Rudi, the gentle giant

One of the main features of the 20th century is the extraordinary status acquired by science. It now affects every walk of life, shaping the fate of individuals and the destiny of humankind. To a large extent this is due to the phenomenal transformation of physics - from a cottage industry, so to speak, to a giant multinational complex.

At the start of the century, experimental physics was still using "sealing wax and string" techniques. The great discoveries about the atom and its constituents, for which many Nobel prizes were awarded, were made with simple apparatus built by the scientists themselves. When I started my research work in the early 1930s, the Geiger counter had just been introduced and was hailed as a milestone in technology, but I had to make it with my own hands, every part of it, including glass blowing. Most scientific publications were by single authors.

At the end of the century this has become practically impossible. If I were to start now a research career in experimental physics, I would most probably be a member of a team of several dozen scientists and technicians, building an apparatus costing several million pounds, in preparation for an experiment that would eventually be carried out on an accelerator situated in Geneva, because the United Kingdom could not finance from its own budget a machine costing hundreds of millions of pounds and needing thousands of people to maintain it. The paper reporting the results of the experiment would have a multiple authorship, with the list of authors occupying more space than the abstract of the paper.

Many of the practical applications of physics are also big business. An obvious one is the nuclear industry, which now supplies a significant - in some countries a predominant - proportion of electricity. In medicine, diagnosis of disease is dominated by the technology of scanners - CAT, PET and NMR - each costing millions, yet without which no respectable hospital would be seen dead.

But the biggest impact of physics was in the area of world security. The development and use of the atom bomb during the second world war, and the consequent nuclear arms race, resulted in the accumulation of obscenely huge nuclear arsenals, creating a potential threat to the further existence of the human race. On several occasions during the cold war we came perilously close to the use of the weapons. Physics is no longer the innocent pursuit of knowledge, as it appeared to be at the beginning of this century. Now, it is held responsible for forging the sword of Damocles that hangs over our heads and threatens to bring the human species to an end.

A vital element in all this was theoretical physics. Its major role, apart from advancing original ideas, is to interpret experimental results. This usually leads to imaginative ideas which, in turn, are tested in new experiments. Nowadays, theoretical physicists use sophisticated computer technology and tend to work in teams, but progress still depends on the intellectual power of the individual scientist. The ideas of the theoreticians from the early part of this century - Max Planck, Albert Einstein, Niels Bohr, Werner Heisenberg, Wolfgang Pauli, Paul Dirac - still dominate the thinking of contemporary physics on the fundamental laws of nature.

Sir Rudolf Peierls - Rudi, to all who knew him - was a great theoretical physicist. His life-span of 88 years covered nearly all of the 20th century. He studied under, or corresponded and collaborated with, these giants. Apart from his own enormous contributions to many aspects of physics, he has created schools of theoretical physics training thousands of disciples, many now distinguished scientists. But he is mainly renowned as a prime mover in the development of nuclear weapons, although he later devoted much of his time and energy to avert the dangers to humanity that arose from his work.

In the course of a long scientific career, Rudi wrote hundreds of papers in scientific journals on various aspects of quantum mechanics and nuclear physics. He also wrote numerous essays of a nontechnical nature, but relating to science or scientists. A selection from these publications has now appeared as a book under the title Atomic Histories, described by the publishers as "a walk through the beginnings of the atomic age with one of its true pioneers".

The book was published by the American Institute of Physics as one in its series, Masters of Modern Physics. The inclusion of Peierls's essays in this series is by itself a testimony to the standing of the author. The purpose of the series is to introduce some of the work and thought of "the most celebrated physicists of our day". Among the authors of the previous volumes in the series are Nobel laureates Hans Bethe, Sheldon Glashow and Charles Townes, but the criteria for the Masters of Modern Physics include a keen ability to communicate with the general public; prominence in shaping debates in science, technology, and public policy; and distinction in social and cultural spheres outside one's field of research. Rudi Peierls fully met all these criteria.

Whether in a highly specialised scientific paper or in a popular article, Rudi displayed a unique talent to write concisely and precisely. He also had the knack for describing a person, summarising a discussion or reporting on a meeting, with the minimum number of words, yet lucidly, comprehensively and absolutely fairly. There is a famous story relating to this characteristic. During the latter part of the second world war, he was a member of the British team working in Los Alamos on the Manhattan project. When the leader of the British team, James Chadwick, moved from Los Alamos to Washington DC to head the British mission there, he nominated Peierls to be his deputy in Los Alamos.

