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(Phys.org)—For more than 100 years, scientists have debated the question: when light travels through a medium such as oil or water, does it pull or push on the medium? While most experiments have found that light exerts a pulling pressure, in a new paper physicists have, for the first time, found evidence that light exerts a pushing pressure.

The scientists suggest that this apparent contradiction is not a fundamental one, but can be explained by the interplay between the light and the fluid medium: if the light can put the fluid in motion, it exerts a pushing force; if not, it exerts a pulling force.

The researchers, Li Zhang, Weilong She, and Nan Peng at Sun Yat-Sen University in Guangzhou, China, and Ulf Leonhardt at the Weizmann Institute of Science in Rehovot, Israel, have published a paper on the first evidence for the pushing pressure of light in a recent issue of the New Journal of Physics.

Continue reading “Physicists make first observation of the pushing pressure of light” »

New fundamental research by UT Dallas physicists may accelerate the drive toward more advanced electronics and more powerful computers.

The scientists are investigating materials called topological insulators, whose surface electrical properties are essentially the opposite of the properties inside.

“These materials are made of the same thing throughout, from the interior to the exterior,” said Dr. Fan Zhang, assistant professor of physics at UT Dallas. “But, the interior does not conduct electrons — it’s an insulator — while the electrons on the surface are free to move around. The surface is therefore a conductor, like a metal, but it is in fact more robust than a metal.”

Continue reading “Creation of Weak Materials Offers Strong Possibilities for Electronics” »

Interesting…

First, we take ‘Time’, as we know it’s one of those things that we take for granted—time moves forward and never backward. But did you ever stop to wonder why it moves in one direction, as opposed to the other?

The question continues to stump physicists. After all, there are certain physical processes that are actually time-reversible—they look the same no matter which way you run them.

Continue reading “New Research Suggests Dark Energy Might be the Reason Time Runs Forward” »

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 dark matter.

“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 dark matter candidates, 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.

Continue reading “Assessing the Scientific Potential of Small CubeSat Satellites — New Report” »

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.

Continue reading “Physicists just found a link between dark energy and the arrow of time” »

The most fundamental limitations of modern physics might not be so limiting after all.

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.

Continue reading “Magnetic Hyperbolic Optical Metamaterial Could Advance Thermophotovoltaics” »

A proposed Japanese accelerator could solve those mysteries the LHC did not.

By Howard Baer, Vernon D. Barger, Jenny List on June 1, 2016.