New calculations support an alternative to "superfluidity" of a solid as the explanation for the behavior of an isotope of helium, 4He, at temperatures approaching Absolute Zero, according to a report in Physical Review Letters.
Among the most provocative recent reports in condensed materials science were studies interpreting the behavior of solid 4He in an oscillating chamber as a "supersolid." In this current paper, John S. Wettlaufer, professor of geophysics andphysics at Yale University, and his colleague J. G. Dash, emeritus professor of physics at University of Washington, offer another possible explanation.
"If you rotate a container of nearly-frozen liquid 4He, even gently, it does unusual things -- hydrodynamically," said Wettlaufer. Superfluidity has long been shown to occur as liquid 4He is cooled to within two degrees of Absolute Zero. In this state, the liquid can flow without any resistance; rotating in a container it can continue without slowing, as long as it is kept at the low temperature. The state is an effect of quantum physics known as Bose-Einstein condensation (BEC).
Janet Rettig Emanuel | EurekAlert!
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A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
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In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
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The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.
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Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water
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The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.
Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...
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