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Maintaining Excellence Our nation excels in physics. Since World War II, the United States has played a leadership role in essentially every area of physics, and our research has won the admiration of scientists everywhere. Excel- lence in physics, however, is fragile. It requires a fortunate combina- tion of circumstances: a talented and well-educated population of scientists, a society that is interested in and appreciative of new dis- coveries, institutional structures that give scientists the freedom to follow wherever science leads, open lines of communication among fellow scientists everywhere, and the economic resources for carrying out research at the frontiers of knowledge. Excellence in physics also requires harmony between the aims of science and the goals of society. We cannot take for granted the continued excellence of physics in the United States. Many of the same social and economic pressures that have affected our nation have also affected physics. Career patterns and professional opportunities for physicists have changed; reduction of support for basic physics in favor of mission-oriented research has caused problems in some areas; and the need for large facilities is generating increased economic pressures. This chapter addresses the problem of maintaining the quality of physics in the United States. Underlying the discussion is the assump- tion that continued excellence is essential to our national interests. To recapitulate the arguments presented in Chapter 1, physics is vital to the nation for the following reasons: 44

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MAINTAINING EXCELLENCE 45 The longing to understand nature and the cosmos is deeply rooted in mankind, and, in our time, physics has taken a profound step toward realizing this longing. By making our appreciation of nature and life stronger, the discoveries of physics enrich all society. Our achieve- ments in science help the United States to maintain its role as a world leader because the achievements are respected by nations everywhere. Physics is a central discipline. The concepts of physics, and the techniques and instruments developed in its laboratories, have been widely adopted by the other physical sciences, by the life sciences? and by medicine. Excellence in physics in this nation contributes broadly to the quality of science and medicine throughout the world. The nation requires technologies of an ever-higher level because without them our economy cannot flourish. The world demands new technologies to sustain and enhance the quality of life in the face of increasing population and the depletion of natural resources. We must be prepared to create the technologies needed at home and abroad. Basic science is the driving force behind new technology; excellence in physics today is essential to leadership in technology tomorrow. We must be able to educate the skilled physicists who are needed to carry forward our national programs in energy, the environment, and defense, who can meet the many demands of industry, and who can advise the government on the scientific and technical issues that often underlie urgent policy issues. For our universities and colleges to attract able students and train them at the forefront of knowledge, the quality of research in this nation must be maintained at the highest possible level. For all these reasons, continued excellence in physics is vital to the United States. The following sections discuss issues that broadly affect our ability to meet the challenges that face physics' and they present recommendations for moving forward. THE FUNDING PROCESS Priority recommendations and decisions on the funding of research in physics are made in several stages involving a progressively broader range of scientific and societal considerations. They ultimately encom- pass political decisions at the level of the President and the Congress based on considerations of national purpose such as national security, economic progress, international competition, national pride, and the distribution of scarce resources. The nature of the scientific input to the decision-making process

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46 PHYSICS THROUGH THE 1990s: AN OVERVIEW depends on the character of the particular research. In some fields the research is performed chiefly by individuals or small groups. These fields advance along many fronts and the scientific priorities are dominantly established by the numbers of researchers who commit themselves to pursue each particular subject area. Further input often comes from disciplinary assessments. In fields that use major facilities, an organized consensus is generally necessary to establish the scientific need for a new facility. Special panels or workshops are usually convened to establish the relative scientific priority of the various facility proposals within each field. Because decisions on the support of physics involve issues that extend far beyond purely scientific considerations, physicists have an obligation to inform the public and its elected decision makers by explaining the nature of their research, the scientific opportunities, and the roles that each subfield plays in science and on the national scene. Meeting this obligation is a central goal of the Physics Survey. EDUCATING THE NEXT GENERATION OF PHYSICISTS This nation's success in educating and training physicists of the next generation depends on the quality of our educational institutions, from kindergarten through graduate school. The quality of education in the United States ultimately reflects our national ideals and the value that our society places on intellectual achievement and the search for new knowledge. Throughout the nation today, there is growing concern about education at all levels. Primary and Secondary Education With respect to primary and secondary education, the National Commission on Excellence in Education in the report, A Nation at Risk: The Imperative for Educational Reform, summarizes our situa- tion with the following chilling statement: For the first time in the history of our country the educational skills of one generation will not surpass, will not equal, will not even approach, those of their parents. The facts on education in science and mathematics are grim. The National Science Foundation report, Science and Engineering for the 1980s and Beyond, reveals that the fraction of students who have any contact with physics is so small that we are becoming a nation of

