137 - Arthur I. Miller [50]
Pauli undoubtedly read Einstein’s views as well as the famous polemic in the first decade of the twentieth century between Mach and the discoverer of quantum theory, Max Planck, whose opinions were similar to Einstein’s. Planck accused Mach of degrading physics whereupon Mach simply withdrew in disgust: “I cut myself off from the physicist’s mode of thinking.”
Einstein believed, as did many scientists, in a world beyond perceptions in which electrons actually existed. Philosophers called this view “scientific realism.” There were scores of hybrid philosophies besides scientific realism and positivism which asserted that in fact there was nothing “out there.” Pauli counted himself a “‘heretic,’ not bowing down to any God, authority or ‘ism.’”
As a philosophical opportunist, Pauli saw that positivism offered a way out of the morass of 1925, when Bohr’s theory of the atom had collapsed with nothing to replace it. He thus advised Heisenberg to drop the unmeasurable concept of electron orbits and focus instead on measurable concepts like energy and momentum. This meant dropping the reassuring visual image of the atom as a solar system. Pauli’s belief was that once the “systems of concepts are settled,” that is, once the new atomic theory had been worked out, then “will visual imagery be regained,” as he wrote to Bohr. At Bohr’s Institute, Heisenberg and Bohr shared all correspondence from Pauli and eagerly awaited it.
Quantum mechanics—the new atomic physics
Heisenberg’s quantum mechanics identified individual electrons within atoms by the radiation they emitted while jumping between different stationary states, that is, the condition of an electron characterized by four quantum numbers as well as its momentum and energy, measurable as spectral lines. The transitions, or jumps, of the electrons maintained the flavor of the discontinuous quantum jumps in Bohr’s theory of the atom. Discontinuities were a fact of life in the world of the atom, especially in a theory based on electrons as particles.
Pauli was convinced that Heisenberg’s quantum mechanics would make it possible to solve problems that he had been unable to solve with the old Bohr theory. Late in 1925, he set out to calculate the stationary states for the simplest atom—hydrogen—using quantum mechanics. It involved juggling very complex mathematics but he came up with the answer with amazing speed.
Werner Heisenberg in 1925, when he discovered quantum mechanics.
Bohr applauded Pauli’s “wonderful results.” Heisenberg complained he was “a bit unhappy” that he had not solved the problem himself, but was full of admiration and surprise that Pauli had done it “so quickly.”
Irked that Pauli had stolen a march on him, just a month later Heisenberg, along with Pascual Jordan, another brilliant young physicist, tried applying quantum mechanics to the problem that had driven everyone to despair—the anomalous Zeeman effect. Just as Kepler’s ellipses had eliminated the cumbersome circles moving on circles, so Pauli’s new concept of spin—part of Heisenberg’s quantum mechanics—at a stroke swept away the concepts of massive inert cores with their two-valuedness and strange forces which had cluttered up Bohr’s theory. The problem had finally been put to rest, and the solution also helped set Heisenberg’s quantum mechanics on a firm basis. This time they had the theory right.
Physicists applauded these calculational breakthroughs. But no one—including Bohr, Heisenberg, and Pauli—really understood the theory itself, because the properties of atomic entities were so impossible to imagine. Not only was it unfamiliar and difficult to use, the mathematics of Heisenberg’s quantum mechanics lacked any helpful visual image. Being a hybrid version of Bohr’s virtual oscillators, it was like trying to visualize infinity. Its fundamental particles