The Hindu : News : India joins multinational telescope project

The Hindu : News : India joins multinational telescope project

Brownian motion of particles

Science/AAAS | This Week in Science: 25 June 2010; 328 (5986): "Nearly 200 years ago, the botanist Robert Brown noted that pollen particles floating on a liquid displayed a random motion, jittering under the microscope as if the particles were alive. In 1905, Albert Einstein described this Brownian motion in terms of statistical thermodynamics. Now, Li et al. (p. 1673, published online 20 May) use a single, optically trapped silica bead to probe the dynamics of Brownian motion, measuring the predicted instantaneous velocity of the particle and verifying the short-time-scale behavior predicted a century ago. As well as testing fundamental principles of physics, the technique also has practical implications for cooling particles to ultralow temperatures."

Earth's 100,000 years cycle of glaciation and deglaciation

Science/AAAS | This Week in Science: 25 June 2010; 328 (5986)

For the past half-million years, our planet has passed through a cycle of glaciation and deglaciation every 100,000 years or so. Each of these cycles consists of a long and irregular period of cooling and ice sheet growth, followed by a termination—a period of rapid warming and ice sheet decay—that precedes a relatively short warm interval. But what causes glacial terminations? Denton et al. (p. 1652) review the field and propose a chain of events that may explain the hows and whys of Earth's emergence from the last glacial period. Pulling together many threads from both hemispheres suggests a unified causal chain involving ice sheet volume, solar radiation energy, atmospheric carbon dioxide concentrations, sea ice, and prevailing wind patterns.

Defining Time-Zero

Science/AAAS | TWhen a high-energy photon hits an atom and is absorbed, the result can be the excitation and emission of an electron. This photoemission, or photoelectric effect, is generally assumed to occur instantaneously, and represents the definition of "time-zero" in clocking such ultrafast events. Schultze et al. (p. 1658, see the cover; see the Perspective by van der Hart) use ultrafast spectroscopy, with light pulses on the time scale of several tens of attoseconds, to test this assumption directly. They excite neon atoms with 100 eV photons and find that there is a small (20-attosecond) time delay between the emission of electrons from the 2s and 2p orbitals of the atoms. These results should have implications in modeling electron dynamics occurring on ultrafast time scales. his Week in Science: 25 June 2010; 328 (5986)

Neutrino search

A hard-to-observe fundamental particle that travels alone, the neutrino has little or no mass, so rarely interacts with other particles.
Neutrinos are ubiquitous throughout our universe. They were produced during the Big Bang, and many of those are still around. New ones are constantly being created too, through natural occurrences like solar fusion in the sun's core, or radioactive elements decaying in the Earth's mantle, as well as when the particle accelerator at Fermilab purposely smashes protons into carbon foils.
Our sun produces so many that hundreds of billions are zinging through our bodies every second, Coan said. It's hoped the new detector can resolve questions surrounding three different kinds of neutrinos — electron, tau and muon — and their "oscillation" from one type to another as they travel, he said.
Scientists at the new detectors will analyze data from Fermilab's neutrino beam to observe evidence of neutrinos when the speedy, lightweight particles occasionally smash into the carbon nuclei in the scintillating oil of the detector, causing a burst of light flashes, Coan said.
NOvA is looking for the most elusive oscillation of the muon type of neutrino to the electron type, Cooper said.
More information: http://www-nova.fnal.gov/

in reference to: Neutrino data to flow in 2010; NOvA scientists tune design (view on Google Sidewiki)