Physics News and Discussions

User avatar
wjfox
Site Admin
Posts: 1586
Joined: Sat May 15, 2021 6:09 pm
Location: Plague Island
Contact:

Re: Physics News and Discussions

Post by wjfox »

Acoustic tweezers can pick up objects without physical contact

July 26, 2021

Researchers from Tokyo Metropolitan University have developed a new technology which allows non-contact manipulation of small objects using sound waves. They used a hemispherical array of ultrasound transducers to generate a 3D acoustic field that stably trapped and lifted a small polystyrene ball from a reflective surface. Their technique employs a method similar to laser trapping in biology, but adaptable to a wider range of particle sizes and materials.

https://phys.org/news/2021-07-acoustic- ... ntact.html


Image
"Take it easy, nothing matters in the end."
– William Shatner
User avatar
Yuli Ban
Posts: 1729
Joined: Sun May 16, 2021 4:44 pm

Re: Physics News and Discussions

Post by Yuli Ban »

Famous Einstein equation used to create matter from light for first time
In a stunning demonstration of one of Einstein's most famous equations, physicists are claiming to have created matter from pure light for the very first time.

Albert Einstein's famous E=mc2 equation says that if you smash two sufficiently energetic photons, or light particles, into each other, you should be able to create matter in the form of an electron and its antimatter opposite, a positron.

But this process, first described by American physicists Gregory Breit and John Wheeler in 1934, has long been one of the most difficult to observe in physics — mainly because the colliding photons would need to be highly energetic gamma rays, and scientists are not yet able to make gamma ray lasers. Alternative experiments have shown matter being produced from multiple photons, but never in the one to one way needed to most conclusively prove the effect.
And remember my friend, future events such as these will affect you in the future
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Scientists get photons to interact with pairs of atoms for the first time
https://phys.org/news/2021-08-scientist ... atoms.html

Physicists at EPFL have found a way to get photons to interact with pairs of atoms for the first time. The breakthrough is important for the field of cavity quantum electrodynamics (QED), a cutting-edge field leading the way to quantum technologies.

There is no doubt that we are moving steadily toward an era of technologies based on quantum physics. But to get there, we first have to master the ability to make light interact with matter—or more technically, photons with atoms.

This has already been achieved to some degree, giving us the cutting-edge field of cavity quantum electrodynamics (QED), which is already used in quantum networks and quantum information processing. Nonetheless, there are still a long way to go. Current light-matter interactions are limited to individual atoms, which limits our ability to study them in the sort of complex systems involved in quantum-based technologies.

In a paper published in Nature, researchers from the group of Jean-Philippe Brantut at EPFL's School of Basic Sciences have found a way to get photons to 'mix' with pairs of atoms at ultra-low temperatures.
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Unified theory explains how materials transform from solids to liquids
https://phys.org/news/2021-09-theory-ma ... quids.html
by Lois Yoksoulian, University of Illinois at Urbana-Champaign
Years of meticulous experimentation have paid off for researchers aiming to unify the physics that defines materials that transition from solids to liquids. The researchers said a new theoretical model could help develop new synthetic materials and inform and predict civil engineering and environmental challenges such as mudslides, dam breaks and avalanches.

The study, led by University of Illinois Urbana-Champaign chemical and biomolecular engineering professor Simon Rogers, unveils a unified mathematical expression that defines how soft-yet-rigid materials transition from a solid into a liquid flow when they exceed their specific stress threshold. The findings are published in the journal Physical Review Letters.
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Researchers realize a spin field-effect transistor at room temperature
https://phys.org/news/2021-09-field-eff ... ature.html
by Ingrid Fadelli , Phys.org
A crucial goal of spintronics research is to coherently manipulate electron spins at room temperature using electrical current. This is particularly valuable as it would enable the development of numerous devices, including spin field-effect transistors.

In experiments using conventional materials, engineers and physicists have so far only observed coherent spin precession in the ballistic regime and at very low temperatures. Two-dimensional (2D materials), however, have unique characteristics that could provide new control knobs to manipulate spin procession.

Researchers at CIC nanoGUNE BRTA in Spain and University of Regensburg in Germany have recently demonstrated spin precession at room temperature in the absence of a magnetic field in bilayer graphene. In their paper, published in Physical Review Letters, they used 2D materials to realize a spin field-effect transistor.

"In our group, there is a long tradition of studying spin transport in multiple materials, such as simple metals, for instance," Josep Ingla-Aynes, Franz Herling, Jaroslav Fabian, Luis E. Hueso and Felix Casanova, the researchers who carried out the study, told Phys.org via email. "Our main goal is to understand how the spin of the electron can carry information and how this degree of freedom can help to create devices with new functionalities."
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Groundbreaking technique yields important new details on silicon, subatomic particles and possible 'fifth force'
https://phys.org/news/2021-09-groundbre ... licon.html
by National Institute of Standards and Technology
Using a groundbreaking new technique at the National Institute of Standards and Technology (NIST), an international collaboration led by NIST researchers has revealed previously unrecognized properties of technologically crucial silicon crystals and uncovered new information about an important subatomic particle and a long-theorized fifth force of nature.

