Not so fast Einstein, light's got the brakes on

The Sydney Morning Herald, August 8 2002

In a changing world at least something seemed constant - the speed of light. That's what Einstein taught us. Right?

Wrong, says a team of Sydney researchers led by the renowned cosmologist Professor Paul Davies, of Macquarie University.

In a find that could transform our understanding of the universe, the team has shown that the speed of light must have slowed since the Big Bang.

As claims by scientists go, they don't get much bigger than this.

The physical constants of the universe, like c the speed of light have been assumed to be
"God-given, fixed numbers", Professor Davies said. "The fact that one of these appears to be varying with time isn't supposed to happen."

If confirmed, it could herald the biggest scientific revolution since Einstein's theory of relativity, he said. In fact, that cornerstone of modern physics would "have to go".

Textbooks would have to be rewritten. The world's best known physics equation E = mc2 (where E is energy and m is mass) would no longer hold.

The research, published today in Nature, is based on observations of distant bright objects in the universe known as quasars, by the University of NSW astronomer John Webb.

He found that the 12 billion-year-old quasar light had properties that could not be explained by today's laws of nature.

Professor Davies said he was "incredulous" when first told. "It was not the thing a physicist wants to hear." But science was based on "overturning cherished ideas".

So, with Tamara Davis and Charles Lineweaver of the university, he examined the possibilities by calculating the consequences for black holes. They were able to rule out that another physical constant, e, the electronic charge, had varied.

That left c, the speed of light, which appeared to have "hit a speed bump" 6billion years ago, and slowed, Professor Davies said.

One implication was that c might have been infinitely large at the time of the Big Bang. "If the speed of light varies, potentially it could have been anything 12 to 15 billion years ago."

A very high speed would help explain the mystery of why far-flung regions of the cosmos now look so uniform from Earth, with different regions of the early universe able to push and pull on each other at infinite speed.

Light travelling at its present accepted speed, 300,000km/sec, would not have been fast enough to have got from one far-flung region to another.

A University of Western Australia physicist, David Blair, described the team's arguments in the research paper as "very beautiful". But was he convinced that c has changed? "Definitely not."

Big claims required exceptional evidence. More research on quasars was needed by independent teams to confirm the observed effects, Professor Blair said, adding that astronomers would be likely be spurred to do this by the team's controversial proposal.

If their claims did eventually turn out to be true, then "it would be really exciting".

Last week, Professor Davies won the 2002 Michael Faraday Award, given by the Royal Society London to scientists who have done the most to further public communication of science, engineering or technology.

In 1995, he was awarded the prestigious Templeton Prize for progress in religion.

©The Sydney Morning Herald
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