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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.'"
All he is exccluding are gravity-waves. These are different then the basic curvature of space that generates gravity itself. Basically they are little ripples that float on top of the curvature. So blocking them won't levitate us.
Isn't this just a new take on the Podkletnov effect?
I might add after perusing the comments a little about superconductors. First off, liquid nitrogen is not a magic and impossible to find substance. it is cheap and easy to acquire as far as gasses go. Secondly, the city of Chicago has been using superconductors in their power grid for around 2 years. Supposedly the main line carries something on the order of 10s of thousands of amps (I belive 16,000 but I am not sure). Just for scale, you be hard pressed to find a house with any plugs rated above 20 amps, the nuclear structure lab I work at has some lines with 50 amps, but none higher.
No doubt that the symmetry between Maxwell's equations and Einstein's equations is stark, but does this also mean that they are equivalent in meaning and applicability?
If superstring theory is correct, then they've been known to be equivalent since the 1920s. The Kaluza-Klein equations show that in a 5-dimensional space-time (4xspace + 1xtime) or higher, Einstein's equations and Maxwell's equations both come out. See Kaku's Hyperspace for more info.
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
this observation was made years back by a scientist named podkletnov in Europe (hey, I said it was a while ago ;-). He used a super-cooled YBCO (yttrium boron carbon oxygen I believe) superconductor and was able to "reduce the mass of" (ie affect the gravitational effect on) objects. They actually ran an article in wired on him way back when (96-98 sometime). The "gravity society" had a website at www.gravity.org, but currently I cant reach it.
In answer to your question "but does this also mean that they are equivalent in meaning and applicability?" he does state on page 12, that they are similar in nature, yet not identical in either use or nature.
"It should be stressed here that although the above Maxwell-like equations
look formally identical to Maxwell's, there is a basic physical difference between
gravity and electricity, which must not be overlooked. In electrostatics, the
existence of both signs of charges means that both repulsive and attractive
forces are possible, whereas in gravity, only positive signs of masses, and only
attractive gravitational forces between masses, are observed."
The largest problem with this experiment is that he doesn't explain what happens to the superconductor when the electric field's radiation is converted into gravitational energies. He says that the electric field should vanish exponentially the closer you get to the center, since the charge density vanishes as you approach the surface. As I understand that to mean, the only place where gravity is actually cancelled out is at the place where there is no mass in the center of the superconductor.
He also says "However, the behavior of the superconductor as an efficient mirror is no
guarantee that it should also be an efficient transducer from one type of radiation to the
other. For efficient power conversion, a good transducer impedance-matching process from one
kind of radiation to the other is also required."
I don't know about you, but I don't have any spare transducers just lying around my garage... do you??
Anyways, I think that any application of this is so far off from actually being built that we won't have to worry about gravity plating, "anti-gravity machines" or anything else in our lifetimes. But overall it was an interesting paper.
Oh... btw, I totally agree with your comment about this math being way above our heads... Even after taking multivariable calculus it didn't even scratch the surface of what he was using as a proof!
Acutally, that's stored solar power. The fern uses solar enery to grow and blah blah..
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I though the speed of the propogation of gravitational force was equal to the speed of light. Is there something new that's been discovered that I'm not aware of?
Ordinary gravitational attraction is dominated by "gravito-electric" force, or in normal language the force generated by stationary masses. In everyday concerns the Earth is the only mass that matters and it is stationary to a good approximation for nearly everything humans do.
The paper talks solely in terms of affecting "gravito-magnetic" forces, which are those exhibited by moving masses (and generally only significant among masses moving at an appreciable fraction of the speed of light). Simply put there just isn't enough gravito-magnetic force in every day life to notice any change. If there were an appreciable gravito-magnetic force in ordinary everyday gravity then yes you could test it, though I'm not clear how to expect it to react.
To put things another way, Newton described gravity purely in gravito-electric terms and most of us will never notice the more complex gravitiational interactions that Einstein discovered and this physicist cares about.
Thus, the superconductor is not affecting the gravitational field. It is in a sense becoming a magnet itself, producing an exact-opposite magnetic field. This new field simply repels the magnet, producing levitation. By far the coolest effect was spinning/flipping the magnet over the superconductor and having it remain levitated, as the superconductor's magnetic field was always a mirror of the magnet's.
Now, in this I am not talking about the article or paper (I just started reading it). I'm simply talking about the magnetic field that is induced in a superconductor by magnets. My only experience and knowledge of the subject was the experiment in high school.
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I guess the War on Terror really is about freedom!
No, he is hypothesizing. (I don't know if I spelled that right.) Most scientists seem to think it won't work, but he'll probably get a Nobel Prize if it does.
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That was by Eugene (Jevgeni?) Podkletnov, at Tampere University of Technology, Finland. What I find funny is that nobody really wanted to verify the claims, they debunked it immediately. OTOH Podkletnov wasn't AFAIK too helpful in aiding in manufacturing the specially made ceramic discs (which were supercooled and spinning over a magnet).
