Genius: The Life and Science of Richard Feynman

by James Gleick

A theorist who can juggle different theories in his mind has a creative advantage, Feynman argued, when it comes time to change the theories. The path-integral formulation of quantum mechanics might be empirically equivalent to other formulations and yet—given less-than-omniscient human physicists—find more natural-seeming application to realms of science not yet explored. Different theories tended to give a physicist “different ideas for guessing,” Feynman said. And the century’s history had shown that when even so elegant and pure a theory as Newton’s had to be replaced, slight modifications could not suffice. To get something that would produce a slightly different result it had to be completely different. In stating a new law you cannot make imperfections on a perfect thing; you have to have another perfect thing. He understood explanations as a surgeon understands knives. He had a set of practical tests, heuristics, that he applied when reaching a judgment about a new idea in physics: for example, did it explain something unrelated to the original problem. He would challenge a young theorist: What can you explain that you didn’t set out to explain? He knew that why? is a question without an end and that our knowledge of things is inextricable from the language we use. The words and analogies from which we build our explanations are culpably linked with the things explained.