, I believe "number of civilizations that achieve spaceflight" will be abnormally low in comparison to "planets that achieve technological civilization," due to enviromental factors that make further progress all but impossible.I personally like (in addition to your points) the idea of the fact the moon is the same angular size as the sun we have had these rare things called total eclipses of the sun. This stimulated math and science development because of the apocalyptic nature of them and the ability to predict them went hand and hand.
Solar eclipses were not predictable until Newton's laws, and Halley first predicted the eclipse in 1715. That's well after a lot of math and science and development and well after solar eclipses were regarded as "apocalyptic" portents.However, I think it is true to say that the desire to predict phases of the Moon, and more generally events such as tides, solstice, equinox, etc, did spur math and scientific inquiry. The Moon has an intriguing role in our civilization development, but it's hard to say it was a necessary requirement. There is plenty of astronomical stuff to study, and I think such development would take place even without a large moon.I have a hunch our large moon has played an important role in stabilizing the rotation of the Earth, and maybe tides have played an important role in evolution. With a sample of one, it's hard to tell.
OK. I'll bite.A few great points have been brought up about why we haven't seen signatures of FTL-capable civilizations.I'll through in three points of my own (plus a bonus fourth point):1) I brought up a point in a different thread that we may be looking right at those signatures an have not recognized them for what they are. https://forum.nasaspaceflight.com/index.php?topic=19421.msg2184874#msg2184874 For example, we may have over a century of photographic evidence capturing the space-time wake a functioning Alcubierre drive leaves behind it, and we simply haven't looked (see simulated bottom photo below of what a wake would look like against a background starfield). An AI could easily look for this pattern on millions of old digitized plates if someone took the time to setup a project. Similarly, a star that vanishes without a trace (and there are a few) could be a civilization at work absorbing the star or creating a Dyson sphere. But the odds of us seeing the before and after moments such a civilization does such a feat are preposterously low, IMHO, unless Type II and Type III civilizations are both common and wide-spread.
2) Any species is going to be limited by its tolerances to its environment. I've always had a problem with the Kardashev scale because it doesn't account for the frailty of the species' harnessing energy on solar and galactic scales. In other words: What the f-ck would they do with all that energy?!? Other than travelling with Alcubierre drives, there isn't much a species could do out there with stellar levels of power harnessing that wouldn't also kill themselves. War? OK, I guess, but we'd see other signs of an interstellar war releasing stellar or galactic levels of energy.
3) We got quieter within moments of broadcasting our existence into space. Detection of other species may be limited to passive observation. Personally, I think this is the most likely explanation of the Fermi Paradox. Space is big and space faring species are rare even if they make it through the Great Filters all the way up to becoming multi-solar (at least within 80 light years from Earth). https://waitbutwhy.com/2014/05/fermi-paradox.html Our problem is that with a sample size of one, we don't know which side of the Great Filter we are on.
4) I've seen postulated that in a "Prisoner's Dilemma" universe of colonizing and competing species, the only way to survive is to colonize at ever increasing speeds. The preposterous conclusion therefore is that super-survivor (or super-predator depending on your perspective) multi-solar species will eventually encounter each other and expand their civilizations at nearly the speed of light in order to not be overtaken by the other species, and we on Earth would be completely unaware they even exist until colonization overtakes our solar system. This concept may have been mentioned by David Brin in his novel "Existence" (Which is in my mind one of the finest science fiction novels ever written. Do yourselves a favor and read it because it is entirely about the Fermi Paradox). I'll also mention that Brin is a member and occasional poster on NSF! https://www.amazon.com/Existence-David-Brin-ebook/dp/B0079XPMQS/ref=sr_1_12?dchild=1&keywords=david+brin&qid=1621432438&sr=8-12
If an intelligent species lived on a planet with permanent cloud cover, maybe they'd never even conceptualize a broader universe.
This episode of the Hubblecast explores striking new Hubble observations of a variable star known as RS Puppis. This star is growing brighter and dimmer as it pulsates over a period of five weeks. These pulsations have created a stunning example of a phenomenon known as a light echo, where light appears to reverberate through the foggy environment around the star.
It took him about an hour to create the footage.
Is this a good hypothesis?
Quote from: Alex_O on 03/06/2024 02:31 pmIs this a good hypothesis?No. A good hypothesis is falsifiable. Your hypothesis boils down to "maybe some FTL stuff already exists and is moving around." This is simply too broad and poorly defined to be a scientific hypothesis.
