Number 49, September 26, 1991 by Phillip F. Schewe and Ben Stein|
HIGH INDEX OF REFRACTION AND LOW ABSORPTION can be achieved simultaneously in certain materials using quantum interference effects. Marlan O. Scully (505-277-1522) of the University of New Mexico and his colleagues at the Max Planck Institute for Quantum Optics (Munich) first prepare a sample of atoms (e.g., a vapor of sodium atoms) in a "coherent state" with the help of a dye laser, which excites transitions between each of two hyperfine sublevels of the atoms' ground state. This creates a resonant condition which interferes with transitions to a separate, higher-energy state, and hence reduces the absorption of light corresponding to that transition (or, in other words, rendering the sample of atoms transparent at that wavelength). Unlike other induced-transparency experiments, Scully's sample of coherent atoms possesses a high index of refraction. Such low-absorption, index-enhanced optical matter might have applications in laser particle accelerator schemes, in optical microscopy, and in studies of the electroweak force in atoms. (Upcoming article in Physical Review Letters.)
GAMMA RAY BURSTS ARE UNIFORMLY DISTRIBUTED across the sky. Intensely energetic and lasting only seconds, the bursts had previously been thought to originate at neutron stars, which are predominately to be found, along with other stars, in the disk of our galaxy. Gerald Fishman, a NASA scientist analyzing data from the Compton Gamma Ray Observatory (newly renamed for Arthur Compton), said that gamma bursts must now be viewed as some "new type of phenomenon previously unknown and undetectable." (The New York Times, 24 Sept. 1991.)
THE GREAT ANNIHILATOR , the compact gamma source near the galactic center, may be accreting matter not from a stellar companion but from a molecular cloud observed to be in the vicinity by scientists at AT&T Bell Labs. Marvin Leventhal (201-582-3448) was instrumental in monitoring the gamma source for many years at gamma wavelengths with a balloon-mounted telescope. This time he switched to millimeter wavelengths (using a 7-meter antenna at Bell Labs) to study emissions (mostly from CO molecules) from the galactic center, near the gamma source. (Nature, 19 Sept. 1991.)
MICHAEL FARADAY , the discoverer of electromagnetic induction, paramagnetism, and diamagnetism, and the man who first plowed the fields of electromagnetism and electrochemistry, was born 200 years ago on September 22. His anniversary is being celebrated at numerous meetings in Britain, the U.S., and elsewhere. (Chemical and Engineering News, 23 Sept. 1991)
PHYSICS NEWS UPDATE IS ONE YEAR OLD . Judging by the preponderance of entries, the big physics stories of the year concerned Buckyballs, STM images of all sorts, atom traps, and observations by a fleet of satellites---Astro, Hubble, GRO, Rosat, COBE, Granat, Magellan, Galileo, and Ulysses.