The advances and breakthroughs of 20th-century physics have enriched all the sciences and opened a new era of discovery. They have touched nearly every part of our society, from health care to national security to our understanding of Earth's environment. They have led us into the information age and fueled broad technological and economic development. The pace of discovery in physics has quickened over the past two decades. New microscopic devices are being developed with a host of potential applications, and instruments of unprecedented sensitivity and reach are being created and employed. Physics at the tiniest distances is being linked to the origin and fate of the universe itself.
A second quantum revolution is under way. Physicists exploring and controlling the properties of collections of atoms are shrinking the materials they study to sizes at which quantum properties play a key role. The study of this nanoscale regime, smaller than the wavelength of visible light, is ushering in an era of powerful electronic devices.
At the same time, as they study ever more complex systems, physicists are joining forces with biologists to understand life and with geologists to explore Earth and the planets. Dramatic advances in computing are responsible for much of this progress, allowing vast amounts of data to be collected and understood and enabling many of the most complex phenomena encountered in nature to be analyzed numerically.
In astrophysics and cosmology, a new generation of space-based and Earth-based instruments has brought about a golden age. Exciting questions are being addressed: Is the expansion of the universe today accelerating as a result of some mysterious form of energy? Did the universe undergo a
period of very rapid expansion (inflation) at its earliest moments? How do black holes form?
Amazingly, these questions about the cosmos are being linked directly to physics at the tiniest distances. The exploration of the next high-energy frontier at a new generation of particle colliders will illuminate the origins of elementary particle masses and may reveal a profound unification of all the forces of nature.
PHYSICS AND SOCIETY
With physics now connected strongly to the other sciences and contributing to many national needs, education in physics is of vital importance. Physics is at the heart of the technology driving our economy, and broad scientific literacy must be a primary goal of physics education at all levels. To achieve this goal, to provide an education linked to the wider world that is so important for members of the high-tech work force, and to draw more students into careers in science will require the best efforts of university physics departments and national laboratories.
It is an international society that physics and physics education must reach in this new era. The problems that physics can address are global problems, and physics itself is becoming a more international enterprise. New modes of international cooperation must be created to plan and operate the large facilities that are increasingly important for frontier research.
SCIENTIFIC PRIORITIES AND OPPORTUNITIES
The accomplishments of physics, the growing power of its instruments, and its expanding reach into the other sciences have generated an unprecedented set of scientific opportunities. The committee has identified six such “grand challenges,” listed below in no particular order. They range across all of physics, extending from purely theoretical work and numerical simulation to research requiring large experimental facilities. They are selective: Some coincide with the priorities set forth in the area volumes, 1 while others cut more broadly across the whole of physics, overlap other areas of science, or are of growing importance for technology. The committee chose them based on their intrinsic scientific importance, their potential for broad impact and application, and their promise for major progress
1 See the preface for a list of the area volumes and the Web site address through which they can be accessed online.
during the next decade. It urges that these high-priority areas be supported strongly by universities, industry, the federal government, and others in the years ahead.
Developing Quantum Technologies
The ability to manipulate individual atoms and molecules will lead to new quantum technologies with applications ranging from the development of new materials to the analysis of the human genome. This ability allows the direct engineering of quantum probabilities, producing novel phenomena such as the presence of many atoms in the same quantum mechanical state with a high probability of spatial overlap and entanglement. Quantum overlap can sometimes extend over distances very large compared to a single atom, as in gaseous Bose-Einstein condensates. A new generation of technology will be developed with construction and operation entirely at the quantum level. Measurement instruments of extraordinary sensitivity, quantum computation, quantum cryptography, and quantum-controlled chemistry are likely possibilities.
Understanding Complex Systems
Theoretical advances and large-scale computer modeling will enable phenomena as complicated as the explosive death of stars and the properties of complex materials to be understood at a depth unavailable only a few years ago. The rapid advances of massively parallel computing, coupled with equally impressive developments in theoretical analysis, have generated an extraordinary growth in our ability to model and predict complex and nonlinear phenomena and to visualize the results. Problems that may soon be rendered tractable include the strong nuclear force, turbulence and other nonlinear phenomena in fluids and plasmas, the origin of large-scale structure in the universe, and a variety of quantum many-body challenges in condensed-matter, nuclear, atomic, and biological systems. The study of complex systems is inherently of great breadth: Improvements in the understanding of radiation transport, for example, will advance both astrophysics and cancer therapy.
Applying Physics to Biology
Because all essential biological mechanisms ultimately depend on physical interactions between molecules, physics lies at the heart of the
most profound insights into biology. Problems central to biology such as the way molecular chains fold to yield the specific biological properties of proteins will become accessible to analysis through basic physical laws. Current challenges include the biophysics of cellular electrical activity underlying the functioning of the nervous system, the circulatory system, and the respiratory system; the biomechanics of the motors responsible for all biological movement; and the mechanical and electrical properties of DNA and the enzymes essential for cell division and all cellular processes. Tools developed in physics, particularly for the understanding of highly complex systems, are vital for progress in all these areas. Theoretical approaches developed in physics are being used to understand bioinformatics, biochemical and genetic networks, and computation by the brain.
Creating New Materials
Novel materials will be discovered, understood, and employed widely in science and technology. The discovery of materials such as high-temperature superconductors and new crystalline structures has stimulated new theoretical understanding and led to applications in technology. Several themes and challenges are apparent—the synthesis, processing, and understanding of complex materials composed of more and more elements; the role of molecular geometry and motion in only one or two dimensions; the incorporation of new materials and structures in existing technologies; the development of new techniques for materials synthesis, in which biological processes such as self-assembly can be mimicked; and the control of a variety of poorly understood, nonequilibrium processes (e.g. turbulence, cracks, and adhesion) that affect material properties on scales ranging from the atomic to the macroscopic.
