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Category: particle physics – Page 205

Simulation observes three distinct phases of superconducting dynamics

In physics, scientists have been fascinated by the mysterious behavior of superconductors—materials that can conduct electricity with zero resistance when cooled to extremely low temperatures. Within these superconducting systems, electrons team up in “Cooper pairs” because they’re attracted to each other due to vibrations in the material called phonons.

As a thermodynamic phase of matter, superconductors typically exist in an . But recently, researchers at JILA became interested in kicking these materials into excited states and exploring the ensuing dynamics. As reported in a new Nature paper, the theory and experiment teams of JILA and NIST Fellows Ana Maria Rey and James K. Thompson, in collaboration with Prof. Robert Lewis-Swan at the University of Oklahoma, simulated superconductivity under such excited conditions using an atom-cavity system.

Instead of dealing with actual superconducting materials, the scientists harnessed the behavior of strontium atoms, laser-cooled to 10 millionths of a degree above absolute zero and levitated within an optical cavity built out of mirrors.

The northern lights in 2024 are set to be the best in 20 years

It’s all thanks to what is called the “solar maximum,” when the sun is reaching its peak of a roughly 11-year cycle, which NASA says began again in December 2019. The sun’s activity has been ramping up since then, with an expected peak in July 2025.

MORE: Pilot performs mid-flight maneuver to give passengers a rare view of the northern lights

The northern lights, also known as the aurora borealis, happen in regions around the earth’s magnetic pole. They appear when electrons from solar flares interact with atoms and molecules in the Earth’s atmosphere. That in turn creates lights and multiple colors in the sky.

New theory unites Einstein’s gravity with quantum mechanics

A radical theory that consistently unifies gravity and quantum mechanics while preserving Einstein’s classical concept of spacetime is announced today in two papers published simultaneously by UCL (University College London) physicists.

Modern physics is founded upon two pillars: quantum theory on the one hand, which governs the smallest particles in the universe, and Einstein’s theory of general relativity on the other, which explains gravity through the bending of spacetime. But these two theories are in contradiction with each other and a reconciliation has remained elusive for over a century.

The prevailing assumption has been that Einstein’s theory of gravity must be modified, or “quantised”, in order to fit within quantum theory. This is the approach of two leading candidates for a quantum theory of gravity, string theory and loop quantum gravity.

Gravity helps show strong force strength in the proton

The power of gravity is writ large across our visible universe. It can be seen in the lock step of moons as they circle planets; in wandering comets pulled off-course by massive stars; and in the swirl of gigantic galaxies. These awesome displays showcase gravity’s influence at the largest scales of matter. Now, nuclear physicists are discovering that gravity also has much to offer at matter’s smallest scales.

New research conducted by at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility is using a method that connects theories of gravitation to interactions among the smallest particles of matter to reveal new details at this smaller scale. The research has now revealed, for the first time, a snapshot of the distribution of the strong force inside the proton. This snapshot details the shear stress the force may exert on the quark particles that make up the proton. The result was recently published in Reviews of Modern Physics.

According to the lead author on the study, Jefferson Lab Principal Staff Scientist Volker Burkert, the measurement reveals insight into the environment experienced by the proton’s building blocks. Protons are built of three quarks that are bound together by the .

Scientists accidently tie the world’s smallest, tightest knot

This self-assembling ‘metallaknot’ of gold emerged when gold acetylide was combined with a carbon structure known as a diphosphine ligand.

Since 1989, chemists have been exploring ways to tie molecular knots using metal ions to guide helical chains into specific configurations. These knots are typically secured by the presence of metal atoms, which are removed at the end of the process to prevent untying.

However, the self-assembly of the new gold knot suggests a different mechanism at play, one that even the researchers, including chemist Richard Puddephatt from the University of Western Ontario, find mysterious.

Fermi Gamma-ray Space Telescope detects Surprise Gamma-Ray feature Beyond our Galaxy

Astronomers analyzing 13 years of data from NASA’s Fermi Gamma-ray Space Telescope have found an unexpected and as yet unexplained feature outside of our galaxy.

“It is a completely serendipitous discovery,” said Alexander Kashlinsky, a cosmologist at the University of Maryland and NASA’s Goddard Space Flight Center in Greenbelt, who presented the research at the 243rd meeting of the American Astronomical Society in New Orleans. “We found a much stronger signal, and in a different part of the sky, than the one we were looking for.”

