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Category: physics – Page 244

LIVINGSTON, La. — About a mile and a half from a building so big you can see it from space, every car on the road slows to a crawl. Drivers know to take the 10 mph (16 km/h) speed limit very seriously: That’s because the building houses a massive detector that’s hunting for celestial vibrations at the smallest scale ever attempted. Not surprisingly, it’s sensitive to all earthly vibrations around it, from the rumblings of a passing car to natural disasters on the other side of the globe.

As a result, scientists who work at one of the LIGO (Laser Interferometer Gravitational-Wave Observatory) detectors must go to extraordinary lengths to hunt down and remove all potential sources of noise — slowing down traffic around the detector, monitoring every tiny tremor in the ground, even suspending the equipment from a quadruple pendulum system that minimizes vibrations — all in the effort to create the most “silent” vibrational spot on Earth.

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I am going home :3.

Everybody wants a wormhole. I mean, who wants to bother traveling the long-and-slow routes throughout the universe, taking tens of thousands of years just to reach yet another boring star? Not when you can pop into the nearest wormhole opening, take a short stroll, and end up in some exotic far-flung corner of the universe.

There’s a small technical difficulty, though: Wormholes, which are bends in space-time so extreme that a shortcut tunnel forms, are catastrophically unstable. As in, as soon as you send a single photon down the hole, it collapses faster than the speed of light.

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Theoretical physicists from SISSA and the University of California at Davis have developed a new approach to heat transport in materials, which finally allows crystals, polycrystalline solids, alloys and glasses to be treated on the same solid footing. It opens the way to the numerical simulation of the thermal properties of a vast class of materials in important fields such as energy saving, conversion, scavenging, storage, heat dissipation, shielding and the planetary sciences, which have thus far dodged a proper computational treatment. The research has been published in Nature Communications.

Heat dissipates over time. In a sense, is the defining feature of the arrow of time. In spite of the foundational importance of heat transport, the father of its modern theory, Sir Rudolph Peierls, wrote in 1961, “It seems there is no problem in modern physics for which there are on record as many false starts, and as many theories which overlook some essential feature, as in the problem of the thermal conductivity of nonconducting crystals.”

A half-century has passed since, and heat transport is still one of the most elusive chapters of theoretical materials science. As a matter of fact, no unified approach has been able to treat crystals and (partially) disordered solids on equal footing, thus hindering the efforts of generations of materials scientists to simulate certain materials, or different states of the same material occurring in the same physical system or device with the same accuracy.

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A University of Texas at Dallas physicist has teamed with Texas Instruments Inc. to design a better way for electronics to convert waste heat into reusable energy.

The collaborative project demonstrated that silicon’s ability to harvest energy from heat can be greatly increased while remaining mass-producible.

Dr. Mark Lee, professor and head of the Department of Physics in the School of Natural Sciences and Mathematics, is the corresponding author of a study published July 15 in Nature Electronics that describes the results. The findings could greatly influence how circuits are cooled in electronics, as well as provide a method of powering the sensors used in the growing “internet of things.”

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When energy is added to uranium under pressure, it creates a shock wave, and even a tiny sample will be vaporized like a small explosion. By using smaller, controlled explosions, physicists can test on a microscale in a safe laboratory environment what could previously be tested only in larger, more dangerous experiments with bombs.

“In our case, it’s the laser depositing energy into a target, but you get the same formation and time-dependent evolution of plasma,” author Patrick Skrodzki said. “With these small-scale explosions in the lab, we can understand similar physics.”

In a recent experiment, scientists working with Skrodzki used a laser to ablate atomic uranium, stealing its electrons until it ionized and turned to plasma, all while recording as the plasma cooled, oxidized and formed species of more complex uranium. Their work puts uranium species and the reaction pathways between them onto a map of space and time to discover how many nanoseconds they take to form and at which part of the plasma’s evolution.

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It’s not like the one in your car, but a team of physicists at Trinity College Dublin have built what they claim is the world’s smallest engine. The engine is the size of a single calcium ion — about ten billion times smaller than an automobile engine.

Rather than powering your next road trip, the atomic engine could one day be used to lay the foundation for extraordinary, futuristic nanotechnologies.

Here’s how it works: the calcium ion holds an electrical charge, which makes it spin. This angular momentum is then used to convert heat from a laser beam into vibrations.

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By Rachel Courtland

The crust of neutron stars is 10 billion times stronger than steel, according to new simulations. That makes the surface of these ultra-dense stars tough enough to support long-lived bulges that could produce gravitational waves detectable by experiments on Earth.

Neutron stars are the cores left behind when relatively massive stars explode in supernovae. They are incredibly dense, packing about as much mass as the sun into a sphere just 20 kilometres or so across, and some rotate hundreds of times per second.

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The Universe is expanding, and that expansion is speeding up over time. These two facts have been well established through observation, but we don’t know what’s causing that expansion. It seems to be some mysterious, unknown energy that acts like the opposite of gravity.

We call this hypothetical energy “dark energy”, and it’s been calculated to constitute around 72 percent of all the stuff that makes up the Universe. We don’t know what it actually is. But a new experiment has just allowed us to rule out one more thing that it isn’t: a new force.

“This experiment, connecting atomic physics and cosmology, has allowed us to rule out a wide class of models that have been proposed to explain the nature of dark energy, and will enable us to constrain many more dark energy models,’‘said physicist Ed Copeland of the University of Nottingham.

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