Posted on 08/09/2002 9:26:33 PM PDT by chance33_98
Black hole theory suggests light is slowing
13:27 08 August 02
NewScientist.com news service
One of Einstein's most dearly held concepts - that the speed of light is constant - is looking a little fragile. Physicists in Australia claim there is good reason to think the speed of light has slowed over time.
"Einstein would have absolutely hated this," said Paul Davies of Macquarie University in Sydney. "His entire theory of relativity was founded on the notion that the speed of light is an absolute fixed universal number."
The physicists' suggestion follows earlier measurements of a key quantity called the "fine structure constant". This quantity dictates how photons of light interact with particles such as electrons. Observations of the light from distant, superbright galaxies suggest that this "constant" was actually slightly smaller 10 billion years ago (New Scientist print edition, 11 May 2002).
Because the value of the fine structure constant depends on two quantities - the electron's charge (e) and the speed of light (c) - this implies that one of these two quantities has also changed. Either c has decreased over time, or e has increased.
Event horizon
Now Davies and his colleagues say the most likely answer is that c has decreased. They argue that if instead the charge of the electron could go up, then this would mean the event horizon of a black hole - the region from which light and matter cannot escape - would shrink over time. And that would violate one of the golden rules of physics, the second law of thermodynamics.
It is a very speculative suggestion, however, because the detailed physics of black holes are very poorly understood and totally untested. Davies himself admits the arguments are "only suggestive".
But if he is proved right and the speed of light has slowed, it would revolutionise physics. "If these results hold out, we need to start re-examining the very nature of space and time," said Davies.
If the speed of light in the early Universe was much higher than it is now, physicists would have to rethink many of their ideas, such as the theory of inflation, which says space expanded extremely rapidly in the first split second after the big bang.
Journal reference: Nature (vol 418, p 602
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