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Scientists find a practical test for string theory

Scientists find a practical test for string theory | Telos | Scoop.it
Scientists at Towson University in Towson, Maryland, have identified a practical, yet overlooked, test of string theory based on the motions of planets, moons and asteroids, reminiscent of Galileo's famed test of gravity by dropping balls from the Tower of Pisa. String theory is infamous as an eloquent theoretical framework to understand all forces in the universe —- a so-called "theory of everything" —- that can't be tested with current instrumentation because the energy level and size scale to see the effects of string theory are too extreme. Yet inspired by Galileo Galilei and Isaac Newton, Towson University scientists say that precise measurements of the positions of solar-system bodies could reveal very slight discrepancies in what is predicted by the theory of general relativity and the equivalence principle, or establish new upper limits for measuring the effects of string theory. String theory hopes to provide a bridge between two well-tested yet incompatible theories that describe all known physics: Einstein's general relativity, our reigning theory of gravity; and the standard model of particle physics, or quantum field theory, which explains all the forces other than gravity. Building on work done by Kenneth Nordtvedt and others beginning in the 1970s, Overduin and his collaborators consider three possible signatures of equivalence principle violation in the solar system: departures from Kepler's Third Law of planetary motion; drift of the stable Lagrange points; and orbital polarization (also known as the Nordtvedt effect), whereby the distance between two bodies like the Earth and Moon oscillates due to differences in acceleration toward a third body like the Sun. To date, there is no evidence for any of these effects. Indeed, the standard astronomical ephemeris assumes the validity of Kepler's Third Law in deriving such fundamental quantities as the length of the Astronomical Unit. But all observations in science involve some degree of experimental uncertainty. The approach of Overduin's team is to use these experimental uncertainties themselves to obtain upper limits on possible violations of the equivalence principle by the planets, moons and Trojan asteroids in the solar system. "The Saturnian satellites Tethys and Dione make a particularly fascinating test case," said Warecki, who is presenting this work at Session 109 at the AAS meeting today. "Tethys is made almost entirely of ice, while Dione possesses a significantly rocky core. And both have Trojan companions." "The limits obtained in this way are not as sensitive as those from dedicated torsion-balance or laser-ranging tests," said Mitcham. "But they are uniquely valuable as potential tests of string theory nonetheless because they cover a much wider range of test-body materials."
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These Harvard researchers are making a new type of battery using the same molecule in rhubarb | GigaOM Clean Tech News

These Harvard researchers are making a new type of battery using the same molecule in rhubarb | GigaOM Clean Tech News | Telos | Scoop.it
Rhubarb isn’t just good for baking in pies — turns out the natural molecules found in the plant are being used as the basis for a new type of battery for the power grid, developed by a group of Professors at Harvard. The Harvard researchers and engineers set out to build a low cost, metal-free flow battery, which is a type of battery that uses separate liquid tanks to store energy. In contrast, the batteries in your laptop and cell phone (and even in an electric car), use chemicals that are adjacent and enclosed in a casing. But by separating the electrolyte out of the battery, flow batteries can easily scale up and down (using larger and smaller tanks) to deliver the capacity needed, and can thus be lower cost than traditional batteries. Click headline to read more--
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