Number 174, April 15, 1994 by Phillip F. Schewe and Ben Stein
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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