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Category: physics

Kathryn Zurek realized a decade ago that we may be searching in the wrong places for clues to one of the universe’s greatest unsolved mysteries: dark matter. Despite making up an estimated 85 percent of the total mass of the universe, we haven’t yet figured out what it’s made of.

Now, Zurek, a theoretical physicist at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab), says thanks to extraordinary improvements in experimental sensitivity, “We increasingly know where not to look.” In 2006, during grad school, Zurek began to explore the concept of a new “Hidden Valley” model for physics that could hold all of the answers to .

“I noticed that from a model-builder’s point of view that dark matter was extraordinarily undeveloped,” she said. It seemed as though scientists were figuratively hunting in the dark for answers. “People were focused on models of just two classes of , rather than a much broader array of possibilities.”

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In the last few years, hundreds of contained “nano” satellites known as CubeSats have been launched in low Earth orbit for many purposes, including for collecting targeted scientific data. Federal agencies such as NASA and the National Science Foundation are exploring the potential of these highly affordable satellites in advancing research goals.

A new report from the National Academies of Sciences, Engineering, and Medicine concludes that CubeSats have demonstrated usefulness for scientific data gathering and can also augment – but not replace — the capabilities of large satellite missions and ground-based facilities. The report identifies examples of high-priority science goals that could be pursued through the use of CubeSats in areas such as solar and space physics, planetary science, and Earth science.

In order to continue building the capabilities of CubeSats for research, federal support is crucial, the report says, which identifies several steps NASA and NSF should take to ensure that CubeSats reach their full potential.

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For years, physicists have attempted to explain dark energy — a mysterious influence that pushes space apart faster than gravity can pull the things in it together. But physics isn’t always about figuring out what things are. A lot of it is figuring out what things cause.

And in a recent paper, a group of physicists asked this very question about dark energy, and found that in some cases, it might cause time to go forward.

When you throw a ball into the air, it starts with some initial speed-up, but then it slows as Earth’s gravity pulls it down. If you throw it fast enough (about 11 km per second, for those who want to try), it’ll never slow down enough to turn around and start falling back towards you, but it’ll still move more slowly as it moves away from you, because of Earth’s gravity.

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Improving energy efficiencies — nice.

The remarkable properties researchers at the Australian National University (ARC Centre of Excellence CUDOS) and the University of California Berkeley have discovered in a new nano-metamaterial could lead to highly efficient thermophotovoltaic cells. The new artificial material glows in an unusual way when headed.

As shown in the image, the metamaterial comprises 20 stacked alternating layers of 30-nm-thick gold and 45-nm-thick magnesium fluoride dielectric, perforated with 260 x 530 nm holes that are arranged into a 750 x 750 nm square lattice.

Thermophotovoltaics typically use a heated object as a source of radiation that is then converted to electricity by a photovoltaic cell. The caveat is that heated object emits light in all directions and over a broad spectral region, which reduces the efficiency of the light-to-electricity conversion. However, “The demonstrated metamaterial emits thermal radiation predominantly in particular directions and [within] a particular spectral region, which could make the conversion more efficient,” says Dr Sergey Kruk at the Nonlinear Physics Centre in the ANU Research School of Physics and Engineering.

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ACTON, Australia, May 16 (UPI) — A pair of physicists in Australia have trained an artificial intelligence system to replicate the experiment that won the 2001 Nobel Prize.

The experiment involves what is known as a Bose-Einstein condensate, the trapping of an ultra-cool gas in a series of lasers.

At just a billionth of a degree above absolute zero, Bose-Einstein condensates constitute some of the coldest temperatures in the universe — colder than interstellar space.

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Time travel seems much more common in science fiction than it is in reality. We’ve never met anyone from the future, after all. But all of the physics we know indicates that wormholes — another science fiction favourite — could really be used to travel backwards in time.

And according to a paper by Chinese physicists, using wormholes for time travel might actually allow us to beat Heisenberg’s uncertainty principle — described as one of the most famous (and probably misunderstood) ideas in physics — and even to solve some of the most difficult problems in computer science.

Wormholes are like portals between two places in the Universe. If you fell in one side, you’d pop out the other immediately, regardless of how far apart the two sides were. But wormholes are also like portals between two times in the Universe. As Carl Sagan liked to say, you wouldn’t just emerge some where else in space, but also some when else in time.

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BLOOMINGTON, Ill.— An international team of physicists including Illinois Wesleyan University Professor of Physics Gabe Spalding has shown waves of light can seem to travel back in time.

It may seem like science fiction, but the experiment did not violate the laws of physics. Spalding, his physics student Joseph Richards ’16 and a team of scientists tackled a century-old intuition from Lord Rayleigh regarding the speed of sound. Rayleigh theorized that music being played on an object traveling faster than the speed of sound, a supersonic jet for example, would result in a listener hearing the music playing in reverse. The Spalding team simulated what an observer standing still would see when looking at a superluminal (faster than the speed of light) occurrence. The results of the scientists’ experiment, conducted last summer at Heriot-Watt University in Edinburgh, Scotland, have been published in Science Advances.

“The existence of an absolute limit, the speed of light, is the natural source of the question: what would happen if we cross this limit?” lead author Mattero Clerici told a writer for a post on IFLScience. “Light sources, however, may move faster than the speed of light when their speed is not associated with the physical motion of matter. Following this line of thought, we devised a way to experimentally investigate the [effects] of superluminal motion.”

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