Can Superconductors Block Gravitational Fields?

jswitte writes "Raymond Chiao, of the University of California at Berkel, believes that superconductors can convert electromagnetic radiation into gravitational radiation. His full paper can be found here. His theory is based on the idea that superconductors might be able to block the so-called 'gravitomagnetic' field just as they block the electomagnetic field in the famous Meissner effect allowing superconductors to levitate in magnetic fields. He claims that when he 'adds the gravitomagnetic field to the standard quantum equations for superconductivity, he confirms not only the gravitational Meissner-like effect but also a coupling between the two breeds of magnetic field. An ordinary magnetic field sets electrons in motion near the surface of a superconductor. Those electrons carry mass, and so their motion generates a gravitomagnetic field.'"

Re:Sorry, no anti-grav

[Anonymous Coward]

Would it not be possible to generate a region of "zero total force" by generating gravity-waves that oppose the "basic curvature of space"?

[disclaimer: I'm not familiar with the difference between the two forms of gravity, I could have the wrong end of the stick here...]

I want my zero-G sauna, dammit! :o)

Wait for the experimental test

[Animats]

The key point here is that the theory predicts that the conversion of microwaves to gravity waves will be reasonably efficient. So this is testable, and is being tested. There should be a definitive result this year.

Nobel prize material if it works. Footnote in Physical Review Letters if it doesn't.

not yet antigravity

[Anonymous Coward]

First of all, he's talking about blocking "gravitomagnetic" fields, which if I understand correctly you get from moving masses. So the static gravitational effect from e.g. the Earth isn't blocked.

If what he claims is true then first of all he has invented a great new way to emit and detect gravitational waves. It would be awesome for astronomy, useful for submarine communication (and maybe detection), and probably many other things. However, it's not immediately obvious that we're talking "antigravity" here, so don't get too excited.

Also keep in mind that 99+ times out of 100 these sorts of claims are completely bogus and a waste of time. Just sit tight and wait for rebuttals or confirmation to appear on the LLNL server.

Re:Temperature is a hurdle

[Chris Coster]

Correct, but that doesn't mean that they haven't already found significant commercial applications [slashdot.org] (more than once [slashdot.org]) in the real world.

I had a friend once . . .

[Ezubaric]

I had a friend who was working on this for a while. He kept building larger and larger metal units, cooling them down more and more, trying to get a rotating disk to speed up in a very, very, strong (par. magnetic field). If it sped up, then this was a reduction in the moment of inertia, and a decreased effective mass.

After two years of working on it, he gave up. He did get a measurable increase, but it was too little to be more than measurement error.

Not Anti-Gravity

[FatlXception]

If I understand the Scientific American article correctly, what we're talking about here is NOT blocking gravitational fields in the standard sense. The normal, static gravitational effect we associate with massive objects is really a manifestation of the gravitoelectric field. Superconductors, however, are believed to block the gravitomagnetic field, which occurs when a massive object is in motion or rotating. This is also referred to as the Meissner effect, or "frame-dragging". Note the effect of earth's gravitomagnetic field is very small; physicists have only barely been able to prove its existence based on minor course corrections needed for satellites in earth orbit, where the earth is the massive rotating object. So no, the effect of superconductors on gravity (if true at all), will not directly lead to hover technology. What it might lead to is a better method of detecting and generating gravitational waves; in theory, such waves could someday be used for communication the way EM waves are today.

Re:Wait for the experimental test

[Wocko]

It is based on the fact that not only should gravity waves convert to microwaves, but that the inverse should be true.

So, if you imagine the following experiment:

Inside a Faraday cage, place a superconductor and a microwave source.

Inside another Faraday cage, place a superconductor and a microwave detector.

From inside the first Faraday cage, fire the microwave source at the superconductor. The theory predicts that a gravitation wave will be emitted.

Aim the (suspected) emitted gravitation wave at the second superconductor (inside the second Faraday cage).

Detect any microwave radiation after the gravitation wave has been converted by the second superconductor.

The Faraday cages block electromagnetic radiation so they ensure that no microwaves can leak from the emitter to the detector, and therefore gravitation waves must be the culprit.

Re:Note that it can't generate antigravity fields

[Anonymous Coward]

True, but if you could create directional gravitational waves and receive them, you would have a powerful signaling/communications device that is much less susceptible to interstellar interference. Years ago, it occurred to me that the answer to Fermi's Paradox may be that civilizations may use radio for only a short period of time (compared to the lifetime of a civilization) and that the reason why we don't detect advanced civilizations is because we're not "listening" in the right way. This might be the communications mechanism used by such advanced civilizations... or not.

Scientific American Settles it...

[i1984]

When I first glanced at this thread I figured this was just another crank story like the time machine or the previous anti-gravity superconductor, but then I saw it was in Scientific American I knew that if it wasn't crank science, it was at least probably being blown out of proportion, sensationalized, and/or taken out of context.

Perhaps that's a bit too harsh, but Scientific American has come down in the world quite a bit since the late eighties or early nineties. As I recall, they got a new editor many years ago and he was hell bent on dumbing the magazine down, fluffing it up with low-attention-theshold filler, and generally reducing it to a level of depth, insight, and relevance typical of USA Today or Omni Magazine. He suceeded, and many of the science professionals I knew cancelled their subscriptions shortly thereafter.

This subject strikes me as the researcher noting to himself "oh, hey...if I make some interesting assumptions, I get this cool effect popping out. And I might as well test it since it's so easy to test." Or an April Fools joke*. Which falls short of us dismissing the idea out of hand, but does suggest it doesn't deserve much media coverage -- at least until any positive results are verified. In other words, it was just sensationalist enough to get Scientific American's attention (they dig this kind of stuff), but not so far to the side of quackery that it has (yet) been featured in the Fortean Times [217.206.205.129].

* By the way, the paper missed April Fools day by four days; the date is stamped April 5, 2002. There's also a second date stamp of April 11, 2002. (A slightly earlier date stamp would have cleared things up pretty quickly!)

Re:Mmm... Time machine

[Sklivvz]

Do you have any evidence or reason to believe that there's not an _infinite_ number of dimensions?

Well, you seem to forget the reason why those extra dimensions were put in string theory! The K-K equations show that adding an extra (curled up) dimension makes EM a consequence of GR. So, in simple terms, you do see the extra dimension, but you "measure" it as EM charge. The other dimensions are added up to provide for the other charges (i.e. weak and strong charges). Is that so strange? Not to me, not stranger than allowing for phantomatic "charges" (what is EM charge made of?).

So basically, we don't have an infinite number of dimensions because we don't have an infinite number of different possible charges.

Re:Wait for the experimental test

[FuzzyDaddy]

This is absolutely right. I was a physics grad student at Berkeley when I first heard about this idea. The excitement was not about antigravity, but about producing and detecting gravitational waves. The predicted coupling of gravitational waves to matter is very weak, and experiments to date (using very large block cooled to very low temperatures, and looking for vibrations) have been inconclusive. Their extistence is pretty well confirmed by the observation, over a long period of time, of the decay in the orbits of a binary star system. (Two people from Princeton won the Nobel prize for this, but I've forgotten who and when). Chiao's idea was that a superfluid would move instaneously, because it was a single quantum state. His proposed experiment is exactely as Wocko describes, and is a version of the classic experiment which detected electomagnetic radiation. If you're into pie-in-the-sky application possibilities, imaging wireless communications, except because the wave interacts so weakly with matter, there is almost no interference from intervening matter or other radiation sources. Sort of like ELF except with some real bandwidth.