Albert Einstein (1879-1955)
Autograph letter signed (with initials, 'A.E.') to Cornelius Lanczos, n.p., 21 March 1942
In German. Two pages, 280 x 216mm. Provenance: Sotheby's, 26-27 November 1980, lot 162.

'It seems hard to get a sight of what God's cards are. But I cannot believe for an instant that he plays dice'. Einstein has read Lanczos's paper with great interest, indeed 'with more than merely intellectual interest. For you are the only person known to me, who has the same attitude to physics as I have: a belief in the ability to grasp reality through something logically simple and consistent. / It impresses me how stubbornly you have thought through the equations of the fourth order, in order to suppress to a minimum the arbitrariness in the choice of the Hamilton function and how you have thought out a way of bypassing the difficulty caused by the permanent existence of electrical masses'. After this laudatory beginning, Einstein proceeds to play 'devil's advocate', a role to which he has become accustomed after his own 'hard experiences', and he advances three numbered objections to Lanczos's approach: first that he has 'no formal occasion' to move to equations of the fourth order; second, that 'The introduction of the fundamental wave system ensures that the construction based on this possesses no special-relativistically invariant invariance of the actually interesting quantities; third, it is not clear 'how the energy-momentum conservation law is supposed to have an exact, i.e. non-statistical character for the "observed" quantities'. On similar grounds, Einstein had himself excluded the approach Lanczos is following. As for his own work, 'I am currently workin on an idea which is admittedly simple in form but adventurous in terms of physics, that of substituting the coordinate space by a space with complex coordinates. The adventurous aspect lies in the doubling of the number of dimensions': he hopes to be able to send a formal account to Lanczos soon. Einstein ends by a reformulation of one of his most famous sayings: 'It seems hard to get a sight of what God's cards are. But I cannot believe for an instant that he plays dice and uses telepathic means (as is expected of him by current quantum theory)'.

The phrase ‘God does not play dice’ (in German, ‘Gott würfelt nicht’) is probably Einstein’s single most famous saying, expressing his belief in a universe governed by deterministic laws. The phrase appears most significantly in a letter to Max Born on 4 December 1926, and summarises Einstein’s fundamental objection to the dominance of probability in the Copenhagen Interpretation of quantum mechanics advocated by Born, Niels Bohr and others.