Paragraph from The Large and the Small
In a letter to Max Born in 1947 Einstein said of the statistical approach to
quantum mechanics, which he attributed to Born, “I cannot seriously believe in it
because the theory cannot be reconciled with the idea that physics should represent a reality in time and space, free from spooky action at a distance” (the actual phrase used by Einstein was German, “spukhafte Fernwirkung”. Spooky, or ghostly, is a reasonable translation, although “spooky” was not in common usage in English in 1947).
The correspondence has been published in The Born-Einstein letters: correspondence between Albert Einstein and Max and Hedwig Born from 1916–1955, with commentaries by Max Born. Macmillan. 1971. p. 158.
Einstein's problem stems from the assumption of a reality in time and space. Although it is implicit in the assumptions of his paper on special relativity that spacetime consists only of relationships found in measurement, he was never able to fully embrace the implications of his argument, that there is no spacetime independent of measurement. Had he done so, he would have been able to recognise that the statistical approach, formalised by von Neumann, is indeed the correct way to understand quantum mechanics.
