In 1947, the pion was actually observed. Much had happened in the interim, not the least of which was the discovery of the muon in 1937, and of the "strange" particles in 1944, so named for their inexplicably long lifetimes. In the '50s, many more new particles were discovered. Suddenly, "the elementary particles" did not seem quite so elementary.

One gets the impression of a jumble of particles and physicists. In fact, things were somewhat more orderly than they might seem. Glashow explains the scheme in a diagram accompanying an article he wrote last July. He first divides elementary particles into "carriers of force" and "carriers of mass." Carriers of force are the mediating particles described above (although the pion is not a member of this class). Carriers of mass comprise everything else.

The carriers of mass can be further divided into leptons, which do not feel the "strong" force, and hadrons, which do. There are four leptons: the electron, the muon, the electron neutrino and the muon neutrino. There are hundreds of hadrons. The neutron and proton are both hadrons and so are subject to the paull of the "strong" force.

Leptons and carriers of force are orderly families. Hadrons are particles of definite mass.

In an attempt to bring some order to the unruly world of hadrons, Murray Gell-Mann, a physicist at the California Institute of Technology, proposed the quark theory. All hadrons, said Gell-Mann in 1963, can be composed of two or three quarks or their anti-particles. Quarks come in three "flavors"--up, down and sideways. Down quarks ('d') have an electric charge of -1/3, up quarks ('u') have charge + 2/3. And then there are sideways quarks ('s'). Sideways quarks are used to make "strange" particles, the ones with the long lifetimes, and are said to have "strangeness" 1. All other quarks have strangeness zero. The anti-particle of each quark (designated here by an *) has properties exactly opposite the appropriate quark. Thus the 's*' quark has charge +1/3 and strangeness+1.

Gell-Mann's theory, modified so that each quark also comes in three different "colors" (no kidding), proved tremendouly successful. One could then describe every hadron by some quark combination, and every quark combination by an observed hadron. (A proton, for instance, is the combination 'uud.' The neutral K-meson, which has strangeness *1, is the combination 's*d.')

Finally the story moves to Glashow's contribution, which came in 1964. Motivated by considerations of grace and elegance in theories which combined the electromagnetic force and a force called the "weak force" (to distinguish it from the "strong force"), Glashow and another physicist, James D. Bjorken, postulated an additional flavor of quark, and named it the "charmed" quark. Glashow writes in a New York Times article:

"The case for charm--or the fourth quark--became much firmer when it was realized that there was a serious flaw in the familiar three-quark [flavor] theory, which predicted that "strange" particles would sometimes decay in ways that they did not. In an almost magical way, the existence of the charmed quark prohibits these unwanted and unseen decays, and brings the theory into agreement with experiment. Thus did my recent [1970] collaborators, John Iliopoulos, Luciano Maiani and I justify another definition of charm as a magical device to avert evil."

More support for Glashow's work came in 1974 with the discovery of the J or psi particle at Brookhaven National Laboratory and the Stanford Linear Accelerator Center. The particle was eventually interpreted as a combination of a charmed quark (c) and a charmed anti-quark (c*). But final confirmation came in May 1976, when the Stanford team, led by Gerson Goldhaber, found incontrovertible evidence that charmed particles exist.

"I saw Gerson at a conference in April," Glashow said, "and told him he'd better get on the stick. I said, 'Look, Gerson, this is getting embarassing for you. You'd better find some charmed particles.' Three weeks later he called me up and told me he'd found them."

Glashow is currently examining the ways in which quarks combine to form elementary particles, a subject he calls "chromodynamics," an allusion to the "color" attributed to quarks. Actually, neither "color", "flavor," "charm," nor "strangeness" has any correlation to the common-sense meaning of the words. They are just ways of labeling the various attributes of quarks and could just as easily be called "beauty," "faith" or "hope."

***

Glashow attended the Bronx High School of Science, a public school for the scientifically gifted. He once claimed that the school made the single most important contribution to his education. He no longer holds this view, although he still calls his high school experiences "particularly significant."

Glashow's closest friends in high school were Steven Weinberg, who is now Higgins Professor of Physics, and Gary Feinberg, now a professor of physics at Cornell. "We learned a great deal by talking and competing with one another. We'd ride the subway to school together. On the way, one of us would say something like 'Quantum mechanics isn't so hard--I learned it last night,' and then explain whatever he'd read," Glashow said. Not to be outdone, someone else would read about another topic that evening and explain it the following morning. "In this way, we certainly learned the language of physics, although nothing in detail," Glashow said.

Glashow's memories of school are somewhat less sublime. "For 'physics' we had a choice between automotive and electrical engineering...My teacher was 'Mad-Dog' Tyson, who had a mania for keeping students quiet in the halls. He was also preoccupied with neat notebooks."