The rest of what you said before this is just wild assumptions as a pseudo-justification for the hypothesis, they don't add anything.The rest of your post after this is a combination of irrelevant nonsense, and demonstrations that you have never bothered to do basic research on the topic of what FTL means in the context of special relativity, and other basic relevant topics.
Quote from: dustinthewind on 04/10/2017 01:07 amThe negative gravity speculation was just that, but speculating that dark matter ...Good catch! In the next posts I will detail this idea of primordial antimatter lacking, parallel universes and negative gravity in cosmology. A cosmological model exists, exactly behaving how you said, and has been published though peer review with recent (2014-2015) progress.
The negative gravity speculation was just that, but speculating that dark matter ...
FTL means literal time travel. you seem unaware of this, and make a bunch of arguments that make no sense as a result. a particle travelling backwards in time from a distance would like like it is just travelling backwards no "faster camera" would detect this as interesting, it would just look like something moving in the opposite direction, you would need to have something tell you about the illogical reversal of causality, which a line moving through a nebula wouldn't.
Also, it is trivial for a particle beam (such as that from a pulsar) to "appear" to be moving FTL, but this is just like motion of a shadow, the pulsar is rotating, and the fact that tracking that motion along a surface many lightyears away is FTL along that surface is simply meaningless, it just means that each particle was travelling below the speed of light, but in different directions for many years.
Here, we analyse archival multi-epoch VLBI imaging data at five frequency bands from 1.7 to 15.4 GHz covering a period of more than 25 years from 1995 to 2020. We constrain apparent proper motions of jet components in PKS 2215+020 for the first time. Brightness distribution modeling at 8 GHz reveals a nearly 0.02 mas yr−1 proper motion (moderately superluminal with apparently two times the speed of light)...
Quote from: CoolScience on 03/06/2024 10:18 pmQuote from: Alex_O on 03/06/2024 02:31 pmIs this a good hypothesis?No. A good hypothesis is falsifiable. Your hypothesis boils down to "maybe some FTL stuff already exists and is moving around." This is simply too broad and poorly defined to be a scientific hypothesis.Yes. My idea is based on solid physics and solid observational facts.
1st observational fact. There is a developed civilization on planet Earth that has scientific knowledge. And the known civilization is a new version....From the first observational fact it follows that in the universe there are many developed civilizations.
2nd observational fact. From the history of science it is known that all modern knowledge was created based on the results of astronomical observations.
3rd observational fact. The mystery of fast, applied space logistics, travel faster than the speed of light, has not yet been revealed.
4th observational fact. Prominent theories report that engines for moving matter at superluminal speeds, in practical designs, require the use of very high energies, equivalent to stellar masses.
I made a bold generalization and justified the research program. This is a proposal for falsification.
And then, I'm just trying to increase the probability. Recently, people have expanded their horizons of knowledge by observing pulsars in the light of relic gravitational waves.
In these posts, flux_capacitor actually described the history of the development of science that is trying to uncover the mystery of superluminal fast flights.
Quote from: CoolScience on 03/06/2024 10:18 pmFTL means literal time travel. you seem unaware of this, and make a bunch of arguments that make no sense as a result. a particle travelling backwards in time from a distance would like like it is just travelling backwards no "faster camera" would detect this as interesting, it would just look like something moving in the opposite direction, you would need to have something tell you about the illogical reversal of causality, which a line moving through a nebula wouldn't.I'm not trying to discuss time travel. But I can show the idea of a sensor for recording time waves that can transmit impulse from the future to the past. But this will be offtopic.
Revisiting a Core–Jet Laboratory at High Redshift: Analysis of the Radio Jet in the Quasar PKS 2215+020 at z = 3.572https://www.mdpi.com/2218-1997/10/2/97QuoteHere, we analyse archival multi-epoch VLBI imaging data at five frequency bands from 1.7 to 15.4 GHz covering a period of more than 25 years from 1995 to 2020. We constrain apparent proper motions of jet components in PKS 2215+020 for the first time. Brightness distribution modeling at 8 GHz reveals a nearly 0.02 mas yr−1 proper motion (moderately superluminal with apparently two times the speed of light)... Are you talking about this? The apparent motion in the image at the telescope's focus (or the phase velocity of the EM wave) can be faster than the speed of light, and as the article showed, there is valuable information in this data.