Quantum_ Einstein, Bohr and the Great Debate About the Nature of Reality - Manjit Kumar [143]
Bohr never used the term the 'Copenhagen interpretation', nor did anyone else until Heisenberg in 1955. Yet from a handful of adherents it quickly spread so that for most physicists the 'Copenhagen interpretation of quantum mechanics' became synonymous with quantum mechanics. Three factors lay behind this rapid dissemination and acceptance of the 'Copenhagen spirit'. The first was the pivotal role of Bohr and his institute. Inspired by his stay in Rutherford's laboratory in Manchester as a young postdoctoral student, Bohr had managed to create an institute of his own with the same zing in the air – the sense that anything was possible.
'Bohr's Institute quickly became the world centre of quantum physics, and to paraphrase the old Romans, "all roads lead to Blegdamsvej 17"', recalled the Russian George Gamov who arrived there in the summer of 1928.69 The Kaiser Wilhelm Institute of Theoretical Physics of which Einstein was the director existed only on paper, and he preferred it that way. While he usually worked alone, or later with an assistant who carried out the calculations, Bohr fathered many scientific children. The first to rise to prominence and positions of authority were Heisenberg, Pauli and Dirac. Though only young men, as Ralph Kronig later recalled, other young physicists did not dare to go against them. Kronig, for one, had not published the idea of electron spin after Pauli ridiculed it.
Secondly, around the time of Solvay 1927 a number of professorships became vacant. Those who had helped create the new physics filled nearly all of these. The institutes they headed quickly began to attract many of best and brightest students from Germany and across Europe. Schrödinger had secured the most prestigious position, as Planck's successor in Berlin. Immediately after the Solvay conference, Heisenberg arrived in Leipzig to take up his post as professor and director of the institute for theoretical physics. Within six months, in April 1928, Pauli moved from Hamburg to a professorship at the EHT in Zurich. Pascual Jordan, whose mathematical skills had been vital to the development of matrix mechanics, succeeded Pauli in Hamburg. Before long, through regular visits and the exchange of assistants and students between each other and Bohr's institute, Heisenberg and Pauli established Leipzig and Zurich as centres of quantum physics. With Kramers already installed at the University of Utrecht and Born at Göttingen, the Copenhagen interpretation soon became quantum dogma.
Lastly, despite their differences, Bohr and his younger associates always presented a united front against all challenges to the Copenhagen interpretation. The one exception was Paul Dirac. Appointed Lucasian Professor of Mathematics at Cambridge University in September 1932, a chair once occupied by Isaac Newton, Dirac was never interested in the question of interpretation. It seemed to him to be a pointless preoccupation that led to no new equations. Tellingly, he called himself a mathematical physicist, whereas neither his contemporaries Heisenberg and Pauli nor Einstein and Bohr ever described themselves as such. They were theoretical physicists to a man, as was Lorentz, the acknowledged elder statesman of the clan who died in February 1928. 'To me personally,' Einstein wrote later, 'he meant more than all the others encountered in my lifetime.'70
Soon Einstein's own health became a matter of concern. In April 1928 during a short visit to Switzerland he collapsed as he carried his suitcase up a steep hill. At first