Translated and annotated by Bertram Schwarzschild Einstein writes to Besso, his close friend since 1897, six months after completing the general theory of relativity and a few days after the death, at age 42, of Karl Schwarzschild, who found the first exact solutions of the theory’s field equations.
Berlin, 14 May 1916
Dear Michele,
All went well on my journey [from Switzerland] and later…. Our real-life Sterne novel 2 is at least as nice as the original; it calls for a sequel.
That stuff about Brownian motion is just tipsy talk [eine Bieridee] from [thermodynamicist Aurel] Stodola. I’ve already tried, in vain, to talk him out of it…. I hope your teaching [a course in patent law] is giving you pleasure. I still remember well that one has to give oneself a real push to overcome the initial aversion, and that one always thinks that everything one says is too obvious. But that’s an optical illusion. Do you remember how courteously you always came to my [radiation theory lectures] in Bern? And now I can’t reciprocate. I have to give another really amusing expert opinion in a patent case. I’ll tell you about it when next we see each other.
At the moment I’m working rather moderately; so I’m feeling quite well, living in tranquil contemplation without any discord. In gravitation, I’m looking for the boundary conditions at infinity. But it’s interesting to consider to what extent a finite universe exists, that is, a universe of naturally measured finite extension, in which all inertia is relative. Today was the funeral of Schwarzschild, the director of the Potsdam Observatory. Surely I’ve told you about him; it’s a sad loss. 3 Had he been as decent [anständig] as he was clever [gescheit], he would have been a pearl.
…. I’ve found a cute simplification for the thermodynamic derivation of the photochemical ħv [equivalence] law, somewhat in the style of [Jacobus] van’t Hoff…. Soon I’ll be able to send you the extensive paper on gravitation in which everything is explicitly calculated.
Greeting to you, Anna, and Vero, from your
Albert
The private reservations about Schwarzschild expressed in this letter reflect the different attitudes of the two men toward Germany’s war effort. Whereas Einstein was a well-known opponent of the war, Schwarzschild, despite his age and directorship of Germany’s premier observatory, volunteered for the army in 1914. He served as a headquarters artillery officer behind the Russian front, mostly doing ballistics calculations for long-range guns. In his spare time, he made his contributions to general relativity. Early in 1916, he was sent home with pemphigus, the autoimmune skin disease of which he died in May.
