Number 34, May 15, 1991 by Phillip F. Schewe and Ben Stein THE GREAT ANNIHILATOR , the powerful source of gamma rays (from electron-positron annihilation) near, but not at, the galactic center, has dimmed by two thirds from its peak brightness recorded last October, according to scientists working with the French-Soviet satellite GRANAT. Independent observations at radio, microwave, and x-ray wavelengths are zeroing in on the location of the source. (Science News, 11 May.) SONOLUMINESCENCE is the conversion of sound energy into light energy. At a recent meeting of the Acoustical Society of America in Baltimore, Seth Putterman of UCLA described the most detailed study yet of this interesting effect. He observed 100 psec pulses of light emanating from small nitrogen bubbles trapped in a mixture of water and glycerine. The bubbles first absorb sound energy (from an applied 20-kHz field) and expand to a size of 100 microns; then they collapse to a size of a few microns, releasing light. Then the process begins again. Putterman considers the concentration of energy (the optical pulse being much briefer than the sound-wave cycle) to be a "spectacular phenomenon." (Science News, 11 May.) THE SPACE INFRARED TELESCOPE FACILITY was given the highest priority by the National Academy of Science's astrophysics. There are several reasons for this. First, technological innovations in the 1980's---much better solid-state IR detection chips and longer-duration liquid-helium coolant systems---have greatly enhanced the sensitivity and sharpness of IR images. Furthermore, there are several physics reasons for the increased interest in the infrared: (1) many stars, all planets, and interstellar clouds shine primarily in the IR; (2) the birth of stars inside molecular clouds and the view of our galactic center are obscured at optical wavelengths but not in the IR; (3) characteristic IR spectra allow the study of a wide range of atoms and molecules; (4) the radiation from many important physical processes in the early universe have been redshifted by the Hubble expansion into the IR. (Physics Today, April 1991.) BLACKS, HISPANICS, AND AMERICAN INDIANS constitute 22% of the U.S. population but only (in 1988) 4.4% of the 4.5 million people identified as natural scientists or engineers, an imbalance which a number of scientific societies and government agencies are trying to correct. The NSF is instituting a number of programs (scholarships, teacher training, science day camps) aimed at increasing the number of minority PhD's in science and engineering from the current 350 per year to 2000 by the end of the decade. (Chemical & Engineering News, 15 April 1991.) THE PHYSICS FACULTY IS AGING . The 1990 Faculty Workshop Survey, the latest in a biennial series of reports on physics faculties, shows that the median age for physics professors in 1987 (the most recent year for which data are available) is 50.0 In 1973 the median was 40.7. For the 1987 pool, the median age of assistant professors was 35.9, for associate professors 44.5, and for full professors 53.1. Only 12% of the professors were under the age of 40. (June 1991 Bulletin of the American Physical Society.)