Planck, Max and Werner Heisenberg.

Planck. Max. Autograph letter, signed ("M. Planck"), to the American physicist George Pegram, thanking him for the English edition of his eight lectures on theoretical physics, stating that he has sent the translator Prof. Wills as a thank-you his latest publications, recalling the eventful weeks he spent in America seven years earlier, mentioning the war, his second wife and his new child, discussing his older offspring, one of whom is a prisoner of war in France, and asking to be remembered to Pupin and Davis, 4 pages, 8vo (22 x 14cm), Berlin-Grunewald, 20 February 1916, splitting to horizontal fold. Heisenberg, Werner. Autograph letter signed ("Werner Heisenberg"), to the Dutch-American physicist Samuel Goudsmit, about Rutherford and Bohr and the present state of nuclear physics, stating that Rutherford has news of developments at Cambridge, although not much has changed since July, thanking him for his hospitality at Ann Arbor, remembering fondly the physics they did together there, and commenting on Bohr's excellent apartment, 3 pages, 8vo (21 x 13.8cm), on printed stationery of the Universitetets Institut for Teoretisk Fysik, Copenhagen, 21 September 1932



...Hier in Kopenhagen wird viel über Kernphysik diskutiert, Rutherford weiss manches Neue aus Cambridge, aber eigentlich hat sich seit Juli nichts mehr geändert...

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Planck's distinguished correspondent is the American physicist George Braxton Pegram (1876-1958), one of the central figures in the Manhattan project. Samuel Goudsmit (1902-1978), the addressee of Heisenberg's letter, celebrated for his proposal with George Uhlenbeck in 1925 of the concept of electron spin, was at the time Professor at the University of Michigan.