Number 30, April 18 1991 by Phillip F. Schewe and Ben Stein|
THE NATIONAL ACADEMY OF SCIENCES STUDY ON GLOBAL WARMING admits that it is difficult to make firm predictions about greenhouse effects, but does suggest that a temperature rise of 1-5 C may occur in the near future. The report recommends that certain measures, such as increasing auto fuel efficiency and further decreasing greenhouse-gas emissions, be taken to mitigate possible human-induced warming tendencies. (Science 12 April 1991.)
VENUS DOES NOT HAVE "'MID-OCEAN" RIDGES. The notion that ridges in the Ovda Regio section of Venus were caused by crustal spreading was dispelled by new radar pictures from the Magellan spacecraft. An extensive summary of the Magellan mission so far appears in the 12 April issue of Science.
THEORIES THAT RIVAL THE BIG BANG have not gone away, despite the Big Bang's success in accounting for such cosmological features as the expansion of the universe, the cosmic microwave background, and nucleosynthesis. Dissenters from the majority of astronomers who favor the Big Bang framework include Geoffrey Burbidge of UC San Diego (619-534-6626), one of those who expounds a sort of steady-state universe, and Hannes O. G. Alfven of the Royal Institute of Technology in Stockholm, who holds that the overall structure of the universe is dominated not by gravity but by the electromagnetic force in the form of plasma interactions. (Science News, 13 April.)
THE COST OF THE SUPERCONDUCTING SUPERCOLLIDER may have to go up again from the current "final estimate" of $8.25 billion. Some scientists at the SSC would like to increase the aperture of the quadruple magnets used to focus the proton beams from 4 up to 5 cm., an improvement that might cost $100 million.
(Chronicle of Higher Education, 10 April.)
PHOTON SCANNING TUNNELING MICROSCOPY (PSTM) and near-field scanning optical microscopy (NSOM) are two new techniques that use photons instead of tunneling electrons to image surface structure. Although neither PSTM or NSOM can match the atomic-scale resolution of more conventional scanning microscopes, they are both able to achieve resolutions smaller than the wavelength of the light, the traditional limit for optical microscopy; also they can image non-conducting samples. PSTM, developed at Oak Ridge National Lab (Robert Warmack, 615-974-3342), employs a sharp probe which detects small pulses of light that emerge when the surface being imaged is illuminated from below. In NSOM, developed by AT&T Bell Labs (Eric Betzig, 201-582-3737), light shoots down a very thin glass pipette and reflects from a piece of the sample smaller than the light's wavelength; this technique that may be valuable in checking microcircuit chips. (Science, 5 April.)