Number 89, July 22, 1992 by Phillip F. Schewe and Ben Stein
THE GRAVITATIONAL WAVE BACKGROUND created during the inflationary expansion of the early universe may account for part (perhaps even a large part) of the measured anisotropy in the cosmic microwave background (CMB). This anisotropy is often associated with fluctuations in the density of primordial matter but, according to Lawrence Krauss (303-925-2585) and Martin White of Yale, long-wavelength gravitational waves (with wavelengths as big as the visible universe itself) would result in a CMB quadrupole anisotropy with a value comparable to that actually measured by the Cosmic Background Explorer (COBE). Indeed, the cold dark matter model prediction for the size of the quadrupole, based only on density fluctuations, comes out too low anyway, so, Krauss asserts, it is plausible that some of the quadrupole anisotropy should be due to the gravitational wave background. Future, higher-sensitivity measurements of the CMB, coupled with particle-physics experiments searching for "supersymmetric" particles, may be able to differentiate between the relative influence of gravitational waves and matter-density fluctuations on the CMB. (Article in the 10 August 1992 issue of Physical Review Letters.)
THE GREAT ANNIHILATOR MAY BE A MICROQUASAR . The object 1E1740.7-2942 near the center of the Milky Way is an x-ray emitter and also the brightest source of positrons in the sky; the positrons reveal themselves through their collisions with electrons, resulting in the characteristic gamma radiation at 511 keV and hence the name Great Annihilator. A team of French astronomers, using the Very Large Array in New Mexico, has now studied the object at radio wavelengths and found that it exhibits radio-emitting jets whose behavior is synchronous with the variable gamma source. All of this suggests to the French astronomers that the core of 1E1740.7-2942 resembles a sort of mini-quasar. (Nature, 16 July 1992.)
BUCKYBALLS OCCUR NATURALLY . Scientists at Arizona State University have isolated C-60 and C-70 fullerenes in a 600-million year old sample of shungite, a type of rock that comes from the Russian village of Shunga (Science, 10 July 1992). Other scientists examining meteorite debris collected with the orbiting Long Duration Exposure Facility (LDEF) have also found evidence of naturally-occurring fullerenes. (Science News, 11 July 1992.)
THE ORBITS OF ALL NINE PLANETS ARE CHAOTIC . Gerald Sussman and Jack Wisdom of MIT have carried out the most detailed calculation yet of the motions of the planets into the far future---over a 100-million period---and found that after only about 4 million years planetary positions cannot be predicted with any certainty. These new calculations, which required considerable computer time, confirm earlier (1989) but less detailed studies by Jacques Laskar of the Bureau des Longitudes in Paris indicating chaotic behavior throughout the solar system. (Science, 3 July 1992.)
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