A national discussion about the future of U.S. global leadership in science, technology, and innovation has been unfolding over the past few years. In October 2005, echoing widespread concerns,1 the report Rising Above the Gathering Storm outlined a program designed to enhance the U.S. science and technology enterprise so that the nation can sustain its cultural vitality, continue to provide leadership, and successfully compete, prosper, and be secure in an increasingly globalized world. In particular, the report identified basic research in the physical sciences as a key underpinning for the nation’s strategic strengths.
Against this broader backdrop, the work of the Committee on Elementary Particle Physics in the 21st Century took on a special significance. By recognizing the need for U.S. leadership in particle physics, and by articulating an approach to ensuring that leadership, this report offers a compelling opportunity for action in the national discussion of the U.S. role in science and technology. Simply stated,
See, for example, House Committee on Science, Unlocking Our Future: Toward a New National Science Policy, September 1998, available online at <http://www.house.gov/science/science_policy_report.htm>; T.L. Friedman, The World Is Flat: A Brief History of the Twenty-first Century, New York: Farrar, Strauss, and Giroux, 2005; National Academy of Sciences (NAS), National Academy of Engineering (NAE), and Institute of Medicine (IOM), Rising Above the Gathering Storm: Energizing and Employing America for a Brighter Economic Future, Washington, D.C.: The National Academies Press, 2005 (Prepublication); U.S. Domestic Policy Council, American Competitiveness Initiative, February 2006.
given the excitement of the scientific opportunities in particle physics, and in keeping with the nation’s broader commitment to research in the physical sciences, the committee believes that the United States should continue to support a competitive program in this key scientific field.
However, despite the sense of excitement and anticipation within particle physics, the U.S. tradition of leadership in the field is not secure. The major U.S. particle physics experimental facilities are entering an era of change, with some facilities being closed and others transitioning to new purposes, and support for particle physics in the United States has stagnated. As a result, the intellectual center of gravity within the field is moving abroad. Within a few years, a majority of U.S. experimental particle physicists will be involved in experiments being conducted in other countries.
The U.S. program in particle physics is at a crossroads. The continuing vitality of the program requires new, decisive, and forward-looking actions. In addition, sustained leadership requires a willingness to take the risks that always accompany leadership on the scientific frontier. Thus, the committee recommends the thoughtful pursuit of a high-risk, high-reward strategy.
The most important components of such a strategy are the establishment of a set of important new experiments in the United States (including a large accelerator facility), a determination to work together with colleagues abroad in mutually beneficial joint ventures, adoption of a compelling set of priorities within a broad strategic framework, and the provision of reasonable levels of resources. The committee particularly emphasizes the increasing benefits of establishing cooperative ventures with programs in other countries, whether the experimental facilities are located in the United States or abroad. These joint ventures will provide U.S. students and scientists with a full range of exciting scientific opportunities and meet the obligation to deploy public funds responsibly.
The committee arrived at three strong conclusions regarding both particle physics and the U.S. role in this global scientific and technological enterprise:
Particle physics plays an essential role in the broader enterprise of the physical sciences. It inspires U.S. students, attracts talent from around the world, and drives critical intellectual and technological advances in other fields.
Although setting priorities is essential, it also is critical to maintain a diverse portfolio of activities in particle physics, from theory to accelerator R&D to the construction and support of new experimental facilities. The committee believes that accelerators will remain an essential component of the program, since some critical scientific questions cannot be explored in any other manner.
The field of elementary particle physics is entering an era of unprecedented potential. New experimental facilities, including accelerators, space-based experiments, underground laboratories, and critical precision measurements of various kinds, offer a variety of ways to explore the hidden nature of matter, energy, space, and time. The availability of technologies that can explore directly an energy regime known as the Terascale is especially exciting. The direct exploration of the Terascale could be the next important step toward resolving questions that human beings have asked for millennia: What are the origins of mass? Can the basic forces of nature be unified? How did the universe begin? How will it evolve in the future? Moreover, at Terascale energies, formerly separate questions in cosmology and particle physics become connected, bridging the sciences of the very large and the very small.
The results of the committee’s analysis have led to its chief recommendation:
The United States should remain globally competitive in elementary particle physics by playing a leading role in the worldwide effort to aggressively study Terascale physics.
To implement the committee’s chief recommendation, the Department of Energy and the National Science Foundation should work together to achieve the following objectives in priority order:
Fully exploit the opportunities afforded by the construction of the Large Hadron Collider (LHC) at the European Center for Nuclear Research (CERN).
Plan and initiate a comprehensive program to become the world-leading center for research and development on the science and technology of a linear collider, and do what is necessary to mount a compelling bid to build the proposed International Linear Collider (ILC) on U.S. soil.
Expand the program in particle astrophysics and pursue an internationally coordinated, staged program in neutrino physics.
The LHC will begin exploratory research at the Terascale within the next few years. Physicists expect it to produce evidence for the Higgs particle that is hypothesized to be responsible for generating the mass of all matter. In addition, theoretical arguments point to the possibility of discovering a new symmetry, known as supersymmetry, at the LHC in the form of new particles that are partners to the currently known particles; some of these new supersymmetric particles may turn out to constitute the mysterious “dark matter” that pervades the universe.
When the LHC has outlined the territory of Terascale physics, more precise and sensitive measurements will be needed. For that purpose, a new accelerator facility that collides electrons and positrons will be required. The committee believes that the United States should invest the capital needed to host the proposed ILC as the essential component of U.S. leadership in particle physics in the decades ahead.
The committee recognizes that more than one strategy could be pursued in the next decade, but in its judgment the priorities it has outlined have the highest risk-adjusted return and constitute the strategy most likely to sustain U.S. leadership in particle physics.
The next few decades will represent a culmination of the human effort to understand the elementary constituents of the universe. The United States has an unprecedented opportunity, as a leader of nations, to undertake this profound scientific challenge.