Gravitating Toward Wave Theory

In October 1954 I arrived at King's College, London, as the new professor of applied mathematics. In a small department with a small research group, the choice of topic for myself and my closest colleagues was clearly crucial. I felt it had to be a subject not widely pursued at the time because we could not compete with the big battalions. Having already had some interest in the theory of gravitation and having at London C.W. Kilmister, with F.A.E. Pirani soon to follow me from Cambridge, the choice of general relativity and gravitation as a topic was fairly obvious. Work on various problems began that winter but was not particularly focused. In June 1955 I was pleased to be invited to what turned out to be a superb conference in Berne to celebrate 50 years since special relativity. The conference, organized by An-the Mercier and chaired by Wolfgang Pauli, was excellent. My only surprise was that I, as a relatively junior person, had been invited. So many of the great figures of physics were there; it was indeed a very fine occasion. It was one of the rare public appearances then of Max von Laue, who was almost the same age as Einstein. (Einstein himself had died a few months earlier.) Von Laue still had a most acute mind, and I recall in particular an astute intervention of his in the discussion on clocks in gravitation, where many of us had got confused about how to fit in the pendulum clock among other time-keeping devices. Then von Laue said most concisely, "Remember, a pendulum clock is not the box you buy in a shop. It is that box plus the Earth." This cleared up the confusion completely. On another occasion I was trying to help him, somewhat incompetently, into his coat when he said, "No thank you; it is difficult enough if one does it oneself." Discussions were good, and puzzlement about what the theory said about gravitational waves was still prevalent at the time. Markus Fierz, professor of theoretical physics at the Federal Technical University in Zurich, was much in evidence; we had met before, and had come to like each other. At the end of one such discussion, he turned to me and said, "The problem of gravitational waves in general relativity is now ripe for solution and you are the person to solve it." After this impressive remark, the work at King's College indeed took on a definite direction. We started a whole series of papers on the highly complicated issues of gravitational waves and were joined on and off by many other outstanding researchers, including Andre Trautmann from Poland, Ivor Robinson and Leslie Marder. We produced a steady stream of papers ifiuminating first this, then that, corner of a very intricate subject. In 1958-59, with the help of M.G.J. van der Burg, I solved the problem, to my satisfaction at least, and one or two of the remaining obscurities were dealt with during a visit to Cornell in the spring of 1960 with A.WK. Metzner. Being a little slow in writing up something difficult, I did not complete the paper until 1962, when it appeared in Proceedings of the Royal Society A. What I particularly like about it is that, whereas so many of my friends and colleagues at King's had gone off on novel and highly abstract mathematical methods, in this paper I used strictly classical approaches, as is my habit, and I was very pleased that I got there first. It turned out, I should say, to be first by a nose because Ted Newman and Roger Penrose, using very abstract methods, published their important paper just after ours came out. It covered similar ground but from a wholly different approach. In the many discussions I had on questions arising about gravitational waves, I was asked particularly searching questions about their reception. In thinking about this, I naturally was led to look at the corresponding problems with electromagnetic waves and was intrigued to find no discus- sion in the literature that satisfied me. The trouble was that all the analyses I could find dealt only with harmonic waves, whereas of course information can only be conveyed by; nonharmonic, indeed nonanalytic, waves. I therefore published in 1960 a paper on the reception of electromagnetic waves. Though few have read it (and perhaps even fewer have understood it), I always look back to it with particular pleasure, as the knowledge required for it had been available for well over half a century. Be that as it may, the seven years from 1955 to 1962 had been under the sign of the remark made reasonably seriously to me by Markus Fierz in Berne in the summer of 1955 and cover what may well have been the most scientifically productive period of my academic life. Sir Hermann Bondi, master of Churchill College in Cambridge, has done work in cosmology, gravitation, relativity and astrophysics. In 1948 he was, with Fred Hoyle and Thomas Gold, one of the original proponents of the steady-state theory, according to which the universe looks the same in every direction as viewed from every location and when viewed at any time. Bondi was director-general of the European Space Research Organization from 1967 to 1971, chief scientific adviser to the U.K. Ministry of Defense between 1971 and 1977, chief scientist in the Department of Energy from 1977 to 1980, and chairman of the Natural Environment Research Council from 1980 to 1985. Born in Vienna in 1919, Bondi was educated there and in Cambridge, England, joining the Admiralty during World War II before launching his academic career. Knighted in 1973, Bondi is a talented popularizer who can hold an audience spellbound with his ruminations on Olber's paradox. He is president of the British Humanist Association and a former president of the Association of British Science Writers.

Gravitating Toward Wave Theory

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