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MAINTAINING EXCELLENCE 47 scientific illiterates. Our standards for secondary education in science and mathematics are woefully below those of Japan, the Soviet Union, and many of the European countries. The majority of high school physics teachers are underqualified; the supply of qualified new teachers has essentially vanished. Raising the educational standards in our elementary and high schools presents to the nation a major challenge that demands local, state, and national efforts. Dealing with this complex issue is beyond the scope of the Physics Survey, but we would be negligent not to emphasize the critical nature of the problem and not to endorse efforts to improve secondary education, particularly education in science. In this regard, we welcome the re-establishment by the National Science Foundation of the Directorate in Science and Engineering Education. Undergraduate Education Education at the undergraduate level in our colleges and universities is also a matter of concern. A student's undergraduate experience is usually a crucial factor in that student's decision on whether to pursue a career in physics. To achieve scientific excellence, the nation must maintain the highest possible standards in its undergraduate programs, but our colleges and universities face increasing difficulties in doing so. The recent report, Involvement in Learning: Realizing the Potential of American Higher Education, prepared by the study group on the Conditions of Excellence in American Higher Education, cites such problems as underpaid faculty, overspecialized curricula, and deterio- rating buildings. Physics, as part of the core of higher learning, shares these problems. Undergraduate training in physics is carried out roughly equally at Ph.D.-granting and non-Ph.D.-granting institutions. At many universi- ties, undergraduate education benefits from the research programs of the faculty. The 4-year colleges, lacking this advantage, are more vulnerable to shrinking enrollments, the loss of financial resources, and the problems arising from decreased interest in undergraduate educa- tion at the national level. The status of undergraduate education in physics is being surveyed by the Committee on Education of the American Physical Society (APS). Preliminary studies reveal the need for concern on such issues as updating and augmenting undergraduate instructional equipment, facilitating faculty and student participation in research, strengthening visiting scientist programs, and encouraging the development of new courses and curricula. There is, for example, a real need for senior-

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48 PHYSICS THROUGH THE 1990s: AN OVERVIEW level courses in plasma and fluid physics. The creation of the College Science Instrumentation Program by the National Science Foundation is a welcome step toward enhancing undergraduate education. We urge the colleges, universities, and federal agencies to be responsive to the findings of the APS Committee on Education, as well as to forthcoming studies by other interested groups. whir The broad problems of precollege and undergraduate education in the United States deserve serious attention. The discussion here, however, will focus on professional training at the graduate level. Education at the Graduate Level We look to our universities to train the physicists who will extend the frontiers of knowledge, carry forward our national programs, and help create new technologies. The scientific and cultural vitality of the universities, the quality of the faculties, and the excitement of the research are all crucial factors in attracting and educating capable young scientists. Because it is essential for the health of physics and because we find it to be in difficulty, university research is a central issue of this report. Most nations isolate forefront research from their educational insti- tutions; the United States does not. On the contrary, student partici- pation in research at the highest professional level is at the heart of U.S. graduate education. This tradition is widely regarded as a special source of our strength in physics. More than half of this nation's basic research in physics is carried out within the universities. Thus, our universities not only provide an essential educational service but they are in themselves a vital force in research. Because professional training in physics for capable young men and women is essential to the welfare of this nation, and because university research is the largest single element in our basic research effort, maintaining excellence in physics demands that we maintain excellence in our universities. This overview report provides a natural forum for addressing the issue of research in our universities' which affects every field of physics and every style of research. The issue needs urgently to be addressed because evidence in the panel reports indicates that the climate in which university research takes place is generally troubled. The critical factor underlying any discussion of the climate for research in the universities is the strength of physics itself the challenges, the opportunities, the sense of excitement and progress that animates science. The panel reports that constitute the main body of this Physics Survey provide evidence of an enormous vitality in

