2 1 2 D O C U M E N T 2 1 7 F E B R U A R Y 1 9 2 4
demonstrates that the influence of ρ (or of the field) on A and B is unsystematic (not
equally strong for all lines) and can very well vanish.
b) on page 155. My derivation of Bohr’s frequency condition ignores the motion of
the atom, which surely is permissible as long as one deals only with energy, not
momentum.[8]
One just has to set the mass of the molecule as infinitely large, of
course. For the consideration on the atom’s Brownian motion, Bohr’s equation
gives
only approximately, however, where signify the internal energies of the
atom. But this circumstance does not disturb the validity of my ¢derivation² analy-
sis on the dynamic behavior of the molecules, as you will easily be able to convince
yourself upon contemplation.
c) But now comes the main point. It is incorrect that through examination, such as
the one I carried out with Mr. Ehrenfest, and as you indicate on p.
157,[9]
one could
render unnecessary the earlier observation about the Brownian motion of atoms
and, therefore, the hypothesis of the momentum properties of the elementary pro-
cesses. For, when deriving equation (7), one leaves open the magnitude of the mean
frictional force that a moving atom
experiences.[10]
But since there is no doubt
about the magnitude of this mean
force,[11]
knowledge about it can be safely used,
and thus one obtains more than equation (7), namely: a statement about the momen-
tum properties of the elementary processes. This is obscured by your arguments.
Hoping that you will correct your claims yourself, I am, most respectfully yours,
A. Einstein.
217. To Rita von Gonzenbach[1]
Berlin, 26 February 1924
Dear Mrs. Gonzenbach,
I conscientiously thought about your letter and what is connected with
it[2]
and
come to the apparently strange conclusion that I should not participate in such a
well-meaning matter. The situation is, you see, thus:
Germany was in an almost privileged economic situation before the war. The
consequence of that was that a relatively large percentage of the population could
take up, and did take up, professions that did not directly generate vital products.
Many intellectual professions, about whose value to civilization I need not mention
ν
ε ε –
h
---------------12
-=
ε2 und ε1