A few scant equations can explain a variety of phenomena in our universe, over vast gulfs of space and time. Here’s a taste of just how powerful modern physics can be.
Category: physics – Page 259
New study detects ringing of the global atmosphere
A ringing bell vibrates simultaneously at a low-pitched fundamental tone and at many higher-pitched overtones, producing a pleasant musical sound. A recent study, just published in the Journal of the Atmospheric Sciences by scientists at Kyoto University and the University of Hawai’i at Mānoa, shows that the Earth’s entire atmosphere vibrates in an analogous manner, in a striking confirmation of theories developed by physicists over the last two centuries.
In the case of the atmosphere, the “music” comes not as a sound we could hear, but in the form of large-scale waves of atmospheric pressure spanning the globe and traveling around the equator, some moving east-to-west and others west-to-east. Each of these waves is a resonant vibration of the global atmosphere, analogous to one of the resonant pitches of a bell. The basic understanding of these atmospheric resonances began with seminal insights at the beginning of the 19th century by one of history’s greatest scientists, the French physicist and mathematician Pierre-Simon Laplace. Research by physicists over the subsequent two centuries refined the theory and led to detailed predictions of the wave frequencies that should be present in the atmosphere. However, the actual detection of such waves in the real world has lagged behind the theory.
Now in a new study by Takatoshi Sakazaki, an assistant professor at the Kyoto University Graduate School of Science, and Kevin Hamilton, an Emeritus Professor in the Department of Atmospheric Sciences and the International Pacific Research Center at the University of Hawai?i at Mānoa, the authors present a detailed analysis of observed atmospheric pressure over the globe every hour for 38 years. The results clearly revealed the presence of dozens of the predicted wave modes.
Contest between superconductivity and insulating states in ‘magic angle’ graphene
If you stack two layers of graphene one on top of the other, and rotate them at an angle of 1.1º (no more and no less) from each other—the so-called ‘magic-angle,’ experiments have proven that the material can behave like an insulator, where no electrical current can flow, and at the same can also behave like a superconductor, where electrical currents can flow without resistance.
This major finding took place in 2018. Last year, in 2019, while ICFO researchers were improving the quality of the device used to replicate such breakthroughs, they stumbled upon something even bigger and totally unexpected. They were able to observe a zoo of previously unobserved superconducting and correlated states, in addition to an entirely new set of magnetic and topological states, opening a completely new realm of richer physics.
So far, there is no theory that has been able to explain superconductivity in magic angle graphene at the microscopic level. However, this finding has triggered many studies, which are trying to understand and unveil the physics behind all these phenomena that occur in this material. In particular, scientists drew analogies to unconventional high temperature superconductors—the cuprates, which hold the record highest superconducting temperatures, only 2 times lower than room temperature. Their microscopic mechanism of the superconducting phase is still not understood, 30 years after its discovery. However, similarly to magic angle twisted bi-layer graphene (MATBG), it is believed that an insulating phase is responsible for the superconducting phase in proximity to it. Understanding the relationship between the superconducting and insulating phases is at the center of researcher’s interest, and could lead to a big breakthrough in superconductivity research.
Mysterious spinning neutron star detected in the Milky Way proves to be an extremely rare discovery
On March 12th 2020 a space telescope called Swift detected a burst of radiation from halfway across the Milky Way. Within a week, the newly discovered X-ray source, named Swift J1818.0–1607, was found to be a magnetar, a rare type of slowly rotating neutron star with one of the most powerful magnetic fields in the universe.
Spinning once every 1.4 seconds, it’s the fastest spinning magnetar known, and possibly one of the youngest neutron stars in the Milky Way. It also emits radio pulses like those seen from pulsars—another type of rotating neutron star. At the time of this detection, only four other radio-pulse-emitting magnetars were known, making Swift J1818.0–1607 an extremely rare discovery.
In a recently published study led by a team of scientists from the ARC Center of Excellence for Gravitational Wave Discovery (OzGrav), it was found that the pulses from the magnetar become significantly fainter when going from low to high radio frequencies: It has a steep radio spectrum. Its radio emission is not only steeper than the four other radio magnetars, but also steeper than ~90% of all pulsars. Additionally, they found the magnetar had become over 10 times brighter in only two weeks.