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MAINTAINING EXCEL f ENCE 49 physics today. Their descriptions of discoveries in recent years, summarized in the previous chapter, provide an accounting rich in scientific achievement. Scientific opportunities today are abundant. For the promises of physics to be fulfilled, however, the climate for res Arch in our universities must be healthy. The factors that make for health in research organized around major facilities and national laboratories~are somewhat different from the factors important to university-centered research. In fields like elementary-particle phys- ics, which depends on major facilities, the quality of university research is tightly linked to the quality of the facilities and the laboratories that support them. Careful attention must be given to particular issues that affect university research in these areas, including such matters as the special quality of educational experience in a large laboratory, the effect of off-campus (and sometimes out-of-country) research, and career development in large groups. These issues are discussed in the panel reports of each of the relevant subfields. Beyond these special considerations, however, it is essential that, in planning for large facilities and major programs, adequate support be set aside for the university-based component of the research. Otherwise, the nation runs the risk of having the facilities of the future without the physicists to use them. Most basic research in physics is not carried out by groups working at major facilities, however, but by small groups, which usually work with equipment in their own laboratories. These activities, which we shall call collectively "small-group physics," constitute the backbone of university research. When viewed on a one-by-one basis, they appear as a collection of relatively small and somewhat disconnected research efforts. We believe, however, that it is essential to view small-group physics not one by one but as an entity, because only in this way can one obtain a coherent picture of research in the univer- sities and on the national scene. The following section explains this point of view. RESEARCH IN SMALL GROUPS Small-group research encompasses those areas in which the research is generally pursued by a few investigators working together, possibly only a single scientist with a few students, most often using equipment in their own laboratories. Much of condensed-matter physics operates in this style, as do atomic, molecular, and optical physics; fluid phys- ics; and certain areas of astrophysics and nuclear physics. Theoretical physics in many subfields is organized in this mode, as well as most of

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50 PHYSICS THROUGH THE 1990s: AN OVERVIEW the research that interfaces with the other sciences (for instance, biophysics and medical physics). Most areas of small-group physics usually advance by a multitude of discoveries that fit together to reveal a major scientific advance, in contrast to research that is organized around a single conceptual theme. We are, for example, beginning to understand surfaces with the detail and clarity that are characteristic of basic physical theory. Our understanding of two-dimensional structures, of the relation between orderly and chaotic motion, and of the nature of surface dynamics has been dramatically deepened. Applications of this research to the creation of new materials and to catalysis promise to have important influences on industry. In viewing the creation of contemporary sur- face physics, however, it is not possible to cite the one crucial experiment, new technique, or theoretical breakthrough that should be credited for the advances. The progress is due to theoretical advances and to research by many groups using a host of techniquessome highly novel, others traditional. Achievements of small-group research include such discoveries as spontaneous symmetry breaking and renormalization group theory, the creation of new forms of matter such as clusters and one-dimensional conductors, and rapid progress in the understanding of chaos and turbulence. Because of the relatively small scale of the individual research activities, small-group research is flexible and can move rapidly in response to discoveries. New fields can spring into exist- ence; artificially structured materials and femtosecond spectroscopy are two recent examples. The intellectual challenge and the flexible style of small-group research attract some of the most able physicists, as the high number of Nobel Prizes awarded in these areas attests. Small-group physics has had a major impact on the nation's economy through generating advanced technologies and new industries. Our modern optics and electronics industries, for example, have their roots in small-group research. Much of the advanced instrumentation now used by industry, science, and medicine has come from these areas. Research carried out in such groups plays a major role in educating professional physicists. Condensed-matter physics and atomic, molec- ular, and optical physics train slightly more than half of all the students who receive doctorates in physics; more than 70 percent of the doctorates in the United States are awarded for research in small groups. In fact, the most important aspect of small-group research may well be the opportunities for initiative and innovation provided for research students working in these areas. These aspects are precisely

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MAINTAINING EXCELLENCE 51 those that must be experienced by young scientists if physics is to continue its rapid intellectual advancement. In the universities, the various fields of small-group research face a number of similar problems. Foremost is a critical need for laboratory equipment or instrumentation. Inadequate support for instrumentation in the United States was identified as a growing problem in the early 1970s in the previous Physics Survey (Physics in Perspective, National Academy of Sciences, Washington, D.C., 19721. The situation has steadily deteriorated since then. The most recent studies, Revitalizing Laboratory Instrumentation (National Academy Press, Washington, D.C., 1982) and Academic Research Equipment in the Physical and Computer Sciences and Engineering (National Science Foundation, 1984), report that essential instrumentation in university research laboratories is obsolete or simply nonexistent. Lack of up-to-date equipment is cutting off the universities from forefront research. The research groups are losing their ability to compete on an international level, and our students are not being trained in the state-of-the-art techniques needed by industry and government. There is a shortage not only of larger pieces of equipment, such as laser systems, molecular- beam epitaxy machines, and surface-scattering apparatuses (which can cost from a quarter of a million dollars to more than $1 million), but also of equipment such as superconducting solenoids or high-vacuum systems (which can cost $50,000 or more), and even of small instru- ments like oscilloscopes and signal generators. The Department of Defense-University Instrumentation Program illustrates the size of the problem. This program, budgeted at $30 million per year for 5 years, received requests totaling more than $64S million for the first year, and this figure represented only a fraction of the total need. A second problem common to small-group research in the universi- ties is the loss of the infrastructure of support services that are essential in forefront research. Machine shops, electronics shops, and special services such as materials preparation have deteriorated or disap- peared from universities across the nation. The lack of instrumentation and support services is symptomatic of a single underlying problem in small-group research. Since the early 1970s, the base level of support in these fields has lagged far behind the costs of competitive research. There is a widespread misperception of the costs of competitive research in small groups. Equipping a modern experimental laboratory can require over $1 million, though a few hundred thousand dollars is a more typical figure. Operating Costs for

