2 8 4 D O C U M E N T 3 8 M A Y 1 9 2 0
wahrscheinlich die Früchte dieses Kollegs nicht mehr ernten werde, denn wenn
nicht alles trügt, bin ich das letzte Semester in
Zürich.[9]
Meyer und Weyl waren in Deutschland und sind erst vorgestern zurückgekehrt.
Weyl werden Sie wohl in Berlin gesprochen
haben,[10]
Meyer war in Tübingen, er
hat sich gut erholt, ist aber über den reaktionären Geist an der Universität ent-
setzt.[11]
In der letzten Zeit habe ich in psychiatrischen Kreisen einige populäre Vorträge
über Relativitätstheorie gehalten. Es ist merkwürdig, warum gerade diese Leute
plötzlich so ausserordentlich relativistisch interessiert sind. Der interessanteste ist
Bleuler,[12]
der wirklich den Fragen auf den Grund zu gehen versucht.
Mit achtungsvollen Grüssen verbleibe ich Ihr ganz ergebener
Paul Epstein.
ALS. [10 558].
[1]A year earlier, Edith Einstein turned to Paul Epstein (1883–1966) for help in preparing her thesis
on the theory of the radiometer, a topic suggested to her by Einstein (see Edith Einstein to Einstein,
29 April 1919 [Vol. 9, Doc. 31], and Paul Epstein to Einstein, 2 May 1919 [Vol. 9, Doc. 32]).
[2]Probably Janka Meissner, with whom Edith Einstein shared an apartment (see Vol. 9, Doc. 31).
[3]Einstein attempted to reconstruct what he had written for Edith Einstein in his reply of 4 June
1920 (see Doc. 42).
[4]The integral is the xx component of the pressure tensor denoted below as ;
is the probability that the velocity components of a molecule are within the interval
, to d , d , d . The thrust of Edith Einstein’s dissertation research was to produce
a more modern and extended treatment of Maxwell’s theory of the radiometer (Maxwell 1879). For
historical background to this theory, see Edith Einstein to Einstein, 29 April 1919 (Vol. 9, Doc. 31),
note 4, and Paul Epstein to Einstein, 2 May 1919 (Vol. 9, Doc. 32), note 6, as well as Brush 1976 and
Woodruff 1968.
[5]In Edith Einstein’s eventual publication (Einstein, E. 1922) the fourth condition, besides the
three given here, is that there should be no current or net transport of matter in the gas. In the notation
employed here, U is the internal energy of the gas and S its entropy.
[6]Boltzmann’s H-function is defined as . The related H-theorem states that this
quantity never increases; it is therefore interpreted as being proportional to the negative of the entropy.
[7]In fact, Einstein, E. 1922 does begin with calculations based on Boltzmann’s H-function, fol-
lowing Epstein’s suggestion.
[8]Edgar Meyer had proposed Paul Epstein as Privatdozent of a four-hour course on boundary
value problems in mathematical physics, for the summer semester 1920 (see Hans Wehrli, Dekan, to
Erziehungsdirektion des Kantons Zurich, 22 May 1920, SzZSA, U 110 d .2 [121]).
[9]On 4 March 1920, the Philosophical Faculty II of the University of Zurich had voted down a pro-
posal to appoint Epstein to an extraordinary professorship (see Einstein to Paul Ehrenfest, 1 March
1920 [Vol. 9, Doc. 347], note 11). The university commission of the Education Department, however,
reversed the faculty’s decision since it seemed that the question of filling the professorship was not
yet sufficiently clarified. The commission agreed with the faculty that the ranking of the three candi-
dates under consideration should be Epstein, Franz Tank, and Simon Ratnowsky, but concluded from
the current state of affairs that it could not formulate a recommendation. The commission decided on
25 May 1920 to recommit to the faculty its proposals of 16 March for the filling of the professorship
of theoretical physics for further research and the formulation of a new proposal (see Alfred Wolfer,
Dekan, to Erziehungsdirektion des Kantons Zürich, 16 March 1920, SzZSa, U 110a; and Auszug aus
dem Protokoll des Erziehungsrates des Kantons Zürich, 3 June 1920, SzZSa, U 110a).
xx
f d d d
f logf d d d