Particle Researchers Lag for Want of a Good Collision
It’s a question probably asked by the first hairy proto-humans: What is the world really made of?
By the end of the 20th century, physicists had managed to unravel atoms to their cores, unleashing the fire that fuels the stars and making possible modern technologies from PET scans to silicon chips. Using particle accelerators as high-powered “microscopes,” they roamed around inner space, discovering entire families of tiny particles: electrons, neutrinos and quarks both “strange” and “charmed.”
It was a stupendous achievement. Not surprisingly, particle physicists became the superstars of science, and for the last half century, the U.S. led the way.
And then, in 1993, Congress stopped construction of the crown jewel of U.S. particle physics--the superconducting super collider--and the action moved to Europe.
Meantime, astronomers and cosmologists started grabbing all the attention with their heart-stopping headlines about black holes and drop-dead photos of glowing stellar nurseries. Some loudly pronounced a “golden age” of cosmology in which everything in the universe was present and accounted for, even its fate determined.
My dog’s bigger than yours, the cosmologists seemed to say--and a lot more photogenic too. In a sense, they were right.
But now, in a version of the old Charles Atlas ads, the little guys are beefing up to fight back. On July 1, thousands of them ascended to the peaks of the Rocky Mountains here to stage a three-week extravaganza that includes everything from technical talks to balloon launches and science fairs.
The organizer of the meeting, Chris Quigg of Fermilab, one of the nation’s leading physics research centers, counted on 500 participants, hoped for 700 and, at last count, had nearly 1,100, including all the directors of the major international laboratories. Their charge is to figure out the next big step for the little-particle guys. “Our community was in a depression,” Quigg said. “Our excitement had been killed.”
There’s more at stake than just academic morale. Labs will thrive or die on the outcome. The discussions will help set the agenda for fundamental physics for years.
Unlike astronomers, who gaze at whatever the universe serves up, particle physicists must create their own worlds inside massive accelerators. Subatomic particles revved up to near light speed can be used as precision probes to “see” the structure of atoms. Or two beams of particles can be made to collide, creating a burst of energy that comes close to recreating (on a small scale) the birth of the universe itself. As the energy of the collision congeals into particles (according to E=mc 2), the fundamental ingredients of the universe are revealed.
Increasingly, those fundamental building blocks look a lot less like particles and more like the vibrations produced by a well-struck bell. Physicists would like to know, among other things, why these particular “bells” ring out in our universe and not others. It’s even possible that the “bells” are vibrating strings that extend into unseen dimensions.
Particle physicists believe some answers are around the corner. “There’s no question that we’re very close,” said Jonathan Dorfan, director of the Stanford Linear Accelerator Center.
It will take bigger accelerators to find out, but exactly what kind of machine remains controversial. Electron colliders produce clean results because electrons are point-like particles. Proton colliders can go to much higher energies, but protons are in turn composed of quarks, which makes collisions messy and results hard to read.
All week, physicists have been arguing their cases in technical “show and tell” sessions. Honchos hunched in closed-door meetings debated and prepared reports.
By week’s end, some things were clear: The particle people need the astronomers, cosmologists and string theorists on their side. So they are here in force, explaining everything from extra-dimensional cosmology to the details of gravity probes and dark matter searches.
The big-picture scientists are happy to oblige. “I’m here so that I can [persuade] particle physicists that there’s a lot of particle physics to be done by looking at the [cosmic] microwave background,” said Princeton’s Suzanne Staggs, who works on deciphering the microwave afterglow of the Big Bang.
It’s equally clear that the next big machine, whatever it is, will have to be an international effort, although Dorfan notes that the United States will have to take the lead. Many believe that what killed the collider was too little international involvement too late.
Albrecht Wagner, head of DESY, a major physics center in Germany, is promoting a global accelerator that would work the way major telescopes do--allowing researchers from anywhere to experiment remotely from home.
Whatever the details, it looks as if the little guys are gearing up for a big-time comeback.
Fundamentally speaking, it’s a small world after all.
