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Gravitational Radiation Discussion With Bruce

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Posted by Richard Ruquist on November 7, 2002 14:45:39 UTC

Bruce and I are having a discussion of Van Flandem's work on the speed of the force of gravity on the God&Science forum. It is more appropriate for this forum as it applies to the behavior of black holes. My response is to his reference of a paragraph from the Graviational Radiation MIT physics project he provided the link for below. I'll copy the link as an attachment to this post for anyone interested in reading it for themselves.

I would like to take this discussion to the top because of what I read on the succeeding 6-13 lines. You asked me to read lines 1-5 plus the last two lines from the first page.

I will retype the paragraph you refer to because at least on my machine, acrobat cannot be copied.

"When Einstein formulated special relativity and saw that it required that no information could travel faster than the speed of light, he realized that Newtonian gravity would have to be modified. Not only would static gravitational fields change in the vicinity of compact masses, but time varying fields would have to propagate with the speed of light. Otherwise gravity could be used to send informtion faster than the speed of light, destroying the fundamental basis of relativity."

Before going on to the succeeding lines, I wish to comment that in the EPR experiments we have evidence that 'something' is traveling faster than the speed of light. But it has been shown that that the 'something' cannot tranmit information. Thus, special relativity is prserved for EPR even though the coupling between distant particles, called entanglement, seems instantaneous. It is well known that Einstein was wrong that 'nothing' could travel faster than the speed of light.

Now please consider the following lines from the link you provided, lines 6-8.

"Einstein had a conceptual prototype for gravitational radiation: electromagnetic radiation. The idea of Electromagnetic radiation had been discoverd by Jamrs Clerk Maxwell in 1873 and had been experimentally measured by Heinrich in 1888....."

So it seems that we can use EM experiments as a conceptual model for gravitational waves. Right? If we can show instances where light exceeds the speed of light, then we can reasonably expect that gravity can work the same way.

OK? Well, the experiments have already been done demonstrating that for evanescent waves, the speed of light in the evanescent medium is much faster than the speed of light- instantaneous as far as anyone can tell.

A series of experiments hve been performed in several labs where light is propagated through a thin medium where absorption dominates and the wave becomes exponential. Several interesting results have been obtained- like the peak of a pulse leaving he medium before it enters it.

But the bottomline is that the speed of light is exceeded in a near field where the wave is exponential. One can reasonably expect gavity to work the same way. Probably it can be shown that information cannot be transmitted faster than the speed of light using the force of gravity, just as it was for the EPR experiments and I believe also for the light transmission experiments. But the force of gravity of nearly static bodies is a near field effect. It would appear that even in GR the curvature of space is a near field effect and can be modified a speeds faster than the speed of light.

Since such propagation has been demonstrated for light, and also electrons in the EPR case, wouldn't we expect it to apply to gravity as well. I'll try to find some links for you if you wish to read about the experiments I am refering to. But I do not have any right now.
The conventional wisdom about the gravity of black holes is that the history of all the mass ever absorbed by the hole is still seen by us from outside the event horizon. But using the same conceptual model of light for gravity, we know that the light radiated to us from ouside the event horizon suffers red shift and loss of energy. I expect that if the force of gravity came from outside the event horizon it would experience the same kind of loss.

Perhaps that is true, that black holes lose force with time. But I prefer to believe that the gravitational force of black holes does not diminuish with time. And that means that the speed of gravity exceeds the speed of light for it to escape the event horizon and for the black hole to retain its attractive force.


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