What Future Will We Choose for Physics?

Science in the United States is in a time of pain and uncertainty. The pain is felt most acutely by young scientists, who are having great difficulty establishing their careers. The uncertainty about the duration and outcome of the current situation stems from its roots in ponderous events of recent history—the end of the cold war, industrial downsizing, government deficits and demographic trends. Although budget difficulties and lack of jobs plague most of the sciences, the atmosphere of uncertainty about the future is palpably different from one profession to the next. Our concern here is with the profession of physics. Disciplines Physical Sciences and Mathematics | Physics This journal article is available at ScholarlyCommons: http://repository.upenn.edu/physics_papers/491 WHAT FUTURE WILL WE CHOOSE FOR PHYSICS? S in the United States is in a time of pain and uncertainty. The pain is felt most acutely by young scientists, who are having great difficulty establishing their careers. The uncertainty about the duration and outcome of the current situation stems from its roots in ponderous events of recent history—the end of the cold war, industrial downsizing, government deficits and demographic trends. Although budget difficulties and lack of jobs plague most of the sciences, the atmosphere of uncertainty about the future is palpably different from one profession to the next. Our concern here is with the profession of physics. The natural tendency, especially among those of us in the physics community whose careers are well established, is to hope that current problems will work themselves out, as they have in the past, and that better times will resume without substantive changes in our way of life. The data to be presented here suggest that such complacency is dangerous, both because the extrapolation of current trends is clear and undesirable, and because there are steps that can be taken to alter the path of events. It seems to us, the authors of this article, that serious discussion about the future of the physics profession should focus less on external events that physicists cannot control and more on the field itself. We therefore believe that this is precisely the right time for our community to undertake a soul-searching analysis of the profession—its historical evolution, its current health and, above all, our aspirations for its future. The analysis presented here focuses primarily on academic physics, where serious problems exist and where important decisions must soon be made. But we believe that what we are saying is very important for the field as a whole, and that all of us, especially physicists in industry and government, must participate in making these decisions. Some unpleasant facts Our analysis of the current state of physics begins with two startling sets of data. First, as figure 1 shows, the median age of physics professors in US universities has been rising almost linearly at the remarkable rate of eight months per calendar year for about two decades. By 1992 fully half of the full professors were at least 54 years old. Second, as the table on page 27 shows, the distribution of academically employed PhD physicists among the subfields of physics has remained nearly static over roughly the same period of time. Both of these data sets convey much the same message. Events culminating US physics faculties are aging rapidly and responding far too slowly to new opportunities across the sciences. We must reverse the trends if we are to preserve the historic vitality of the profession. Sol M. Gruner, James S. Langer, Phil Nelson and Viola Vogel faculties and, along with them, their areas of specialization. The implications of this change were dramatic. In effect the term "physics" as the name of an academic discipline ceased to mean a broad-ranging mode of everchanging scientific inquiry and came to denote a fixed set of topics that are studied and taught by physicists. Is this a bad thing? Very much so, in our opinion. We say this despite the fact that, intellectually, almost every one of the mainstream subfields in physics has evolved dramatically in recent years. There is every reason to take pride in the beautiful developments in cosmology, astrophysics, particle physics, atomic and optical physics, the physics of superconductors and quantized mesoscopic systems, and a large number of similar accomplishments. Certainly the stability shown in the table on page 27 is indicative of the richness of the mainstream specialties. But it is also indicative of a reluctance to continue the historical extension of physics into newly emerging scientific areas. Why, for example, despite the unprecedented wealth of new observational data, has astrophysics not been expanded within physics departments? Why does the physics that emerges from biology—the science that is having the most impact on today's world—not even merit an explicit place on our list? We know that there are a few biophysicists within the categories called "condensed matter" or "other physics," but we also know that there are, indeed, only a few. Where is the physics of pattern formation and complex systems on this list? How many physicists are addressing the emerging