2 9 0 D O C U M E N T 3 6 9 S E P T E M B E R 1 9 2 2 I hope your wife is well again. I deeply regret that you could not come to Leipzig for that reason but believe that for the rest not much good has been lost by it. The strength of your evidence will suffice in asserting your fine ideas about colloids. Truth does not need to be defended, because it is strong enough on its own! If you wish to donate something to science in Germany, be sure not to give it to organizations that reach their decisions according to the principle of least odium, rather than according to the free assessment of a few competent people. With best wishes to you and your family and cordial regards, I am yours, A. Einstein. P.S. If it should be a matter of support for academic institutions, I would like to draw your attention to the Jewish university fund in Kaunas [Kowno], which ven- ture to assist Eastern Jewish students is waging a truly heroic battle for survival.[3] 369. From Michele Besso Bern, 24 September 1922 Dear Albert, I don’t know anything about your travel itinerary these lines will perhaps still reach you in Berlin to bring you my farewells for the long journey. If all goes well, these two-times-six weeks’ sea voyages will be good periods of rest for you to enjoy to the fullest. The last I heard of you reached me through my cousin Arrigo Cantoni,[1] who was very pleased about your friendly welcome. I haven’t heard directly from you for ages now you didn’t receive my last two letters[2] or you thought that it ought to have already been clear to me that I should have left you alone about the related content because it lies beyond your field of activity. In connection with the familiar paradox (which forgets the basic assumption of the special theory of relativity) according to which an observer, who is moving away from us and back again at quasi-velocity of light, has our clocks necessarily seem to have come to a virtual standstill, just as his clocks do for us, Vero raised the question of what the situation is for an observer, moving against us at quasi- velocity of light, who makes a tour around the spherical world: “To him we would be aging noticeably during the world tour, just as much as he would to us.” This paradox is similar to the one I already presented to you of the Lorentz contraction of two rings moving most rectilinearly against each other and is solved in the same way. Nevertheless, this case does seem interesting to me didactically, as homework for a sufficiently developed beginner to think through exactly. (It is a fact that the
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