Number 17, January 17, 1991 by Phillip F. Schewe and Ben Stein
ROSAT, THE GERMAN X-RAY SATELLITE , has taken pictures of the sky farther out in distance, or equivalently further back in time, than any other x-ray images previously recorded. These pictures reveal a great density---with a suggestion of clustering---of quasars at redshifts between one and two. Such a clustering seems to be further bad news for the cold-dark-matter version of the big bang model which cannot easily account for such large structure so early in the history of the universe. Guenther Hasinger of the Max Planck Institute near Munich, one of the leaders of the Rosat project, said at a meeting of the American Astronomical Society in Philadelphia that Rosat (Roentgen Satellite) can see x-ray sources up to 2.5 times fainter than the Einstein x-ray satellite (which no longer operates) and that Rosat has been able to resolve up to 40% of the heretofore diffuse x-ray background into point sources. Launched last June, Rosat has spent much of its observing time doing an all-sky survey at x-ray wavelengths, but the satellite also carries a telescope for observing the sky at extreme-ultraviolet wavelengths, permitting a first-ever survey in that range. (U.S contact for Rosat: Steve Holt, NASA Goddard.)
A SUPERCONDUCTING FLUX FLOW TRANSISTOR (SFFT) , a new device developed at Sandia National Lab, exploits magnetic flux creep. This phenomenon in high-temperature superconductors, in which magnetic flux bundles begin to move under the influence of a supercurrent, may result in the loss of the superconducting state. In the SFFT this normally bothersome effect is used to switch (by breaking a linking conductive path) the device on or off. Sandia scientist David S. Ginley believes that the device can operate at a rate of 100 gigahertz and that applications for this technology may appear "in a year or two." (Scientific American, February 1991.)
LOW-TEMPERATURE RESEARCH MAY BE HAMPERED BY COSMIC RAYS some day. According to Robert Richardson (607-255-6053), head of Cornell's Microkelvin Laboratory, the heat from cosmic rays, about 10 picowatts of heating per cubic cm in most metals, may eventually force low-temperature research into deep underground caves. That amount of heating becomes important if future refrigeration techniques can reduce the temperature of the electrons in the atoms of a metal sample to the nanokelvin range. Such a temperature has been achieved for nuclei at the Helsinki University of Technology (using a process called nuclear demagnetization) but not yet for electrons. (Mosaic, Winter 1990/91.)
PHYSICS HAD THE LOWEST "UNCITEDNESS" of all the sciences. A study conducted by the Institute for Scientific Information showed that 36.7% of all physics papers in journals covered by ISI's survey did not receive a single citation in the five years after publication, which was better than for chemistry (38.8%), biology (41.3%) and various other sciences. The rate for engineering papers was 72.3%. Among certain physics subdisciplines, the uncitedness fraction was 9.2% for atomic, molecular, and chemical physics, 16.7% for particle physics, 19.1% for condensed matter physics, 40.1% for acoustics, and 49.1% for optics. (Science, January 4, 1991.)
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