No. 105: May-Jun 1996
Just over a year ago, particle physicists at the Fermi National Accelerator Laboratory (Fermilab) announced that they had at last found the top quark, the final particle needed to flesh out the so-called Standard Model of subatomic physics. Then, all seemed serene in the world of quarks and gluons. Quarks, you see, are held to be the smallest building blocks of matter and now they had all been found and cataloged. The collection was complete.
But a storm cloud has now appeared on the event horizon, casting a shadow on the solidity of the quarks themselves. Are they really fundamental; that is, indivisible? Fermilab scientists now wonder, for when they crash protons into antiprotons head-on at very high energies, the resulting debris clouds display an anomaly. Some of the supposedly indestructable quarks seem to have fragmented, too. The collision energies seem high enough penetrate the integument of the quarks if they are divisible. There may be other explanations of the deviation from theory, but right now quarks seem a bit more fragile than they did just a few months ago.
(Wilczek, Frank; "A Crack in the Standard Model?" Nature, 380:19, 1996. Also: Walker, Gabrielle; "The Secret Heart of a Quark," New Scientist, p. 17, February 17, 1996)
Comment. If quarks can be split, perhaps their fragments can, too. Do any fundamental particles really exist? Who knows? We started a couple millennia ago with earth, air, fire, and water. We then found atoms, then protons, then quarks. There may be no floor to the universe; it's quicksand all the way down. There may be no roof either, because astronomers are finding ever larger clumps, skeins, and assemblages of galaxies. Matter could be infinitely ag gregative as well as infinitely divisible.
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