First real challenge to General Relativity?, (and not from Gravity Probe-B) Options

[Guest_BruceMoomaw_*]

...in the form of what may be an accidentally discovered artificial gravity generator, with possible practical applications!:
http://www.esa.int/SPECIALS/GSP/SEM0L6OVGJE_0.html

If this effect is real, it's fully 1/10,000 G -- which is not to be sneezed at, and might conceivably lead us to Bigger Things.

[Guest_Richard Trigaux_*]

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.

[Marz]

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!

[Guest_Richard Trigaux_*]

[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.

[Marz]

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. )

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? More importantly: what does it mean?

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