Rudi undertook to keep Chadwick informed by letter about the progress of the work on the atom bomb. General Leslie Groves, the head of the whole Manhattan project was always much concerned about security. When he heard about these letters, he summoned Rudi. But instead of the expected reprimand for writing letters about the progress of the work, Groves asked Peierls to send him copies of his letters to Chadwick, because he said he gained from these a much better insight of what was going on in Los Alamos than from the official reports he was receiving.

Atomic Histories consists of three parts, entitled "A physicist's portrait gallery", "Atomic energy and arms control" and "Physics, politics and pleasures". Each contains essays published over a period of nearly 50 years (1946-94), in scientific and popular magazines, journals and newspapers. Rudi made the selection himself, and he also wrote the preface to the book, but the publication was not complete by the time of his death, in September 1995.

As the title of the first part indicates, it consists of profiles of a number of distinguished scientists, written either as obituaries or in reviews of biographical books about them.

Apart from the great theoreticians Bohr, Dirac, Heisenberg, Pauli, Landau and Planck, the sketches include some very distinguished experimental physicists, Ernest Rutherford, James Chadwick, Robert Frisch, Mark Oliphant (still alive), and the bomb makers, Robert Oppenheimer and William Penney.

Rudi's inimitable style is clearly seen in these essays. Each profile comes to life in the brief factual description in language easily understood. The sketches also bring out another of Rudi's characteristics, his innate kindness and gentleness. Even when disagreeing with a certain point of view, he always finds a good word for it. But he does not condone distortion of facts. In a review of a book describing the history of the German atom bomb project, Peierls takes issue with the author's presentation of Heisenberg's role in it, as well as taking him to task for factual misrepresentations.

The second part of the book, "Atomic energy and arms control", consists of articles on civil and military aspects of nuclear energy, and a number of reviews of books on this topic. The most important of these, and the most dramatic in the effect it produced, is the first item, written in 1940 but not made public until much later. It is the Frisch-Peierls memorandum on the possibility of the atom bomb. This memorandum has a special meaning for me: it produced the occasion when I met Rudi for the first time in the flesh.

In early 1940 I had been engaged for some time in experiments to prove the feasibility of the bomb, working with Chadwick at the University of Liverpool. At the latter's request, Peierls and Robert Frisch visited me in Liverpool. In my shabby digs they told me about their calculations of the critical mass of uranium that would produce an explosion. Suddenly the whole project became a practical proposition.

We became so engrossed in the discussion that we did not notice that it was past sunset. This created a problem for Frisch about the return to his hotel. As an enemy alien (he was Austrian) he was not allowed to be out of doors after sunset. As a matter of fact, I too, though a friendly alien (Polish), was subject to the same restrictions. Here is a vivid illustration of the nonsense of rigid regulations; we were engaged on top secret work but we were not allowed to ride a bicycle or to possess a map. The height of this absurdity was when Peierls and Frisch were not allowed, for a time, access to their own memorandum!

The memorandum is a model of brevity. In three pages it explains the scientific basis of the atom bomb; its likely effects and methods of dealing with them; concrete proposals for the steps to manufacture the bomb; and the justification for making it as a deterrent to a German bomb.

The third part of the book is an assortment of reviews and essays on a variety of topics from light-hearted (on English food) to highly philosophical conjectures about the end of physics and the crisis in science. One article, "The Jew in 20th-century physics" discusses the disproportionate number of Jews among the most distinguished scientists, particularly in theoretical physics. While unable to explain the phenomenon, the author points out that it is not uniform in the world, being much more pronounced in Germany (before Hitler), Russia and the United States than in Britain, France and Italy.

In another article he deals with the role of scientists in public affairs, "Between the ivory tower and the arena". Starting from the fact that nowadays scientists take a more active part in debates on matters of public affairs, he suggests that this is not only because of the greater impact of scientific developments but also because scientists seem to be well-qualified to make contributions to such debates. Not because scientists are necessarily wiser, more honest or less prejudiced than other people, but mainly because by their training and tradition they acquire certain attitudes - primarily a fundamental respect for facts.

Rudi's own contributions to the debate on public affairs are contained in the second part of the book, the bulk of which deals with the aftermaths of Hiroshima and Nagasaki and the ways to prevent a nuclear holocaust. Rudi Peierls devoted much time and energy to this task, mostly through his participation and leadership in the Pugwash Conferences on Science and World Affairs. He kept up these activities until the end of his life. Indeed, the last paper he wrote, but did not complete, was for a Pugwash symposium held in London in September 1995.

Three weeks after his death, the efforts of Pugwash to prevent a nuclear war received recognition by the award of the 1995 Nobel peace prize, an accolade for which much credit should go to Rudolf Peierls.

Joseph Rotblat is president, Pugwash Conferences on Science and World Affairs; he was awarded the Nobel peace prize in 1995.