Quantum_ Einstein, Bohr and the Great Debate About the Nature of Reality - Manjit Kumar [164]
Nevertheless, the Copenhagen view assigns a privileged position to the observer, be it human or a mechanical device, in the construction of reality.
But all matter is made up of atoms and therefore subject to the laws of quantum mechanics, so how can the observer or measuring apparatus have a privileged position? This is the measurement problem. The Copenhagen interpretation's assumption of the prior existence of the classical world of the macroscopic measuring device appears circular and paradoxical.
Einstein and Schrödinger believed it to be a glaring indication of the incompleteness of quantum mechanics as a total world-view, and Schrödinger tried to highlight it with his cat-in-a-box. Measurement in the Copenhagen interpretation remains an unexplained process, since there is nothing in the mathematics of quantum mechanics that specifies how or when the wave function collapses. Bohr 'solved' the problem by simply declaring that measurements can indeed be made, but never offered an explanation of how.
Schrödinger met Bohr while in England in March 1936 and reported the encounter to Einstein: 'Recently in London spent a few hours with Niels Bohr, who in his kind, courteous way repeatedly said that he found it "appalling", even found it "high treason" that people like Laue and I, but in particular someone like you, should want to strike a blow against quantum mechanics with the known paradoxical situation, which is so necessarily contained in the way of things, so supported by experiment. It is as if we are trying to force nature to accept our preconceived conception of "reality". He speaks with the deep inner conviction of an extraordinarily intelligent man, so that it is difficult for one to remain unmoved in one's position.' Yet Einstein and Schrödinger both remained steadfast in their opposition to the Copenhagen interpretation.56
In August 1935, two months before the EPR paper was published, Einstein finally bought a house. There was nothing to distinguish 112 Mercer Street from its neighbours, but because of its owner it became one of the most famous addresses in the world. It was conveniently located within walking distance of his office at the Institute for Advanced Study, although he preferred to work in his study at home. Located on the first floor, a large table covered with the usual paraphernalia of the scholar dominated the centre of the study. On the walls there were portraits of Faraday and Maxwell, later joined by one of Gandhi.
The small clapboard house with its green shutters was also home to Elsa's younger daughter Margot, and Helen Dukas. All too soon the domestic tranquillity was shattered as Elsa was diagnosed with heart disease. As her condition worsened, Einstein became 'miserable and depressed', Elsa wrote to a friend.57 She was pleasantly surprised: 'I never thought he was so attached to me. That, too, helps.'58 She died aged 60 on 20 December 1936. With two women to look after him, Einstein quickly came to terms with his loss.
'I am settling down splendidly here', he wrote to Born.59 'I hibernate like a bear in its cave, and really feel more at home than ever before in all my varied existence.' He explained that this 'bearishness has been accentuated still further by the death of my mate, who was more attached to human beings than I'. Born found Einstein's almost casual announcement of Elsa's death 'rather strange' but unsurprising. 'For all his kindness, sociability, and love of humanity,' Born said later, 'he was nevertheless totally detached from his environment and the human beings included in it.'60 Almost. There was one person to whom Einstein was deeply attached, his sister Maja. She came to live with him in 1939 after Mussolini's racial laws forced her to leave Italy, and stayed until her death in 1951.
After Elsa's death, Einstein established a routine that as the years passed varied less and less.