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Physics News Update
The American Institute of Physics Bulletin of Physics News
Number 108, December 28, 1992 by Phillip F. Schewe and Ben Stein
NEW MEASUREMENTS OF THE COSMIC MICROWAVE BACKGROUND (CMB) reinforce
the conclusion, reached earlier this year by scientists using the COBE
satellite, that tiny temperature fluctuations in the early universe can
be observed. A balloon-mounted detector has now mapped one-third of the
sky (COBE covered the whole sky) at four microwave frequencies (different
from COBE's) with an angular bite of 3.8 degrees (twice as narrow as COBE's).
For all the differences in the two detectors, the balloon measurements
of the CMB fluctuations were similar in magnitude and in distribution to
those of COBE. The new results were reported by scientists from MIT (Stephan
Meyer, 617-253-8153), NASA/Goddard, and Princeton at a recent cosmology
meeting in Berkeley. (Science News, 19 & 26 Dec. 1992.)
TUNGSTEN DISULPHIDE STRUCTURES can form closed concentric polygons and
cylinders. Before now only carbon layered structures (e.g., Buckytubes)
had been known to exhibit such closure. Scientists at the Weizmann Institute
in Israel created WS2 concentric objects in sizes ranging from less than
10 nm to more than 100 nm. (Nature, 3 Dec. 1992.)
MONTE CARLO TECHNIQUES , widely used in computer simulations of physical
systems, entail the wholesale generation of random numbers. A new study
by scientists at the University of Georgia (Alan Ferrenberg, 404-542-8460)
shows that even the most advanced random-number generators are biased under
certain circumstances (A.M. Ferrenberg et al., 7 Dec. Physical Review Letters).
Using one state-of-the-art program, the Marsaglia-Zeman random-number generator,
Ferrenberg discovered that a simulated performance of the two-dimensional
Ising model (which models the behavior of a plane of neighboring spins)
did not agree with the results when calculated exactly by mathematical
methods. He traced the discrepancy to the random-number generator. Other
generators tried had differing faults. (Science News, 19 & 26 Dec.)
BILL CLINTON'S SCIENCE ADVISOR WILL BE JOHN GIBBONS , currently head
of the Office of Technology Assessment. Like many recent presidential science
advisors, Gibbons is a physicist by training. (The New York Times, 25 Dec.
1992.) GALILEO GALILEI WAS UNJUSTLY CONDEMNED by the Roman Catholic Church
for promoting a Copernican cosmology, says Pope John Paul II. The Pontiff
issued the reassessment of this famous 1633 case after a special Vatican
commission finished its investigation of the matter. Mr. Galileo was unavailable
for comment. (Sky & Telescope, Jan. 1993.)