Metal atoms like zinc and aluminum are often present in trace amounts in the clouds. The absorption of light by such atoms creates dark spikes at various wavelengths in the quasar's spectrum, with a pattern so well defined that it is often likened to a fingerprint. The value of those wavelengths is directly related to the value of the fine structure constant. But the fingerprint seemed to change in time, Mr. Murphy said, indicating that the constant grows larger as one goes nearer to the present and was not really constant. String theory, for example, could accommodate changes in quantities that accepted physics theory considers immutable.
String theorists postulate that space contains tiny, unseen dimensions.
Dr. Steinhardt said most theorists would have expected those changes to have occurred in the first seconds of the universe's life and be virtually unobservable by astronomers today. Still, he pointed out that several years ago, other astronomers unexpectedly found that the present universe is apparently filled with a mysterious kind of energy that counteracts gravity on large scales. Perhaps the two effects are somehow related, Dr. Steinhardt said. Other scientists pointed out that geologic processes, like naturally occurring nuclear fission, have been used to determine that the fine structure constant has probably changed little over the past two billion years on Earth. But researchers on the new paper point out that their results reach back much farther in time, and that interpreting the geological results is also a complicated matter.