Dr. Podkletnov was discounted as a hoax by many sources (cited that rising gases from the coolant, air flow from spinning or magnetism influenced his results), his university ejected him and now he has retreated to a hermetic existence.
Here is a story on Wired for your reading pleasure.
Much more to look if you search Google.
pronoblem
"Mind, as manifested by the capacity to make choices, is to some extent present in every electron." -Freeman Dyson
He did get a measurable increase, but it was too little to be more than measurement error.
Do you realize that your statement does not make any sense? If he got not more than a measurement error could acount for, then he did not get a measurable increase.
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Imagine a discreet electron moving through a positive lattice. The positive lattice will be attracted towards the negative electron. If the electron was still, the lattice would move towards it locally, and screen its charge. Because the electron is moving, and the lattice has intertia, the positive induced charge will lag behind the electron. This will slow down the electron, and also might attract any following electron if it is traveling at roughly the same speed. This is often described as electron-phononon coupling, and is rather more complicated than that simple explanation would suggest, but there is a weak force that does tend to cause electrons to match their velocities provided they maintain a respectful distance.
If electron-phonon coupling was all there was, then metals would only superconduct at a few milliKelvin. However the electrons are moving so slowly, and their wavelengths are so long, that each electron wavefunction may overlap with many thousands of others. If some of the electrons go into some ordered state, then it becomes energetically more likely for the neighbours to fit in too, and all of a sudden you get an energy gap between the ordered (superelectron) state and the disordered eletron states. This energy gap is much larger than the individual pairing energies.
If you are going to get the same sort of coupling and condensation using gravitiational waves, then you are going to need to balance the gravitational force with some sort of other repulsive force with the right sort of range. You might find this sort of balance in a neutron star, but I don't see it happening in the lab. But maybe I'm missing something...
Carl Sagan's original quote was that "extraordinary claims require extraordinary evidence".
Patrick Doyle
I mod down every jackass who puts his moderation policy in his sig. Oh, wait a sec....
...the method described is science in action, the way it is supposed to work.
No, actually this isn't how things work these days. Science has become so specialised that there are very, very, few people that can do both theoretically and experiemental work at the cutting edge.
Most of us have a fairly good knowledge of a very small corner of one field, a slightly less good knowledge of the entire field, and an educated layman's knowledge of the rest of our discipline. Outside of our own discipline our knowledge is fairly scanty, most physicist's knowledge of chemisty for instance is probably no better than your average layman.
It's just not possible to keep up with everything even in your own field anymore.
The characteristic of bogus (or "junk") science is theories that give predictions that are untestable, or theories that predict things that have already been proved experimentally to be untrue.
While I haven't read the paper, not alot of point as I'm not a quatumn physicist, and my knowledge of quatumn field theory is fairly basic, this guy seems to have made predictions which are provable. This is good science. Whether he is right or wrong is imaterial (to the scientific process), his theory is interesting enough that some experimentalist will pick this up and run with and then we'll find out whether the theory is correct (or not).
Just because he hasn't provided extrordinary proof, doesn't mean that he's doing bad science.
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gravity isn't a force
;-)
GR says that gravity is an apparent force which comes out of the bending of spacetime. On the other hand, gravity IS a force according to quantum theory. The whole paper we're discussing treats gravity as a field (author calculates Laplacian and Hamiltonian to derive the coupling). Hence my reasoning. Of course if gravity is NOT a force, but the others are, then you can say goodbye to most unified theories, which sounds wrong to me (Einstein would agree with me on this
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There are so many grossly misinformed posts on this article, that it's hard to choose which one to respond to. I'll take a crack at this one.
"gravito-xxxxxx" forces are a quite common (among astrophysicists) way of referring to some very real consequences of the Einstein equation. The Einstein equation is the complicated, non-linear equation which describes how mass/energy and pressures couple to the curvature of spacetime. At its face, it is hardly similar to the Maxwell equations which describe electric and magnetic fields.
One way to make the Einstein equation tractable is to linearize it. I.e. start with a flat (Euclidean) spacetime, and only consider 1st-order perturbations on that. This results in a linear theory which is quite capable of describing gravitational waves, Mercury's precession, and many other "common" consequences of General Relativity (not black holes, worm holes, or any other region of strong gravity).
These linearized equations, like the Maxwell equations, do leave gauge freedom. For a particular choice of gauge, you can cast the linearized Einstein equations in a form which bears a striking resemblance to the Maxwell equations. There are some key differences, perhaps the most critical of which is the lack of a displacement current in the gravitational Ampere's Law. This is what prevents screening of the gravitoelectric field (at least to linear order).
In any event, this similarity between the Maxwell equations and the linearized Einstein equations is what gives rise to the gravitoelectric and gravitomagnetic fields (analogues to the electric and magnetic fields, of course). So don't think "bunk" when you encounter these terms. They're quite real, and are commonly found in the General Relativity literature.