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What's the Matter? "We," says Caltech's Theoretical Physicist Murray Gell-Mann, at 31 one of the brightest new stars of U.S. science, "think that one of the most exciting things the human race can do is to understand the laws of nature. It is sad that it is so hard for others to follow us in this chase."
Gell-Mann compares the work of physics to cleaning out a cluttered basement. "Once the debris has been swept away," he says, "the basement's outline can be seen." This always happens in physics, but there is one hitch: "Somebody has discovered over in a corner a trap door, leading to a subbasement. First we had to learn about atoms, but when we got atoms cleared up, we found a trap door to the next subbasement, the atomic nucleus, which was then completely unknown. Now that this is being swept out a bit, the next trap door leads us into the new world of the subatomic particles and what makes them tick."
The tools of the high-energy physicists are enormous machines—cyclotrons, synchrotrons, linear accelerators—that smash atoms and subatomic particles to bits and expose them to study. Already, the physicists know of some 30 particles that form atoms or can be knocked out of them by high-energy collisions. The great challenge confronting the physicist is to formulate sets of laws describing the interaction of such particles and, at an even deeper level, to explain the reason for their existence. Therein lies the key to the understanding of the matter—and of all nature.
The world of the physicist can be an eerie one—and that is part of its fascination. In the field of high-energy physics, few are involved in more eerie or more fascinating work than Berkeley's Italian-born Emilio Segrè, who discovered the antiproton, which turns into a flash of energy when it hits an ordinary proton.
Many other anti-particles have since been found, including anti-electrons, anti-neutrons and anti-mesons. Segrè believes that a full set of anti-particles will be found, existing only for tiny fractions of a second in the debris left by high-energy collisions. The anti-particles cannot last long on earth, where ordinary matter, their enemy, is prevalent, but Segrè suggests that they are dominant elsewhere. The concept of symmetry, he says, calls for equal numbers of particles and anti-particles, gathered into equal amounts of matter and anti-matter in the universe. Some of the galaxies seen in far-off space, he says, may in fact be anti-galaxies made up of anti-stars with anti-planets revolving about them. "While you and I sit talking here," he tells an interviewer, "there exists somewhere else an anti-you scribbling with an anti-pencil while an anti-I fiddles with an anti-letter opener. To an anti-you, it would look just like the letter opener here in my hand, but the present you would not live to see it. The anti-matter in an anti-letter opener of this size would create a bigger explosion than the biggest nuclear bomb."