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The Australian Centre for Astrobiology |
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Speed of light has changed, claims ACA physicist Australian theoretical physicist, Professor Paul Davies, has proposed that one of the so-called “constants” of the universe – the speed of light – has in fact slowed over time, a revelation that will cause a rethink of many of our accepted laws of physics as well as our “understanding” of the beginning of the universe. Davies’ paper, Black holes constrain varying constants, is published in the August 8 edition of leading science journal, Nature. Davies, a Professor of Natural Philosophy at the Australian Centre for Astrobiology at Macquarie University, Sydney, completed the paper in collaboration with Tamara M. Davis and an associate member of the ACA, Charles H. Lineweaver of the Department of Astrophysics, University of New South Wales, Sydney. The paper solves the riddle posed by UNSW astronomer John Webb, who earlier this year revealed that light from a distant quasar had absorbed certain photons from interstellar clouds of metals on its 12 billion year journey to Earth. Webb’s analysis created a scientific dilemma, as the light had absorbed the wrong photons according to known laws of physics. Webb observed that the fine structure content, or alpha, of the quasar light was about a millionth smaller than the accepted value of approximately 1/137. This suggested that alpha is not a constant number throughout the universe, as had previously been believed. The constant nature of alpha currently underpins many of our laws of physics, including Einstein’s Theory of Relativity. “The laws of nature include certain numbers,” Davies explains, “known as physical constants. One assumes that these are God-given, fixed numbers. The fact that one of these appears to be varying with time isn’t supposed to happen.” Davies has taken Webb’s discovery one step further by investigating which of the two ‘constants’ that alpha is built upon, electron charge or the speed of light, has actually varied over time. He was able to discount the theory that electron charge had changed over time, because it would come into conflict with another of the basic laws of the universe – the so-called second law of thermodynamics. Davies was able to reach this conclusion by considering what would happen to a black hole endowed with an electric charge as the charge increased with time. That leaves the speed of light – currently believed to be 300,000km per second - as the only acceptable variant. While Davies’ theory will cause much debate in the scientific community and cause many physics assumptions to collapse, it will account for many other puzzles, such as why far-flung parts of the universe are roughly at the same temperature and how elements such as helium formed in the early universe. “If the speed of light varies, potentially it could have been anything 12-15 billion years ago when the Big Bang occurred,” Davies says. “The speed of light could have been infinite at that time, which would explain a lot about our current universe.” Greg Welsh, Acting Media Manager, Macquarie University
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