2 8 0 D O C U M E N T 1 6 3 O C T O B E R 1 9 2 0
correspond to a repulsion by the filament which, however, would be much too small
to make it noticeable.
There is, secondly, also the Debye effect as a result of the polarizability of
molecules;[5]
polarizable things are drawn into the stronger field. This effect obvi-
ously occurs for every kind of molecule, not just for dipolar molecules. Yet this ef-
fect ought to be much too small to let itself be detected (I have not calculated it, but
that is very easily done).
Thus I come to the result that deflections probably are not detectable. If no zero-
point energy of rotation existed, there would be a certain fraction of nonrotating
molecules that—provided they are of a dipolar nature—would probably have to ex-
hibit a deflection. However, the specific heat function of H2, as well as the Bjerrum
spectrum of HCl, speaks for a zero-point energy of
rotation.[6]
With cordial regards, yours,
Einstein
P.S. Forgive the hasty editing. I have to leave tomorrow
morning[7]
—I therefore
have little time.
163. To Paul Ehrenfest
[Benzingen,] 7 October 1920
Dear Ehrenfest,
So, I am coming around the 22nd, with dress coat, to
Leyden[1]
and am then stay-
ing until Nov. 3, on which day I am giving a talk in
Hannover.[2]
Don’t be indignant
about the short length of my stay; I’ve been away from home for so long. I passed
on the message to Berliner and hope that our Russian colleagues will receive the
other desired things as
well.[3]
At [Bad] Nauheim, there was a bullfight cockfight
of sorts, about relativity; Lenard figured, in particular, as my
opponent.[4]
To my
knowledge, it did not come to any kind of manifestations of the sort you
expected.[5]
There was a very large
attendance.[6]
To a happy reunion, yours,
Einstein.
Best regards to all of you, also from my boys.
Many thanks for procuring the money for my
wife.[7]
Also think of the reim-
bursement for my last stay. I now have accumulated hefty debts with you; but it will
soon be set right again.