Posted on 05/17/2006 9:04:18 AM PDT by SunkenCiv
The proof that faster-than-light (FTL) propagation is not allowed by nature is simple. Special relativity (SR) forbids it because, in that theory, time slows and approaches a cessation of flow for any material entity approaching the speed of light. So no matter how much energy is brought to bear, the entity cannot be propelled all the way to, much less beyond, the point where time ceases. The entity’s inertia simply increases towards infinity as the speed barrier is approached.[*] But most importantly, relativists are confident that SR is a valid theory because it has passed eleven independent experiments confirming most of its features and predictions. Moreover, the very successful theory of general relativity (GR) is based on SR, and has likewise passed several major experimental tests. So SR is confirmed by observations and forbids FTL propagation and travel.
As solid as this reasoning appears to be, it has a logical flaw because another theory exists about which the same supporting claims can be made, but which has no universal speed limit. This replacement theory is the so-called "Lorentzian relativity" (LR). Let’s briefly review the origin of this theory, what it says, how it differs from SR, and what the experiments have to say about it.
(Excerpt) Read more at metaresearch.org ...
Lorentzian Relativity mentioned:
http://www.FreeRepublic.com/forum/a393999a16260.htm#144
http://freerepublic.com/focus/f-news/1347416/posts?page=42#42
A Rare Blend of Monster Raving Egomania and Utter Bats--t Insanity
The Bactra Review: Occasional and eclectic book reviews by Cosma Shalizi 132
Mostly written July-August 2002; dusted off and made public 21 October 2005 | Cosma Shalizi
Posted on 01/20/2006 10:36:16 PM EST by strategofr
http://www.freerepublic.com/focus/f-news/1562020/posts
All-American Alien Boy bump.
No, this is not known at all. Both fields propagate at the speed of light.
This reminds me of when I was around 5 or so, and tried to think about what was up in the sky and how it could ever end. Anyway, I've heard that all we know about things like this is really meaningless because we only know a very, very small fraction, and it's not enough to make sense out of anything. It all boils down to, not being capable of using but a small bit of our brain's capacity...
The Speed of Gravity – What the Experiments SayAs viewed from the Earth's frame, light from the Sun has aberration. Light requires about 8.3 minutes to arrive from the Sun, during which time the Sun seems to move through an angle of 20 arc seconds. The arriving sunlight shows us where the Sun was 8.3 minutes ago. The true, instantaneous position of the Sun is about 20 arc seconds east of its visible position, and we will see the Sun in its true present position about 8.3 minutes into the future. In the same way, star positions are displaced from their yearly average position by up to 20 arc seconds, depending on the relative direction of the Earth's motion around the Sun. This well-known phenomenon is classical aberration, and was discovered by the astronomer Bradley in 1728.
by Tom Van Flandern
Physics Letters A 250:1-11 (1998)
Orbit computations must use true, instantaneous positions of all masses when computing accelerations due to gravity for the reason given by Eddington.
That's right. This situation however, is a thought experiment. In reality, no energy can just disappear.
The carrier of the electromagnetic field is the photon. It is light, so obviously it travels at the speed of light. In a vacuum, it's always c. In the presence of matter it's always something less.
The carrier of the gravitational field is the graviton. The only way to see a change in the gravitational field is by observing the field of at least 2 oscillating objects. The field thus emanating from the objects will then contain waves, which travel at the speed of light. Since gravity is so weak, these haven't been found yet. Some results should be in sometime next summer, I think.
The sum of the energy of the objects that exist in the universe and the energy of the gravitational field between them is zero.
The fields already exist. The Earth basically follows the geometry of space due to the presence of the energy of the bodies contained within that space. The Sun being the major energy body, is the object that is cheifly responsible for the curvature of the space around it. It's akin to laying tracks. The Earth follows the track in space laid down by the Sun. The Sun does not radiate gravity, as it does light.
some abstracts re gravitons, from Scirus:
Local Photon and Graviton Mass and its Consequences
Authors: M. Tajmar, C.J. de Matos
http://arxiv.org/abs/gr-qc/0603032
Graviton emission from a higher-dimensional black hole
Authors: A. S. Cornell, Wade Naylor, Misao Sasaki
http://arxiv.org/abs/hep-th/0510009
Gravitomagnetic London Moment and the Graviton Mass inside a Superconductor
Authors: Clovis Jacinto de Matos, Martin Tajmar
http://arxiv.org/abs/cond-mat/0602591
Any force mediated by a massless vector boson will propogate at the speed of light.
It's not so clear that gravity is such a force: do we believe string theory's attempts to construct a theory with a graviton, despite string theory predicting a contra-factual massless scalar field, and still not being well-forumlated (is the background 10 dimensional? 11 dimensional?. . .), or do we take the fairly well-validated approach of general relativity in which gravity is the curvature of space-time, and not a field that propogates at all?
The second paper is too much to read. I'm sure it does not contradict what I said about spacial curvature. Physically, there is no difference in the effects.
The third paper is not applicable to the space of the solar system. It regard the mass of a complex object(the Cooper pair in the Nb superconductor), not the mass of any free photons, or gravitons.
GR predicts the propagation of gravitational waves from mass/energy quadupoles (2 or more objects).
"string theory's attempts to construct a theory with a graviton, despite string theory predicting a contra-factual massless scalar field,"
The graviton naturally emerges as a spin 2 massless particle in any string theory. It is the closed string. The Hamiltonian for this closed string includes the momentum of the string which is a vector, so I don't see how it can be called a "scaler field".
"(is the background 10 dimensional? 11 dimensional?"
More like 26, since it takes that many to include chiral fermions. These theories though have duals. The 10/11 dimentional theories are equivalent to 3D 2t(time) theories and it depends whether deSitter, or anti-deSitter space is considered. The closed string in anti-deSitter space can exist off the branes and explains why gravity is so weak. Open strings are required to have their endpoints on a brane. In general it's better to use the simplest picture to conceptualize the phenomina.
It's not the graviton that's the scalar field--the massless scalar field is something string theory predicts which is not observed in nature--hence my scepticism that string field theory of any sort is actually the theory of nature. Well, that and 40 plus years without a testable prediction.
"Well, that and 40 plus years without a testable prediction."
Well, next year should be big when the LHC comes on line (though I would expect quite some time before "results" come out). However, I am skeptical as well, and I do not expect to hear about a new Higgs boson being found.
I don't understand this. What is the massless scalar field you're talking abut? Can you describe it?
It seems to be called the dilaton or radion, and I can't describe it physically because it has never been observed (doesn't exist?). It seems to show up in all string field theories, and a great deal of effort has been put into explaining why we don't observe it (under the assumption that string theory is right).
Personally, I expect the GUT (in Einstein's sense--*all* of the forces, not all but gravity) will be purely algebraic, along the lines of A. Connes reconstruction of the standard model from non-commutative geometry and the Barrett-Crane model for QG, with the appearance that we live in a Ricci-flat smooth Minkowskian 4-manifold being an artifact of the theory.
I myself am a pure mathematician who works in areas influenced by quantum physics (often collaborating with Crane) so I don't think I can do justice to the explanation for a physicist.
OK, but no pics of [Harvard Physicist and some-time goddess] Lisa Randall?
Cheers!
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