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52 PHYSICS THROUGH THE 1990s: AN OVERVIEW a healthy university group, including the acquisition of instruments, typically range from $200,000 to $400,000 a year, and some indepen- dent groups may require an annual budget of $1 million. In contrast to these costs, the average grant size in many small-group areas is about $80,000 or less a year. This enormous disparity between the size of the grants and the costs of research is making it increasingly difficult to carry research forward. The most serious impact of underfunding, however, is on the development of young talent. The number of new grants funded across the nation every year is small; a prospective faculty member must face the possibility of having to wait several years to launch a research project. Beyond this difficulty lies the prospect of pursuing a research career in a situation of perpetual shortage. As a result, academic careers have become significantly less attractive than they were in former years. In some areas, the universities are no longer able to compete with industry or government laboratories for the best talent. Unless the climate for research in the universities is significantly improved, we face the possibility of a critical shortage of highly qualified young physicists to fill these positions. The Panel on Condensed-Matter Physics and the Panel on Atomic, Molecular, and Optical Physics, meeting separately and addressing different research communities, arrived at the same conclusions: the need for instrumentation is urgent, and it is essential to bring the support of the groups up to a realistic level. The panels estimated the costs by somewhat different processes, in one case by estimating broadly across many research activities having different needs, in the other case by carrying out a group-by-group tally of research costs. The results were essentially identical: to allow a reasonable number of groups to pursue the new scientific opportunities, and to allow some young investigators to enter the field, the level of operating funds must be doubled over about a 4-year period. The major fraction of small-group research is carried out in univer- sities, and one can make reasonable estimates of the actual cost of this component of research. The federal expenditure for physics research in the universities in 1983 was $339 million. Approximately $260 million of this total was spent in support of independent-group activities: $150 million for condensed-matter physics and atomic, molecular, and optical physics and $110 million for other areas. In addition, approxi- mately $65 million was spent in the universities for large facilities. To allow independent-group activity in physics to flourish, the base support of the work in the universities needs to be augmented by $260

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MAINTAINING EXCELLENCE 53 million over a 4-year period, or by $70 million per year in 1985 dollars, for each of the 4 years. When one views small-group research collectively and witnesses its enormous elect on science education and our universities, as well as the abundant returns it yields to society, the endeavor surely repre- sents one of the most important ways for the nation to invest in research. LARGE FACILITIES AND MAJOR PROGRAMS Progress in basic and applied experimental physics depends ulti- mately on progress and innovation in the apparatus and instrumenta- tion used in experiments. Often the great forward strides in physics have been based on the invention of new kinds of physics instruments or on major changes in experimental techniques. Major instrument inventions in the last half century include the laser, the electron microscope, the particle accelerator, and the magnetic confinement apparatus used in plasma fusion studies. Examples of major changes introduced into physics techniques are the use of integrated circuits and high-speed computers, the use of rockets and satellites for atmo- spheric and space physics, and the use of very low temperatures to study the properties of matter. Some instruments (lasers and low-temperature equipment, for ex- ample) are small and of moderate cost; they can be owned and used by a single laboratory of average size. But other instruments or techniques involve large, complex, and expensive equipment. Examples are particle accelerators (Figure 3.1), magnetic and inertial plasma- confinement apparatuses (Figures 3.2 and 3.3, respectively), and space satellites. Such instruments and techniques require the large facilities and major programs discussed in this section. These facilities, which are located mostly at laboratories and centers supported by the Department of Energy (DOE), play an essential role in physics research. Large facilities have been developed to allow the physicist to work at the cutting edge of research in many areas of physics. (The types of facilities used by the various subfields are listed in Table 3. 1; the costs of some of the proposed new facilities are listed in Table 3.2.) Cutting-edge research offers the highest probability of breaking through into new areas of science and technology and the best promise of answering the deepest questions. Much cutting-edge research can be done with instruments of moderate size and cost, but some aspects of

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54 PHYSICS THROUGH THE 1990s: AN OVERVIEW - FIGURE 3.1 The Cornell Electron-Positron Storage Ring (CESR). The diameter is about 800 ft. _ FIGURE 3.2 The Tokamak Fusion Test Reactor at the Princeton Plasma Physics Laboratory.

