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First real challenge to General Relativity?, (and not from Gravity Probe-B)
The Messenger
post Mar 24 2006, 03:22 PM
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QUOTE (ugordan @ Mar 24 2006, 01:14 AM) *
Nope, that would be radial acceleration as the acceleration vector points to the center of rotation. The angular velocity remains the same. Angular acceleration is the change (or derivation) of omega, which is the angular velocity. They even mentioned in one part of the paper thew were using two electric motors, one could go up to 6500 RPM but provided a slower spin-up speed and the other could go to (IIRC) 4500 but had a faster spin-up. They wouldn't mention that if the effect is totally determined by RPMs alone, IMHO.
Have you read the paper? Apparently they conducted numerous experiments because they were as well reluctant to believe what they were seeing. They did isolate the accelerometers inside Faraday cages to get rid of electromagnetic side-effects. As Bruce points out, they think this is totally independent of Podkletnov's claims.

There is a potential, in an accelerating superconducting environment, of spawning shearing "Eddy moments" at unclockable frequencies. The resulting frequency domain of such a magnetic field - (if possible) - would only weakly interact with matter, and slice through any Faraday cage like a neutrino. For those of use who think this is what gravity is, there are many situations where similar shear fields can and do bleed off gravitational field energy.

Bruce jumps all over me for going off on this Teslaian concept. But I think it is real, has a major effect upon orbital calculation of masses, and ultimately predicts many of the quirky observations of Galileo and Cassini.
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Guest_BruceMoomaw_*
post Mar 24 2006, 03:35 PM
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Oops. I was indeed wrong about the definition of angular acceleration; it is indeed a measurement of the change in rotation rate, rather than simply the measurement of a constant rotation rate and radius:
http://whatis.techtarget.com/definition/0,...i774878,00.html

Well, I did warn you that my scientific understanding is strictly on a Mr. Wizard level. I'm reminded of George Lichtheim's reference to "the mental chaos typical of the autodidact".
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gpurcell
post Mar 24 2006, 04:15 PM
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QUOTE (dtolman @ Mar 24 2006, 03:02 PM) *
So basically, unless someone invents a perpetual motion machine, this can be used to create strong, but short lasting gravity fields or weaker, but relatively longer lasting gravity fields (depending on how quickly you ramp up to the maximum RPM).

Even if this can't be used to make artificial gravity plating in my space yaucht - its exciting to think that General Relativity has finally had a hole poked into it within my lifetime!


Hm. Spin it fast enough for a surge of negative g acceleration away from a planetary body...a gravity rocket!
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The Messenger
post Mar 24 2006, 04:36 PM
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QUOTE (gpurcell @ Mar 24 2006, 09:15 AM) *
Hm. Spin it fast enough for a surge of negative g acceleration away from a planetary body...a gravity rocket!

When I started talking about using the magnets on the MNR to build a 'gravity camera', certain people got nervous and essentially banned me from the room.

I don't know that this implies a negative g force can be created - this would assume the detected field can be polarized, and they have not made that distinction. Gravity fields are (no matter who's physics you use) most likely chaotic, and therefore we are stuck with conventional means of overcoming gravity.

It should not be assumed that only in superconductive enviroments gravo-electro coupling can occur, so even if they are differentiated forces, this coupling could crop up places we have not expected. For example, it could lead to weak resonances in orbital stability, and stuff unexpected braking energy into comets as they pass through these weakly resonant fields. Ever wonder why earthquakes disrupt the ionosphere, and thunderstorms produce gamma rays? This completely opens up the astrophysical field, redefining possible solar history scenarios and on and on.

A field strength 30 orders of magnitude greater than predicted by GR is nothing to sneeze at, and also has severe implications for GR restrictions on gravitational redshifts, lensing and dark matter content.

And then of course, there is the matter of the Newtonian predictions of the masses of the planets smile.gif
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nprev
post Mar 24 2006, 08:08 PM
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QUOTE (dtolman @ Mar 24 2006, 07:02 AM) *
Even if this can't be used to make artificial gravity plating in my space yaucht - its exciting to think that General Relativity has finally had a hole poked into it within my lifetime!


