Press Release

Speed of light has changed, claims Macquarie physicist

By SpaceRef Editor
August 8, 2002
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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, was
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,
completed the paper in collaboration with Tamara M. Davis and
Charles H. Lineweaver of the Department of Astrophysics,
University of New South Wales.

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

"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 300,000 km per second — as the only acceptable

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."

SpaceRef staff editor.