Typed letter signed ('A. Einstein') to Cornelius Lanczos, Old Lyme, Connecticut, 14 September 1935

Albert Einstein (1879-1955)
Typed letter signed ('A. Einstein') to Cornelius Lanczos, Old Lyme, Connecticut, 14 September 1935
In German. 1¼ pages, 282 x 217mm, with autograph additions in black and green ink including two equations and three further mathematical terms. Provenance: Sotheby's, 26 November 1980, lot 157.

On a mathematical difficulty which 'cooled my confidence below freezing point': Einstein reflects on an article by Lanczos. Einstein expresses the great pleasure he has found in the 'beauty of the whole construction' of Lanczos's latest article: 'The fact that the pure Maxwellian case is excluded is actually in appearance only; for in k₂=k₁+ε you can make ε really infinitely small'. He goes on: 'The first field equation reminds me of a pain I felt in previous efforts that led to similar additions to the gravitational equations as yours (to a first approximation)', and he writes out the relevant equation. 'If this is a true relationship for Maxwell's field, then the right-hand side does not disappear for an electrostatic, centrally symmetric field. In particular, consider the 14 etc. component. You then get strange g₂₄ g₂₄ g₃₄, which cooled my confidence below freezing point ... The fact that ga₄₁ is obtained at all in such a static case goes against the grain for me, considering the dynamic nature of these components according to the phenomenological theory. Did that not give you serious concerns?'.