Abstract  

Wonderful opportunities await particle physics over the next decade, with new instruments and experiments poised to explore the frontiers of high energy, infinitesimal distances, and exquisite rarity. I will review the insights of the decade just past and show how they lead us to the brink of a new period of rapid and profound discovery. We expect answers to questions that speak to our understanding of the everyday world: why are there atoms? why chemistry? why stable structures? and even what makes life possible? We are probing the meaning of identity for the fundamental particles: what makes an electron an electron, a neutrino a neutrino, and a top quark a top quark? Important clues, including the remarkable neutrality of atoms, lead us to investigate the unity of the two main classes of matter, the quarks and leptons. Gravity and particle physics, long separate disciplines, are enjoying a stimulating reunion, and we are learning how to investigate?with experiments--new conceptions of spacetime.
    We look forward to the Large Hadron Collider at CERN to explore the a new and critical energy scale of one trillion electron volts. If we are inventive enough, we may be able to follow the LHC's rich menu with the physics opportunities offered by a linear electron- positron collider, a (muon storage ring) neutrino factory, and experiments that use natural sources. I expect a remarkable flowering of experimental particle physics, and of theoretical physics that engages with experiment.

Introduction to speaker:               Chriss Quigg

As a child, Chris Quigg wanted to make the laws of nature. He thought                           that was the difference between physics and engineering: physicists make                                   the law and engineers apply the law.

Quigg grew up in Bethlehem, a steel town in eastern Pennsylvania. “In that town and at that time,” he recalls, “being an engineer was really a big deal, and so a lot of my friends aspired to that.” But Quigg perceived the difference between physics and engineering, though in a rather misguided way. “In a child’s caricature, if I could be making the laws instead of applying the laws, that sounded much better to me.”

Now 59 years old and a particle theorist at Fermi National Accelerator Laboratory, Quigg knows that physicists don’t exactly make the laws of nature, but he is still passionate about discovering them. Of his early childish misperception of physics, Quigg says, “You have to be misguided in a certain way to be encouraged.”

Like many scientists, Quigg always liked exploring and trying to figure things out. During his childhood, his grandfather worked on a crane with an electromagnet, picking up pieces of iron ore and steel. As he remembers it, (though he cautions that “invention is of course much more acute than memory,”) “I thought the entire universe would stop if he wasn’t operating his crane. Because it had an electromagnet, somehow early on I got interested in things like playing with coils of wire wrapped around big railroad spikes and connected to dry cell batteries, and learning for myself about resistance because the wire got hot when I connected it. I think these things are now forbidden by safety regulations.”

These rather dangerous experiments encouraged his interest in physics, and even though he is now a theorist and doesn’t get to spend much time tinkering with such gadgets anymore, Quigg still takes much of his stimulation from experiment. In fact, from 1987 to 1989, he helped lead the team that designed the Superconducting Super Collider, an enormous accelerator scientists planned to build in Texas until Congress cancelled the funding. “I’m still bleeding,” says Quigg.

Quigg is especially proud of his work on the 1-TeV energy scale. He and colleagues derived a formula for a bound on the mass of the Higgs boson, the yet-to-be found particle that physicists believe gives elementary particles their mass. The work suggested that 1TeV is “an energy scale that’s magic,” he says, “for understanding why the world is the way it is, why there are atoms and chemistry and complicated structures and life itself, why the forces of nature turn out to be the way they are.” Accelerators are just beginning to search those energies.

More recently, Quigg has been studying the mysterious, newly-discovered particle known as X(3872). Though scientists observed the particle at the KEK accelerator in Japan and confirmed it at Fermilab last year, they haven’t reached a consensus on what this particle actually is.

Based on its mass, 3872 million electron volts, about the mass of the helium atom, some scientists think that the new particle might be a new type of molecule made up of two mesons, particles consisting of a quark and an anti-quark. Others, including Quigg, interpret the X(3872) as a previously undiscovered state of charmonium, a meson consisting of a charm quark and an anti-charm quark.

Quigg has found his research on the X(3872) especially stimulating because of the unusually rapid exchange between experiment and theory. “For a lot of the things I do in particle physics, the payoff between brilliant theoretical idea and experimental test seems to take 30 years, and here in the space of a few months you get to be told you’re wrong.”