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64 PHYSICS THROUGH THE I990s: AN OVERVIEW as soon as possible, because the high brightness of these facilities will serve the short-term needs of the next 3 to 5 years. Capabilities of advanced wiggler and undulation insertion devices be explored, because of their potential for even higher brightness. New insertion devices be implemented at existing facilities and new optical devices be developed in parallel to take advantage of those sources. Finally, the characteristics of current synchrotrons are not optimal for use with a large number of insertion devices. Consequently, a new synchrotron facility optimized for use of insertion devices should be constructed. The increased brightness of such a synchrotron radiation source would create new opportunities in the studies of photoabsorp- tion, EXAFS and its variant spectroscopies, x-ray scattering, and other techniques. It would also make possible new applications to biology, medicine, and earth science. The major facilities report cited above favored a 6-GeV synchrotron for this purpose because it would cover the region of the spectrum in which most x-ray physics is performed, but it also recommended a 1-2 GeV facility to serve the VUV and XUV communities. NEUTRON FACILITIES Neutron scattering offers unique opportunities for studying struc- tures and phase transitions in new exotic materials, in magnetic systems, and in systems of lower dimension, under extreme conditions such as high pressures and low and high temperatures. It is also used to study the structure and dynamics of polymers and macromolecular systems and to make precision measurements, such as the determina- tion of the upper limit to the electric dipole moment of the neutron. In order for the United States to stay at the forefront of this research, cold-neutron guide halls and associated instrumentation need to be established at U.S. reactor facilities. This instrumentation will allow new, very-low-energy, and momentum regimes to be probed. In recent years, a new type of neutron source has been developed for materials research. These sources, called pulsed spallation sources, have been constructed at Argonne National Laboratory and Los Alamos National Laboratory (LANL). They offer new opportunities to explore condensed-matter physics. The United States should continue to explore the use of pulsed spallation sources by the timely completion of the facility at LANL. As we look to the future, a new high-flux reactor with an order-of-

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MAINTAINING EXCEL f ENCE 65 magnitude increase in intensity over existing facilities will be needed because most neutron experiments are intensity limited. A properly designed reactor could, with such intensity, allow new types of measurements using neutronsthe only probe of matter that can look at excitations with large momentum transfers and relatively low energies. The current facilities were built in the 1960s, and a new reactor would represent their timely replacement and improvement. HIGH MAGNETIC FIELDS Magnetic fields above 25 teslas are feasible only in pulsed operation. The United States lags behind Japan and Europe in developing high pulsed fields, which allow the exploration of magnetic-field-induced phases that cannot otherwise be explored. Therefore, we recommend increased efforts to produce high pulsed magnetic fields and enhanced instrumentation at the National Magnet Laboratory. Plasma Physics Much of the research in plasma physics is directed toward the goal of controlled thermonuclear fusion in a fusion reactor, leading to the production of energy. Reaching this goal requires the simultaneous achievement of high temperatures, high densities, and long confine- ment times in plasmas- similar to the plasma conditions at the centers of stars. Two types of large facilities are used to carry out cutting-edge research under these extraordinary conditions: devices for magnetic confinement of plasmas (such as tokamaks and magnetic mirror machines) and inertial fusion devices driven by very-high-power laser beams or ion beams. The scientific feasibility of controlled fusion is likely to be demonstrated in the coming decade, and the program outlined below is designed to accomplish this goal. MAGNETIC FUSION RESEARCH In all the main approaches to the magnetic confinement of fusion plasmas, the principal measures of performanceplasma density, temperature, and confinement time improved by more than an order of magnitude as a result of intensified fusion research in the 1970s. One approach, the tokamak, has already come within a modest factor of meeting the minimum plasma requirements for energy breakeven in deuterium-tritium plasmas. The science of plasma confinement and heating has reached a stage that justifies a vigorous research program in magnetic fusion, with the following principal features:

