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Number 432, June 7, 1999 by Phillip F. Schewe and Ben Stein
ELEMENTS 118 AND 116 have been discovered at Lawrence Berkeley Lab by crashing a beam of krypton atoms into lead atoms. The three detectable atoms of element 118 have nuclei possessing 118 protons and 175 neutrons for a mass total of 293. The new elements are even further along in the Periodic Table than element 114, whose existence was announced back in January 1999 by scientists in Russia (see Update 412), and further into the "island of stability", the supposed nuclear regime in which certain combinations of neutrons and protons lead to a relatively long life. For all that, the atoms of element 118 still decay after less than a millisecond into element 116 plus an alpha particle. Element 116 then promptly decays into element 114 plus another alpha particle. Ken Gregorich (510-486-7860) led the LBL group that discovered the new nuclei. Four of the team members are German nationals, which prompted DOE secretary Bill Richardson to emphasize the continuing value of international scientists working at US national labs. (LBL press release, June 7.)
THE SPEED OF LIGHT IS INDEPENDENT OF FREQUENCY within a factor of 6x10-21. Bradley Schaefer of Yale (203-432-3806, schaefer@grb2.physics.yale.edu) bases this estimate on the observed arrival of gamma rays from distant explosive events in the cosmos, such as gamma-ray bursters. If the speed of light (c) were slightly different for the different frequency ranges, then some light waves would show up before the others, but this is not the case. The best previous effort to locate a frequency dependency for c, deduced from light coming from the Crab pulsar, was at the 5x10-17 level. Why would c vary with frequency? Einstein's theory of relativity, and its insistence on a universal light speed, might be at fault. Or photons might have mass. Schaefer*s analysis addresses this issue, and puts an upper limit of 10-44 g on any putative photon mass, not quite as sharp a limit as those based on the observed strength of the galactic magnetic field (a nonzero photon mass would allow the fields to decay away). The new sharper limits on any possible frequency-dependency for c is a vindication of relativity. By the way, the prefix for anything as small as 10-21 is "zepto" (Shaefer, Physical Review Letters, 21 June; journalists can obtain the article from AIP.)
THE SURFACE OF MARS has been mapped to 13-meter precision, better than for some places on Earth. Laser light sent from and returning to the orbiting Mars Global Surveyor spacecraft reveals that the southern hemisphere is one big highland (6 km higher) compared to the northern hemisphere. Surface water, if there was any, would have collected in the North, although there is not yet definitive proof of any boreal ocean. One thing that is known about the northern lowland: it is the flattest place in the solar system. The South's elevation is due at least in part to an immense amount of material raised during an ancient impact which fashioned a huge crater known as the Hellas basin. (Science, 28 May 1999.)
THE PAINTINGS OF JACKSON POLLACK, famous for their seemingly random distribution of drips and streaks, are fractal in nature. Physicists at the University of New South Wales (Australia) subjected Pollack's handiwork to the kind of mathematical scrutiny usually given to fractures in crystals and distributions of galaxies. They found that the paintings bore similar features at each of many size scales, the hallmark of fractalness. The object's characteristic "fractal dimensionality" is roughly related to the indentedness of the object's texture. Apparently the dimensionality of Pollack's work increased through the years. (Nature, 3 June 1999.)
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