EINSTEIN, ALBERT

Typed letter signed with mathematical ink annotations in Einstein's hand, on "The Institute for Advanced Study" stationery, addressed to the physicist Behram Kurşunoğlu. Princeton: January 29, 1952. 8 1/2 x 11 inches (28 x 21.5 cm); 22 lines (plus salutation and felicitation), including three lines of manuscript mathematical notation and many notations and values in the text supplied in ink, with a three-line postscript with further equations. Usual folds, about fine. Framed.

An important letter from Einstein to Behram N. Kursunoglu regarding the latter's work on Einstein's unified field theory and general relativity. Kursonoglu (d. 2003) was a noted theoretical physicist who, at the time of the receipt of this letter, was completing his doctoral degree in physics under Paul Dirac at the University of Cambridge. He published a paper on Unified Field Theory in 1951 (see Proceedings of the Physical Society, Section A, Volume 65, Number 2). He had written to Einstein the same year regarding various theoretical aspects of his research (a retained copy of his four-page presentation to Einstein of his mathematical findings, dated 14 June, 1951 is included with the lot), and the present letter provides extensive details in mathematical form of the reservations that Einstein held towards certain of the young physicist's formulations. The two men met later that year for direct consultation on a generalized theory, and he then worked with Einstein and Schrödinger on a form of Unified Field Theory known in the literature as "Einstein-Schrödinger-Kurşunoğlu theory." In 1958 he was appointed professor at the University of Miami and later founded the Center for Theoretical Studies and the Global Foundation Institute at the University.

The letter reads as follows (N.B. the mathematical portions has been elided here, please refer to the accompanying image for these):

"January 29, 1952

Behram Kursonoglu, Fitzwilliam House, The University, Cambridge, England

My dear Mr. Kursonoglu:

I have to excuse myself for not answering your interesting communication of June 14.

I must confess that the argument for equating [...] to [...] is not convincing to me, for the simple reason that I believe the Minkowski space (flat space) should be a possible field.

But this is not the main point. The essential thing is that the existence of the Bianchi identities is not enough to make the system [...] (11) compatible in the usual sense. If you, for consistency assume that [...] have been expressed by the [g...] (from the first equation), you have 16 + 4 equations (really only 16 + 3 independent equations) for the [...]. This means you have 3 equations too many, which are not balanced by the identities.

There is, therefore, the risk that the manifold of solutions may be too small. I have taken the same risk in the Appendix to my book on Relativity, but later considerations make it very improbable that such a risk is justified from a physical standpoint (too few solutions).

Sincerely yours,

A. Einstein

Albert Einstein

P.S. The variation principle [...] does not yield [...]."