The next, next big machine

The next big machine in the world of science is the Large Hadron Collider, an $8 billion particle accelerator due to start operations late this year on the French-Swiss border. The LHC just might lift the veil on exotic physics such as the "God particle" and the extra dimensions in which we live.

There's yet another next big machine, in a slightly different field: the $13 billion ITER experimental fusion reactor, slated to be built in France by 2015. That could eventually open the door to clean, abundant, relatively safe nuclear power.

So what's the next, next big machine? What future international science project might the United States pursue? As far as the world's leading physicists are concerned, that would be the International Linear Collider - a huge multibillion-dollar installation that would follow up on the leads generated by the LHC. But is it really necessary? And is there really any chance of bringing the project to the United States?

Let's face it: Europe is now becoming the pre-eminent place on the frontiers of physics, with Japan, China, India and other countries competing hard as well. Meanwhile, particle physicists in the United States are preparing to shut down experiments at the SLAC B Factory in 2008, and the Tevatron in 2009.

The prestige gap dates back to 1993, when Congress shut down the partially built Superconducting Super Collider early in its construction phase. Since then, the cost of high-energy physics has risen to the extent that no one country can afford to build state-of-the-art facilities by itself. And it's not clear how much the international science community would trust the United States to follow through on the next, next big machine.

"The United States has to do something to improve its reputation," said Nigel Lockyer, a high-energy physicist at the University of Pennsylvania who helped write a report on the state of the nation's particle-physics research. "It's already not in good shape. We definitely have to fix that."

Lockyer and other leading physicists sized up the Large Hadron Collider and the International Linear Collider last week during a panel discussion at the American Astronomical Society's winter meeting in Seattle.

The dean of string theorists, Edward Witten of the Institute for Advanced Study at Princeton, said physicists would need both colliders to gain deep insights into the mysteries of physics - ranging from extra dimensions and exotic particles to the nature of dark energy and dark matter.

The ILC would actually achieve lower collision energies than the LHC - in the range of 500 billion to 1 trillion electron volts, compared with the LHC's 14 trillion electron volts. But the ILC would deal with electron-positron collisions, which would provide a much clearer picture of the subatomic world than the LHC's proton-proton collisions.

Witten said a collider like the LHC usually provides the "best way to discover new phenomena." However, he added, "it's not necessarily the best way to learn about those new phenomena."

That's why the international community is already talking about what shape the ILC might take, and where it might be built - even if it won't be built until sometime after 2010. Helen Quinn, a theoretical physicist at the Stanford Linear Accelerator Center, said that if the United States decided to enter the competition for the ILC, the likeliest site would be somewhere around the Fermi National Accelerator Laboratory in Illinois, which has housed the nation's biggest accelerators in the past.

Eventually, an international consortium called the Funding Agencies for the Linear Collider will decide where the ILC will go - just as similar consortia worked out the locations for the LHC and ITER in the past. Scientists such as Witten, Quinn and Lockyer are already meeting amongst themselves, as well as with officials at the Energy Department and other agencies, to draw up the best case for America.

To get an overview of the issues involved - in physics as well as politics - you can't do better than "Revealing the Hidden Nature of Space and Time," a report drawn up last year by a committee of the National Research Council and available free online.

You can also refer to these archived MSNBC articles on the current frontiers of physics as well as the search for extra dimensions and the theory of everything. But if you want to delve into a book-length discussion of physics' strange frontiers, here are some recommendations from the three physicists:

• "The Elegant Universe" by Brian Greene (which was adapted for television by PBS).
• "Warped Passages" by Lisa Randall.
• "The Charm of Strange Quarks" by R. Michael Barnett, Henry Muehry and Helen Quinn. (Guess who suggested that one.)

Online, you'll find great resources at "The Particle Adventure" Web site and at Interactions.org. You can also page through Symmetry magazine. And if you're wondering what the next, next, next big machine might be, I have three words for you: Compact Linear Collider.