Gravitational Casimir effect - split from distortions in space to overcome gravity

[StringJunky]

Theorist suggests a way to test gravitational Casimir attraction

 

(Phys.org)—James Quach, a research fellow at Tokyo University is suggesting that it might be possible to observe a gravitational Casimir attraction by carrying out an experiment he has envisioned. In his paper published in the journal Physical Review Letters, he suggests that it might be possible to detect such an attraction using two mirrors that are able to reflect gravitational waves....

 

....Not mentioned are the ramifications should the experiment succeed. An ability to reflect gravity "waves" it would seem, would allow scientists to create shields or coatings that when applied to objects would make them weightless, because the gravity pulling them down would be reflected away. That, of course, would completely change such things as transportation, industrial processing and of course air and space travel.

 

Read more at: http://phys.org/news/2015-03-theorist-gravitational-casimir.html#jCp

Arxiv paper: Gravitational Casimir Effect

Edited March 8, 2015 by StringJunky

[swansont]

Before anyone latches onto this and runs with it, read it carefully.

 

one may imagine plates which are opaque to the gravitational field, so that the Casimir effect would then be a manifestation of the quantisation of the gravitational field, or gravitons. The difficulty is in finding such a medium, as ordinarily materials are transparent to the gravitational field

 

 

IOW, the plates are made up of a material that doesn't actually exist, or is made of normal materials having a property that has not been unambiguously measured. (i.e. if real, it's really small)

 

What they find is that if some other proposal pans out, you could get a gravitational effect at low temperatures which is comparable to the regular Casimir force. Small value at short distances.

 

"would completely change such things as transportation, industrial processing and of course air and space travel." is typical pop-sci hyperbole, extrapolating the effect many orders of magnitude beyond what is claimed. Unless e.g. air travel is to be carried out a few nm above the ground, and both plane and ground are near absolute zero, that's not a reasonable conclusion.

[StringJunky]

Trust you you to shatter my dreams of seeing wheeless skateboards and people on anti-gravity skis, sticks in hand, whizzing down the road. I thought it interesting because science says it can't be done but there's competent people always testing the consensus, even if indirectly. as in this idea. It shows that the scientific method is robust, working just fine and keeping it's eyes open for signs of change.

 

I suppose the first hurdle to be overcome, before finding reflective material, is to find conclusive evidence of gravitons because it won't work at all theoretically with GR's model of curved spacetime will it?

Edited March 8, 2015 by StringJunky

[swansont]

I suppose the first hurdle to be overcome, before finding reflective material, is to find conclusive evidence of gravitons because it won't work at all theoretically with GR's model of curved spacetime will it?

 

The experiment will work if gravitons exist —as they point out, it would be evidence of them — but it also depends on this superconductive coupling being true at the level that was predicted. A null result doesn't rule them out.

 

I am under the impression that this is not a GR prediction, much like the Casimir effect is not a classical prediction. Plus, gravitational waves are not a steady state condition, like the vacuum energy and EM modes are. But people who actually study GR would know better than me.

[StringJunky]

 

.... Plus, gravitational waves are not a steady state condition, like the vacuum energy and EM modes are. But people who actually study GR would know better than me.

You can correct me, but isn't the phys.org article being inaccurate calling them "gravity waves" because they are actually a perturbation in spacetime and not an actual featured behaviour of spacetime normally; the waves in GR are a consequence of drastic change in mass of a cosmic body, like ripples on water?

Edited March 8, 2015 by StringJunky

[imatfaal]

You can correct me, but isn't the phys.org article being inaccurate calling them "gravity waves" because they are actually a perturbation in spacetime and not an actual featured behaviour of spacetime normally; the waves in GR are a consequence of drastic change in mass of a cosmic body, like ripples on water?

 

If they call them gravity waves then they are almost certainly inaccurate - gravity waves are a liminal fluid interaction; they occur when a force disturbs the interface of two media and gravity restores.

 

Gravitational waves are the propagation of change in the spacetime continuum - a simple mass in space does not generate them - but a binary star for example does (pretty minimal) and a pulsar really does. We can predict the slow down of pulsars by the loss of energy that we know must be radiated by the predicted gravitational waves. We have not yet directly detected gravitational waves - but lots of effort is going into creating the precision and isolation needed; but as they are a result of general relativity and we can indirectly detect them, and our predictions work out with observation we are pretty sure about them

[StringJunky]

 

Theorist suggests a way to test gravitational Casimir attraction

 

(Phys.org)—James Quach, a research fellow at Tokyo University is suggesting that it might be possible to observe a gravitational Casimir attraction by carrying out an experiment he has envisioned. In his paper published in the journal Physical Review Letters, he suggests that it might be possible to detect such an attraction using two mirrors that are able to reflect gravitational waves....

 

....Not mentioned are the ramifications should the experiment succeed. An ability to reflect gravity "waves" it would seem, would allow scientists to create shields or coatings that when applied to objects would make them weightless, because the gravity pulling them down would be reflected away. That, of course, would completely change such things as transportation, industrial processing and of course air and space travel.

 

Read more at: http://phys.org/news/2015-03-theorist-gravitational-casimir.html#jCp

Arxiv paper: Gravitational Casimir Effect

 

As you can see (see bolded) they are conflating the two. If I understand you right, gravity waves are more local than gravitational waves which are produced by, say, a supernova?

Edited March 8, 2015 by StringJunky

[imatfaal]

As you can see (see bolded) they are conflating the two. If I understand you right, gravity waves are more local than gravitational waves which are produced by, say, a supernova?

 

Sorry - I wasn't explicit. Gravity waves are just waves in which gravity is a driver / restorer. Waves on a pond caused by a dropped stone are a gravity wave. If you have two fluids (ie air and water) with a stable boundary and you displace some of the fluid away from the boundary then gravity a/o buoyancy will counteract this displacement and act to restore situation - it will overshoot and then buoyancy / gravity will make it go back in the opposite direction and you end up with a wave. Gravity waves are a huge part of our atmospheric transfer system of energy and momentum between layers and areas. You can spot them in nacreous clouds - or if you are lucky and up early noctilucent clouds (which we are at the latitude here in the UK to see).

 

Gravitational waves are almost entirely different being a propagation of varying curvature in the spacetime continuum. They are an oscillation of stretching and compressing space. Here is a great page on them from Cambridge

 

http://www.ast.cam.ac.uk/research/cosmology.and.fundamental.physics/gravitational.waves

 

It doesn't mention Supernovas although they are a source of Gravitational Waves from glancing at other sources- but frankly I cannot get my head around how a symmetrical collapse / bounce should generate waves. If you want to get an handle on them I think the most obvious source to study is quasars / active rotating galactic centres

[swansont]

And that's a question I have — AFAIK the Casimir force from graviton modes would be different from gravitational waves, and yet they discuss gravitational wave boundary conditions in the paper. I say "they" - it's a single author, from the Institute for Solid State Physics at U of Tokyo. Perhaps it's a case of someone over-reaching into GR, and conflating the quantized field with gravitational waves.