Number 204, November 23, 1994 by Phillip F. Schewe and Ben Stein
ELEMENT 110 HAS BEEN CREATED artificially at the Heavy Ion Research
Center in Darmstadt, Germany. With an atomic weight of 269 this heaviest
of atoms was made in a collision between lead and nickel atoms; it decays
promptly into lighter elements. The German scientists, led by Peter Armbruster,
hope to make an even heavier isotope of element 110. They are also hoping
to make element 114. (Associated Press, 18 November 1994.)
DARK MATTER DOES NOT CONSIST OF RED DWARF STARS. The existence of nonluminous
matter has been invoked to explain the rotation and interactions of certain
galaxies. What is the nature of this dark matter? One possibility is that,
like matter here on Earth, the dark matter consists of baryons---neutrons
and protons---residing in atoms which make up faint stars such as red dwarfs.
Indeed in the vicinity of our own Sun there are many such dim stars. But
further afield in the Milky Way the density of red dwarfs, surveyed by
the Hubble Space Telescope (HST), is surprisingly low. The HST measurements
conclude that red dwarfs can account for no more than 6% of the mass of
the galactic halo and 15% of the galactic disk. Dark matter therefore will
have to consist of even lighter objects, such as brown dwarfs, or exotic,
hypothetical particles not yet detected. (The Washington Post, 16 November
1994.)
A SINGLE-ATOM LASER , a device that produces laser light using one atom
at a time, has been created by MIT researchers (K. An et al., 19 Dec. 94
in Physical Review Letters; contact Michael Feld, 617-253-7700). Conventional
lasers employ billions upon billions of excited, light-producing atoms
or molecules confined in a resonator, a structure that provides the required
geometry for laser action. The MIT researchers designed a resonator consisting
of two ultra- highly reflecting parallel mirrors spaced 1 mm apart. They
then passed a beam of barium-138 atoms between the mirrors in such a way
that one atom or less was inside the resonator at any one time. The mirror
spacing was fixed to within 10 picometers to maintain proper alignment,
and highly efficient detectors recorded the 791-nm-wavelength laser light
produced by the barium atoms. The use of a single atom eliminates the effect
of inter-atomic interactions; therefore this laser device will be useful
for performing precision studies of the interaction between atoms and electromagnetic
fields. Moreover, because so few atoms contribute to the electromagnetic
field in the resonator, some of the statistically averaged properties that
apply to light emitted by conventional lasers do not apply to the so called
"non-classical light" emitted in the single-atom laser. (MIT
Press Release, 17 November.)
THE MOST DISTANT GALAXY ever observed lies at a redshift of 4.25. The
previous galaxy redshift record was 3.8. The newly discovered galaxy, 8C1435+635,
was glimpsed by astronomers using the Herschel Telescope in the Canary
Islands. This finding, along with the detection in past years of other
galaxies at high redshifts, reinforces the idea that some galaxies had
formed very early in the history of the universe, within a few billion
years of the big bang. (Science, 11 Nov.)
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