Particle Physics!
Chris Quigg

Wonderful opportunities await particle physics, with new instruments and experiments poised to explore the frontiers of high energy, infinitesimal distances, and exquisite rarity. We look forward to the Large Hadron Collider at CERN to explore the 1-TeV scale (extending efforts at LEP and the Tevatron to unravel the nature of electroweak symmetry breaking) and many initiatives to develop our understanding of the problem of identity: what makes an electron an electron and a top quark a top quark. Here I have in mind the work of the B factories and the hadron colliders on CP violation and the weak interactions of the b quark; the wonderfully sensitive experiments around the world on CP violation and rare decays of kaons; the prospect of definitive accelerator experiments on neutrino oscillations and the nature of the neutrinos; and a host of new experiments on the sensitivity frontier. We might even learn to read experiment for clues about the dimensionality of spacetime.

If we are inventive enough, we may be able to follow this rich menu with the physics opportunities offered by a linear electron-positron collider and by new-technology neutrino beams based on muon storage rings. I expect a remarkable flowering of experimental particle physics, and of theoretical physics that engages with experiment.

Experiments that use natural sources also hold great promise. We suspect that the detection of proton decay is only a few orders of magnitude away in sensitivity. Dark matter searches and astronomical observations should help to tell us what kinds of matter and energy make up the universe. The areas already under development include gravity wave detectors, neutrino telescopes, cosmic microwave background measurements, cosmic-ray observatories, gamma-ray astronomy, and large-scale optical surveys. Indeed, the whole complex of experiments and observations and interpretations that we call astro/cosmo/particle physics should enjoy a golden age.

Our theories of the fundamental particles and the interactions among them are in a very provocative state. The standard model summarizes a simple and coherent understanding of an unprecedented range of natural phenomena, but our new understanding raises captivating new questions. In search of answers, we have made far-reaching speculations about the universe that may lead to revolutionary changes in our perception of the physical world, and our place in it. Truly, we are entering a remarkable age of exploration and new physics!

From my chapter, "Particles and the Standard Model," in The New Physics, edited by Gordon Fraser (Cambridge, 2006)