One of science’s great puzzles (still only partly solved) is how to reconcile the regularities of classical physics — like the bending light beam — with the probabilistic laws of quantum mechanics. Light, after all, consists of photons, which are capable of doing all kinds of strange things. In moving from A to B, a photon may take any number of different paths, even ones that seem absurd — spiraling in curlicues, changing speeds in midair. With Feynman’s method, these acrobatics can be added together, the weirdest ones canceling one another out, to yield the motion we observe in the familiar world.
This triumph came early in his career. His later thinking (about solid-state physics, for example, or quantum cosmology) was just as original. Maybe sometimes too original, Krauss suggests. Science usually proceeds by building on what came before. The maverick in Feynman kept him from accepting even the most established ideas until he had torn them apart and reassembled the pieces. That led to a deeper understanding, but his time might have been better spent at the cutting edge.
“He continued to push physics forward as few modern scientists have,” Krauss writes, “but he tended to lead from the rear or, at best, from a side flank.”