6 V O L U M E 5 , D O C U M E N T 2 4 2 a
certainly differ from it; a priori it is not clear at all how K should be defined. If one
defines the force on moving bodies by the relation between force and the magni-
tude of motion, it can be shown that
must be true,
just as it also results from your special example.
Thank you very much for your kind invitation to give a talk in Karlsruhe.[3]
However, whenever possible I avoid giving talks before larger audiences.
With great respect, yours very sincerely,
A. Einstein.
Vol. 5, 242a. To Heinrich Zangger[1]
[Zurich, 1 January 1911]
Dear Mr. Zangger,
Cordial New Year’s greetings to you and your wife![2] One doesn’t write to a
prolific writer the way you do to me. I carefully rechecked my calculations con-
cerning the viscosity of suspensions[3] but deemed everything in order. I also re-
quested Mr. Hopf to check it over.[4] Who knows whether Perrin didn’t have some
strong swelling of the particles (1.4-fold in diameter).[5] Bredig thinks it very well
possible. He considers it very difficult to make well-defined suspensions.[6]
I believe I found a new kind of influence by a magnetic field on electrons, but
the magnitude of the effect still needs to be calculated.[7] In radiation theory the evil
spirit is constantly leading me around by the nose.[8] Did you eventually get the
Tammann?[9] I looked for you everywhere before your departure but was unable to
track you down.
I hope your stay will do you & your wife a lot of good. With cordial greetings,
yours,
A. Einstein
Best regards & and greetings from my wife.[10]
Vol. 5, 255a. To Vladimir Varic;ak
Zurich, 24 February 1911
[Not selected for translation.]
K K 1
v2
c2
---- -–=