4 1 2 D O C U M E N T S 4 1 9 , 4 2 0 J A N U A R Y 1 9 2 5
419. To Leo Kohn
[Berlin,] 12 January 1925
Esteemed Mr. Kohn,
I am very pleased that you want to promote the universities and the library in Pal-
estine among our Jewish intellectual workers and among other men interested in
our hopeful cultural
endeavors.[1]
I have already been able to note with joy that
these efforts find warm approval and effective support among the righteous of our
nation. I wish you the best of success and scarcely need to assure you that I shall
do all that lies within my power to promote this project.
In great respect,
A. Einstein.
420. From Paul Langevin
Paris, 13 January 1925
My dear Friend,
I received your
letter[1]
only with great delay due to my absence from Paris for
a vacation, in search of rest, which I greatly needed. I also needed some time to see
some people before I could respond to the question you asked me.
I must tell you right away that I encountered the best reception, first from Pain-
levé, who, despite the multiple worries he is burdened with, will willingly collab-
orate on the homage that you would like to extend in honor of such a genius as
Riemann.[2]
I also saw Borel and
Hadamard.[3]
The committee concerned with the
publication can approach them with full confidence. I have not yet been able to
speak with
Cartan,[4]
who is particularly qualified from the point of view of geom-
etry, but I do not doubt his acceptance.
The experiment by Geiger and
Bothe[5]
appears to me quite important: I had
seen the notice and will read their article with great interest—the more so as my
teaching this year at the Collège de France addresses these questions.
I had occasion in this regard go back over the theory of radiation of a charged
particle—from the point of view of classical electromagnetism, and especially as
concerns the case of
Born’s[6]
hyperbolic motion. One finds oneself before this ap-
parently paradoxical fact, which is furthermore susceptible to extension to other
laws of motion—that the particle effectively radiates relative to an inertial system
(contrary to what Laue seems to be saying in his first volume on
relativity)[7]
and
yet does not radiate relative to a reference system in accelerated motion in which it