🚀 go-pugleaf

[Written by individuals at the American Institute of Physics and
merely posted by me, so respond to <pfs2@aip.org> or other
references below.  Always posted here on sci.research; sometimes
crossposted to an eclectic and hopefully appropriate selection
of other newsgroups, with followups directed here. Back issues
may be ftp'd from NIC.HEP.NET, along with the news column FYI
and the American Physical Society news/opinion column WHAT'S NEW;
or from pinet.aip.org. Enjoy! -jc]

PHYSICS NEWS UPDATE
A digest of physics news items by Phillip F. Schewe, American
Institute of Physics
Number 192  August 30, 1994                   physnews@aip.org

A SOURCE OF COHERENT X RAYS, an x-ray laser, is hard to
achieve because of the enormous power needed to bring about a
population inversion in which atoms in the laser medium reside in
excited states long enough in time and high enough in energy to
promote a worthwhile laser action.  In general the power requirement
is proportional to the inverse fifth power of the wavelength of the
emitted light.  Charles Townes of the University of Illinois at Chicago
has partly gotten around this problem by using light from an
ultraviolet laser to excite not atoms but clusters of atoms.  The
incoming pump light excites outer electrons in the cluster (xenon)
atoms and these in turn can, by consolidating their energy, ionize a
more tightly-bound, inner electron in one of the atoms, creating
thereby a sort of "hollow" atom.  The ejected electron is quickly
replaced by an outer electron in a transition that gives rise to a hard
x ray with a wavelength of 2-3 angstroms.  This whole process seems
to be aided by a self-focusing of the pump laser beam along the
ionization trail through the laser medium.  X-ray lasers in this
wavelength range, when fully realized, will facilitate microscopy with
a much better spatial resolution than is now possible.  (A. McPherson
et al., Nature, 25 August 1994.)

COULD QUANTUM MECHANICS PLAY A ROLE in the workings
of the conscious mind?  Some physicists, like John Taylor of Kings
College London, hold the negative view: they believe that information
born at the quantum level would be overwhelmed in the warm, wet,
and noisy environment of living cells.  By contrast, other scientists,
such as Stuart Hameroff of the University of Arizona, assert that
under some circumstances quantum information could indeed be
sustained at the cellular level.  Hameroff points to microtubules, tiny
rodlike proteins (only discovered in the 1970s) existing in all bodily
cells, as a possible theater of quantum consciousness.  These rods,
according to Hameroff, might possibly serve either as waveguides for
photons or as the host medium for persistent vibrational standing
waves.  In this model the action of many rods in neighboring cells,
acting in concert, would constitute a physical matrix for thoughts or
memories.  All these ideas were discussed earlier this year at a
conference held in Arizona.  At the conference partisans of the
quantum approach were a small minority. Even scientists who gave
some credence to the quantum hypotheses had to admit that
experimental searches for coherent effects in microtubule behavior
had found nothing.  (New Scientist, 20 August.)

THE EXPERIMENTAL ULTRAVIOLET INDEX, to be issued daily
by the National Weather Service, is a forecast of the noontime
ultraviolet level in 58 U.S. cities.  So in addition to smog, pollen,
and the weather itself, people can now worry in a quantitative way
about the cancer-causing or cataract-causing effects of UV. An index
of 6, for example, is considered "moderate."  At that level a person
with skin very susceptible to sunburn, would burn after 10 minutes of
direct exposure, while a much less susceptible person would burn
after 50 minutes.  The general advice of the Environmental Protection
Agency is that if you can see your shadow, you may want to use
some protection against UV radiation.  (Science News, 23 July.)