Paul Davis is a big shot in string theory.
Posted on 08/07/2002 12:53:40 PM PDT by Darth Reagan
SYDNEY (Reuters) - A team of Australian scientists has proposed that the speed of light may not be a constant, a revolutionary idea that could unseat one of the most cherished laws of modern physics -- Einstein's theory of relativity.
The team, led by theoretical physicist Paul Davies of Sydney's Macquarie University, say it is possible that the speed of light has slowed over billions of years.
If so, physicists will have to rethink many of their basic ideas about the laws of the universe.
"That means giving up the theory of relativity and E=mc squared and all that sort of stuff," Davies told Reuters.
"But of course it doesn't mean we just throw the books in the bin, because it's in the nature of scientific revolution that the old theories become incorporated in the new ones."
Davies, and astrophysicists Tamara Davis and Charles Lineweaver from the University of New South Wales published the proposal in the August 8 edition of scientific journal Nature.
The suggestion that the speed of light can change is based on data collected by UNSW astronomer John Webb, who posed a conundrum when he found that light from a distant quasar, a star-like object, had absorbed the wrong type of photons from interstellar clouds on its 12 billion year journey to earth.
Davies said fundamentally Webb's observations meant that the structure of atoms emitting quasar light was slightly but ever so significantly different to the structure of atoms in humans.
The discrepancy could only be explained if either the electron charge, or the speed of light, had changed.
IN TROUBLE EITHER WAY
"But two of the cherished laws of the universe are the law that electron charge shall not change and that the speed of light shall not change, so whichever way you look at it we're in trouble," Davies said.
To establish which of the two constants might not be that constant after all, Davies' team resorted to the study of black holes, mysterious astronomical bodies that suck in stars and other galactic features.
They also applied another dogma of physics, the second law of thermodynamics, which Davies summarizes as "you can't get something for nothing."
After considering that a change in the electron charge over time would violate the sacrosanct second law of thermodynamics, they concluded that the only option was to challenge the constancy of the speed of light.
More study of quasar light is needed in order to validate Webb's observations, and to back up the proposal that light speed may vary, a theory Davies stresses represents only the first chink in the armor of the theory of relativity.
In the meantime, the implications are as unclear as the unexplored depths of the universe themselves.
"When one of the cornerstones of physics collapses, it's not obvious what you hang onto and what you discard," Davies said.
"If what we're seeing is the beginnings of a paradigm shift in physics like what happened 100 years ago with the theory of relativity and quantum theory, it is very hard to know what sort of reasoning to bring to bear."
It could be that the possible change in light speed will only matter in the study of the large scale structure of the universe, its origins and evolution.
For example, varying light speed could explain why two distant and causally unconnected parts of the universe can be so similar even if, according to conventional thought, there has not been enough time for light or other forces to pass between them.
It may only matter when scientists are studying effects over billions of years or billions of light years.
Or there may be startling implications that could change not only the way cosmologists view the universe but also its potential for human exploitation.
"For example there's a cherished law that says nothing can go faster than light and that follows from the theory of relativity," Davies said. The accepted speed of light is 300,000 km (186,300 miles) per second.
"Maybe it's possible to get around that restriction, in which case it would enthrall Star Trek fans because at the moment even at the speed of light it would take 100,000 years to cross the galaxy. It's a bit of a bore really and if the speed of light limit could go, then who knows? All bets are off," Davies said.
There you go again ... making me think. This one isn't going to go down easy. But I'll work on it.
The use of the word "observer" implies a vantage point (i.e., an inertial frame).
The second law is that = ("You can't break even.")
They are actually the laws of life, and
there are three of them, all told.
You can't win.
You can't break even.
You can't get out of the game.
Well, it certainly doesn't vindicate CDK, as we're talking about a change of one part in 100,000 over 12 billion years. As for it being a crock, this result isn't a theory but a measurement, and while it may be in error, I have no reason to doubt it (although I still don't see how a change in the electron charge can be ruled out any more than a change in the speed of light).
There is one possible mechanism by which the speed of light may have changed. If there are large (order 1 mm) extra dimensions, some models predict that the compactification scale (the radius of curvature for the extra dimensions) will "relax" slightly over time after the universe forms. A tiny change in the speed of light may be a signature of that relaxation. If this is the case, relativity is unmolested. What we are seeing is the principle of relativity applied to a universe whose geometric structure is changing slightly over time.
I am always amazed at how often Linda Lovelace quotes have applicability to scientific problems.
;-)
A creationist would counter that magnitudes are unimportant where principle is involved. A woman who would have sex with me for a million dollars is a hooker, right? That clears the way to negotiate a better price! (OK, old joke!)
As for it being a crock, this result isn't a theory but a measurement, and while it may be in error, I have no reason to doubt it (although I still don't see how a change in the electron charge can be ruled out any more than a change in the speed of light).
I was merely establishing an either-or dichotomy between CDK vindication and reality. But I was wrong on one thing. The CDK loyalists don't seem to have the word yet.
Ouch! Can we have an ice pack over here? I think I sprained something trying to wrap my brain around this.
Did you say that if the shape of the universe is changing it could effect the speed of light?
a.cricket
Anybody got a nice physics symbol font?
The theory of relativity won't be retired. It might have a small adjustment added, a fine structure velocity factor perhaps. There is no reason to altogether dump a theory that still has some uses, especially if a new replacement theory is vastly more cumbersome.
A "couple if decades" aren't the only thing that she's had that were..... oh, never mind!
;-)
Prude.
;-)
If so, then how does light travel at the speed of light? The condition above does not hold: light has zero rest mass.
why is it effected by gravity? It is not affected by gravity directly: the space trough which it travels "changes" in the presence of gravity.
From 2002.
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