Edition: U.S. / Global

ESSAY; Searching for Dark Matter, With Both Eyes Closed

Published: May 2, 2000

Thirty years ago this month, I flew from Boston to San Francisco with another M.I.T. graduate student, eager to begin physics research on a new, two-mile-long atom smasher at Stanford. Just west of Chicago, we passed above a circular gouge in the earth four miles around -- the footprint of another particle accelerator then under construction.

Working with these cutting-edge tools, physicists in the United States shocked the scientific world with the revolutionary discovery of quarks, the elementary particles at the heart of the atomic nucleus. It was my good fortune to be a foot soldier in this grand upheaval.

Those heady times came to mind recently after I learned about surprising results from an underground experiment in Italy. Although much debated, the results suggest that physicists are closing in on the mysterious dark matter, believed to be a vast halo of subatomic particles swirling surreptitiously throughout our Milky Way galaxy and holding it together gravitationally.

Billions of these particles may in fact be whizzing harmlessly through my body every second. And if certain cherished theories hold true, they are but the lightest members of a large clan of exotic bits of matter that mirror the electrons, protons and other garden-variety particles of everyday existence. They are the shadows of creation, ghostly remnants of the Big Bang birth of the universe.

But particle physicists in the United States are ill prepared to join their European colleagues in following up these stunning results, should they turn out to be true.

The best instrument to pursue this research, a huge particle smasher known as the superconducting super collider, suffered an early death. Had it been built as originally planned, this $10 billion machine, designed to speed protons around a 54-mile track and collide them, would now be producing results.

But because Congress killed it in a deficit-reduction measure in 1993, there are no data, only a long tunnel, filling up with ground water, beneath the plains of North Texas.

Although sensitive subterranean and satellite-borne detectors have taken great strides in the past decade in unraveling the fabric of the heavens, they are no substitutes for the precise, controlled experiments that physicists perform with powerful particle accelerators or colliders. Such sophisticated detectors may glimpse the Big Bang's afterglow and sift through its ashes, but these big particle smashers can mimic its fire.

To recreate the primordial conditions in which the universe was born, researchers must generate and clash two beams of high-energy particles. Physicists in the United States already do this kind of work on colliders at Fermilab in Illinois and at Stanford. But concentrating enough energy to create the ultraheavy ghosts believed to exist will require a mammoth machine, a multibillion-dollar investment. There is no cheap alternative.

Because of the super collider's demise, however, graduate students entering particle physics will soon be unable to work at a machine in this country that can probe the far frontiers of their chosen field. For the next several years, they can do interesting research at Fermilab and Stanford, but these now-aging laboratories will be eclipsed around mid-decade.

Once the Large Hadron Collider, a 16-mile proton smasher to be built near Geneva, starts churning out results after 2005, particle physicists from the United States will have to cross the Atlantic if they wish to continue doing forefront research. By pooling their resources across national borders and patiently building advanced instruments at this site for half a century, European physicists have established a laboratory that is about to assume unchallenged leadership in a prestigious field their counterparts in the United States had pioneered.

Another type of particle collider able to create such extreme conditions is on drawing boards in Europe, Japan and the United States. Accelerator builders have been designing miles-long, arrow-straight machines to collide trillion-volt beams of electrons with their antimatter opposites, known as positrons. Violent electron-positron collisions can provide physicists a complementary and clearer picture of what occurred in the primordial fire. This gargantuan ''linear collider'' is the natural next step for particle physics.

But although American physicists pioneered this alternative, they are now struggling to assure financing for the conceptual design of this machine, which would stretch some 20 miles and cost more than $5 billion. Last year, with memories of the super collider debacle still fresh, Congress almost slashed federal support for the linear collider design effort. Its future remains precarious.

Given its hefty cost and the fact that scientists of many nations will have access to it, this huge machine must be built as a truly international project. That is one obvious lesson of the super collider, which was widely viewed as a United States national project that later came begging for foreign contributions.

And since our government will probably have to pay a substantial part of the new machine's cost, it should be in, or at least near, the United States. By far the deepest pool of expertise in building and operating linear colliders exists right here in America.

If this nation hopes to remain an active player in particle physics, it must support such a quark-busting machine, sharing the burdens of this enormously expensive research. Sending all our top practitioners overseas will never suffice if Americans are to be equal partners.

Moreover, a healthy particle physics program in the United States needs a major new collider that can serve as the common focus for theorists, experimenters and accelerator builders while promoting scientific exchanges with other countries. Insights gained on one continent can then be confirmed (or, perhaps, rejected) and extended on the other. Science thrives when there are multiple competing points of view.

But after the super collider's inglorious demise, other nations regard the United States as a capricious scientific partner. Congress finances major construction projects on a year-to-year basis and jealously guards its option to terminate them. Building a truly international scientific center on American soil will be a truly challenging enterprise.

Thus, particle physicists in the United States face a difficult future. There is a wealth of exciting research begging to be done on the dark matter particles -- and their kin -- thought to contribute most of the mass of the universe. And to observe the intense primordial fire that forged them requires that we build a new multibillion-dollar machine.

But the United States possesses a dismal record of international cooperation on scientific megaprojects. Unless its record improves drastically, this physics will soon be done elsewhere. The next generation of American particle physicists will not enjoy the research opportunities I was so lucky to have had.

Photo: The future of particle physics? Big discoveries will most likely come from research centers like the European Laboratory for Particle Physics in Switzerland, which runs the Large Electron-Positron accelerator above. (CERN)