Number 724, March 25, 2005
by Phil Schewe and Ben Stein
Direct Detection of Extrasolar Planets
Direct detection of Extrasolar Planets has been achieved for the first
time. Previously the existence of planets around other suns has been
inferred from subtle modulation of the light emitted by the star. Now
light from the planet itself has been recorded directly at infrared
wavelengths by the Spitzer Space Telescope (www.spitzer.caltech.edu).
The planets, one with the prosaic name of HD 209458b (153 light years
away), the other TrES-1 (489 light years away), orbit their stars more
tightly than does Mercury around our sun. This makes the Jupiter-sized
planets hot enough to be viewed by Spitzer. (NASA press conference,
23 March; report to be published in Nature, 7 April.)
Superfluid Solid Hydrogen
Quantum science allows for collective behavior that runs counter to
human intuition. For example, at very low temperatures helium-4 atoms,
in their wavelike manifestation, can begin to overlap. When this happens
the atoms are indistinguishable and indeed constitute a single quantum
state. In this state liquid helium-4 will flow without friction. Comparably
chilled, quantum-condensed dilute gases (Bose-Einstein condensates,
or BEC) also exhibit superfluid behavior.
What about solids? Can they
“flow” without friction? Last year Moses Chan (Penn State) announced
the results of an experiment in which solid helium-4 was revolved like
a merry-go-round. It appeared that when the bulk was revolved at least
part of the solid remained stationary. In effect part of the solid was
passing through the rest of the solid without friction. Chan interpreted
this to mean that a fraction of the sample had become superfluid (see
www.aip.org/pnu/2004/split/669-1.html
and www.aip.org/pnu/2004/split/699-2.html).
Now, Chan sees evidence for superfluid behavior in solid hydrogen as
well. Speaking at this week’s meeting of the American Physical Society
(APS) in Los Angeles, Chan said that his hydrogen results are preliminary
and that further checks are needed to be made before ruling out alternative
explanations. The concept of what it means to be a solid, Chan said,
needs to be re-examined.
How Effective Will Flu Vaccine Be?
A new way to study this
important issue is to use the tools of statistical physics. At the
APS meeting, Michael Deem of Rice University (mwdeem@rice.edu)
described a new way of predicting the flu vaccine's efficacy (a
higher efficacy means that fewer vaccinated individuals get the flu
relative to unvaccinated individuals). To predict efficacy,
researchers examine each strain's hemagglutinin (H) protein, the
major protein on the surface of influenza A virus that is recognized
by the immune system.
In one standard approach, researchers study
all the mutations in the entire H protein from one season to the
next. In another approach, researchers study the ability of
antibodies produced in ferrets to recognize either the vaccine
strain or the mutated flu strain, which had been thought to be a
good method for predicting flu vaccine efficacy in humans.
However,
these approaches are only modestly reliable indications of the
vaccine's efficacy. Deem and his Rice University colleagues point
out that each H protein has 5 "epitopes," antibody-triggering
regions mutating at different rates. The Rice team refers to the
one that mutates the most as the "dominant" epitope. Drawing upon
theoretical tools originally developed for nuclear and
condensed-matter physics, the researchers focus on the fraction of
amino acids that change in the dominant epitope from one flu season
to the next.
Analyzing 35 years of epidemiological efficacy data,
the researchers believe that their focus on epitope mutations
correlates better with vaccine efficacy than do the traditional
approaches. Deem and his colleagues Vishal Gupta and Robert Earl
believe that this new measure may prove useful in designing the
annual flu vaccine and in interpreting vaccine efficacy studies.
Solvay: The Movie
Arguably the most famous photograph of
physicists is the group portrait taken at the 1927 Solvay Conference
in Belgium. It turns out that a brief motion picture of that event
also exists. In the course of this three-minute film, a dozen or
more present and future Nobel laureates walk in and out of the
frame, including Albert Einstein, Marie Curie, Niels Bohr, and Max
Planck.
Forgotten or neglected for decades, the film was shown in public for
the first time at the APS meeting by Nancy Greenspan, author of “The
End of the Certain World,” the first full biography of Max Born (http://www.maxborn.net).
Born is credited with the insight that the wavefunction appearing in
Erwin Schrodinger’s famous equation provided not the exact location
of an electron inside an atom but rather merely a statistical likelihood
of the electron being at various locations.
This view of quantum reality
would later take on the name of the “Copenhagen interpretation,” in
honor of Niels Bohr. Greenspan argues that Born has been
underappreciated in histories describing the establishment of
quantum science. Speaking at a press conference, APS president
Marvin Cohen (Univ California, Berkeley) underscored this point.
Max Born’s group at the University of Gottingen, active over the
period from 1922 to 1932, was, Cohen suggested, the most illustrious
theoretical physics “school” of all time.
The list of Born students
or junior colleagues includes no less than Werner Heisenberg,
Wolfgang Pauli, Enrico Fermi, Maria Goeppert-Mayer, Linus Pauling,
Eugene Wigner, and Robert Oppenheimer.
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