Y. T. Didenko, K. S. Suslick/D. Shapira, M. Saltmarsh
Nature (Print issue: July 25, 2002)/Under consideration by Physical Review Letters
The controversial claims of nuclear fusion in sonoluminescence by Taleyarkhan, et al. (Science 295, 1868 (2002)) have been cast into strong doubt by new investigations of single bubble sonoluminescence. Didenko and Suslick have performed the first direct measurements of the chemical reactions inside individual bubbles. They see that most of the acoustic energy goes into driving chemical reactions and leaves little for nuclear processes and suggest that bubble fusion in acetone, as claimed by Taleyarkhan, would be "exceedingly difficult" if at all possible. Meanwhile, Shapira and Saltmarsh have repeated the Taleyarkhan experiment and found no signs of fusion. They are able to account for the neutrons observed by Taleyrkhan without needing any fusion process. Their paper is currently under review by Physical Review Letters.
Physics News Update: http://www.aip.org/enews/physnews/2002/split/599-3.html
Journal article: http://www.nature.com/cgi-taf/DynaPage.taf?file=/nature/journal/v418/n6896/abs/nature00895_fs.html
2) Splitting photons
Sh. Zh. Akhmadaliev, et al.
Physical Review Letters (Print issue: August 5, 2002)
The rare event of a single photon spontaneously splitting into two photons has been observed in Russian experiments. About 400 photon-splitting events were seen out of more than one billion trials. This is the first time that photon-splitting has been confirmed experimentally.
Physical Review Focus: http://focus.aps.org/v10/st3.html
Journal article: http://link.aps.org/abstract/PRL/v89/e061802
3) Cosmic rays cause ice ages
N. J. Shaviv
Physical Review Letters (Print issue: July 29, 2002)
New research suggests that ice age epochs on the earth may result from our solar system's trek through the spiral arms of the Milky Way. This hypothesis rests on correlations found between apparent changes in the flux of cosmic rays reaching the earth and geological evidence for major ice ages in the past billion years. The author deduced the earth's exposure to cosmic rays by considering the cosmic ray exposure of 42 iron meteorites. The meteorite record seems to indicate that the cosmic ray flux varies with a period of about 143 million years, which correlates well with both the geological records of ice age epochs and the solar system's location relative to the spiral arms.
Physics News Update: http://www.aip.org/enews/physnews/2002/split/599-2.html
Journal article: Available on request
4) Quantum tweezers for atoms
R. B. Diener, B. Wu, M. G. Raizen, Q. Niu
Physical Review Letters (Print issue: August 12, 2002)
Trapping single neutral atoms is a hit and miss process. Although experiments are able to confine single atoms, the methods all involve a random chance of actually obtaining an atom in the trap. A new proposal shows how any desired number of neutral atoms can be trapped, guaranteeing a certain outcome. The process involves dragging optical tweezers over a Bose-Einstein condensate. The speed that the tweezers move dictates exactly how many atoms will be plucked out of the condensate.
Journal article: Available on request
5) Nanotube hoses
A. Berezhkovskii, G. Hummer
Physical Review Letters (Print issue: August 5, 2002)
Transport of molecules through molecular pores is essential for many biological and technical processes from cell functioning to fluid filtering. Simulations show that water molecules move single file through small pores such as carbon nanotubes. The water molecules act as a chain with bonds between the water molecules causing the entire chain to move in concert through the pore. The simulations correctly model experimental observations of flow through pores.
Journal article: http://link.aps.org/abstract/PRL/v89/e064503
6) Studying the sun's interior through surface waves
J. Christensen-Dalsgaard
Reviews of Modern Physics (Print issue: October, 2002)
A review of how looking at the oscillations and seismic activity of the sun's surface provides a window into its interior. Oscillations detected on the solar surface provide a unique possibility for investigations of the interior properties of a star. Through major observational efforts, including extensive observations from space, as well as development of sophisticated tools for the analysis and interpretation of the data, scientists have been able to infer the large-scale structure and rotation of the solar interior with substantial accuracy and are beginning to get information about the complex subsurface structure and dynamics of sunspot regions, which dominate the magnetic activity in the solar atmosphere and beyond.
Preprint: http://www.arxiv.org/abs/astro-ph/0207403
7) Mapping the Earth's core with neutrinos
M. Lindner, T. Ohlsson, R. Tomas, W. Winter
arXiv preprint server
The authors investigate the possibility of using the neutrinos coming from a future galactic supernova explosion to map the Earth's core. The measurements could be made with existing and planned neutrino observatories and provide complementary information to geophysical studies, with comparable precision.
Preprint: http://www.arxiv.org/abs/hep-ph/0207238