...or, from another viewpoint, effects arising from quantum-level gravitational interactions might be finally observable at the macro level. I still think of GTR as the "big-picture" view of gravity (with Newtonian physics as a special case thereof applicable at low relative velocities), and I think that it will always stand.

What has always struck me about our understanding of gravity is that the mainstream theories generally describe observed effects without predicting a mechanism or engine (if you will) that actually produces these effects. We really need a quantum theory of gravity to make any forward progress from an engineering viewpoint, if that's even possible... huh.gif

Hmm...Now that I think about it...rotation...superconductor....gotta wonder if Andrei Sakarhov's 1967 conjecture (lately amplified in a way by Haisch, Rueda, & Puthoff) that gravity and inertia are Van Der Walls interactions between virtual particle pairs & "real" matter was correct? An angularly accelerating mass would tend to "plow into" more virtual particle pairs than when at rest, and maybe the superconductive nature of the mass in the experiment facilitates charge distribution (from the disruption of natural virtual pair destruction) across the entire mass, thus producing the observed weak "gravitational" gradient.... blink.gif


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Guest_Richard Trigaux_*
post Mar 24 2006, 08:33 PM
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Heeeeemmmm...

many wild speculations in latest posts. Many words that relativity scientists themselves will not understand.

Cool, guies, cool. If the effect indicated is real, it implies many theory by knowledgeable people before we ignorants understand it.

And if the observed effect was simply the deformation of the frame of the experiment aparatus under the heavy strain of a strongly accelerated large disk, no matter of what it is made of? It would produce the same output from the accelerometres than a magnetogravitationnal field, and be proportional to acceleration too. And easily larger than a magnetogravitationnal field...

I think we all wish that one day would be discovered something allowing us to travel in space as easily as in Starwars. But nothing proves that it really exist.

Experiments like this one must be monitored carefully, as they have the potential to lead to important discoveries. But usually they don't.

This thread reminds me the one about Heim which was also using a rotating disk and interaction between gravitation and electromagnetic field to drive a spacecraft.
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Marz
post Mar 24 2006, 09:07 PM
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QUOTE (Richard Trigaux @ Mar 24 2006, 02:32 AM) *
The Lens-Thiring effect, or magnetogravitationnal field, is the exact equivalent to gravitation and mass of what the magnetic field is to electric field and charge.

This is because the two domains mostly obey to the same equations.

When electric charges move, for instance rotate in a transformer coil (say to simplify a ring) they produce a magnetic field, with a north pole at one side of the ring, and a south pole at the other side. This magnetic field can in turn induce an electric field and a current into a secondary ring (coil).
Similarly, a ring of matter rotating produces a magnetogravitationnal field, which can in turn induce the rotation of a secondary ring besides the first.
This is a known consequence of the relativity. At a pinch, that relativity predicts the existence of the magnetogravitationnal field makes that it predicts too... the magnetic field, which is thus a BIG consequence of relativity at human scale.

Alas for us, the gravitomagnetic field is so weak that any human scale test is still unable to detect it, only at space scale the gravity probe B could detect it (results please?). But it may play an important role in the realm of neutron stars and black holes, for instance the rotation energy of a black hole could be extracted to accelerate an accretion disk. (and for instance produce jets)

What is new with this experiment is that a magnetogravitationnal field is said to result from electromagnetic effects alone, a thing hich is not predicted by relativity and is said (in the paper) to result from the violation of a basic physical symmetry.

If it is true, it may be a breakthrough into our understanding of the relation between relativity and the quantum world. But I wait for others reproducing the results before inflating imagination.

Anyway the gravitationnal field resulting from a Lens-Thiring field is ROTATING, so that it cannot be used to produce anti-gravitation or any propulsive gravitationnal field. At least not directly. At a pinch two Lens-Thiring rings repell each other, if they show both the same pole to the other. But it is much more complicated than using simply the magnetic properties of superconducting rings. And we are still far of producing a 1 G effect, if we need for this a rotation at 64 MILLIONS RPM...

