A lepton event—a neutrino interacting with an electron and emerging as a neutrino. The first observation of “neutral currents” in the Gargamelle heavy liquid bubble chamber at CERN. Courtesy of CERN Geneva
Physics in the United States is at a crossroads. There are scientific discoveries just within reach whose impact is likely to transform and even transcend the field. Yet US particle physics facilities are being closed or converted to other uses, federal investments are stagnating, and the intellectual center of gravity is moving overseas with the construction of new facilities in Europe and Japan.
These were the conclusions of the committee for the National Academy of Sciences, which I had the honor of chairing. Our mandate was to examine the current state, and make recommendations regarding the future shape, of a US particle physics program that has yielded innumerable discoveries and played a defining role in American scientific leadership.
As we toured the world’s top labs, we quickly realized that particle physics is enjoying a moment of exceptional excitement. New technologies have enabled the exploration, under controlled laboratory conditions, of the Terascale, and of dark matter and dark energy. Distinct scientific areas have experienced a type of convergence of interests that have presaged exciting scientific developments. From cosmology, there is growing interest in dark matter and dark energy; from particle physics, there is great interest in supersymmetry, the origins of mass, and Einstein’s dream that all the physical forces can be unified. And the Large Hadron Collider (LHC) at CERN in Geneva begins operations in late 2007, with more than half of the US community of particle physicists and their students actively participating in this next generation of particle physics research.
When we looked at the state of the US domestic particle physics program, however, we were sobered. The major experimental facilities that have defined the US program are coming to the end of their scientifically useful lives with no compelling follow-on strategy in place. It almost seems as if we have adopted an exit strategy, intentionally allowing the intellectual center of gravity to move abroad. We seem to have lost the realization that a strong role for particle physics, as well as other physical sciences and mathematics, is necessary if the United States is to sustain its leadership in science and technology over the long term.
So, what to do?
US scientists need to continue to pursue the most exciting science on the frontier of this field at the LHC and CERN. But we should also be looking at the other tools needed to explore this frontier, including the next generation of particle accelerators: the International Linear Collider (ILC). The ILC, currently being designed by a team of scientists from around the world, would consist of two accelerators firing electrons and anti-electrons at each other head-on, probing in great detail conditions that existed just a fraction of a second after the universe’s birth. The facility will be of such a scale and complexity that—similar to the LHC—a global, cooperative effort is the only way to make it possible.
The US must prepare to mount a compelling bid to host the ILC: It needs to establish a strong and credible position from which a final decision could be evaluated, contingent upon (among other factors) whether the ILC costs are “reasonable,” the international partnership is in place, and the scientific case remains compelling.
Future large projects in particle physics will require a new level of global partnership in their conception, not just execution. Although the LHC was conceived and developed largely by CERN with international participation, the ILC should remain a global project, conceived by the worldwide community. In that sense, the ILC is an opportunity to demonstrate global cooperation, no matter where the project is eventually located.
A US bid to host the ILC should inspire students, attract talented scientists from throughout the world, create a suite of high-technology jobs, and strengthen our national leadership in science and technology.
The ILC would be a flagship scientific facility. It will focus on some of the most profound and awe-inspiring questions in science. It will fire the creativity and imagination of many of the world’s brightest young minds. I expect that hosting the ILC would increase American students’ interest in pursuing science and engineering and thus enhance the nation’s scientific and technological workforces, just as many of today’s engineers and scientists were attracted to these fields by the nation’s commitment to the space program in the 1960s and 1970s.
A US-based ILC would also attract thousands of talented scientists and students from around the world. As has happened in the past, when highly talented and motivated scientists from around the world come to the US to work, many will choose to remain and continue contributing to the nation’s technological leadership, which in turn will stimulate domestic economic growth through scientific and technological innovation. Moreover, some of the world’s best scientists undoubtedly will join the nation’s universities to be close to the project, thus enriching the scientific vitality of these institutions. US academic research institutions are recognized for their direct and easy access to the world’s premier research facilities and infrastructure; hosting the ILC would extend this pattern of success into the 21st century. In short, constructing and operating a world-class facility will create an unparalleled intellectual environment to stimulate innovation and creativity.
The LHC at CERN may end up not revealing nature’s secrets as easily as some hope. International cooperation and agreement might not coalesce over the ILC. Fiscal realities here in the US might make the substantial investment in a linear collider untenable. But, for the sake of continuing to develop America’s scientific leadership, the US needs to become the leading center for R&D relating to the ILC and prepare to mount a compelling bid to host the facility.
We need this vision to bring US physics global distinction, focus, and above all, continued success. The riskiest path is to simply maintain our present course.
—Dr. Harold Tafler Shapiro, Ph.D, is president emeritus of Princeton University and is professor in the departments of economics and public policy at the University.
Originally published November 20, 2006