"The only natural generalisation of the gravitational equations"
Autograph letter signed ("A. Einstein").
4to. 1 page. In German.
€ 28.000,00
To the Hungarian-born physicist Cornelius Lanczos (1893-1974) with thanks for sending him a copy of his book "The Variational Principles of Mechanics" (1949) and for his having dedicated it to him, pointing out that it has freed him for the time being from the burden of being a passionate non-reader. Einstein ironically adds that despite everything he has learned so far about the American people he hopes the work will gradually find general distribution in U.S. universities: "Sie wissen, dass ich ein leidenschaftlicher Nichtleser bin. Aber Ihr Buch wird mich für eine Zeit von diesem Laster befreien [...] Ich zweifle nicht, dass dies Buch allmählich eine allgemeine Verbreitung in den hiesigen Universitäten finden wird, trotz allem was ich von unseren neuen Landsleuten allmählich in Erfahrung gebracht habe".
Returning to their shared obsession with gravitational theory, Einstein provides three equations which he now feels certain constitute the "overdetermined system" which is "the only natural generalisation of the gravitational equations". The reasoning that has brought him to this conclusion appears as an appendix in "the new edition of my old relativity book", which he will send Lanczos as soon as he has a copy.
Very well preserved.
