Genius_ The Life and Science of Richard Feynman - James Gleick [43]
These new kinds of lumpiness in the way science conceived of energy were the essence of quantum mechanics. It remained to create a theory, a mathematical framework that would accommodate the working out of these ideas. Classical intuitions had to be abandoned. New meanings had to be assigned to the notions of probability and cause. Much later, when most of the early quantum physicists were already dead, Dirac, himself chalky-haired and gaunt, with just a trace of white mustache, made the birth of quantum mechanics into a small fable. By then many scientists and writers had done so, but rarely with such unabashed stick-figure simplicity. There were heroes and almost heroes, those who reached the brink of discovery and those whose courage and faith in the equation led them to plunge onward.
Dirac’s simple morality play began with LORENTZ. This Dutch physicist realized that light shines from the oscillating charges within the atom, and he found a way of rearranging the algebra of space and time that produced a strange contraction of matter near the speed of light. As Dirac said, “Lorentz succeeded in getting correctly all the basic equations needed to establish the relativity of space and time, but he just was not able to make the final step.” Fear held him back.
Next came a bolder man, EINSTEIN. He was not so inhibited. He was able to move ahead and declare space and time to be joined.
HEISENBERG started quantum mechanics with “a brilliant idea”: “one should try to construct a theory in terms of quantities which are provided by experiment, rather than building it up, as people had done previously, from an atomic model which involved many quantities which could not be observed.” This amounted to a new philosophy, Dirac said.
(Conspicuously a noncharacter in Dirac’s fable was Bohr, whose 1913 model of the hydrogen atom now represented the old philosophy. Electrons whirling about a nucleus? Heisenberg wrote privately that this made no sense: “My whole effort is to destroy without a trace the idea of orbits.” One could observe light of different frequencies shining from within the atom. One could not observe electrons circling in miniature planetary orbits, nor any other atomic structure.)
It was 1925. Heisenberg set out to pursue his conception wherever it might lead, and it led to an idea so foreign and surprising that “he was really scared.” It seemed that Heisenberg’s quantities, numbers arranged in matrices, violated the usual commutative law of multiplication that says a times b equals b times a. Heisenberg’s quantities did not commute. There were consequences. Equations in this form could not specify both momentum and position with definite precision. A measure of uncertainty had to be built in.
A manuscript of Heisenberg’s paper made its way to DIRAC himself. He studied it. “You see,” he said, “I had an advantage over Heisenberg because I did not have his fears.”
Meanwhile, SCHRÖDINGER was taking a different route. He had been struck by an idea of DE BROGLIE two years before: that electrons, those pointlike carriers of electric charge, are neither particles nor waves but a mysterious combination. Schrödinger set out to make a wave equation, “a very neat and beautiful equation,” that would allow one to calculate electrons tugged by fields, as they are in atoms.
Then he tested his equation by calculating the spectrum of light emitted by a hydrogen atom. The result: failure. Theory and experiment did not agree. Eventually, however, he found that if he compromised and ignored the effects of relativity his theory agreed more closely with observations. He published this less ambitious version of his equation.
Thus fear triumphed again. “Schrödinger had