ults. Since 1925 quantum mechanics had been an infallible guide to the atomic world, universally accepted, but difficult to interpret. "Nobody understands quantum mechanics," grumbled Richard Feynman. The advent of lasers, computers, and fast electronics led to the substitution of real experiments for mere thought experiments. Observations of the behavior of the individual photons and atoms brought about increasingly convincing proofs that nature really is as bizarre as quantum mechanics makes it appear. To describe nuclear and particle physics, a consistent theory based on quantum mechanics, relativity, and quarks had in two decades been refined to such a degree that it acquired the name Standard Model. Although it left many questions unanswered, it successfully accounted for all known particles and forces except gravity. The Standard Model confidently predicted the existence of a sixth and last quark named "top." But when the top quark was finally found in 1995, its huge mass turned out to be so grotesquely out of proportion with the others that it became a new enigma itself. On the human scale, the phenomenon of superconductivity, which had been discovered in 1911 and explained in 1957, also produced a bombshell: the detection of superconductivity at much higher temperatures than had been thought possible. What's more, the old explanation did not fit the new observations, so theorists had to start all over again. On the cosmic scale, new instruments mapped out the microwave background radiation discovered in 1965 at an unprecedented level of detail. The new date encouraged cosmologists, including the British physicist Stephen Hawking, to tackle a theory of "quantum cosmology", which deals with the wave function of the entire universe, and the beginning of time. If successful, it will be the ultimate union of atomic and cosmic physics. A look back over a century of physics reveals an era of vigorous growth, not only in ...
