D O C U M E N T 1 9 5 J U L Y 1 9 2 1 1 3 5
195. From Walther Nernst
Berlin, 26a Am Karlsbad, 29 July 1921
Dear colleague Einstein,
Thank you very much for your kind lines of the 23rd of this mo. The tests of the
new valve will be very difficult, I fear, and with our means only feasible over a
longer period of
time.[1]
A whole series of different valves with compressors would
have to be built, and the friction loss would have to be determined. This is, of
course, feasible, but would have to be weighed very carefully and discussed thor-
oughly beforehand.
The large compressor, which, per revolution, pumps more than four times the
volume of the small one, is now mounted on a transmission; on Monday we hope
to conduct the first trials. I am very excited about the result. If it works, the refrig-
erator ought to work well without any adjustment, i.e., the motor’s energy should
deliver more than three times the refrigerating capacity.
I just received a very strange reply from Esslingen. The
company[2]
writes that
the experiments “for such a small machine had yielded an unusually large refriger-
ating capacity of 20–2300 cal per HP and hour” (we had never claimed more). But
then follows a quite confusing calculation, according to which the great work from
the looping would overcompensate the gain compared to the NH3-refrigerator and
that they therefore would have to decline.—Evidently, as they also suggest, fear of
a fire hazard is the true reason for the rejection.
Before new negotiations can start, the large compressor will have to be tried out,
which, as mentioned above, should happen as soon as possible; then these kinds of
poss[ible] objections become invalid from the outset.–
Yesterday I spoke before the Academy about “The Age of Fixed
Stars,”[3]
then
about a confirmation of the equivalency law for photographic plates, the mecha-
nism of which is simply and, as I think, securely cleared up in a paper by Eggert
and
Noddack.[4]
As concerns the first point, it is a huge deficiency that we have no information
about the masses of normal stars, i.e., about the single, nonbinary stars (except for
the Sun). Binary stars perhaps lead far astray as peculiar structures formed by the
division of a large star. Perhaps only the large stars with one very small satellite are
usable.
Your comparison Sun–Earth becomes perhaps much more cogent in the case of
binary stars that are composed of a light and a dark star. I find, incidentally, that
according to stellar statistics the Sun as a nebulous star emitted c. 50 times as much
energy as it does today, which is naturally entirely incompatible with
Eddington,[5]
if we assume long periods of emission (in terms of the great age of the Earth). I