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Physics News Update
Number 459, November 29, 1999 by Phillip F. Schewe and Ben Stein

UNDERSEA VOLCANO. Like astronomers who team up to view supernova eruptions at a variety of wavelengths, geophysicists have been able to mount an in-depth study of the eruption in January 1998 of the Axial Volcano, lying 1500 m underwater about 200 miles off the Oregon-Washington coast (see figure at Physics News Graphics). Axial, which is a large volcanic edifice lying along a rift zone in the Northeast Pacific where new ocean floor is being created, is one of the few places on the worldwide 60,000-km mid-ocean ridge system (Iceland and the Azores are other examples) where volcanic activity can be monitored in real time. In this case the coverage consisted of Navy hydrophone arrays (listening for quakes rather than subs), surface ships, moored sensors, and instruments placed on the very summit of the caldera in anticipation of an eruption. The 1998 event is chronicled in a variety of ways in a series of articles in the December 1 and 15 issues of Geophysical Research Letters. For example, C.G. Fox reports (via on-the-spot seafloor measurements) a 3-meter drop in the caldera floor; Baker et al. provide the first in-situ observation of the water temperature change above an erupting rift zone (constituting the "largest vent field heat flux yet measured"); Embley et al estimate that up to 76 million cubic meters of lava were produced, modest by land volcano standards, but the largest outpouring in 20 years of monitoring along the Juan de Fuca Ridge. (Robert Embley, Pacific Marine Environmental Laboratory, embley@pmel.noaa.gov, 541-867-0275.)

SWIRLED SPHERE MAGIC NUMBERS. Physicists love to detect patterns in nature, whether in the crystalline structures of atoms in solids, or the groupings into "shells" of electrons inside atoms or protons and neutrons within nuclei. Even in a system as simple as a bunch of spheres swirled around in a dish patterns can emerge. Scientists at the Max Planck Institute in Dortmund, Germany (Karsten Kotter, koetter@mpi-dortmund.mpg.de, and Mario Markus), and the University of Chile (Eric Goles) have determined that for certain "magic" numbers of spheres, such as 19, 21, or 30, the spheres congregate into solid-like shell structures with stable rings (see figure at Physics News Graphics). The swirled balls are a form of granular material. Studies of agitated grains had uncovered stable structures before (such as "oscillons") but not any that had depended on the number of particles present. The researchers noticed that when they increased the size of the dish a puzzling transition between stable and disordered states would occur intermittently. (Kötter et al., Physical Review E, December 1999; Select Article.)

THE TOP PHYSICISTS IN HISTORY are, according to a poll of scientists conducted by Physics World magazine, 1. Albert Einstein, 2. Isaac Newton, 3. James Clerk Maxwell, 4. Niels Bohr, 5. Werner Heisenberg, 6. Galileo Galilei, 7. Richard Feynman, 8. Paul Dirac, 9. Erwin Schrodinger, and 10. Ernest Rutherford. Other highlights of Physics World's millennium canvas: the most important physics discoveries are Einstein's relativity theories, Newton's mechanics, and quantum mechanics. Most physicists polled (70%) said that if they had to do it all over again, they would choose to study physics once more. Most do not believe that progress in constructing unified field theories spells the end of physics. Ten great unsolved problems in physics: quantum gravity, understanding the nucleus, fusion energy, climate change, turbulence, glassy materials, high-temperature superconductivity, solar magnetism, complexity, and consciousness. (December issue of Physics World, published by the Institute of Physics, the British professional organization of physicists celebrating its 125th anniversary this year.)