This new, super-accurate way to pinpoint our solar system’s center may help spot monster black hole crashes
Astronomers have found a way to pinpoint our solar system’s center of mass to within a mere 330 feet (100 meters), a recent study reports.
Such precision — equivalent to the width of a human hair on the scale of a football field — could substantially aid the search for powerful gravitational waves that warp our Milky Way galaxy, study team members said.
“Supernova machine” recreates cosmic blasts in the lab
Supernovae are some of the most energetic events in the universe, and the resulting nebulas are a favorite for stargazers. To better understand the physics behind them, researchers at Georgia Tech have created a “supernova machine” in the lab.
Stars are basically big volatile balls of gas, sustained for millions of years by a delicate balancing act. Intense gravity wants to pull the matter towards the center, but nuclear fusion in the core is pushing outwards at the same time. Eventually though, the core inevitably runs out of nuclear fuel, and gravity wins the battle.
The star then collapses inwards very quickly, and the resulting shock wave sends material flying outwards at extreme speeds. The event is a supernova, the swirling gas and matter is a nebula, and the dense object formed in the center is a neutron star or a black hole.
Physicists Observe Branched Flow of Light
Physicists from the Technion-Israel Institute of Technology and the University of Central Florida have experimentally observed optical branched flow in liquid soap films.
Instead of producing completely random speckle patterns, the slowly varying disordered potential gives rise to focused filaments that divide to form a pattern resembling the branches of a tree.
Researchers observe branched flow of light for the first time
A team of researchers from the Technion – Israel Institute of Technology has observed branched flow of light for the very first time. The findings are published in Nature and are featured on the cover of the July 2, 2020 issue.
The study was carried out by Ph.D. student Anatoly (Tolik) Patsyk, in collaboration with Miguel A. Bandres, who was a postdoctoral fellow at Technion when the project started and is now an Assistant Professor at CREOL, College of Optics and Photonics, University of Central Florida. The research was led by Technion President Professor Uri Sivan and Distinguished Professor Mordechai (Moti) Segev of the Technion’s Physics and Electrical Engineering Faculties, the Solid State Institute, and the Russell Berrie Nanotechnology Institute.
When waves travel through landscapes that contain disturbances, they naturally scatter, often in all directions. Scattering of light is a natural phenomenon, found in many places in nature. For example, scattering of light is the reason for the blue color of the sky. As it turns out, when the length over which disturbances vary is much larger than the wavelength, the wave scatters in an unusual fashion: it forms channels (branches) of enhanced intensity that continue to divide, or branch out, as the wave propagates. This phenomenon is known as branched flow. It was first observed in 2001 with electrons, and had been suggested to be ubiquitous and occur also for all waves in nature, for example sound waves and even ocean waves. Now, Technion researchers are bringing branched flow to the domain of light: they have made an experimental observation of branched flow of light.
Physicists Have Observed Light Flowing Like a River, And It’s Beautiful
Picture in your mind the delta of a river — the way the main channel splits into smaller rivulets and tributaries. Something similar occurs in waves as they propagate through a certain kind of medium: the path of the wave splits, breaking up into smaller channels like the branches of a tree.
This is called a branching flow, and it’s been observed in such phenomena as the flow of electrons (electric current), ocean waves, and sound waves. Now, for the first time, physicists have observed it in visible light — and all it took was a laser and a soap bubble.
Depending on the structure of the medium, different things can happen to waves travelling through; they can attenuate, disperse, bend, spread, or continue flowing.
It happened in just zeptoseconds
Australian and US physicists say they have calculated the speed of the most complex nuclear reactions and found that they’re, well, really fast. We’re talking as little as a zeptosecond – a billionth of a trillionth of a second (10-21).
The finding follows a comprehensive project to calculate detailed models of the energy flow during nuclear collisions.
Cedric Simenel from the Australian National University worked with Kyle Godbey and Sait Umar from Vanderbilt University to model 13 different pairs of nuclei, using supercomputers at ANU and in the US.