Is basic law of physics changing?

Legislators change laws from time to time, but Mother Nature's laws are eternal — or so it has seemed.

Now, though, scientists are debating clues that suggest the laws of physics change over time, threatening to shake up our basic notions of reality.

At stake is one of the fundamental values in physics: the arcane-sounding "fine structure constant," which measures how subatomic particles interact with light and with each other.

Some astrophysicists have proposed that the value of the fine structure constant, a k a "alpha," has changed subtly over billions of years. They base this proposal on their work — using telescopes like the giant Keck telescope, which sits atop a dormant Hawaiian volcano — analyzing light from interstellar gas and galaxy-gobbling super-furnaces called quasars on the outskirts of the universe.

If they're right, then our theories of the cosmos might be due for an overhaul. One speculation is that alpha is changing over time because of now-unknown alternate dimensions. As these hidden dimensions change shape, they change the fine structure constant.

But skeptics, citing observations that contradict the claim that alpha is changing, are plentiful — and even the pro-change claimants are being cautious, partly because there's so much at risk. The notion that the laws of physics are eternal and unchanging is one of the ground-floor assumptions of everyday life — when you drop a ball, for example, you expect it to fall, not to rise — and no one wants to abandon that assumption unless they've got compelling reasons.

"We are claiming something extraordinary here," acknowledged astrophysicist Michael Murphy of Cambridge University in England, one of the scientists who reported possible evidence of a change in the fine structure constant at a scientific conference earlier this year. "And the evidence, though strong, is not yet extraordinary enough."

At another science conference, a group of Berkeley, Calif., scientists reported that alpha is not changing, based on their independent analysis of light from galaxies.

Murphy defends his observational technique as more precise than that of critics. As he reported recently, his latest observations have "a precision of 1 in a million. So it's about a factor of 30 better" than the technique deployed by critics, he said.

The critics disagree. They say that their observational technique is relatively simple and, thus, yields pretty unambiguous results, whereas Murphy's technique is an especially complex one that is vulnerable to all kinds of "systematic errors," in scientific lingo.