Are the glory days of American physics over?
On a Sunday morning early in January, about two dozen prominent physicists gathered behind closed doors at the California Institute of Technology to ponder the state of their craft.
American physicists were not exactly sitting on the sidelines last July when CERN announced the probable discovery of the long-sought Higgs boson, the key to understanding the origin of mass and life in the universe.
The United States contributed $531 million to building and equipping the Large Hadron Collider, the multibillion-dollar European machine with which the discovery was made. About 1,200 Americans work at CERN, including Joe Incandela from the University of California, Santa Barbara, who led one of the two teams making the July announcement.
But as science goes forward, American particle physicists are wondering what role, if any, they will play in the future in high-energy physics — the search for the fundamental particles and forces of nature — a field they once dominated.
"There is enormous angst in the field," said Michael S. Turner, a physicist and cosmologist at the University of Chicago, who attended the Caltech meeting.
After canceling the Superconducting Super Collider, which would have been the world's most powerful physics machine, in 1993, and shutting down Fermilab's Tevatron in 2011, the United States no longer has a machine of its own to explore the frontier where new particles and forces in the universe might be discovered. The only collider now operating in the United States is the Relativistic Heavy Ion Collider on Long Island, which shoots gold ions at each other to study the interactions of quarks. It, too, is threatened to be shut down.
Fermilab's biggest project going forward is a plan to shoot a beam of neutrinos, ghostlike particles, 800 miles through the earth to a detector at the old Homestake gold mine in Lead, S.D., to investigate their shape-shifting properties.
The results could bear on one of the deep-seated and intractable problems in cosmology, namely why the universe is made of matter and not antimatter, but there is not enough money in the project's budget to put the detector below ground, at the bottom of the mine, where it would be sheltered from cosmic rays and able to observe neutrinos from distant supernova explosions, instead of on the surface.
Americans who want to taste the thrills of the frontiers of high-energy physics have to cast their eyes east to CERN's collider, which is set to dominate the field for the next 20 years. Or they might look west, to Japan, which is budgeting about $120 billion in stimulus money to help recover from the disaster at the Fukushima nuclear power plant after the earthquake and tsunami in 2011 and wants to use some of it to host the next big machine, the International Linear Collider, which would be 20 miles long and could manufacture Higgs bosons for precision study.
In February, in a ceremony at a physics conference in Vancouver, British Columbia, the team that had been designing the collider for the last decade handed over the plans to a new consortium, the Linear Collider Collaboration, directed by Lyn Evans, who built the Large Hadron Collider at CERN. Dr. Evans said the next big highlight of his career would be seeing construction start in the next couple of years in Japan.
How desperately does the United States want to participate in these projects, from which the next great advances in our understanding of the universe could come?
"Our issue is that Europe and Asia are contemplating or have made $10 billion investments in particle physics," explained Jim Siegrist, associate director for high-energy physics at the Department of Energy, who says that kind of money is not going to be forthcoming in the United States. "How we compete is a problem for us."
Physicists are hoping to have some answers by this summer when they convene in Minneapolis for Snowmass, a planning conference named after the Colorado resort where it used to be held until the place got too expensive. In the meantime there are only questions, like what is the country's future relationship with CERN?
The United States is presently an observer at CERN, but that arrangement expires in 2017. Joining as a full member would cost somewhere around $250 million a year and is out of the question. "Neither the agencies nor Congress is interested," Dr. Siegrist said. Nor, he thought, was CERN itself interested in having the United States Government Accountability Office and others "crawling down their shorts."
For only about $25 million, however, the United States could become an associate member, an outcome favored by CERN's director general, Rolf-Dieter Heuer.
This article has been revised to reflect the following correction:
Correction: March 6, 2013
An earlier version of this article referred incorrectly to the number of particle colliders in the United States. Brookhaven National Laboratory on Long Island runs the Relativistic Heavy Ion Collider, or RHIC. It is not the case that the United States does not own a particle collider.
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