Session Report: “Sidney Coleman Remembered: Correspondence and Commentary”

From the early 1960s into the 21st century, Sidney Coleman was an iconic figure in the Cambridge, Massachusetts community of theoretical physics, both at Harvard, where he taught, and at the numerous surrounding institutions of higher learning. Among an evolving galaxy of stars and superstars, Coleman stood out for his precise and piercing intellect, for his wit, and for the idiosyncrasies that gave rise to a seemingly endless supply of stories and anecdotes.

In 2003 Coleman took medical leave from Harvard, and he died, at age 70, in 2006 after a long battle with diabetes and Parkinson’s disease. Now his widow, Diana, and historians Aaron Wright at Harvard and David Kaiser at MIT, are engaged in collecting and editing Coleman’s correspondence, much of which is preserved in carbon copy; they are also seeking copies of letters, and other memorabilia, that may be in the hands of his friends and correspondents.

Stimulated by this activity, the Forum organized a session at the April Meeting devoted to remembering Coleman. The first speaker was Wright. He was followed by Erick Weinberg of Columbia, who was Coleman’s graduate student in the early 1970s, and by Howard Georgi, a longtime faculty colleague of Coleman’s at Harvard.

Wright began by reading a message from Diana Coleman, who had been invited but was unfortunately unable to attend. In her message, she said that re-reading letters to and from Coleman impressed on her that “Sidney had the courage to be an original. He did boldly provocative things, epitomized by the purple suit he wore around campus, and his notorious quips, which some students printed on a tee shirt. Of course, a few students were shocked and offended by him, especially the student who complained that Sidney used a four-letter word during a lecture. He ‘didn’t expect that from a Harvard professor!’

“There are many priceless examples of Sidney’s humor in the letters, and of the rebellion that often underlay them — but probably the most revealing is the long correspondence between Sidney and Nino Zichichi, as they fought over Sidney’s Erice lectures.”

Wright explained that from the late 1960s to the early 1980s, Coleman was a regular participant in the Erice Summer School that took place annually in Sicily; Zichichi was its founder and chief organizer. Coleman’s lectures at the school were valued so highly that preprint copies of them, increasingly blurry from having been Xeroxed many times, were passed from generation to generation of graduate students. In 1985 most of them were collected in a classic volume, “Aspects of Symmetry”, published by Cambridge University Press.

The correspondence that Wright shared with the audience consisted of a back and forth between Zichichi, also a colorful character, and Coleman, in which the former sought to induce the latter in 1969 to lecture on some recent work by Gabriele Veneziano, which to Coleman was unacceptable. Zichichi attempted flattery, praising Coleman for being able to lecture on anything, but Coleman refused to yield to his blandishments, at one point sending Zichichi a letter whose sole content was the sentence “I will not lecture on Veneziano” repeated a dozen times. Zichichi got the message, and Coleman ended up lecturing instead on “Acausality”, the lecture notes for which begin with the instruction to read them last week. (Unfortunately, “Acausality” is one of only two sets of Erice lectures not included in “Aspects of Symmetry.”)

Weinberg showed the audience some rare examples of problem sets and final exams that he still had from courses taken with Coleman in the late ‘60s and early ‘70s. Coleman often taught the same courses over a number of years, during which time he not only refined the contents but also polished the “spontaneous” jokes that went with them; when delivered, the jokes were punctuated with bouts of laughter from Coleman, because no one thought the jokes funnier than he did.

The problem sets and exams were likewise peppered with apt quotations from the likes of Paracelsus and the Grand Grimoire. In the final lecture for a course in General Relativity, Coleman offered the students the following advice: “You may have enjoyed this course and decided that you want to do your thesis research on General Relativity. DON’T. Einstein spent the last 30 years of his life working on General Relativity and it led to nothing. And he was smarter than you.” This illustrates Coleman’s rapport with his students, and his style of communication, but it also provides a quaint snapshot of the state of relativity research at the time (1970). Subsequent developments have ensured that no one would give such unequivocal advice today.

Weinberg reminded the audience of Coleman’s notable achievements in research in the ‘60s and ‘70s, beginning with the Coleman-Mandula theorem of 1967 showing that internal and spacetime symmetries cannot be combined in a non-trivial way (except for supersymmetry, which they did not consider). In addition, Weinberg mentioned the work that established the equivalence between the sine-Gordon and Thirring models, and his own work with Coleman on “Radiative Corrections as the Origin of Spontaneous Symmetry Breaking”, which introduced the key idea of dimensional transmutation. Weinberg also showed a list of the 40 graduate students supervised by Coleman between 1964 and 2001, better than one a year, among whom are many physicists who have gone on to distinguished careers of their own.

Georgi placed Coleman in the context of the Harvard of that era, mentioning his colleagues Shelly Glashow, with whom Coleman had a fruitful collaboration, and Steven Weinberg, as well as younger physicists such as Tom Appelquist, Helen Quinn, Joel Primack and Erick Weinberg, and Georgi himself. Georgi commented on Coleman’s role as an oracle, saying that “he often understood the theoretical ideas better than the original authors.”

Coleman was famous for working late into the night, and then sleeping past noon. Georgi said that, at one point, due to a revolt of the junior faculty, senior faculty were called upon to teach beginning undergraduate classes, which required Coleman to make the supreme sacrifice of getting up early. But as Weinberg noted, when he could get away with it, Coleman was also capable of showing up for the first 10 am class of the semester, and announcing that henceforth the class would meet at two in the afternoon.

Another aspect of Coleman that Georgi talked about was his passion for science fiction, which complemented his life as a physicist. This had been mentioned as well by Diana Coleman, who said that “the science fiction crowd prided itself on being much freer and wilder. Purple suits were not startling there….[Sidney]’s science fiction friends were a quite different gang, with different traditions.”

Georgi, who has posted the written version of his talk about Coleman on the arXiv (Coleman talk on the Arxiv website), also alluded to some of Coleman’s later important contributions, as did Weinberg. These include a series of articles on the decay of the false vacuum, partially in collaboration with Curtis Callan and Frank DeLucia, in the period 1977-1980, and the article “Why there is nothing rather than something: a theory of the cosmological constant” in 1988. As Weinberg pointed out, the title was a riposte to Leibniz’s “Why is there something rather than nothing?” (1714).

The preface to “Aspects of Symmetry” ends with a revealing paragraph, quoted by Weinberg, that is quintessential Coleman, not only for its wit and flair, but for the underlying passion for physics about which he was very serious indeed. It reads: “These lectures span fourteen years, from 1966 to 1979. This was a great time to be a high-energy theorist, the period of the famous triumph of quantum field theory. And what a triumph it was, in the old sense of the word: a glorious victory parade, full of wonderful things brought back from far places, to make the spectator gasp with awe and laugh with joy. I hope some of that awe and joy has been captured here.”

Sidney Coleman