A New Era of Discovery
The Committee's Work
In this volume, Physics in a New Era: An Overview, which is the culmination of the National Research Council's six-volume survey Physics in a New Era, the committee has considered the science of physics as a whole, reviewing the field broadly and describing its impact on the wider society. This breadth is reflected in the committee's priorities and recommendations, which are meant to sustain and strengthen all of physics in the United States, enabling it to serve important national needs.
In this chapter, the committee identifies six focused areas of research, which, in its view, are of especially high priority for the discipline as a whole. Some of these important areas coincide with those identified in the earlier volumes of the survey (because they are devoted to various broad areas of physics, those volumes are known as the area volumes1). Others are cross-cutting: They reflect new trends in physics, overlap other areas of science, or hold special promise for the development of technology.
In Chapter 11, the committee recommends improvements in the support for cutting-edge physics research, revisions in physics education, and a strengthening of the role of physics in national security.
In Chapter 12, the committee makes recommendations on issues of importance to the field as a whole, such as the formation of research partnerships among universities, industry, and national laboratories; the impact on physics of the management policies of the federal science agencies; and the role of information technology in physics.
1 See the preface for a list of the area volumes and the Web site address through which they can be accessed online.
The great milestones of 20th-century physics included the discovery of special and general relativity, which revolutionized our view of space and time; the development of quantum mechanics, which provided a roadmap for understanding the subatomic world; the discovery that matter could be transmuted by nuclear fission and fusion, which led to an understanding of the stars; the development of a unified description of the electromagnetic and weak interactions, which was an important step toward a unified theory of the basic forces in nature; the discovery of the Hubble expansion and the cosmic microwave background, which led to an understanding of the birth of the universe; the discovery of new states of matter in superfluids and superconductors, leading to new technologies; the invention of the transistor, the laser, and fiber-optic communication, which gave birth to the information age; and the development of new tools such as x rays, accelerators, and magnetic resonance imaging (MRI), which led to great strides in the biomedical sciences and health care.
These advances and breakthroughs have reshaped all of science and the technology that drives our economy and have opened a new era of discovery. The structure of the physical world may now be probed over distances ranging from 10,000 times smaller than the atomic nucleus to 100,000 times larger than our galaxy. For the first time, phenomena as complex as supernova explosions and weather patterns may be analyzed and understood.
New areas in physics are emerging in response to experimental techniques of unprecedented scope and sensitivity as well as the increasing power of computation. We can now control single atoms, observe properties of matter at densities greater than that of the atomic nucleus, design materials with novel properties, study the molecular motors responsible for distributing genetic information during cell division, and probe the earliest moments of the universe.
At the beginning of the 21st century, physics has become more important for the other sciences, enabling progress in materials science, astronomy, chemistry, geology, and the biomedical sciences. Many of the problems in these areas are increasingly becoming physics-dependent problems; that is, the basic laws of physics play an important role in their understanding.
Physics is increasingly important for broad technological and economic development. It has long been a fertile ground for the development of technology—the transistor, the Internet, and MRI are just three examples. The pace of U.S. economic development in the information sciences and other areas will create an increased need for basic physics research in the next decade.
Physics is now so central to many areas of science and to the solution of problems in health, the environment, and national security that education in physics is more important than ever to advance these areas and to provide a technically trained workforce.
Physics is increasingly becoming a global enterprise. The rapid exchange of scientific information enabled by the Internet and the excellence of physics in Europe and Asia are enough to ensure that. Moreover, the scale of some of the most exciting scientific experiments, on the ground and in space, make international collaboration in science an economic necessity.
Keeping pace with these trends is a challenge for universities, industry, national laboratories, Congress, federal science agencies, and individual scientists. All are key players and all must do their part if physics is to fulfill its promise for the nation in the years ahead.
SCIENTIFIC PRIORITIES AND OPPORTUNITIES
The accomplishments of physics, the increasing power of its instruments, and its expanding reach into the other sciences have generated an unprecedented set of scientific opportunities. The committee has described many of them in this volume, and it believes that some are so promising for the decade ahead that their pursuit should be a matter of high national priority. Accordingly, it has identified six “grand challenges,” listed below in no particular order. They range across all of physics and overlap other areas of science and engineering. They are selective, some coinciding with the priorities of the area volumes and others cutting more broadly across traditional subfields. Several are of growing importance for technology and economic development. The committee chose them based on their intrinsic scientific importance, their potential for broad impact and application, and their promise for major progress during the decade. In each of the six areas, recent theoretical advances have opened up new questions and set the stage for further synthesis. And in each case, the promise seen for the near future hinges on the emergence of a new generation of instruments provid-
ing exquisite precision, great energy and reach, and powerful computational capability. The committee urges that these six 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 the size of 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 to a degree unimaginable only a few years ago. The rapid advances in 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 bio-informatics, 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 decade ahead 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. This decade will see much progress toward the goal of discovering a unified theory of the forces of nature.
The scale and complexity of the physics necessary to advance these six priority areas will require increased levels of strategically directed investment and international cooperation. In the United States, the investment must be broad based: from the federal government, from industry, from colleges and universities, and from other supporters of physics research and education. The committee believes that as a result of this focused investment, the decade ahead will see dramatic progress in the above areas and in the many other frontiers described in this overview and in the earlier volumes of the survey. There is little doubt that the new ideas and technologies developed in these quests will enable progress in all the sciences, contribute to the needs of the nation, and benefit the lives of people everywhere.