So the thing is anyway to follow carefully, as soon as the primary results are reproduced.


Ok... um... duh.... I don't even have a Mr. Wiz level of understanding of these concepts. It's the first time I've ever heard the word 'magnetogravity', and I'm not happy about it. :-p

I always thought Einstein's view of a Gravitational "Field" was a literal distortion of space-time. That's why I thought quantum-gravity is, from where I sits, crazy! (If gravity is in discrete quanta, then that must mean time AND space can be defined in discrete quanta - please tell me this ain't so!)

The idea that a gravitational "field" can rotate means really stupid things to me, like time & space must rotate with it?
For instance, if ya'll are already speculating on rotating mass to create "negative" gravity, then why not "negative" space-time too?

Um... check please!
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Guest_BruceMoomaw_*
post Mar 24 2006, 09:36 PM
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I can vouch for the fact that quantum gravity theories DO require the quantization of space and time -- that is, there are specific minimal sizes for both below which it is impossible for any physical phenomena to be separated from each other either in spatial position or in timing. (Some of these describe space-time as a "foam", although my knowledge goes no farther than that.)
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Guest_Richard Trigaux_*
post Mar 24 2006, 09:44 PM
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[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
I always thought Einstein's view of a Gravitational "Field" was a literal distortion of space-time.
[/quote]

If you imagine a flat surface, with a ball which rolls on it. The ball goes straight ahead. But if there is a bump on the surface, then the ball undergoes a trajectory change when it passes on the bump. This is the two dimention equivalent to the idea of a three dimentional distorted space. But seems from above, our two dimention equivalent shows just a force changing the trajectory of the ball: The two dimention equivalent of a three dimentionnal gravitation field. So the descriptions of a distorted space time and of a gravitation field are just two concepts to describe the same reality.


[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
The idea that a gravitational "field" can rotate means really stupid things to me, like time & space must rotate with it?
[/quote]

Yes it does, and is the reason why the "magnetogravitationnal field" is also called frame drag. Around a rotating black hole, the space rotates with the black hole. This effect exists around Earth too, but much weaker, this is why we need a very sensitive experiment like Gravity Probe B.



[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
I always thought Einstein's view of a Gravitational "Field" was a literal distortion of space-time. That's why I thought quantum-gravity is, from where I sits, crazy! (If gravity is in discrete quanta, then that must mean time AND space can be defined in discrete quanta - please tell me this ain't so!)
[/quote]

Yes they should. But nobody yet knows how they do. Relativity and quatum theory are in contradiction, and there is no yet sure mean to reconcile them, only speculations. Unifying gravitation with the other forces (which are quantum) is the dream of all the physicists, object of the largest theoretical search.


[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
It's the first time I've ever heard the word 'magnetogravity', and I'm not happy about it. :-p
[/quote]

It is not very well known, and until recently I heard it only into fringe science. But it is an old prediction of general relativity which today comes to test with Gravity Probe B. Often scientists (and still more journalist who speak of science) do some "simplification" when they expose their results to the general public. Science is like the human body, in a way: there are parts that they do not like to show, even if it is the parts we most desire to see. Scientists don't like to speak of what they don't really understand themselves (like UFOs, but this is another story) and enjoy very much to speak of their success. So "magnetogravitationnal "is a word likely to be very well known in some years, although it exists still Einstein.


[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
For instance, if ya'll are already speculating on rotating mass to create "negative" gravity, then why not "negative" space-time too?
[/quote]
Never heard of this.



[quote name='Marz' date='Mar 24 2006, 10:07 PM' post='47406']
Um... check please!
[/quote]

Check yourself, in articles of science reviews which speak of relativity, Probe B, standard theory, quantum theory, unification theories. This is not of an easy access, but it remains understandable for anybody with a science bachelor level.
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The Messenger
post Mar 24 2006, 09:49 PM
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QUOTE (Richard Trigaux @ Mar 24 2006, 01:33 PM) *
And if the observed effect was simply the deformation of the frame of the experiment aparatus under the heavy strain of a strongly accelerated large disk, no matter of what it is made of? It would produce the same output from the accelerometres than a magnetogravitationnal field, and be proportional to acceleration too. And easily larger than a magnetogravitationnal field...