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66 PHYSICS THROUGH THE 1990s: AN OVERVIEW A base research program involving moderate-size experimental facilities is essential. The program should emphasize both increased scientific understanding of hot, dense plasmas and research on im- proved confinement concepts (advanced tokamaks, tandem mirrors, and other approaches). The program goals should be both to increase our knowledge of the physics of plasmas and to improve the prospects for fusion reactors. Historically, the interplay between these two research efforts has led to the most creative physical insights and concepts. Such a program is essential to technical progress and to the education of talented new people. The demonstration and experimental study of an ignited fusion plasma is the obvious next research frontier after attainment of the energy breakeven point in a plasma. While the scientific understanding of many key plasma phenomena can best be gained on moderate-size experimental facilities, ultimately plasma-confinement properties must be investigated under conditions of intense alpha-particle heating, which will require an ignited plasma core. Fusion research is at the point where consideration of such experiments can proceed with some degree of realism. Obviously, ideas will continue to evolve rapidly as results from experiments, particularly from the Tokamak Fusion Test Reactor (TFTR), become available over the next several years. In the near future, studies of a burning-core experiment should emphasize maximum scientific output with minimum project cost, in a manner consistent with the recommendations of the Magnetic Fusion Advisory Committee (MFAC). INERTIAL FUSION RESEARCH During the past decade, a vigorous research effort has been estab- lished to investigate the inertial-confinement approach to fusion. In this approach a pellet is to be driven into fusion by the sudden and intense injection of energy from a laser or particle beam. An impressive array of experimental facilities has been developed; inertial fusion drivers include neodymium-glass and CO2 lasers and light-ion accelerators. This has led to considerable scientific and technological progress. On the basis of such progress, it is important to implement the following near-term strategy for inertial-confinement fusion research: Use present driver facilities to determine the physics and scaling of energy transport and fluid and plasma instabilities to regimes characteristic of high-gain targets.

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MAINTAINING EXCELLENCE 67 Use the new generation of drivers coming into operation to implode deuterium-tritium fuel mixtures up to 1000 times liquid density required for high-gain targets and to implode scale models of high-gain targets to the density and temperature of the full-scale target. Identify and develop cost-effective, multimegajoule driver ap- proaches. Timely execution of this strategy will provide the basis for a decision in the late 1980s on the next generation of experimental facilities. Drivers in excess of a megajoule would allow demonstration of high-gain targets for both military and energy applications. Space and Astrophysical Plasmas A broad variety of plasmas exists in outer space, ranging from the hot, dense plasmas in the interiors of some stars to the tenuous plasmas of space itself. Research in space and astrophysical plasmas is corre- spondingly broad, involving major research programs and space re- search facilities in other sciences as well as physics. We note here by way of summary that cutting-edge research in this area of plasma physics requires implementation of the comprehensive research strat- egy outlined in the report of the Committee on Solar and Space Physics' of the NRC Space Science Board, Solar System Space Physics in the 1980's (National Academy of Sciences, Washington, D.C., 1980~. These programs, and especially the International Solar Terrestrial Program, are the primary ones that will explicitly contribute to our knowledge of the physical processes in large-scale plasmas. The comprehensive programs proposed in the report of the NRC Astron- omy Survey Committee, Astronomy and Astrophysics for the 1980s (National Academy Press, Washington, D.C., 1982), will make signif- icant contributions to many problems in plasma astrophysics. Gravitation, Cosmology, and Cosmic-Ray Physics Physicists conduct a broad range of research under the general heading of astrophysics~osmology, nuclear astrophysics, solar phys- ics, and plasma physics, to name a few. To avoid duplication with the report of the Astronomy Survey Committee, the Physics Survey Committee has concentrated on three research areas: gravitational radiation and general relativity; cosmology, particularly as it relates to elementary-particle physics and gravitation; and cosmic-ray physics.

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68 PHYSICS THROUGH THE 1990s: AN OVERVIEW SEARCH FOR GRAVITATIONAL RADIATION This fundamental consequence of general relativity has not yet been directly observed, but a variety of astrophysical sources are predicted: supernovae collapse, neutron-star binary coalescence, and black-hole formation. Resonant cryogenic bar detectors are approaching interest- ing levels of sensitivity in the kilohertz frequency range, and at lower frequencies a laser interferometer with 5-km arms is being considered. The vigorous program of the National Science Foundation in gravita- tional radiation research is strongly supported, and the Long Baseline Gravitational Wave Facility is strongly endorsed. RELATIVITY GYROSCOPE EXPERIMENT This experiment uniquely addresses the important magnetic aspects of general relativity by a precision measurement of the precession rate of a gyroscope in an orbiting satellite. Clearly, this is an exceedingly difficult experiment that is many times more sophisticated than any yet attempted in space. The Space Science Board's Committee on Gravi- tational Physics (see Strategy for Space Research in Gravitational Physics in the 1980's, National Academy Press, Washington, D.C., 1981) has recommended that the National Aeronautics and Space Administration (NASA) attempt this difficult but important experi- ment, and the recommendation is supported by the Physics Survey Committee. VIGOROUS SPACE PROGRAM IN ASTROPHYSICS We are in a period of great excitement in cosmology; our under- standing of the physics of diverse cosmological epochs and processes is undergoing fundamental changes. Much of the change is traceable to the highly successful U.S. space program. Besides providing unique observations from satellites, space-inspired technology has greatly enhanced the capabilities of ground-based telescopes. The NASA program is sound and forward looking. The following large facility projects, in various stages of development, will make important con- tributions to cosmology: Rubble Telescope, Cosmic Background Ex- plorer, Gamma Ray Observatory, Shuttle Infrared Telescope Facility, Advanced X-ray Astronomy Facility, Large Deployable Reflector, and an orbiting antenna for the Very Long Baseline Array.

