Constants in physics equations usually lead monotonous lives, but at least one fundamental constant may be changing its ways. The fine structure constant, which is associated with the interactions of atoms and light, could be as much as 10 parts in a million larger than it was six billion years ago, according a group of Australian researchers. This result, which appears in the August 27 issue of Physical Review Letters, suggests that the physics governing our universe could be slowly changing.

The fine structure constant determines what kind of light atoms absorb and emit and how well they hold together. Its current value of roughly 1/137 can¿t have changed too much in the past six million years or we wouldn¿t be here to talk about it: a variation of the constant by as little as a factor of 10 would render carbon atoms, the building blocks of life, unstable.

But the constant could be changing by a small yet detectable amount, reports John Webb of the University of New South Wales in Australia. Webb and his colleagues used the powerful Keck telescope in Hawaii to look at ancient light from quasars shining through three- to 10-billion-year-old clouds of cosmic dust. They compared the light absorbed by atoms in the primordial clouds with that emitted by modern atoms and found a tiny deviation that could be explained only if the fine structure constant is increasing.

Not everyone is convinced of the team¿s result. Lennox Cowie of the University of Hawaii notes that some sources of error still need to be analyzed. For their part, Webb and his colleagues believe that if they are right, then billions of years ago the universe was a slightly different place than it is today.

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