Intriguingly, the gamma-ray signal is found in a similar direction and with a nearly identical magnitude as another unexplained feature, one produced by some of the most energetic cosmic particles ever detected.

Long-Range Resonances Slow Light in a Photonic Material

Light can behave in strange ways when it interacts with materials. For example, in a photonic material that consists of periodic arrangements of nanoscale optical cavities, light can slow to a crawl or even stop altogether. Theorists have explained this phenomenon for some of these photonic “metacrystals” using the simplifying assumption that the light in each cavity interacts only with the light in its nearest neighbor cavities. But recent observations of photonic metacrystals with larger unit cells suggest that longer-range interactions should also be considered. Now Thanh Xuan Hoang at the Agency for Science, Technology and Research in Singapore and collaborators have theoretically confirmed the importance of long-range interactions for slowing or stopping light in a one-dimensional photonic metacrystal [1]. The team says that the finding could be used to help researchers design nanoparticle arrays for analog image processing and optical computing.

For their study, Hoang and his collaborators modeled the light–matter interactions within a row of identical dielectric nanoparticles whose diameters were similar to the wavelength of the light. Such a system is relatively tractable with precise solutions, making it a useful tool for investigating the long-range effects hinted at by recent experiments.

When the researchers extended their one-dimensional system to hundreds of nanoparticles, they found that they could collectively excite the particles by oscillating a nearby electric dipole. The resulting system displayed a resonant state that slowed a specific wavelength of light. This outcome occurred only when long-range interactions between particles were permitted. Hoang likens the dipolar emitter to the conductor of an orchestra and the particles to musicians. The nanoparticles harmonize under the conductor’s direction to create a cohesive piece, he says.

A Big Bang from a Quantum Quark?

The universe is governed by four known fundamental forces: gravity, electromagnetism, the weak force, and the strong force. The strong force is responsible for dynamics on an extremely small scale, within and between the individual nucleons of atomic nuclei and between the constituents – quarks and gluons – that make up those nucleons. The strong force is described by a theory called Quantum Chromodynamics (QCD). One of the key details of this theory, known as “asymptotic freedom”, is responsible for both the subatomic scale of the strong force and the significant theoretical difficulties that the strong force has presented to physicists over the past 50 years.

Given the complexity of the strong force, experimental physicists have often led the research frontier and made discoveries that theorists are still trying to describe. This pattern is distinct from many other areas of physics, where experimentalists mostly search for and confirm, or exclude, theoretical predictions. One of the QCD areas where experimentalists have led progress is in the description of the collective behavior of systems with many bodies interacting via the strong force. An example of such a system is the quark-gluon plasma (QGP). A few microseconds after the Big Bang, the universe is supposed to have existed in such a state. The way the universe evolved in these brief moments and the structure that subsequently developed over billions of years is studied, in part, through experimental research on collective QCD effects. This briefing describes a recent exciting development in that research. To better understand the results, we begin with a series of analogies.

Imagine you are on a large university campus. You observe student movements in the middle of a busy exam period and find that the number of students entering the library in the morning is related to the number of students leaving in the evening. Perhaps this indicates some conserved quantity, like the number of students at the school. Each student in the library wants enough room to lay out their supplies and textbooks and get comfortable while studying. The library is nearly full and the students are evenly distributed across all the floors and halls of the library to ensure they have ample space. Recognizing and quantifying correlations like these can be useful for studying collective systems. By counting students “here” you can predict how many students are “there”, or by counting students “now” you can predict how many students you will get “later”. In this example, you may have insight into basic temporal and spatial correlations.

Particle Accelerators in the Sky: NASA’s IXPE Explores “Microquasar” Mechanics

Insights from NASA ’s IXPE mission have transformed our understanding of particle acceleration in black holes, using the microquasar SS 433 as a case study to reveal aligned magnetic fields within its jets.

The powerful gravity fields of black holes can devour whole planets’ worth of matter – often so violently that they expel streams of particles traveling near the speed of light in formations known as jets. Scientists understand that these high-speed jets can accelerate these particles, called cosmic rays, but little is definitively known about that process.

Recent findings by researchers using data from NASA’s IXPE (Imaging X-ray Polarimetry Explorer) spacecraft give scientists new clues as to how particle acceleration happens in this extreme environment. The observations came from a “microquasar,” a system comprised of a black hole siphoning off material from a companion star.