Posted on 09/23/2002 9:27:50 AM PDT by vannrox
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Black hole theory suggests light is slowing |
13:27 08 August 02 |
Hazel Muir |
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.
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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13:27 08 August 02 |
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Among some assumptions on the structure of the universe is that it is the same everywhere. If it turns out otherwise, then our theories will be complicated much more.
It is a proximate empirical observation of a phenomenon. At the quantum level, it is violated all the time. It must be violated at thermal equilibrium as well (unless at absolute 0, which would violate the third law) - so it is a statistical phenomenon seen in bound systems when regarded at a certain scale.
As an observational phenomenon, a system's degree of order or randomness is subjective. A new deck of cards is ordered. After shuffling, it becomes disordered - it is highly unlikely that the deck of cards will ever become ordered as originally after any number of shuffles. But the idea that one arrangement of the cards is peculiar is subjective, all sequences are as likely, we just think that some are unusual.
The second "law" summarizes a practical observation, and gets us to looking for an external energy source when an otherwise closed system seems to increase its order. It is useful when we want to make a reservoir for energy or extract energy from a system. (We can use clumsy methods). But have you seen a formula relating energy to the degree of order in a system? I haven't.
What about self-organizing system? Complex systems seem to form ordered structures all the time, without consuming energy. One might describe these phenomena as eddies in the entropy flow, I suppose, but it is hardly conclusive. Just because we are able to discern organization in a constrained system, I am not convinced that it means that it is energetically different from any other arrangement of its constituents.
I see a green light much sooner than the dim-bulb on the cell phone in front of me. However, sound has remained a constant in that my cars horn can speed the green light signal up such that they can see it. If the horn thing doesn't work then the physical, anti-inertial assault from my bumper to theirs will speed it as well.
Stay safe; stay armed.
PS: I think that the author is full of crap. I cannot see a mechanism that can slow light's speed except for a physical barrier. Black holes can refract light, bend light and even alter its course by 180 degrees, but not slow it down. However, I am almost always wrong!!!
The more promising the reason for rethinking a sacred premise in the light of additional experience.
Science is a human pursuit--and its course is more determined by the culture of the society in which it is pursued than by anything else.
In the laws of thermodynamics, we have a foundation for Western science--an entire system that would be invalidated were those laws seen as erroneous.
Entire careers depend on protecting the sanctity of those laws.
So there is reason to believe that those laws may not be challenged often enough or objectively enough.
Fertile ground for the iconoclast.
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