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MAINTAINING EXCELLENCE 69 LONG-DURATION COSMIC-RAY EXPERIMENTS The development of space exploration has resulted in recent dra- matic advances in our understanding of cosmic-ray phenomena. For example, we now know that the most abundant cosmic rays represent a sample of matter significantly different from that of our solar system. The development of a series of long-duration (1 or 2 years) cosmic-ray experiments in space is needed. GROUND-BASED COSMIC RAYS The only practical means of observation of the most energetic cosmic rays is through the observation of extensive air showers. The Utah Fly's Eye is a unique and successful facility for air-shower studies, and its exploitation and upgrade merit strong support. Ground-based observation of the highest-energy gamma rays now reveals sources, probably discrete, of energetic cosmic rays. The potential for development in this young field is great, and the deploy- ment of new dedicated detectors for its studies is endorsed. NEUTRINO ASTRONOMY The enigma of the discrepancy between theory and observation of solar neutrinos begs for resolution. New solar-neutrino experiments should be developed. MANPOWER AND EXCELLENCE As discussed in detail in Supplement 2, the current demand for physicists and their supply appear to be reasonably balanced but only precariously so. The supply of Ph.D. physicists for industry and government has been sustained only because of the decline in the number of academic positions and the increase in foreign graduate students. Many colleges and universities expanded rapidly in the post-Sputnik era, and their staffs have not yet started to retire at a significant rate. Financial problems and shrinking student enrollments have also reduced the number of appointments for young faculty. The problem of forecasting the future demand for physicists and their supply is complex. The best current estimate is that it should be possible to maintain the balance between demand and supply through 1991, provided that the decrease of U.S. students does not accelerate, that we can continue to attract a reasonable share of foreign students,

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70 PHYSICS THROUGH THE 1990s: AN OVERVIEW and that no special demands occur such as major new national programs. We must also not fail to recognize that the increasing reliance on foreign-born physicists who now constitute 40 percent of our entering Ph.D. students- is cause for unease. Starting early in the 1990s, faculty positions will become available at an accelerating rate. At that time the demand for physicists will most probably outstrip the supply. Because actions to increase the supply take at least 5 to 7 years to have an effect, we should take steps now to avoid the possibility of a serious shortage of scientists in the 1990s. Among such steps will be making the pursuit of graduate studies and research more attractive. Our specific recommendations are as follows: Increase the number of predoctoral fellowships in physics to help reverse the decline in U.S.-born graduate students. These fellowships represent a visible signal to students that the nation needs scientists and that it recognizes and rewards excellence in science. The number currently awarded 45 to 50 each yearcould be doubled. Attract young scientists to academic careers to assure the contin- ued vitality of university research and to assure continuity in the teaching of physics. Programs such as Sloan Fellowships, Presidential Young Investigator Awards, and the DOE Outstanding Junior Inves- tigator Program are important in this regard. We encourage govern- ment funding agencies to work toward attracting young scientists to universities, and we urge industry to participate in the effort. Facilitate the entry of U.S.-trained foreign-born physicists who wish to pursue a career in this country. Given the large number of foreign citizens receiving advanced training in the United States, our immigration laws should be simplified to make it easier for these experts to remain in the United States and to use their skills for the benefit of this country. Encourage more women and minorities to become physicists. Women and minorities represent an important reservoir of talent in this nation, and every effort should be made to attract them to careers in physics. POLICY ISSUES CONNECTED WITH MAINTAINING EXCELLENCE General policies of the federal government having to do with science and technology affect physics research in the United States and are therefore of importance in determining its future. Here we mention two of these policies that have been of importance in the past several years and state our recommendations regarding them.

