Built on Facts

John Derbyshire, writing in his beautiful book Prime Obsession, talks of a conversation he had with the mathematician Andrew Odlyzko. Derbyshire asked if he though the Riemann Hypothesis was true or not. The truth or falsehood of that hypothesis is the most importnat problem in mathematics, but despite more than a century of effort no mathematician has yet been able to give an answer. There’s considerable evidence in both directions, but in math evidence without proof counts for very little. Derbyshire asked Odlyzko to give his personal opinion:

JD: What do you think about this darn Hypothesis? Is it true, or not?

AO: Either it’s true, or else it isn’t.

JD: Oh come on, Andrew. You must have some feeling for an answer. Give me a probability. Eighty percent it’s true, twenty percent it’s false? Or what?

AO: Either it’s true, or else it isn’t.

Physics shares this principle. Any law, any hypothesis, any guess is either true or else it’s false. Personal wishes, expert opinion, philosophical debate are in the end just air. Everything stands or falls on the observed facts. It’s not quite as clean as mathematics, where absolute proof is possible. A physics experiment can only prove a theory wrong, while a million successful experiments can’t absolutely assure you a theory is right. The million and first might be the one that falsifies a previously well-established theory. But end the end, for every hypothesized law of nature - either it is true, or else it isn’t. We physicists wouldn’t have it any other way.