Exploring the Universe
New instruments through which stars, galaxies, dark matter, and the Big Bang can be studied in unprecedented detail will revolutionize our understanding of the universe, its origin, and its destiny. The universe itself is now a laboratory for the exploration of fundamental physics: Recent discoveries have strengthened the connections between the basic forces of nature and the structure and evolution of the universe. New measurements will test the foundations of cosmology and help determine the nature of dark matter and dark energy, which make up 95 percent of the mass-energy of the universe. Gravitational waves may be directly detected, and the predictions of
Einstein's theory for the structure of black holes may be checked against data for the first time. Questions such as the origin of the chemical elements and the nature of extremely energetic cosmic accelerators will be understood more deeply. All of this has given birth to a rich new interplay of physics and astronomy.
Unifying the Forces of Nature
Experiment and theory together will provide a new understanding of the basic constituents of matter. The mystery of the nature of elementary particles deepened in the 1990s with the discovery of the extraordinarily heavy top quark and the observation of oscillations in neutrinos from the Sun and the upper atmosphere, suggesting that neutrinos have extremely tiny masses. During the next decade the unknown physics responsible for elementary particle masses and other properties will begin to reveal itself in experiments at a new generation of high-energy colliders. Possibilities range from the discovery of new and unique elementary particles to more exotic scenarios involving fundamental changes in our description of space and time.
Determining this new physics is an important step toward an historic goal: the discovery of a unified theoretical description of all the fundamental forces of nature—the strong nuclear force, the electroweak forces, and gravity. The most promising and exciting framework for unifying gravity with the other forces is string theory, which proposes that all elementary particles behave like strings at very tiny distances. String theory has also given birth to new and vibrant intersections between physics and pure mathematics. The next decade will see much progress toward the goal of discovering a unified theory of the forces of nature.
From this survey of physics and its broad impact and the identification of six high-priority scientific opportunities, the committee has developed a set of nine recommendations. They are designed to strengthen all of physics and to ensure the continued international leadership of the United States. They address the support of physics by the federal government and the scientific community; physics education; the role of basic physics research in national security; the increasingly important role of partnerships among universities, industry, and national laboratories; the stewardship of federal science agencies; and the rapidly changing role of information technology in physics research and education.
Recommendation 1: Investing in Physics. To allow physics to contribute strongly to areas of national need, the federal government and the physics community should develop and implement a strategy for long-term investment in basic physics research. Key considerations in this process should include the overall level of this investment necessary to maintain strong economic growth driven by new physics-based technologies, the needs of other sciences that draw heavily on advances in physics, the expanding scientific opportunities in physics itself, the cost-effectiveness of stable funding for research projects, the characteristic time interval between the investment in basic research and its beneficial impact, and the advantages of diverse funding sources. The Physics Survey Overview Committee believes that to support strong economic growth and provide essential tools and methods for the biomedical sciences in the decade ahead, the federal investment in basic physics research relative to GDP should be restored to the levels of the early 1980s.
Recommendation 2: Physics Education. Physics departments should review and revise their curricula to ensure that they are engaging and effective for a wide range of students and that they make connections to other important areas of science and technology. The principal goals of this revision should be (1) to make physics education do a better job of contributing to the scientific literacy of the general public and the training of the technical workforce and (2) to reverse, through a better-conceived, more outward-looking curriculum, the long-term decline in the numbers of U.S. undergraduate and graduate students studying physics. Greater emphasis should also be placed on improving the preparation of K-12 science teachers.
Recommendation 3: Small Groups and Single Investigators. Federal science agencies should assign a high priority to providing adequate and stable support for small groups and single investigators working at the cutting edge of physics and related disciplines.
Recommendation 4: Large Facilities and International Collaboration. While planning and priority setting are important for all of physics, they are especially critical when large facilities and
collaborations are necessary. To plan successfully, the community of physicists in the United States and abroad must develop a broadly shared vision and communicate this vision clearly and persuasively. Planning and implementation for the very largest facilities should be international. The federal government should develop effective mechanisms for U.S. participation and leadership in international scientific projects, including clear criteria for entrance and exit.
Recommendation 5: National Security. Congress and the Department of Energy should ensure the continued scientific excellence of the Department of Energy's Office of Defense Programs' national laboratories by reestablishing the high priority of long-term basic research in physics and other core competencies important to laboratory missions.
Recommendation 6: Partnerships. The federal government, universities and their physics departments, and industry should encourage mutual interactions and partnerships, including industrial liaison programs with universities and national laboratories; visitor programs and adjunct faculty appointments in universities; and university and national laboratory internships and sabbaticals in industry. The federal government should support these programs by helping to develop protocols for intellectual property issues in cooperative research.
Recommendation 7: Federal Science Agencies. The federal government should assign a high priority to the broad support of core physics research, providing a healthy balance with special initiatives in focused research directions. Federal science agencies should continue to ensure a foundation that is diverse, evolving, and supportive of promising and creative research.
Recommendation 8: Peer Review. The peer review advisory process for the allocation of federal government support for scientific research has served our nation well over many decades and is a model worldwide for government investment in research. The peer review process should be maintained as the principal factor in determining how federal research funds are awarded.
Recommendation 9: Physics Information. The federal government, together with the physics community, should develop a coordinated approach for the support of bibliographic and experimental databases and data-mining tools. The use of open standards to foster mutual compatibility of all databases should be stressed. Physicists should be encouraged to make use of these information technology tools for education as well as research. The bibliographic archive based at Los Alamos National Laboratory has played an important role and it should continue to be supported.