problems in advanced materials? In the environmental and Earth sciences? In information systems? The few who are working in these areas are not yet having much impact within US physics departments. Indeed, many of the best find that they have to leave physics departments to function effectively. Our thesis, in short, is that academic physicists are setting themselves apart from too many of the areas of intellectual prosperity that properly belong within the discipline. It is urgently necessary that this trend be corrected so that academic physics can retain its vitality during the difficult times ahead. How has our community arrived at this situation? Is today's relatively narrow definition of "physics" consistent with the history and traaround 1970 froze into place the membership of physics SOL GRUNER is a professor of physics at Princeton University, in Princeton, New Jersey. JAMES LANGER is a professor of plrysics at the University of California, Santa Barbara. P H I L N E L S O N is an associate professor of physics at the University of Pennsylvania, in Philadelphia. VlOLA VOGEL is an assistant professor ofhioengineenng and an adjunct assistant professor of physics at the University of Washington, in Seattle. The authors initiated this article while at the Institute for Theoretical Physics during the fall of 1994. ditions of the field? Is it even consistent with physicists' own self-image? What changes are feasible? What changes are essential? None of these questions are easy to answer—especially the last two. But we must try to answer them if we are to 1995 American Institute of Physics DECEMBER 1995 PHYSICS TODAY 25 MEDIAN AGE OF US PHYSICS FACULTY, 1951-92. Datum for 1951: median age of all physicists employed full-time. From AIP statistics published in 1962. Datum tor 1960: median age of all physicists. From AIP statistics published in 1962. Daaim for 1964 (lower point): median age of physics faculty in universities granting PhDs in physics. From AIP statistics published in 1966. Data for 1964-70: median age of all physics PhDs in US colleges and universities. From 1972 NAS survey of physics. Data for 1973-87: median age of university professoriate (all professors) with physics PhDs. From unpublished National Research Council data. Datum for 1989: median age of university professoriate. From unpublished NRC data. Datum for 1992: median age of university physics full professors. From AIP survey of member societies. FIGURE 1 understand the problem and take effective action. How did we get here? Why, in its current academic definition, is physics identified with a fixed and tightly constrained range of subjects? Simply put, the situation is a consequence of successes in the decades immediately following World War II. The importance of technological developments during World War II, such as radar and nuclear weapons, convinced people in power, in both government and industry, to support an unprecedented growth in physics. The bulk of this support was directed at a rich but narrow set of questions that appeared to be relevant to the defense and electronics industries. Basic research without obvious short-term applications was justified because of the success and importance of these applications. The atmosphere in those days was one in which the diversity of physics was not an issue because industrial growth and the cold war provided ready employment for as many physicists as could be educated. The areas being supported were intellectually exciting, thus it was easy to lose sight of the fact that the universe of physical phenomena is far richer and broader than that encompassed by the industrial or military needs of the post-World War II decades. That would not have been a bad state of affairs had physics been able to continue the nearly exponential growth that, as figure 2 shows, persisted for 50 years following World War I. Had growth remained rapid, new faculty would have continued to be a large fraction of the total and would have continued to bring new research areas with them. But exponential growth never can continue indefinitely. We see in figure 3 that growth in physics came to a sudden halt in about 1970. Since then, the rate at which younger faculty have been replacing the old has been exceedingly slow. This is readily seen in the tenure statistics: Lee Grodzins estimates that 47 percent of the PhDs of 1959-60 who entered the physics job market were eventually tenured. This proportion dropped to 8% for the cohorts of the early 1970s. The result is evident in the data of figure 1 and the table. There has been little change in the distribution among physics subfields since the early 1970s because there has been little turnover in personnel. The slow turnover that has occurred has tended to keep the relative sizes of the subfields constant. In effect the sudden change in academic employment of 1970 froze the distribution of physics subfields into what we see today. The jobs problem No academic discipline can thrive if its graduates cannot find satisfactory jobs. The current employment crisis in physics has been extremely painful, as is all too evident in recent editions of PHYSICS TODAY. There is precedent for today's situation in the 1970 downturn, which shows 195