In 1962, Niels Bohr participated in his first Lindau Meeting. Since he was taken ill during the meeting and passed away in the autumn of the same year, the lecture he gave seems to have been his last public lecture. But he was a Nobel Laureate already 31 years before the first Lindau Meeting on physics was held in 1953, so he had been invited a number of times. The Niels Bohr Archive in Copenhagen holds all the letters of invitation and also copies of Bohr’s replies. These express his wish to attend, but also give reasons why he cannot do so because of his many other commitments, for example a meeting about CERN in 1953 and another with the Atomic Energy Commission in 1959. In 1955 - a chemistry year in Lindau but also the year when Werner Heisenberg had suggested that all Nobel Laureates connected with atomic science should be present - Bohr was invited, but could not attend, giving his best regards to Hahn and the others. So when Dr. Mecke in Freiburg, one of the organizers, sent out the letter of invitation in the spring of 1962, he cannot really have been expecting a positive answer. But on March 12, Bohr accepted the invitation and gave his title as “Atomphysik und menschlische Erkenntnis”, i.e., “Atomic Physics and Human Knowledge”. This was a title that Bohr had used before and which signalled that he wanted to speak on questions of the theory of knowledge that became necessary to address with the advent of the quantum theory. Looking back, this was a fitting title for Bohr’s last lecture, since his deep analysis of these questions probably represents his most lasting contribution to science in general. In their old age, Niels Bohr and his wife Margrethe always brought one of the grandchildren to scientific meetings like the Lindau one. In 1962, the companion was the grandson Christian Bohr, who was going to celebrate his sixteenth birthday on 30 June. Some time after the meeting, young Christian wrote down his memories of the eventful journey and meeting. I have been allowed to quote from his quite long, detailed and interesting Danish text. In my own translation to English, Christian wrote:
“Grandpa and Grandma had invited me to accompany them to a Nobel Laureate Meeting in Lindau in southern Germany, with a stop-over in Cologne, where Grandpa was to give a lecture at Delbrück’s. I was to sit in the front with Jørgensen in the big Lincoln and perhaps be of some help with practical matters. But now I realize that what was most important was that I, with such a journey, should develop in a direction that Grandpa and Grandma would like.”
Max Delbrück received the Nobel Prize in Physiology or Medicine in 1969. Jørgensen was the chauffeur.
“We arrived in Cologne in the afternoon and drove towards Delbrück’s home. I remember the area as very elegant with large lawns that were mown by tractor-like mowers. Grandpa asked a passer-by about the address and could with pride tell us that he had managed to get hold of someone who knew Delbrück very well."
Bohr had been invited on the occasion of the inauguration of the Institute for Genetics in Cologne.
“What happened the next day is not completely clear to me. I know that Grandpa held an interesting lecture on ‘Light and Life’. As far as I remember, it was with regard to this lecture that Grandma told me that Grandpa impressed the audience by translating on the spot a lecture written in English to German. This makes me wonder, though, since I don’t think that Grandpa spoke that good German.”
The title “Light and Life” was used by Niels Bohr already in 1932. The unfinished manuscript of the lecture held by Bohr in Cologne on 21 June 1962 has been published as “Light and Life Revisited”. It has been regarded as his last public address.
“We passed through the city of Konstanz and arrived at Lake Constance. We drove through a smiling landscape with fruit orchards. Grandpa seemed to be busy with his lecture, but rested now and then. It was hot, so I, who sat in the front beside Jørgensen, had the window down and my arm outside, something that I was to regret. We arrived at the hotel. It was not in Lindau (‘im Bodensee’, as its name really is) itself, but on the mainland close to the lake. It looked like a very fashionable hotel.”
Christian’s arm got sunburnt. The hotel, Hotel Bad Schachen, is still used today.
“As I remember it, this or the next was the evening that Grandpa worked very hard on his lecture. Not to disturb Grandma, he put one of the lamps close to the window so that it would shine on a table outside of the window, where he sat to finish the lecture. I don’t know how long Grandpa worked that night, but I am afraid that it influenced what happened the next day. The best rooms at Hotel Bad Schachen have balconies towards the lake.Grandpa’s lecture was scheduled for one of the first days [Monday 25 June], and I remember quite clearly some things from it. I guess that to some extent it only existed in Danish, which had to be translated on the spot. It was about complementarity. But how the argument was presented, I don’t remember. But I do remember that Grandpa at the end said that there was an illustrative example in the classical Danish literature, namely in ‘Licenciaten’ from ‘En dansk students eventyr’. Here Grandpa was seeking a word in English and couldn’t find it. As I remember it, there followed a rather embarrased silence, after which Grandpa asked to be forgiven by the audience. The lecture was over and Grandpa left the podium under applause. As I remember it, there was something depressing about the situation. This also can have contributed (as I felt already at that time) to the heart failure.During the afternoon, I must have done something or the other away from the hotel. Thus it was only sometime after it had happened that I, on my return, learnt that Grandpa had suffered a stroke. Grandma was worried, and even though I didn’t really understand how dangerous the situation was -and, in particular, had been - I couldn’t help noticing that everybody else took it very seriously. It wasn’t very long before I was allowed to visit the sickbed. Only for a short while."
"Also some of Grandpa’s old pupils appeared there. And at least one of them, Dirac, stayed much too long to Grandma’s taste. Dirac was really very fond of Grandpa, and similar sentiments could be felt from many of the other participating physicists. I remember in particular how Hevesy put himself totally at Grandma’s disposition, also to lend her some money."
"By and large I got an interesting impression of many of the personalities behind the names I had heard so much about at home and at Carlsberg: the really kind and warm Heisenberg, the very abstract Dirac, the much respected Lise Meitner (participating outside the program), whom I remember as a tall, thin and rather reserved lady. About almost all of the participants, I heard Grandma say: ‘Yes, they were in Copenhagen in this and that year’.”
According to the standard biography of Bohr, it was a minor cerebral haemorrhage that occurred. In early July the car brought everybody to Frankfurt, from where Bohr and his wife were flown to Copenhagen. Christian and Jørgensen returned by car. Bohr recuperated during the summer, but on November 18 he passed away at the age of 77.
The lecture in Lindau was delivered in English. Although the quality of the tape recording is quite good, it is very difficult for someone not used to listening to Bohr to understand what he is saying. Therefore a transcription has been made by Gro Næs, assisted by Finn Aaserud and Christian Bohr.