Hiroshima_ The World's Bomb - Andrew J. Rotter [45]
Above all, Germany had Werner Heisenberg. He was one of the world’s great theoretical physicists, the man James Chadwick had called ‘the most dangerous possible German in the field because of his brain power’. Heisenberg had taken his doctorate at Munich with Arnold Sommerfeld, finishing the degree in 1923, when he was 22 years old. The previous year he had heard Niels Bohr speak at Gottingen, and had been captivated by the Dane’s depth of understanding, his brilliantly discursive presentation, even the famous mumbling that rendered his words barely audible. Heisenberg had asked Bohr a sharp question, and Bohr invited him for a walk following the lecture. ‘My real scientific career began only that afternoon,’ Heisenberg would write. Thus inspired, Heisenberg began postdoctoral work at Gottingen with Max Born. It was Born who coined, in 1924, the term ‘quantum mechanics’ to describe the nature of matter, especially at the atomic and subatomic levels. It was a way of knowing that would lead to a new understanding of the structure of atoms: they were made of particles, and electrons spun in orbits around their nucleii. Electrons might jump from one orbit to another, gaining (if jumping away from the nucleus) a quantum, or fixed measure, of energy, losing a quantum if jumping toward the nucleus. Bohr worked most imaginatively on the new physics, and it was thus to him that Heisenberg came, in March 1924, in the hope of extending his own investigations. Within five days of arriving in Copenhagen, Heisenberg had been invited to stay the year.
Bohr recognized Heisenberg’s quality. The men talked together for hours each day, often as they walked through the park surrounding Bohr’s institute. It was here that Heisenberg devised his uncertainty principle, which held, broadly speaking, that sure knowledge about a particle’s position in space erased certainty about its momentum, and vice versa. There was something finally unknowable (even if predictable) about the atom. So much for direct causation: ‘In the strict formulation of the causal law—if we know the present, we can calculate the future—it is not the conclusion that is wrong but the premise,’ wrote Heisenberg. Bohr was not altogether convinced, and neither was Albert Einstein—‘God does not throw dice,’ he scoffed—but the uncertainty principle came gradually to gain widespread acceptance and dramatically altered the landscape of quantum mechanics. Perhaps it also became a metaphor for Heisenberg’s life, or more particularly for his ethical position on serving the German state, come what may. If the smallest structures in the universe could not be known or understood in their totality, frozen in time and seen in full as if on a slide under a microscope, how was it possible for a human being, infinitely more complex than an atom, to know for sure what was right? If Einstein was wrong, and God did in fact throw dice, what kind of moral assurance could one expect from men? In November 1933 Heisenberg learned by telegram that he had won the Nobel Prize for physics. Students at the University of Leipzig, where he was now teaching, honored him with a torchlight march through the streets to his home. Heisenberg also thought it necessary to reassure the local head of the Nazi Students League of his support for the Fuhrer now in charge in Berlin.16
By the time Germany attacked Poland in 1939, Heisenberg and the others had taken a strong interest in the release of energy by nuclear fission and knew a good deal about it. Hahn, of course, knew more than practically anyone. Other German scientists grasped at least the rudiments of nuclear science; Harteck and Groth had written to the War Office in April 1939 that a nuclear explosive might be possible. Carl Friedrich von Weizsacker, at the KWI, was close to Heisenberg and had talked to him