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Oh Goody!!! Washington Post 'reports' below. Didn't bother to ask the scientists how much all this cost. Or, if the new info
will allow us to deal |
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New Insight into Reason Matter Exists By Kathy Sawyer
Physicists announced yesterday that they have taken a major, long-awaited step in their struggle to answer one of the weightiest questions in science: Why is there a universe rich with matter instead of an empty void? An international collaboration based at the Stanford Linear Accelerator Center (SLAC) in California reported that it has used its 1,200-ton particle detector, known as "BaBar," to record the strongest, most precise evidence to date of a mechanism by which nature favors the existence of matter. The announcement sent ripples of excitement through the international physics community, which has invested several decades of intense effort to the ongoing quest, as well as hundreds of millions of dollars in the construction of high-precision particle accelerators and detectors for the task. Most scientists today are convinced that the universe blossomed into being in the Big Bang roughly 13 billion years ago. But in the first fraction of a nanosecond, according to this theory, that immense eruption of energy congealed into particles of matter and antimatter in equal portions. Antimatter is most frequently described in science fiction, powering warp drives, but it is as real as the matter we are made of. An antiparticle is almost identical to its matter counterpart -- except that its properties, such as its electrical charge, are reversed. In fact, scientists say, the relationship between a particle and its antiparticle is comparable to that of a hole and the pile of dirt that results from digging it -- opposites, created simultaneously. Whenever matter and antimatter are created from pure energy (according to Einstein's most famous equation, e=mc2), they appear in particle/anti-particle pairs. Antimatter is commonly produced in cosmic rays and, these days, by physicists with advanced machines. When antimatter encounters matter, the result is mutual annihilation: Everything "disappears" in a flash of radiation. When this happened early in the Big Bang, an immaterial universe should have resulted. But clearly, since the stars and planets, "Star Trek" and physicists all exist -- and scientists can detect no stars or galaxies made of antimatter -- there must be some natural imbalance that left a victorious residue of matter on that primordial battlefield. In 1964, James Cronin and Val Fitch of the Brookhaven National Laboratory in New York detected the first hint of this "asymmetry" in particles known as K mesons, in work for which they shared a Nobel prize. But until now, researchers said, it was arguable that this work, and subsequent findings involving the K mesons, represented a peculiar case. Scientists next turned to a heftier, more promising candidate particle -- the B meson -- 10 times as massive as the K meson and able to break down into more observable combinations. (Mesons are fleeting combinations of two fundamental particles called quarks.) The Department of Energy funded the SLAC "B factory," the collider nicknamed BaBar that produces tens of millions of the particles a year. Other B research is underway at the National Laboratory for High-Energy Physics (KEK) in Japan, at the Fermilab near Chicago, and at two labs in Europe. Previous findings by these groups had produced intriguing suggestions of an asymmetry at work in the B particles. But until the new BaBar results, no subatomic particles other than the K mesons had clearly exhibited this phenomenon. The BaBar detector records subtle distinctions in the way B mesons and anti-B mesons decay. (Both are more than five times the mass of protons and survive just over a trillionth of a second.) The scientists are studying a process they call "CP violation" (shorthand for "charge-parity violation") which, as Russian physicist Andrei Sakharov proposed in 1967, could account for the abundance of matter in the universe. In simplest terms, the concept involves the idea that the physical interaction should be the same if all particles are replaced with antiparticles ("charge conjugation," or C) and it ought to be the same whether viewed directly or in a (3-dimensional) mirror ("parity," or P). To describe the degree of "violation" of these two symmetries, the researchers used a technical number that can range from zero (no difference between the rate of decay in B versus anti-B particles) to plus or minus 1, a maximum difference between matter and antimatter Bs. Anything from about 0.5 to 0.9 fits well with the predictions of the theory of how matter and energy operate at the smallest scales, known as the Standard Model. The number announced yesterday is 0.59, with a margin for error of plus or minus 0.14. This means there are now fewer than three chances in 100,000 that there is no violation of symmetry -- no difference between matter and antimatter. "After 37 years of searching for further examples of CP violation, physicists now know that there are at least two kinds of subatomic particles that exhibit this puzzling phenomenon, thought to be responsible for the great preponderance of matter in the universe," said Princeton University physicist Stewart Smith, spokesman for the BaBar collaboration, which includes more than 600 scientists and engineers from 73 institutions in nine countries. "We are poised for further discoveries that should open up new directions for particle physics." Robert Eisenstein of the National Science Foundation said, "I think this is a big event, no doubt about it. It confirms the mechanism of CP violation. . . . It's why the B-factory was built." The BaBar finding does not explain the vast dominance of matter over antimatter that the cosmos exhibits, scientists said. But it seems to confirm that the mechanism detected earlier in the K system was not a fluke but is properly understood in the context of the Standard Model, and it points the way toward further advances. "This is extremely exciting and significant," said Howard Gordon, of Brookhaven. "What is needed are more data" using a variety of approaches, he said. Edward Blucher of Fermilab and the University of Chicago, who studies CP violation in K mesons, said the BaBar result "shows, in a single experiment, statistical evidence that's stronger than all the previous ones combined. . . . This is the first one people would look at and say CP violation is established" and marks only the beginning of at least a decade of deeper probing into the mysteries of asymmetry. Aida El-Khadra, a theorist in high-energy particle physics at the University of Illinois at Urbana, said the fact the BaBar facility already has such precise results is "really exciting." © 2001 The Washington Post Company |
