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THE CASE FOR METALLIC HYDROGEN remains problematic. A group at Harvard (Isaac Silvera, 617-495-9075) studied the optical absorption and reflectance properties of a sample of molecular hydrogen at pressures up to 230 GPa (2.3 Mbar) and over a temperature range of 77-295 K and found no evidence for metallization. In the past two years, scientists have seen hints for phase changes in hydrogen (such as a darkening color) at high pressures but so far no one has observed an unambiguous insulator-to-metal transition. (Upcoming article in Physical Review Letters.)
DIAMOND IS THE "MOLECULE OF THE YEAR," according to the editors of Science magazine. The advent of techniques (e.g., using chemical vapor deposition, CVD) for growing diamond thin films, along with other developments in synthetic diamond technology, have made possible new and future uses for diamonds in transistors, abrasion-resistant tools, scratch-proof lenses, unlubricated bearings, and particle detectors. Carbon-60, or buckminsterfullerene, was one of the runners-up in the Science ranking of molecules. (Science, December 21, 1990.)
THE COLD DARK MATTER version of the big bang theory, one of the most widely accepted models of cosmology, has been hard pressed by a new analysis by Oxford astronomers of 6-year-old data from the Infrared Astronomical Satellite which shows that large extended collections of galaxies and galaxy-voids are even more prevalent than thought before. Cold dark matter, consisting of slow-moving non-radiating particles of unknown identity, is thought by some to account for 90% of the matter in the universe; but a cosmology based on this hypothesis does not seem to have had enough time to allow evolution of the stupendous objects seen in the sky. (Nature, January 3, 1991.)
THE PREDICTIONS OF QUANTUM MECHANICS may sometimes seem bizarre or counter-intuitive, but in experimental tests they take precedence over such seemingly commonsense notions that physical systems may possess properties ("hidden variables") that remain beyond human observation. Two formulations of the "no-hidden-variables" idea---Bell's theorem and the Kochen-Specker theorem---have now been unified into a simpler format by Cornell physicist David Mermin (607-255-9689). (Upcoming article in Physical Review Letters.)
PHYSICS NEWS IN 1990 , the annual review of physics research highlights, consisting of articles prepared by scientists in AIP's Member Societies, is now available. Copies can be obtained from the AIP Public Information Division, 212-661-9404, x520.
SSC DETECTORS MAY COST HALF A BILLION DOLLARS. Like the Superconducting Super Collider itself, the detector facilities where collisions occur will be quite expensive and employ armies of physicists and technicians. Three proposals for two available slots have been examined but not yet judged. The prospective leaders of these collaborations are Sam Ting of MIT, George Trilling of Berkeley, and Michael Marx of Stony Brook. (Science, December 21, 1990.)
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