PHYSICS NEWS UPDATE
The American Institute of Physics Bulletin of Physics News
Number 716 January 19, 2005
by Phillip F. Schewe, Ben Stein

THE MOST DISTANT CRAFT LANDING IN THE SOLAR SYSTEM. The Huygens probe,
given long passage by the Cassini spacecraft into the middle of Saturn's
minor planetary system, has successfully parachuted onto the surface of
Titan, the only moon with a considerable atmosphere. Pictures taken from
miles above the surface during the descent and pictures taken on the
surface itself suggest the presence of boulders or ice chunks and some kind
of shoreline, perhaps of a hydrocarbon lake or sea.  The data gained so far
include a sort of acoustic sampling of the atmosphere during the descent
and some color photographs.  The Titan probe is named for Christaan
Huygens, who first spotted Titan and who also was the first to provide the
proper interpretation of Saturn's ring system.
(http://www.esa.int/SPECIALS/Cassini-Huygens/)

THE SOUND OF THE EARLY UNIVERSE. New published surveys of distant galaxies
are in accord with what you'd expect from standard big bang cosmology. 
Precise measurements of the cosmic microwave background provide in effect
an image of the cosmos just as the first atoms were forming about 400,000
years after the big bang.  The lumpiness of this background testifies to
the shepherding role of gravity in establishing primitive structures. 
Statistical studies of the distribution of the tiny surpluses or deficits
across the microwave sky suggest that at this point in the early universe
(corresponding to a redshift of 1000) colossal sound waves were propagating
through the primordial plasma.  Evidence for these acoustic ripples moving
through early matter has now been seen, again in a statistical analysis, in
the distribution of galaxies occurring billions of years later.  Two large
astronomical collaborations, the Two Degree Field Galaxy Redshift Survey
(2dF) and the Sloan Digital Sky Survey (SDSS), both using automated
telescopes dedicated to measuring lots of galaxy redshifts, reported at
last week's meeting of the American Astronomical Society in San Diego that
the present population of observed galaxies seems to have grown steadily
and consistently, through the agency of gravitational interactions, out of
the lumpy terrain of the earlier microwave background era.  The 2dF catalog
contains 221,000 galaxies, while SDSS's catalog has almost 47,000. (Online
papers, astro-ph/0501171, astro-ph/0501174; www.sdss.org,
www.aao.gov.au/2df/ )
                                        
ELECTRON CLOUDS CAN FREEZE INTO AN "ORBITAL GLASS" at low
temperatures.  In the modern picture of quantum mechanics, electrons take
the form of "clouds" within the atoms and molecules in which they
inhabit.  The clouds, which have various shapes such as spheres or
dumbbells, represent the general boundaries within which one may find an
electron at any one measurement in time.  Typically, processes involving
electron clouds (more formally known as "orbitals") are blazingly
fast.  In the order of a femtosecond (10^-15 s), for example, an electron
orbital can make transitions between degenerate states (those containing
the same amount of energy), transforming from a vertical dumbbell to a
horizontal one with respect to some axis. Now, scientists have found
evidence that these and other orbital processes can slow down
dramatically--to as long as 0.1 seconds, a slowing by 14 orders of
magnitude--for electrons in low-temperature FeCr2S4, a spinel (class of
mineral) with a relatively simple crystalline structure. The researchers,
who hail from the Center for Electronic Correlations and Magnetism at the
University of Augsburg in Germany (Peter Lunkenheimer,
Peter.Lunkenheimer{at}Physik.Uni-Augsburg.de) and the Academy of Sciences of
Moldova (a former Soviet republic), consider these frozen electron orbitals
in spinels to constitute a new class of material which they have dubbed an
orbital glass.  By measuring the response of the material to
alternating-current  electric fields in the audio- to radio-frequency
range, they found that processes involving non-spherical orbitals
dramatically slow down at low temperatures to form a glass-like state, in a
manner very similar to the arrest of molecular motion that occurs when
glass blowers perform their craft. It's not just the orbitals that slow
down; the neighboring atomic nuclei that surround the electrons also
distort more slowly in response to the glacially changing orbitals.  In
contrast to conventional glasses, a complete "freeze" of the
electron clouds does not occur at the lowest temperatures. Completely
frozen orbitals are prevented by quantum-mechanical
tunneling: the clouds keep themselves moving by making transitions between
different low-energy cloud configurations even without the energy they
normally require. (Fichtl et al., Physical Review Letters, 21 January 2005)

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