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Category: physics – Page 314

Sun protection without blinds

Summer. Blue sky. Sunshine. But you don’t notice much of it in the office or in your home, because the blinds block the view so that the heat stays outside. This scenario could soon be a thing of the past: EPFL researchers are working with Empa on a window glass that keeps out the heat in summer and at the same time allows a clear view of the outside world.

Depending on the season, windows must have a different function in order to provide sufficient comfort in offices and apartments. In summer they should keep heat away and prevent glare from the sun. In winter they should distribute the little light optimally in the room. A team led by Andreas Schüler from the Laboratory for Solar Energy and Building Physics at EPFL has recently developed a that meets all these criteria. In cooperation with Empa researchers led by Patrik Hoffmann from the Laboratory for Advanced Materials Processing in Thun, work is currently underway on their manufacture—which could soon make sun blinds redundant. Seasonal window glass reduces summer overheating and glare in buildings and ensures high and daylight input in winter. All this without impairing the view outwards through dimming or blinds.

Jing Gong, a Ph.D. student at EPFL, used Empa’s highly complex laser system in Thun to produce a so-called master form with a microstructured surface with the precision laser. Micro mirrors are then evaporated into these micro-grooves and encapsulated in a polymer film. This film can then be easily inserted into a conventional double-glazed window. The arrangement of so-called “Compound Parabolic Concentrator” (CPC) lenses is used to optimally reflect sunlight with low restrictions in visibility. While the first prototypes have been developed in the laboratory, the researchers are already working on up-scaling. In a pilot project in cooperation with BASF Switzerland, the team is working on a manufacturing process that should make it possible to produce the window glass coating consisting of millions of micro mirrors with high precision, quickly and cost-effectively. This poses a major challenge due to the very high optical quality requirements.

Laser-driven electron recollision remembers molecular orbital structure

Scientists from the Max Born Institute for Nonlinear Optics and Short Pulse Spectroscopy (MBI) in Berlin combined state-of-the-art experiments and to test a fundamental assumption underlying strong-field physics. Their results refine our understanding of strong-field processes such as high harmonic generation (HHG) and laser-induced electron diffraction (LIED).

Strong can extract an electron from a molecule (ionization), accelerate it away into free space, then turn it around (propagation), and finally collide it with the molecule (recollision). This is the widely used three-step model of strong-field physics. In the recollision step, the electron may, for example, recombine with the parent ion, giving rise to high harmonic generation, or scatter elastically, giving rise to laser-induced electron diffraction.

One of the commonly used assumptions underlying attosecond is that, in the propagation step, the initial structure of the ionized electron is “washed out”, thus losing the information on the originating orbital. So far, this assumption was not experimentally verified in molecular systems.

Stephen Hawking’s Final Theory About Our Universe Has Just Been Published, And It Will Melt Your Brain

Posthumous journal.

Groundbreaking physicist Stephen Hawking left us one last shimmering piece of brilliance before he died: his final paper, detailing his last theory on the origin of the Universe, co-authored with Thomas Hertog from KU Leuven.

The paper, published today in the Journal of High Energy Physics, puts forward that the Universe is far less complex than current multiverse theories suggest.

It’s based around a concept called eternal inflation, first introduced in 1979 and published in 1981.

Singularity Hypotheses Analysis

Publication numbers are in: 55 thousand downloads! 🎉😁🍾.

Singularity Hypotheses: A Scientific and Philosophical Assessment offers authoritative, jargon-free essays and critical commentaries on accelerating technological progress and the notion of technological singularity. It focuses on conjectures about the intelligence explosion, transhumanism, and whole brain emulation. Recent years have seen a plethora of forecasts about the profound, disruptive impact that is likely to result from further progress in these areas. Many commentators however doubt the scientific rigor of these forecasts, rejecting them as speculative and unfounded. We therefore invited prominent computer scientists, physicists, philosophers, biologists, economists and other thinkers to assess the singularity hypotheses. Their contributions go beyond speculation, providing deep insights into the main issues and a balanced picture of the debate.

New research could literally squeeze more power out of solar cells

Physicists at the University of Warwick have today, Thursday 19th April 2018, published new research in the fournal Science today 19th April 2018 (via the Journal’s First Release pages) that could literally squeeze more power out of solar cells by physically deforming each of the crystals in the semiconductors used by photovoltaic cells.

The paper entitled the “Flexo-Photovoltaic Effect” was written by Professor Marin Alexe, Ming-Min Yang, and Dong Jik Kim who are all based in the University of Warwick’s Department of Physics.

The Warwick researchers looked at the physical constraints on the current design of most commercial solar cells which place an absolute limit on their efficiency. Most commercial solar cells are formed of two layers creating at their boundary a junction between two kinds of semiconductors, p-type with positive charge carriers (holes which can be filled by electrons) and n-type with negative charge carriers (electrons).

Wormholes Could Cast ‘Shadows’ That We Can Detect

Wormholes, or hypothetical tunnels through space-time that allow faster-than-light travel, could potentially leave dark, telltale imprints in the sky that might be seen with telescopes, a new study suggests.

These slightly bent, oblong wormhole “shadows” could be distinguished from the more circular patches left by black holes and, if detected, could show that the cosmic shortcuts first proposed by Albert Einstein more than a century ago are, in fact, real, one researcher says.

Wormholes are cosmic shortcuts, tunnels burrowing through hyperspace. Hop in one end, and you could emerge on the other side of the universe — a convenient method of hyperfast travel that’s become a trope of science fiction. [8 Ways You Can See Einstein’s Theory of Relativity in Real Life].

A City-Sized ‘Telescope’ Could Watch Space-Time Ripple 1 Million Times a Year

COLUMBUS, Ohio — A gravitational wave detector that’s 2.5 miles long isn’t cool. You know what’s cool? A 25-mile-long gravitational wave detector.

That’s the upshot of a series of talks given here Saturday (April 14) at the April meeting of the American Physical Society. The next generation of gravitational wave detectors will peer right up to the outer edge of the observable universe, looking for ripples in the very fabric of space-time, which Einstein predicted would occur when massive objects like black holes collide. But there are still some significant challenges standing in the way of their construction, presenters told the audience.

“The current detectors you might think are very sensitive,” Matthew Evans, a physicist at MIT, told the audience. “And that’s true, but they’re also the least sensitive detectors with which you can [possibly] detect gravitational waves.” [8 Ways You Can See Einstein’s Theory of Relativity in Real Life].

Scientists Create Beautiful Iridescent Material That Could Be Edible

What makes something red, or blue, or green? It’s all in the way light bounces off its surface. Something that primarily reflects light with shorter wavelengths will appear bluer, while something that reflects longer wavelengths will appear redder. By playing around with that principle, scientists have created a material that, much like soap bubbles and certain insect wings, displays a gorgeous iridescence—a shifting rainbow of colors they can tweak with the same surface.

Even more interestingly, the researchers made this material from common cellulose, the simple stuff that makes up paper and which can be extracted from wood, cotton, or other renewable sources. We’ve already mentioned scientists arranging cellulose fibers in a way that makes them appear incredibly white. But now instead of laying fibers, a team of physicists are molding cellulose films with tiny, regularly spaced impressions (like an upside-down Lego piece).

The outcome was a thin, single-centimeter iridescent film that reflects light based on the spacing of the dots, according to the paper published recently in Nature Photonics.