update.402 (fwd)

[Jim Choate <ravage@EINSTEIN.ssz.com>]

Forwarded message:

> Date: Fri, 13 Nov 1998 14:04:23 -0500 (EST)
> From: physnews@aip.org (AIP listserver)
> Subject: update.402

> PHYSICS NEWS UPDATE                         
> The American Institute of Physics Bulletin of Physics News
> Number 402  November 13, 1998   by Phillip F. Schewe and Ben
> Stein
> 
> IMMISCIBLE QUANTUM LIQUIDS.  The wavelike overlap of
> cooled alkali atoms known as Bose Einstein condensation (BEC)
> represents a new form of condensed matter in which physicists can
> pursue studies of fluid dynamics, sound propagation, persistent
> currents, and many of the coherence phenomena occurring in other
> "super" states such as superfluids and superconductors. One notable
> BEC innovation introduced in the past year by Wolfgang Ketterle
> and his colleagues at MIT was the development of an all-optical trap
> (Update 362)  which can hold condensate atoms in a number of
> distinct (hyperfine) internal states.  And just as helium-3 (which has
> a magnetic substructure) is a more complex superfluid than
> nonmagnetic helium-4, so the multi-component MIT condensate
> ought to exhibit behavior not seen in single-component BEC. 
> Indeed, at the New Horizons in Science meeting in Boston last week
> Ketterle reported that when he immersed his BEC in a uniform
> magnetic field and a stream of radio waves, those portions of the
> condensate in different hyperfine states (m=0 and m=1) quickly
> segregated themselves into alternating domains (differing in energies
> equivalent to only a few nanokelvins) as if they were oil and
> vinegar. Furthermore, these layers unexpectedly persist; in effect
> this arrangement of the condensate constitutes a metastable
> macroscopically occupied excited state.

> THE ARROW OF TIME has been directly measured by two groups
> of physicists, one at CERN in Geneva
> (www.cern.ch/cplear/Welcome.html) and one at Fermilab
> (http://fnphyx-www.fnal.gov/experiments/ktev/ktev.html) near
> Chicago.  Time reversal (T) is one of those symmetries, along with
> charge conjugation (or C, the operation which turns particles into
> antiparticles) and parity (or P, the reversal of a particle's
> coordinates from x,y,z to -x,-y,-z) that were once thought to be
> preserved in interactions at the atomic level.  But then experiments
> showed that P, C, and the combination CP were not sacred.  And
> since the triple symmetry of CPT is still thought to be valid, T by
> itself was thought to be vulnerable.  That is, it is not thought that
> physics does differentiate between the forward or backward
> movement of time.  The two groups have now seen evidence for this
> T violation in the observed decay rates for neutral K mesons. 
> (Science, 2 Oct.; Science News, 31 Oct.)

> SONIC BANDGAPS, frequency ranges in which sound waves are


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