Quantum_ Einstein, Bohr and the Great Debate About the Nature of Reality - Manjit Kumar [92]
On 7 July 1927, Uhlenbeck and Goudsmit received their doctorates within an hour of each other. Flouting convention, the ever-thoughtful Ehrenfest had arranged it that way. He had also secured both of them jobs at the University of Michigan. With few positions then available, Goudsmit said towards the end of his life, the post in America 'was for me a far more significant award than a Nobel Prize'.61
Goudsmit and Uhlenbeck provided the first concrete evidence that existing quantum theory had reached the limits of its applicability. Theorists could no longer use classical physics to gain a foothold before 'quantising' a piece of existing physics, because there was no classical counterpart to the quantum concept of electron spin. The discoveries of Pauli and the Dutch spin doctors brought to a close the achievements of the 'old quantum theory'. There was a sense of crisis. The state of physics 'was from a methodological point of view, a lamentable hodgepodge of hypothesis, principles, theorems, and computational recipes rather than a logical, consistent theory.'62 Progress was often based on artful guessing and intuition rather than scientific reasoning.
'Physics at the moment is again very muddled; in any case, for me it is too complicated, and I wish I were a film comedian or something of that sort and had never heard anything about physics', wrote Pauli in May 1925, some six months after discovering the exclusion principle.63 'Now I do hope nevertheless that Bohr will save us with a new idea. I beg him to do so urgently, and convey to him my greetings and many thanks for all his kindness and patience towards me.' However, Bohr had no answers to 'our present theoretical troubles'.64 That spring, it seemed that only a quantum magician could conjure up the yearned-for 'new' quantum theory – quantum mechanics.
Chapter 8
THE QUANTUM MAGICIAN
'On a Quantum-Theoretical Reinterpretation of Kinematics and Mechanical Relations' was the paper that everyone had been waiting for and some had hoped to write. The editor of the Zeitschrift für Physik received it on 29 July 1925. In the preamble that scientists call an 'abstract', the author boldly stated his ambitious plan: 'to establish a basis for theoretical quantum mechanics, founded exclusively on relationships between quantities which, in principle, are observable.' Some fifteen pages later, his goal achieved, Werner Heisenberg had laid the foundations for the physics of the future. Who was this young German wunderkind and how he had succeeded where all others had failed?
Werner Karl Heisenberg was born on 5 December 1901 in Würzburg, Germany. He was eight when his father was appointed to the country's only professorship of Byzantine philology at Munich University and the family moved to the Bavarian capital. For Heisenberg and his brother Erwin, almost two years older, home became a spacious apartment in the fashionable suburb of Schwabing on the northern outskirts of the city. They attended the prestigious Maximilians Gymnasium, where Max Planck had been a student 40 years earlier. It was also the school where their grandfather was now in charge. If the staff were tempted to treat the headmaster's grandsons more leniently than other pupils, then they quickly discovered there was no need. 'He has an eye for what is essential, and never gets lost in details', Werner's first-year teacher reported.1 'His thought processes in grammar and mathematics operate rapidly and usually without mistakes.'
August Heisenberg's father, forever the teacher, devised all manner of intellectual games for Werner and Erwin. In particular he always encouraged mathematical