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Category: physics

Researchers at Kobe University and Osaka University have successfully developed artificial intelligence technology that can extract hidden equations of motion from regular observational data and create a model that is faithful to the laws of physics.

This technology could enable researchers to discover the hidden equations of motion behind for which the laws were considered unexplainable. For example, it may be possible to use physics-based knowledge and simulations to examine ecosystem sustainability.

The research group consisted of Associate Professor YAGUCHI Takaharu and Ph.D. student CHEN Yuhan (Graduate School of System Informatics, Kobe University), and Associate Professor MATSUBARA Takashi (Graduate School of Engineering Science, Osaka University).

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Physicists from Trinity have unlocked the secret that explains how large groups of individual “oscillators”—from flashing fireflies to cheering crowds, and from ticking clocks to clicking metronomes—tend to synchronize when in each other’s company.

Their work, just published in the journal Physical Review Research, provides a mathematical basis for a phenomenon that has perplexed millions—their newly developed equations help explain how individual randomness seen in the and in electrical and computer systems can give rise to synchronization.

We have long known that when one clock runs slightly faster than another, physically connecting them can make them tick in time. But making a large assembly of clocks synchronize in this way was thought to be much more difficult—or even impossible, if there are too many of them.

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On April 28, 2021, at 933 UT (3:33 a.m. Eastern Daylight Time), NASA’s Parker Solar Probe reached the sun’s extended solar atmosphere, known as the corona, and spent five hours there. The spacecraft is the first to enter the outer boundaries of our sun.

The results, published in Physical Review Letters, were announced in a press conference at the American Geophysical Union Fall Meeting 2021 on December 14. The manuscript is open-access and freely available to download.

“This marks the achievement of the primary objective of the Parker mission and a new era for understanding the physics of the corona,” said Justin C. Kasper, the first author, Deputy Chief Technology Officer at BWX Technologies, and a professor at the University of Michigan. The mission is led by the Johns Hopkins University Applied Physics Laboratory (JHU/APL).

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Nature’s strongest material now has some stiff competition. For the first time, researchers have hard evidence that human-made hexagonal diamonds are stiffer than the common cubic diamonds found in nature and often used in jewelry.

Named for their six-sided crystal structure, hexagonal diamonds have been found at some meteorite impact sites, and others have been made briefly in labs, but these were either too small or had too short of an existence to be measured.

Now scientists at Washington State University’s Institute for Shock Physics created hexagonal diamonds large enough to measure their stiffness using sound waves. Their findings are detailed in a recent paper in Physical Review B.

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Researchers at the University of East Anglia and the University of Manchester have helped conduct a 16-year long experiment to challenge Einstein’s theory of general relativity.

The international team looked to the stars — a pair of extreme stars called pulsars to be precise – through seven radio telescopes across the globe.

And they used them to challenge Einstein’s most famous theory with some of the most rigorous tests yet.

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They’ve become an essential ingredient of astrophysics.

Black holes helped to explain new astronomical discoveries, becoming essential ingredients of astrophysics. Science regarded black holes as abstractions until the 1960s. The recent experimental discovery of gravitational waves has changed our understanding of what black holes are.

In 2016, the LIGO-Virgo collaboration detected gravitational waves generated by two merging black holes, opening a new era of astronomy celebrated by the 2017 Nobel Prize in physics.

In 2019, the Event Horizon Telescope released an image of the supermassive black hole in the nearby galaxy M87. The following year, the Nobel Prize in physics recognized the trailblazing theoretical black hole studies of Roger Penrose and the observational ones by Andrea Ghez and Reinhard Genzel.

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Gravitational waves are cosmic ripples in the fabric of space and time that emanate from catastrophic events in space, like collisions of black holes and neutron stars — the collapsed cores of massive supergiant stars. Extremely sensitive gravitational-wave detectors on Earth, like the Advanced LIGO

The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory supported by the National Science Foundation and operated by Caltech and MIT. It’s designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. It’s multi-kilometer-scale gravitational wave detectors use laser interferometry to measure the minute ripples in space-time caused by passing gravitational waves. It consists of two widely separated interferometers within the United States—one in Hanford, Washington and the other in Livingston, Louisiana.

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A nervous excitement hangs in the air. Half a dozen scientists sit behind computer screens, flicking between panels as they make last-minute checks. “Go and make the gun dangerous,” one of them tells a technician, who slips into an adjacent chamber. A low beep sounds. “Ready,” says the person running the test. The control room falls silent. Then, boom.

Next door, 3 kilograms of gunpowder has compressed 1,500 liters of hydrogen to 10,000 times atmospheric pressure, launching a projectile down the 9-meter barrel of a two-stage light gas gun at a speed of 6.5 kilometers per second, about 10 times faster than a bullet from a rifle.

On the monitors the scientists are checking the next stage, when the projectile slams into the target—a small transparent block carefully designed to amplify the force of the collision. The projectile needs to hit its mark perfectly flush. The slightest rotation risks derailing the carefully calibrated physics.

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Black holes are one of the greatest mysteries of the universe—for example, a black hole with the mass of our sun has a radius of only 3 kilometers. Black holes in orbit around each other emit gravitational radiation—oscillations of space and time predicted by Albert Einstein in 1916. This causes the orbit to become faster and tighter, and eventually, the black holes merge in a final burst of radiation. These gravitational waves propagate through the universe at the speed of light, and are detected by observatories in the U.S. (LIGO) and Italy (Virgo). Scientists compare the data collected by the observatories against theoretical predictions to estimate the properties of the source, including how large the black holes are and how fast they are spinning. Currently, this procedure takes at least hours, often months.

An interdisciplinary team of researchers from the Max Planck Institute for Intelligent Systems (MPI-IS) in Tübingen and the Max Planck Institute for Gravitational Physics (Albert Einstein Institute/AEI) in Potsdam is using state-of-the-art machine learning methods to speed up this process. They developed an algorithm using a , a complex computer code built from a sequence of simpler operations, inspired by the human brain. Within seconds, the system infers all properties of the binary black-hole source. Their research results are published today in Physical Review Letters.

“Our method can make very accurate statements in a few seconds about how big and massive the two were that generated the gravitational waves when they merged. How fast do the black holes rotate, how far away are they from Earth and from which direction is the gravitational wave coming? We can deduce all this from the observed data and even make statements about the accuracy of this calculation,” explains Maximilian Dax, first author of the study Real-Time Gravitational Wave Science with Neural Posterior Estimation and Ph.D. student in the Empirical Inference Department at MPI-IS.

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Can you imagine sound travels in the same way as light does? A research team at City University of Hong Kong (CityU) discovered a new type of sound wave: the airborne sound wave vibrates transversely and carries both spin and orbital angular momentum like light does. The findings shattered scientists’ previous beliefs about the sound wave, opening an avenue to the development of novel applications in acoustic communications, acoustic sensing, and imaging.

The research was initiated and co-led by Dr. Wang Shubo, Assistant Professor in the Department of Physics at CityU, and conducted in collaboration with scientists from Hong Kong Baptist University (HKBU) and the Hong Kong University of Science and Technology (HKUST). It was published in Nature Communications, titled “Spin-orbit interactions of transverse sound.”

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