Good cautionary note, but as I read the experiment, they controlled for the rotating mass by monitoring the effect both above and below the superconductive transition. Something else could be wrong.

Particle physicists have never been able to weld a path between GR and quantum observables, and the fingers have always pointed in both directions. Since partical physics are at least phonomonologically derived, if confirmed, this paper would tend to throw GR out-of-the-boat first. But stay tuned, because once the attributes of this 'induced Newtonian metric' are understood, Planckian limits are next in-line...
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Marz
post Mar 24 2006, 11:00 PM
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QUOTE (Richard Trigaux @ Mar 24 2006, 03:44 PM) *
Never heard of this.

Check yourself, in articles of science reviews which speak of relativity, Probe B, standard theory, quantum theory, unification theories. This is not of an easy access, but it remains understandable for anybody with a science bachelor level.


Thanks for the excellent response. My "negative" space-time comment was only an attempt at humor, since others were also dreaming up space-yachts and gravity rockets in earlier posts. I mean, why stop at just negative gravity? (I don't have Shaka's knack for wit. huh.gif )

I've been trying to get a grip on relativity, but "frame dragging" is pretty tough for me to accept... especially if space-time has a finite quantum definition, as Bruce alluded to. This would mean that if I went near a rotating black hole, then MY timeline could get stretched beyond this quantum limit, and therefore "snap" into another timeline (like streams of foam floating down a drain)?

Another weird conceptual problem I have with this: Imagine Star-A that rotates clockwise, and Star-B of equal mass that rotates counter-clockwise. Their galaxy collides and these two stars end up in a tight binary system orbiting each other closely. What in the heck does their rotating space-time look like? ph34r.gif More importantly: what does it mean?

I'd like a bucket of quantum-secondlets to go, please. rolleyes.gif
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nprev
post Mar 25 2006, 06:11 AM
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QUOTE (Marz @ Mar 24 2006, 01:07 PM) *
Ok... um... duh.... I don't even have a Mr. Wiz level of understanding of these concepts. It's the first time I've ever heard the word 'magnetogravity', and I'm not happy about it. :-p

I always thought Einstein's view of a Gravitational "Field" was a literal distortion of space-time. That's why I thought quantum-gravity is, from where I sits, crazy! (If gravity is in discrete quanta, then that must mean time AND space can be defined in discrete quanta - please tell me this ain't so!)

The idea that a gravitational "field" can rotate means really stupid things to me, like time & space must rotate with it?
For instance, if ya'll are already speculating on rotating mass to create "negative" gravity, then why not "negative" space-time too?

Um... check please!


Well, there is such a thing as the Planck-Wheeler wavelength, which is basically the point at which spacetime becomes discontinuous, so broadly speaking this is the fundamental unit of spacetime. Bruce alluded to "foaminess", and this is probably an indirect reference to Misner, Thorne, and Wheeler's classic Gravitation; what it seems to mean is that the physical universe is a second-order side effect of the considerably greater potential mass/energy "background" of virtual particle production, known in some circles as the zero-point field. (Research note: There is a LOT of marginal pseudoscience that has arisen from these apparently well-established and uncontroversial principles; I urge anyone investigating this material on the Net to maintain a healthy level of skepticism and employ full-strength critical thinking at all times!) blink.gif blink.gif .


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Guest_Richard Trigaux_*
post Mar 25 2006, 07:38 AM
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QUOTE (Marz @ Mar 25 2006, 12:00 AM) *
Thanks for the excellent response. My "negative" space-time comment was only an attempt at humor, since others were also dreaming up space-yachts and gravity rockets in earlier posts. I mean, why stop at just negative gravity? (I don't have Shaka's knack for wit. huh.gif )

I've been trying to get a grip on relativity, but "frame dragging" is pretty tough for me to accept... especially if space-time has a finite quantum definition, as Bruce alluded to. This would mean that if I went near a rotating black hole, then MY timeline could get stretched beyond this quantum limit, and therefore "snap" into another timeline (like streams of foam floating down a drain)?

