D O C U M E N T S 1 , 2 M A Y 1 9 2 0 1 4 9
1. To Ludwik Silberstein[1]
[Berlin,] 1 May 1920
Esteemed Colleague,
I live permanently in
Berlin.[2]
The Stokes-Planck ether leads to a hopeless heap
of independent hypotheses. Such an unfinished theory is, of course, intrinsically
irrefutable.[3]
The problem of connected masses can be treated to first approximation accord-
ing to Newton, of
course;[4]
Newton’s theory is a first approximation, you know. A
more precise calculation is only permitted on the basis of continuum mechanics
(relativistic elasticity theory). For the stress-energy tensor of the connection has an
influence on the motion and does not allow one to regard the connection as merely
kinematical. I find, though, that a rigorous treatment of this problem would not be
worthwhile in any way.
With kind regards,
A. Einstein.
2. From Paul Ehrenfest
[Leyden,] 1 May 1920
Dear Einstein!
As I already wrote you two–3 weeks ago, Onnes sought to accelerate your travel
permit
directly.[1]
—He requested that it be arranged such that you obtain the visa
directly upon inquiry at the Dutch Consulate in
Berlin.—[2]
Did you ask at the Con-
sulate whether such an authorization had been issued from The Hague? At the Em-
bassy
perhaps?![3]
I immediately telephoned Onnes and he, in turn, will
immediately urge them on at The Hague and again ask that they give the Consulate
authorization by telegram.—If upon receipt of this postcard the matter is still not
settled, then please telegraph me again.—Everything is so terribly slow and
sluggish.—One has to wait endlessly for
everything.[4]
We are all expecting you
with great impatience.—The flowers will be blooming just when you come.—Ju-
lius too is very anxious to see
you.—[5]
If the train connection is so unfavorable
again—then spend the night at Julius’s in
Utrecht.[6]
— Do let me know sometime
at what time you are arriving in Utrecht!!! Greetings to all, yours,
P.E.