Text 3. Physics: Its Recent Past and the Lessons to Be Learned. Part I
1. What sort of physics are we to do between now and the end of the century? I will try to look at the next 30 years of physics not avoiding speculation but mainly concentrating on practical questions to face us today. My remarks are sure to have a personal and Princeton flavour, but principles should apply to anyone, anywhere. I will begin with an example from the past, which proves a forecast for 30 years to be sometimes possible and fruitful.
2. When I came as a graduate student to the English Cambridge 24 years ago, I found most of my physicist friends cursing the name of Sir Lawrence Bragg, who had become director in 1938, the year after the death of Rutherford. By that time the younger men thought to be brilliant physicists and known to be establishing schools of their own had left the place. The leadership in high-energy physics had passed to Berkeley. But Bragg made no effort to rebuild. He did not appear to be interested in plans for a new accelerator to be developed. He said: have taught the world very successfully how to do nuclear physics. Now let us teach them how to do something else."
3. The people whom Bragg was interested in supporting were thought to be a strange bunch, doing things which the high energy people would hardly consider to be physics. There was Martin Ryle, who was known to be looking for radio sources in the sky. There was Max Perutz, who was said to have spent 10 years on X-ray analysis of the structure of the hemoglobin molecule and to remark very cheerfully that in another 15 years he would have it. There was a crazy character called Francis Crick, who seemed to have lost interest in, and given up, physics altogether. The place which Bragg was to leave in 7 years had become a centre of first-class international standing in two fields of research that nowadays appear as important as high energy physics: radio astronomy and molecular biology.
4. This history of the last 30 years in Cambridge may seem to be little oversimplified. Nevertheless we can appreciate it if we think of the important lessons which it can give us today. What are the lessons? What enabled Bragg to do so well with what looked in 1938 like disastrous situation? Broadly speaking, he may be said to have followed three rules. The rules are:
1. Don't try to revive past glories.
2. Don't do things just because they are fashionable.
3. Don't be afraid of the scorn of the theoreticians.