H
The Field Equations of Gravitation
14a. From Zurich to BerlinOn November 25, 1915, Einstein presented to the physics-mathematics section of
the Prussian Academy of Sciences a paper in which 'finally the general theory of
relativity is closed as a logical structure' [El]. The title of that paper is identical
with the heading of the present chapter, in which it is described how his field
equations reached their final form.
Einstein was still a professor at the ETII when he presented his report to the
Vienna meeting discussed in Chapter 13. However, by then he had already
decided to leave Zurich.
In the spring of 1913, Planck and Nernst had come to Zurich for the purpose
of sounding out Einstein about his possible interest in moving to Berlin. A com-
bination of positions was held out to him: membership in the Prussian Academy
with a special salary to be paid, half by the Prussian government and half by the
physics-mathematics section of the Academy from a fund maintained with outside
help, a professorship at the University of Berlin with the right but not the obli-
gation to teach, and the directorship of a physics institute to be established. The
new institute was to be under the auspices of the Kaiser Wilhelm Gesellschaft, an
organization founded in 1911 to support basic research with the aid of funds from
private sources.*
Much later, Einstein recalled an interesting exchange between himself and
Planck during this Zurich visit. 'Planck had asked him what he was working on,
and Einstein described general relativity as it was then. Planck said, "As an older
friend I must advise you against it for in the first place you will not succeed; and
even if you succeed, no one will believe you." ' [SI j.
Einstein reacted rapidly and positively to the approach from Berlin. His cor-
respondence from that period makes abundantly clear the principal reason for his
interest in this offer. Neither then nor later was he averse to discussing physics
issues with younger colleagues and students; but he had had enough of teaching
classes. All he wanted to do was think. The catalogue of PhD theses awarded at
"This physics institute started its activities in 1917. In 1921, von Laue took over the main day-to-
day responsibilities.
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