Number 220, April 3, 1995 by Phillip F. Schewe and Ben Stein
THE FASTEST TECTONIC MOTION so far measured anywhere in the world occurs
near the Samoan Islands, where the Pacific plate is subducted at the Tonga
Trench. In this region of the Earth's crust, the Australian and Pacific
plates are in general convergence. Meanwhile a small platelet, the Tonga
microplate, is moving out ahead of the Australian plate toward the Pacific
plate at an even greater rate, opening up a rift called the Lau Basin.
The net convergence, as measured with ground stations using signals from
the Global Positioning System of satellites, is 24 cm/year. The multinational
consortium of scientists performing the observations believe that the high
seismic activity in the region (more earthquakes than other subducting
slabs worldwide) is related to the rapid subduction rate. (Michael Bevis
et al., Nature 16 March 1995.)
DURING A FULL MOON Earth's average global temperature is 0.02 K warmer
than during a new moon. Robert Balling and Randall Cerveny at Arizona State
were able to correlate daily measurements of global temperature for the
period 1979 to 1994 with the 29.53-day lunar cycle. The scientists assert
that their results underscore both the accuracy of daily global temperature
readings and the notion that the lunar phase needs to be considered in
studies of short-term temperature variability on Earth. (Science, 10 Mar.)
TITAN HAS HYDROCARBON SEAS OR LAKES separated by continents. This assessment,
by Stanley Dermott of the University of Florida and Carl Sagan of Cornell,
is a compromise between the notion (derived from photochemical studies)
that the hydrocarbon seas are global and the notion (based on recent infrared
and radar observations) that such seas are discontinuous. Titan's orbit
around Saturn is highly elliptical. Since the tidal effect on large seas
would have made Titan's orbit more circular than it is, Dermott and Sagan
argue that the seas are small, perhaps more like crater lakes. (Nature,
16 March.)
BIOLOGY/CHEMISTRY/PHYSICS is the usual sequence in which yearlong science
courses are taught in American high schools. This means that if only one
or two years of science are required for graduation then physics is shortchanged;
indeed, less than 25% of students enroll in high school physics. Recently,
however, the Chicago School Board voted to establish a 3-year science requirement
for all students by 1998. New York City may also adopt such a curriculum.
Leon Lederman, director emeritus of Fermilab, sees this as an occasion
to institute an integrated 3-year science sequence in which physics would
at last play an important role. Lederman admits that this initiative would
entail extensive revisions in textbooks, testing, and teacher training.
(Physics Today, April 1995.)
AMONG THE 4800 PHYSICS BACHELOR'S DEGREES awarded in 1993, 37% went
to graduate school in physics or astronomy, 22% took up graduate study
in some other field (the largest fraction of these, 43%, went into engineering),
and 41% had employment plans or were uncommitted. Other highlights from
the "1992-93 Bachelor's Degree Recipients Report," recently published
by the Education and Employment Statistics Division of the American Institute
of Physics: the fraction of graduates choosing to continue with physics
was the same for men and women; the estimated fractions of bachelor's recipients
who were black was 4%, Hispanic 2%, and Asian 4%. (Contact Patrick Mulvey,
301-209-3076.)
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