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Category: physics – Page 220

Eindhoven University of Technology researchers found five different phases in mixtures of two substances.

Frozen water can take on up to three forms at the same time when it melts: liquid, ice, and gas. This principle, which states that many substances can occur in up to three phases simultaneously, was explained 150 years ago by the Gibbs phase rule. Today, researchers from Eindhoven University of Technology and University Paris-Saclay are defying this classical theory, with proof of a five-phase equilibrium, something that many scholars considered impossible. This new knowledge yields useful insights for industries that work with complex mixtures, such as in the production of mayonnaise, paint, or LCD’s. The researchers have published their results in the journal Physical Review Letters.

The founder of contemporary thermodynamics and physical chemistry is the American physicist Josiah Willard Gibbs. In the 1870s he derived the phase rule, which describes the maximum number of different phases a substance or mixture of substances can assume simultaneously. For pure substances, the Gibbs Phase Rule predicts a maximum of 3 phases.

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Circa 2017

One of the more curious challenges in physics is to understand the nature of time. At the microscopic level, the laws of physics are symmetric with respect to time—they work just as well whether time runs forwards or backwards. But at the macroscopic level, processes all have a preferred direction. The great physicist Arthur Eddington called this the “arrow of time.”

Just why this arrow points in one direction but not the other is one of the great scientific puzzles. The standard answer is that the arrow of time follows from the Second Law of Thermodynamics—that disorder, or entropy, always increases in a closed system.

That’s why milk mixes easily in tea but never emerges from a brew, why scrambled eggs never spontaneously unscramble, and why your morning mug of coffee heats your hands as you hold it and not the other way around.

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Researchers from the Moscow Institute of Physics and Technology and King’s College London cleared the obstacle that had prevented the creation of electrically driven nanolasers for integrated circuits. The approach, reported in a recent paper in Nanophotonics, enables coherent light source design on the scale not only hundreds of times smaller than the thickness of a human hair but even smaller than the wavelength of light emitted by the laser. This lays the foundation for ultrafast optical data transfer in the manycore microprocessors expected to emerge in the near future.

Light signals revolutionized information technologies in the 1980s, when optical fibers started to replace copper wires, making data transmission orders of magnitude faster. Since optical communication relies on light— with a frequency of several hundred terahertz—it allows transferring terabytes of data every second through a single fiber, vastly outperforming electrical interconnects.

Fiber optics underlies the modern internet, but light could do much more for us. It could be put into action even inside the microprocessors of supercomputers, workstations, smartphones, and other devices. This requires using optical communication lines to interconnect the purely , such as processor cores. As a result, vast amounts of information could be transferred across the chip nearly instantaneously.

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Are you ready?

“if you were the type of geek, growing up, who enjoyed taking apart mechanical things and putting them back together again, who had your own corner of the garage or the basement filled with electronics and parts of electronics that you endlessly reconfigured, who learned to solder before you could ride a bike, your dream job would be at the Intelligent Systems Center of the Applied Physics Laboratory at Johns Hopkins University. Housed in an indistinct, cream-colored building in a part of Maryland where you can still keep a horse in your back yard, the ISC so elevates geekdom that the first thing you see past the receptionist’s desk is a paradise for the kind of person who isn’t just thrilled by gadgets, but who is compelled to understand how they work.”

Then there are the legal questions: Can the cops make you wear one? What if they have a warrant to connect your brain to a computer? How about a judge? Your commanding officer? How do you keep your Google Nest from sending light bulb ads to your brain every time you think the room is too dark?

A wearable device that can decode the voice in your head is a way’s off yet, said Jack Gallant, professor of psychology at University of California, Berkeley and a leading expert in cognitive neuroscience. But he also said, “Science marches on. There’s no fundamental physics reason that someday we’re not going to have a non-invasive brain-machine interface. It’s just a matter of time.

”And we have to manage that eventuality.”

Continue reading “The brain-computer interface is coming, and we are so not ready for it” | >

Long-distance cargo ships lose a significant amount of energy due to fluid friction. Looking to the drag reduction mechanisms employed by aquatic life can provide inspiration on how to improve efficiency.

Fish and seaweed secrete a layer of mucus to create a slippery surface, reducing their friction as they travel through water. A potential way to mimic this is by creating -infused surfaces covered with cavities. As the cavities are continuously filled with the lubricant, a layer is formed over the surface.

Though this method has previously been shown to work, reducing drag by up to 18%, the underlying physics is not fully understood. In the journal Physics of Fluids, researchers from the Korea Advanced Institute of Science and Technology and Pohang University of Science and Technology conducted simulations of this process to help explain the effects.

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Electricity and magnetism are closely related: Power lines generate a magnetic field, rotating magnets in a generator produce electricity. However, the phenomenon is much more complicated: electrical and magnetic properties of certain materials are also coupled with each other. Electrical properties of some crystals can be influenced by magnetic fields—and vice versa. In this case one speaks of a “magnetoelectric effect.” It plays an important technological role, for example in certain types of sensors or in the search for new concepts of data storage.

A special material was investigated for which, at first glance, no would be expected at all. But careful experiments have now shown that the effect can be observed in this material, it only works completely differently than usual. It can be controlled in a highly sensitive way: Even small changes in the direction of the can switch the of the material to a completely different state.

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Three physicists won a $3 million Breakthrough prize for proving there is no fifth force (that we know of). And it all started with a series of table-top experiments using cheap equipment.

Eric Adelberger, Jens Gundlach and Blayne Heckel together lead the “Eöt-Wash Group,” which is devoted to precise tests of physical laws. They take their name from the early-1900s physicist Loránd Eötvös and the University of Washington, where they work. These Eöt-Wash researchers got their start in the mid-1980s, using a device known as a “torsion balance” to disprove claims of an undiscovered fifth force in physics. Since then, they’ve used more elaborate versions of the same device to test the true strength of gravity, detect the tug of dark matter in the Milky Way and search for theoretical physical effects like extra dimensions and “axion wind.”

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