137 - Arthur I. Miller [48]
Heisenberg, who was twenty-four, thought otherwise. Throughout spring 1925 he pushed Bohr’s theory of virtual oscillators to its limits. But it failed. It seemed that Bohr’s theory barely worked even for the hydrogen atom and even then no one really understood why. Atomic physics lay in ruins.
Many physicists spoke of their despair. Pauli did not respond well to crises and was becoming more and more depressed. He joked bitterly that physics was all wrong and wrote to Kronig, “I wish I were a film comedian or something similar and had never heard of physics.” He hoped, he added, that “Bohr will rescue us with a new idea.”
Around this time, Pauli wrote to Bohr about Heisenberg, “I always feel strange with him. When I think about his ideas, they seem dreadful to me and inwardly I swear about them. For he is very unphilosophical, he pays no attention to expressing clearly the fundamental assumptions and their connection with existing theories. But when I talk to him he pleases me very much and I see that he has all sorts of new arguments…. I believe that some time in the future he will greatly advance science.” Pauli was to be proved right.
Unlike Pauli, Heisenberg thrived in periods of chaos. Far from despairing, he would go all out to find a solution. He welcomed the stretch of the imagination required by Bohr’s virtual oscillators. He used his immense experience in every aspect of atomic physics, together with his natural audaciousness, spurred on by Pauli’s critical comments—among them that he should deal only with quantities that can be measured in the laboratory, such as the energy and momentum of electrons, and avoid abstract concepts such as orbits of electrons. “We must adjust our concepts to experience,” was the approach Pauli suggested. Heisenberg worked day and night and came up with a whole new atomic physics that was to become known as quantum mechanics. Full of excitement, Pauli wrote that Heisenberg’s work gave him “new hope and a renewed enjoyment in life.”
“We must adjust our concepts to experience”
Like every highly creative scientist of his era, Pauli was a philosophical opportunist. He picked and chose from whatever philosophy had to offer to tackle the problem at hand. Scientists use philosophy when they ask the deepest of questions, such as What constitutes a scientific theory? What sort of physical objects should it consider and how should it treat them? What is physical reality?
At the beginning of the twentieth century these questions became crucial when scientists had to contend with objects—such as electrons and atoms—that they could not actually see. Classical ways of understanding the world suddenly seemed insufficient. An intellectual tidal wave—the avant-garde—swept across Europe.
Scientific concepts, ways of thinking, and ways of knowing were all being re-examined. Einstein did so when he discovered his special theory of relativity in 1905. This upheaval in thinking pervaded the world outside science too. In 1907 Pablo Picasso launched cubism with his “Les Demoiselles d’Avignon” and in 1910 Wassily Kandinsky unveiled abstract expressionism. In 1913 Igor Stravinsky ruptured all the conventions of classical ballet with his “Rite of Spring.” The postwar 1920s produced the twelve-tone music of Arnold Schönberg, Bauhaus architecture, and James Joyce’s extraordinary novels, which encompassed everything from relativity to cubism. Meanwhile Freud and Jung were investigating the unconscious.
Pauli first encountered this ferment of ideas through his godfather, the positivist Ernst Mach. As a boy he was spellbound by the scientific equipment in Mach’s apartment. Its ultimate purpose, said Mach, was to eliminate unreliable thinking—to demonstrate that the only thing that was really out there was what you can experience with your senses. The rest was all metaphysics—quite literally beyond physics and not worth considering, mere illusion.
Atoms could not be experienced with the senses. Did that mean they were merely “metaphysical,” in Mach’s pejorative sense? Were they