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THIS WEEK ON |  | ||
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A group of researchers at UC Berkeley heard a whistling sound when they had two tanks of superfluid helium connected by tiny channels. Small differences in pressure between the two containers caused particles in one container to change the behavior of particles in the other container, creating pressure oscillations heard as a whistle. The connections between the tanks are too small for molecules of helium to interact by touching each other. Coupled superconductors do something similar, raising the possibility that this effect is a property of many quantum systems. In Geneva, Switzerland, another research team has announced that they have confirmed that two separated photons somehow remain "correlated" to one another. Although similar demonstrations of the effect have been made before, the recent Geneva demonstration is perhaps the most dramatic. When one photon chose to zip through a particular forking in a fiber optic network, its partner, miles away, made an identical choice. It's something that normal physics can't explain - something that Einstein dismissed as "spooky action at a distance." It's just one more example of quantum weirdness that makes people think of faster-than-light communication, perfectly secure codes, and other as-yet-unattainable goals. Plus ... where did the moon come from?It's been generally accepted for the past few years that the Moon once was a part of the Earth, formed from debris separated from our planet early on by a tremendous collision with a passing planetoid. Supported by findings from the Apollo missions, this theory has prevailed over other possibilities of Moon formation, including the theory that it was a passing planet captured by Earth's gravity, or that the Moon was a chunk somehow "spun off" from the Earth's surface. Now, a team of planetary scientists at the University of Colorado at Boulder has concluded that the offending object that collided with the Earth may have been much larger than previously thought - about a third of the Earth's mass. Through computer simulations, the team modelled how a large impact could have affected the Earth, and how the debris created by such a collision could have coalesced together to form our Moon. The issue isn't settled, however. According to the Colorado model, a collision of that size would have left the Earth spinning too rapidly. A similar model, from Harvard University, fits the amount of spin -- but doesn't explain where all the mass of the Moon came from. We'll take a look at the "Big Whack" model of Moon formation, and see if it's all that it's whacked up to be.
Robin Canup
"Quantum oscillations between two weakly coupled reservoirs of superfluid 3He" by S.V. Pereverzev, A Loshak, S. Backhaus, J.C. Davis and R.E. Packard. Nature , July 31 1997. "Where Does the Weirdness Go?," by David Lindley. HarperCollins, 1997. The Quantum
Information European Research Network An
abstract of the moon paper, presented this week at the Division of Planetary
Sciences meeting |
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