PHYSICS NEWS UPDATE A digest of physics news items by Phillip F. Schewe, American Institut

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PHYSICS NEWS UPDATE A digest of physics news items by Phillip F. Schewe, American Institute of Physics Number 174 April 15, 1994 LASER ACTION IN A DISORDERED MATERIAL has been observed by Nabil Lawandy at Brown University (N.M. Lawandy et al., Nature, 31 March 1991). He sent green laser light (at a wavelength of 532 nm) into a cell filled with a dye solution, producing orange light (617 nm). Lawandy discovered that when he added titanium-dioxide nanocrystals (commonly used in white paint) to the dye, the laser light emission from the cell was greatly amplified, even though the cell was not a proper resonator (having no mirrors), and even though the presence of scattering particles (in this case about 250 nm in size) usually only degrades the laser output. Admittedly, the amplified light no longer travels onward as a collimated beam, but its brightness and narrow energy range may still be handy in a number of applications. Lawandy hopes, for example, that a variety of creams, each containing specialized suspensions tailored to produce light at specific wavelengths, could be used by dermatologists for treating skin problems. Laser-excited paint pixels might make possible a new form of flat-panel displays. (The Economist, 9 April; Science News, 9 April.) A NEW NEAREST GALACTIC NEIGHBOR to the Milky Way has been discovered by astronomers at the Royal Greenwich Observatory and at Cambridge University (Mike Irwin, 44-022-333-7524), who reported their finding last week at the European and National Astronomy Meeting in Edinburgh, Scotland. The object in question, a dwarf spheroidal galaxy only 80,000 light years from our solar system in the constellation Sagittarius, had not previously been discovered because our line of sight to the galaxy passed through the heart of the Milky Way, a place already rich in stars. The Sagittarius dwarf is about 1000 light years across and is apparently in the process of being pulled apart by the gravitational pull of the Milky Way, which now is known to have 11 satellite galaxies. (Science News, 9 April.) ULTRAHIGH ACCELERATION OF ELECTRONS has been achieved with plasma waves in an experiment at UCLA. Although carried out only on a small scale---electrons accelerated to 30-MeV energies in the space of 6 mm---this approach may eventually be useful in building high-energy particle accelerators in a fraction of the space now required. At UCLA, two laser beams at two slightly different frequencies interfere to form a "beat wave" which moves through a column of hydrogen plasma. The electric field of this wave accelerates electrons (injected colinearly with the laser beams) to high speeds. The acceleration rate achieved, 2.8 GeV/m, is more than 30 times higher than is possible with conventional technology. (M. Everett et al., Nature, 7 April 1994.) WALL STREET IS BULLISH ON PHYSICS. As jobs recede at universities, industry, and government labs, young physicists have sought out nontraditional careers in farflung areas, including now the world of high finance. Apparently, the mathematical and computer skills learned studying the movement of superstrings in a 10- dimensional lattice come in handy when tracking the movement of stocks and bonds on the Big Board. For example, numerous recent physics PhD's out of Harvard and Stanford, as well as refugees from SSC, have sought shelter, and profit, at financial institutions, where the starting salaries can be as high as $100,000. (Science, 1 April 1994.)


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