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 ρc^{2}What is it? n is the "density number" (number of particles per cubic meter) multiplied by mc^{2}, 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 = α^{2} cosh^{2} ut + t_{o} = α^{2} (1/2 sinh 2u + u)where α and t_{o} 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....