Nagel replies: I am delighted to see such a varied response to my Opinion piece. My intention had been to start a productive discussion, and it seems that has now begun.
George Trilling and Michael Dine assert that particle physics is exciting and may be as productive now as in the past. Those are also the main points made by Joseph Lykken in his Opinion piece ( Physics Today, November 2002, page 56). Drasko Jovanovic points out the important symbiosis between particle physics and cosmology. I am happy to see such arguments made. I hope physicists from all different areas will become eloquent (yet avoid exaggeration) about their optimism for the future. We need to make clear why we find our fields exciting and why the achievement of our goals can open up new vistas for research. Particle physics is perhaps especially important in this regard simply because it may not appear to an outsider to have the same vibrancy it had during the development of the standard model. I commend Trilling, Dine, Jovanovic, and Lykken for starting the process of making the case for their field.
The executive committee of the American Physical Society’s division of condensed matter physics, with input from its counterpart in the division of particles and fields, has organized a symposium entitled “Dreams for the Future of Physics: Where Are We? Where Are We Going?” This will be presented in a plenary session at the 2003 APS March Meeting in Austin, Texas, and I hope it becomes an ongoing tradition. The symposium’s objective is to build a greater sense of continuity in physics by communicating the goals of a few major fields—condensed matter physics, nuclear and particle physics, cosmology and astrophysics, physics in biology, and string theory—and presenting some of the most pressing open questions in those fields. I hope that this symposium will not only be exciting but will also teach us how to convey the enthusiasm we feel for our own specialties to a more general public.
Trilling questions the existence of a widening gap between big and small science. Although increasing sophistication of apparatus occurs in condensed-matter as well as particle physics, so that one can correctly make the claim that both fields are simultaneously getting bigger, a different trend occurs that is not as often noticed. Many soft condensed matter experiments actually use extremely simple apparatus. Such experiments depart from the more technically demanding condensed matter experiments using dilution refrigerators, accelerators, reactors, and the like. Thus the poles of big and small physics have moved farther apart.
Of course, as Trilling says, all physicists should marvel at the intellectual achievement of the standard model. They should also marvel equally at the intellectual achievement represented by semiconductors and superconductors, critical phenomena, polymers, Bose—Einstein condensates, greater understanding of the universe, and others. Likewise, I agree that we all use tools that were developed by others. Not only do condensed matter physicists use accelerators, but particle physicists use superconductors and solid-state detectors. In this vein, I agree with Larry Merkle that we physicists do have much in common, but also find, as does he, that it is difficult to identify exactly what is the glue that holds us together.
The split that I see between theory and experiment is not the kind Trilling mentions. Simply put, I do not think that we train our students to do both kinds of physics. Very few, if any, of our “superstars” do both theory and experiment. In the past we had many great examples (starting with Galileo and Newton, going through Faraday, and up to Fermi) of such a cohesive approach. I do not think such a dichotomy exists in biology-related sciences; that is partly why those are such exciting fields for young scientists these days. The separation of theory from experiment has, of course, gone on for a long time; arguably, the separation occurs because physics has become a mature discipline.
There have been consequences to the split between theory and experiment. I cannot speak for other fields, but in my own area of condensed matter physics, we tend to think of theorists as the intellectual leaders. That is certainly not always true, but is true more often than I would like. I find it disappointing that we experimentalists have often yielded the intellectual leadership to theorists. This issue is complicated and may again be entwined with the maturity of physics. But I do not think it an accident that, of the physicists the general public knows and admires from the 20th century, nearly all are theorists. Richard Feynman and Stephen Hawking are only the two most recent examples. We physicists have raised them up as our common heroes for public admiration. I am uncomfortable that, for many decades, we have not had experimentalists that we have recognized as heroes across all disciplines.
John Rigden’s letter also relates to the maturity of physics. I agree with his opinions, and I wish I had devoted more of my essay to education reform. That topic underlines one of the unappreciated problems of regarding physics as a mature discipline: Maturity may be admirable in many ways, but it may also be a final stage preceding dramatic decline. Educating bright students and training new researchers is the lifeblood of any science. If our curriculum, the artery bringing this lifeblood to our field, has become as rigid as Rigden maintains, we have a classic sign of impending doom. Because we certainly believe that our field has a bright future as well as a distinguished past, we must find ways of revitalizing our curriculum and keeping our field rejuvenated.
A further indication of the crisis in physics has recently appeared: the spate of horrendous data fabrication and scientific misconduct that has reportedly riddled such high-profile research as that of Jan Hendrik Schön on molecular-scale transistors and of Victor Ninov on element 118. As physicists, we have been trained to guard against errors in science in our own work and in that of others. We are probably pretty good at that, although greater care can always be taken. However, guarding against a hoax is entirely different from guarding against a mistake. Can we any longer trust that researchers are reporting their results to the best of their ability? The physics community on the whole seemed rather pleased when Alan Sokal, in Social Text, perpetrated a hoax about postmodern physics. The joke, if there ever was one, has now gone sour. We physicists are as easily duped and as open to ridicule as are our academic colleagues across campus.
