The Changeless Laws of Nature? Guess Again

The Law of Nature. The term has such a clear, comforting sound. We like to think that the universe is governed by the strict rule of law: consistent, predictable, without exception.

Laws of nature seem as indelible as the Constitution, but far more effective. You can avoid taxes, but you can’t defy gravity; you can drive faster than the speed limit, but nothing can exceed the speed of light. But you won’t go to jail for ignoring a law of nature (on the contrary, if you broke one, you’d probably win a Nobel Prize).

The stereotypical view of nature’s strictures is well summarized in a popular T-shirt that shows Einstein as traffic cop, holding a sign: “Speed Limit of the Universe: 186,000 Miles per Second. It’s the Law!”

Indeed, our current national obsession with “zero tolerance” before the law probably stems at least in part from the belief that “zero tolerance” is nature’s way. All legal laws, like all natural laws, the thinking goes, should apply uniformly in all circumstances without exemption.

Alas, this belief is mistaken. Scientists have always been in the business of breaking (or at least stretching) current law. The Ten Commandments may be set in stone, but the laws of nature are not. Good scientists study the laws, but great scientists discover their weaknesses.

“One of the ways of stopping science would be only to do experiments in the region where you know the law,” said the late Caltech physicist Richard Feynman in his classic work on the subject, “The Character of Physical Law.”

Consider a simple, universal law--like the gravitational attraction of every bit of matter in the universe for every other bit of matter. Newton’s laws of gravity set physics on such firm footing that astronomers were able to deduce the existence of Neptune from a slight irregularity in the orbit of Uranus; centuries later, the same laws of gravity set men on course to the moon.

But Einstein showed that Newton’s laws were incomplete. The old laws broke down in subtle ways, or in extreme circumstances--near the fierce gravitational field of a star, for example.

The same story is repeated again and again throughout the history of science. Ultimately, all laws are tentative. “We are never definitely right,” said Feynman. “We can only be sure we are wrong.”

What, then, is a law of nature? According to Feynman, it’s an observed pattern or rhythm to the natural world. Drop an apple (or a desk), and it always falls.

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Sometimes, these patterns are “not apparent to the eye, but only to the eye of analysis,” said Feynman. If you drop a piece of tissue paper, it does not appear to fall in the same way as a rock. But the kinship of the pattern is revealed once you strip away air friction.

A law of nature, in other words, is a steady relationship, something that always happens--or at least as far as we know.

But the most interesting science happens where the laws break down. That’s one reason scientists like to push the laws to the breaking point, to see where they crack.

Currently, most physicists believe that Einstein’s laws of gravity break down in the extreme space and time warps inside black holes or at the origin of the universe. According to Cambridge University physicist Stephen Hawking, Einstein’s gravity predicts its own downfall.

Physicists plumb other cracks in the laws for signs of new and exciting physics. For example, for unknown reasons, the universe is made of matter, but not antimatter--even though known laws predict that it should contain equal amounts of both. “The laws of physics are not quite the same for particles and antiparticles,” says Hawking. Finding out why is a major thrust of massive research efforts on several continents.

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Despite persistent efforts to come up with a “theory of everything,” explaining everything is not what science does well. “Physics does not endeavor to explain nature,” wrote the late physicist Eugene Wigner. “In fact, the great success of physics is due to a restriction of its objectives.”

Limiting objectives allows physicists to learn which laws apply in which circumstances and which don’t. And just as laws against weapons in school may not apply to 8-year-olds carrying penknives in their lunch boxes, laws of gravity may not apply in the extreme time warps of black holes.

When the laws lead to absurd or nonsensical answers, physicists know it’s time to look for new laws.