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.
Wow... Looks like not only have they debunked Einstein, but they have also achieved time travel, having journeyed into the future to publish their findings.
I'll aways recall Davies" last words in his The Mind Of God:
"We were meant to be here."
Please forgive the question, but I have zero background in such matters. It just seems like a logical question...
Photons have no "rest mass". They are essentially zero-mass. In fact, objects with zero mass must travel at light speed.
E=MC2 does not say you can't reach lightspeed.
The Lorentz equations are the operable ones. They predict that the mass of a body increases without limit as "C" is approached. In essence, the energy you are putting in to "push" the object to go faster just gets soaked up in its increasing mass, not in velocity.
Photons have no mass, but the do carry momentum.
The reasons that light is affected by gravity is that light always follows "space-time geodesics". Ordinarily, such geodesics are "straight lines". Near a large mass (like the Sun or a black hole) the geodesics of space-time are not "straight" but bent by the gravitation of the body. Therefore light departs from a "straight line" and travels in a curve. This is because--in effect--the warping caused by the mass causes a curved path to be the "shortest distance" for the light to travel.
--Boris
I'll aways recall Davies" last words in his The Mind Of God:
"We were meant to be here."
I'll always recall God's Last Words to His Creation in Life, the Universe and Everything:
"We apologize for the inconvenience."
Ah, thank you! For both the science lesson AND the grammar correction! I have always mixed those two up...
Sorry, I overlooked this one... By "no rest mass," do you mean that they have no mass when "still"? If objects with zero rest mass must travel at light speed (and are therefore never "resting"), how do we know that they have no mass while at rest? Please tell me to shut up if I'm annoying you with these simplistic questions :-)
The writing--I assume the reporter is a fault--obscures the message. Light does not absorb photons. Interstellar gas and dust absorb photons. Something like that seems intended.
They also applied another dogma of physics, the second law of thermodynamics, which Davies summarizes as "you can't get something for nothing."
That would be the first law. The second law is that entropy always increases in a closed system. ("You can't break even.")
What really bugs me is that the fans of Australian creationist Barry Setterfield (Mr. CDK) will be all over this thread claiming vindication. I see two possibilities. 1) This theory does not vindicate CDK. 2) This theory is a crock.
The "wrong type of photons"? I suppose this is the result of sloppy journalism, so common in accounts like this. But there must be more to it than we're told in this article.
The "rest mass" of a particle by definition is its mass as measured in its own frame of reference. For a photon, m = hf/c2, where h is Planck's constant and f is its frequency.
What's the frequency of a photon in its own frame of reference? In other words, how many wave peaks are passing you per second if you were travelling along side the photon? Zero, right? Therefore, the rest mass of the photon is also zero, theoretically.
Okay, someone who knows more physics than I do swat me down like a fly! :-)
BTW, here's a fun site that touches on lots of questions like that (e.g., see #126). My favorite is question #53: How much energy would be released if a marshmallow hit the Earth travelling 99.99% the speed of light (Answer: As much energy as in a "few dozen good-sized hydrogen bombs.").
I'm assuming you're combining E=hf and E=mc². The problem is that E=mc² doesn't apply to photons.
The general equation is E² = (pc)² + (mc²)² where p is the momentum. For a photon, E=pc; m=0 by geometry.
The problem with your analysis is that the principle of relativity prevents you from constructing--or even envisioning--a frame that is comoving with a photon. Light moves at speed c in all inertial frames; the moment you say that you are in an inertial frame, you are saying that light is moving at c with respect to you. Even in the limiting process where you approach the speed of light, the speed of light with respect to you does not go to zero. It remains fixed at c. Light itself does not have an inertial frame.
Question: But can't we envision being an observer photon moving alongside another photon?
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