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MAINTAINING EXCELLENCE 71 Role of Industry and Mission Agencies in Basic Research Fundamental research in physics is one element of the continuous range of activities that constitute the research and development efforts of this nation. The activities on the frontier of research interact with technology not only by producing new concepts and discoveries but also by using new technology. In fact, basic research is frequently the driving force of new technology. Thus for a nation to maintain its technological strength, it must also maintain its strength in basic research. Those industries and enterprises that are dependent on technology in maintaining their leadership must also contribute to basic research to ensure their future. These statements are particularly true of military technology and the Department of Defense (DOD). Consequently, the Physics Survey Committee strongly recommends that the DOD restore its investment in long-range fundamental research and strengthen its connections with the research community for the mutual benefit of science and national security. To assure that this nation has a viable defense in the future, a constructive relationship between science and the defense establish- ment is essential. The relationship between commercial technology and research is also an important element of the continuum mentioned above. Only a small section of American industry has corporately supported re- search. The U.S. Government and American industry must create an environment, perhaps through tax incentives, that encourages indus- trial participation in basic research. Freedom of International Communication and Exchange Physics is an international enterprise because physical principles know no national boundaries. Physicists everywhere are eager to share in the stimulating exchange of ideas. Evidence for this can be found in the numerous collaborations originating from international visits by members of universities and laboratories, the large international teams that work together on major experiments, and the success of labora- tories like CERN in Geneva that are supported by several nations and operated internationally. For science to flourish, the international freedom of scientists and the free flow of scientific information must be assured. Attempts to curtail the exchange of basic scientific information will only interfere with the growth of science to the detriment of the United States and all nations.

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72 PHYSICS THROUGH THE 1990s: AN OVERVIEW COMPUTATION AND DATA BASES Computers Computers are now used in every area of physics, and their role is steadily growing. Nearly all of today's experiments in physics depend on computers, and many experiments would be impossible without them. They are used to control apparatus, to gather data, and to analyze it. Computers are also widely employed by theorists to carry out calculations far exceeding human capability, thus achieving new orders of precision. Beyond all these applications, large computers are being increasingly used as numerical laboratories in which complex physical systems can be simulated and studied in ways not possible by experiment. Time- dependent processes, such as the motions of electrons during a chemical reaction, the motions of nucleons during collisions, or the evolution of galactic structure, can be visualized, providing a powerful guide to theory. The transition from order to chaosone of the most profound problems in contemporary physicscan be observed and studied in systems ranging from a few particles to the turbulence around an aircraft. In such applications, computers are providing a new approach to understanding nature called simulation physics. Neither precisely theoretical nor experimental, this style of physics possesses enormous potential, and it is growing rapidly. The complete range of computers is needed in physics. Microcom- puters, minicomputers, and large supermini machines are part of the standard instrumentation of physics laboratories and are also widely used by theorists. Such machines need to be adequately supported as part of the general instrumentation of physics. Networking of small computers holds promise of vastly expanding the capabilities of experimenters and theorists. It is a rapidly changing development that needs continuous evaluation. Many areas of research require access to the enormous memories and high computational speeds of supercomputers. Special efforts are needed to provide adequate access to these machines. The general problem of computer needs in science is being addressed by a number of federal agencies. The DOE has taken steps to provide the scientific community with access to supercomputers at both its fusion center and the new supercomputer facility at Florida State University. The National Science Foundation (NSF) has for many years operated a national center for computing in atmospheric physics. Recently the NSF has launched a $40 million initiative to provide four

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MAINTAINING EXCELLENCE 73 new supercomputer centers for university researchers. NASA, DOD, and the National Bureau of Standards are also addressing the need for supercomputers in science. We applaud these initiatives for making supercomputers accessible to scientists, but we also call for continuing attention to the need for access by physicists to a full range of computers. Data Bases In almost every field of physics, there is a vital need for the critical evaluation, compilation, and dissemination of data. These data are needed for basic research and for wide areas of applied research in government and industrial laboratories. Different agencies are respon- sible for maintaining the data bases that provide this essential service in the various subfields. In almost all cases, however, the efforts are understaffed and underfunded. With the rapid experimental advances of the past two decades, the data compilations have often fallen far behind the needs. In this survey, the problem was particularly empha- sized by the Panel on Nuclear Physics and the Panel on Atomic, Molecular, and Optical Physics. When we consider that the actual costs of these services are relatively small, sponsoring agencies should make a determined effort to respond to the need to make the data from physics research widely and readily accessible. The effort should be international in scope and should take advantage of the rapid advances in information technology that have created new tools for the effective dissemination of data.

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