Another weird conceptual problem I have with this: Imagine Star-A that rotates clockwise, and Star-B of equal mass that rotates counter-clockwise. Their galaxy collides and these two stars end up in a tight binary system orbiting each other closely. What in the heck does their rotating space-time look like? ph34r.gif More importantly: what does it mean?

I'd like a bucket of quantum-secondlets to go, please. rolleyes.gif


yes all this is difficult to put into familiar images, and not only for you, for anybody too it is difficult, included high level scientists, who can explore these domains only with the help of extremely complicated mathematics. It is like a blind man exploring a castle with only his fingers, and trying to reconstruct a mental image of it afterward. He could seize some things, like the overal layout and use of the place, but not what the castle really looks like.


I think that the spacetime around rotating black holes can be relevantly compared to a fluid around a whirlpool. Around a rotating black hole, space is deformed in much the same way as the water around the whirlpool. If you put a drop of ink into the water, far away from the whirlpool, it remains a small dot. But approaching the whirlpool, this dot undergoes a shearing, it is elongated, and at last it makes a spiral around the whirlpool. With spacetime, it is much the same, as if it was made of small particles slipping on each other like the water. So, exactly like water manages to remain just plain water with a 1 density everywhere despite any motion or shearing effect, the space remains space as we know it everywhere, around a rotating black hole, and even inside it. (By the way, our timelines can be severely entangled, but they never go back). Or, if you want, the ink blot in the water can be compared to the referential into space, and this gives an image of how this referential can be dragged.
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Guest_Richard Trigaux_*
post Mar 25 2006, 08:35 AM
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QUOTE (nprev @ Mar 25 2006, 07:11 AM) *
(Research note: There is a LOT of marginal pseudoscience that has arisen from these apparently well-established and uncontroversial principles; I urge anyone investigating this material on the Net to maintain a healthy level of skepticism and employ full-strength critical thinking at all times!) blink.gif blink.gif .


Good caution. But it may happen that the solution lies in a domain or idea considered as fringe today.

What is important with non-standard idea, is not to make "alternative" dogmas of them, but to study them with caution and method. Of course many fringe ideas would not pass even the very first step of any serious study, but who knows. Perhaps it is a flaw into the science method itself which prevents us of understanding the truth.

As for me I do not make categories such as "standard" or "fringe". I just consider likeliness or usefulness of ideas. of course standard theories are in the best position (it is why they are standard theories, and the only good reason for them to be standard theories) while many fringe theories quickly appear as ignorant speculations or confusions. But who knows, maybe a new Einstein is breeding somewhere...
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nprev
post Mar 25 2006, 09:08 AM
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QUOTE (Richard Trigaux @ Mar 25 2006, 12:35 AM) *
Good caution. But it may happen that the solution lies in a domain or idea considered as fringe today.

What is important with non-standard idea, is not to make "alternative" dogmas of them, but to study them with caution and method. Of course many fringe ideas would not pass even the very first step of any serious study, but who knows. Perhaps it is a flaw into the science method itself which prevents us of understanding the truth.

As for me I do not make categories such as "standard" or "fringe". I just consider likeliness or usefulness of ideas. of course standard theories are in the best position (it is why they are standard theories, and the only good reason for them to be standard theories) while many fringe theories quickly appear as ignorant speculations or confusions. But who knows, maybe a new Einstein is breeding somewhere...


You are quite correct , Richard, and I apologize to the forum at large; the "wild ideas" of yesterday have, with almost disquieting frequency in the history of science, become the standard theories. It is therefore just as erroneous to dismiss those hypotheses that diverge from the norm as it is to accept established dogma without a qualm. Thank you for the valuable lesson (and reminder) that pragmatic objectivity is THE primary principle in the expansion of human knowledge! smile.gif


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