4. Translation.



München 23

Rheinlandstrasse 1




Dear Bohr!

Please accept my cordial thanks for your congratulations and the article about the genesis of quantum mechanics, which reminded me so vividly of the wonderful time at your Institute and of all that I was able to learn from you. How much physics has changed since those days! It strikes me as almost strange to take part once again, as recently in Brussels, in the battle of opinions and carefully to weigh the various contradictory arguments, just as we did 30 years ago in Copenhagen. The young physicists watch this with some amazement, since they have probably become used to the notion that, in the end, if only sufficiently many physicists are placed at sufficiently big machines, then everything will fall into place in the end. But this letter is not meant to be an elegy; on the contrary, I




greatly enjoyed the discussions in Brussels and most particularly because you were there, too. By the way, I have since had yet a special pleasure: the relative parity of the Sigma and Lambda particles, about which I disagreed with Salam and others in Aix en Provence and Brussels, has in the meantime been measured in California, and it turns out to be odd, just as it came out in Dürr’s and my calculations. Thus, we now begin to understand the complicated spectrum of elementary particles.

I hope that you are in good health and that at the turn of the year you can enjoy the visits from the entire family, children and grandchildren.

With many cordial greetings, also from Elisabeth and the children