By aiming subatomic particles known as neutrons at silicon crystals and monitoring the outcome with exquisite sensitivity, the NIST scientists were able to obtain three extraordinary results: the first measurement of a key neutron property in 20 years using a unique method; the highest-precision measurements of the effects of heat-related vibrations in a silicon crystal; and limits on the strength of a possible "fifth force" beyond standard physics theories.

The researchers report their findings in the journal Science.
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Researchers report an insulator made of two conductors

by ETH Zurich
https://phys.org/news/2021-09-insulator-conductors.html
Ohm's law is well-known from physics class. It states that the resistance of a conductor and the voltage applied to it determine how much current will flow through the conductor. The electrons in the material—the negatively charged carriers—move in a disordered fashion and largely independently of each other. Physicists find it far more interesting, however, when the charge carriers influence one another strongly enough for that simple picture not to be correct anymore.

This is the case, for instance, in "Twisted Bilayer Graphene," which was discovered a few years ago. That material is made from two wafer-thin graphene layers consisting of a single layer of carbon atoms each. If two neighboring layers are slightly twisted with respect to each other, the electrons can be influenced in such a way that they interact strongly with one another. As a consequence, the material can, for instance, become superconducting and hence conduct current without any losses.
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Study provides evidence for 'new physics'
https://phys.org/news/2021-09-evidence-physics.html
by University of Bonn

Is the Standard Model of particle physics incorrect at key points? Recently there has been an increase in experimental observations that deviate from the predictions of this widely accepted physical theory. A current study by the University of Bonn now provides even stronger evidence for the existence of "new physics." The final version of the paper is now published in the journal Physics Letters B. Lead author Chien-Yeah Seng will present the results in mid-October at the fall meeting of the U.S. Physical Society.

The Standard Model of particle physics describes the building blocks that make up the world—us humans, the grains of sand on the beach, the ocean water in which we cool ourselves, but also the sun that burns down on us. The Model also explains what forces act between these elementary particles, and allows us to understand many physical phenomena.

"However, there are also questions that this theory cannot answer," explains Dr. Chien-Yeah Seng, a postdoctoral researcher at the Helmholtz Institute for Radiation and Nuclear Physics at the University of Bonn. "For example, most researchers assume that 95 percent of our universe is made up of dark matter and dark energy, which we cannot detect directly with our measuring instruments. But the existence of these mysterious components cannot be deduced from the Standard Model."
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Physicists make square droplets and liquid lattices

by Aalto University
https://phys.org/news/2021-09-physicist ... tices.html
When two substances are brought together, they will eventually settle into a steady state called thermodynamic equilibrium; examples include oil floating on top of water and milk mixing uniformly into coffee. Researchers at Aalto University in Finland wanted to disrupt this sort of state to see what happens—and whether they can control the outcome.

"Things in equilibrium tend to be quite boring," says Professor Jaakko Timonen, whose research group carried out new work published in Science Advances on 15 September. "It's fascinating to drive systems out of equilibrium and see if the non-equilibrium structures can be controlled or be useful. Biological life itself is a good example of truly complex behavior in a bunch of molecules that are out of thermodynamic equilibrium."

In their work, the team used combinations of oils with different dielectric constants and conductivities. They then subjected the liquids to an electric field.

"When we turn on an electric field over the mixture, electrical charge accumulates at the interface between the oils. This charge density shears the interface out of thermodynamic equilibrium and into interesting formations," explains Dr. Nikos Kyriakopoulos, one of the authors of the paper. As well as being disrupted by the electric field, the liquids were confined into a thin, nearly two-dimensional sheet. This combination led to the oils reshaping into various completely unexpected droplets and patterns.
weatheriscool
Posts: 1587
Joined: Sun May 16, 2021 6:16 pm

Re: Physics News and Discussions

Post by weatheriscool »

Understanding photon collisions could aid search for physics beyond the Standard Model
https://phys.org/news/2021-09-physicist ... uture.html
by Jade Boyd, Rice University
Hot on the heels of proving an 87-year-old prediction that matter can be generated directly from light, Rice University physicists and their colleagues have detailed how that process may impact future studies of primordial plasma and physics beyond the Standard Model.

"We are essentially looking at collisions of light," said Wei Li, an associate professor of physics and astronomy at Rice and co-author of the study published in Physical Review Letters.

"We know from Einstein that energy can be converted into mass," said Li, a particle physicist who collaborates with hundreds of colleagues on experiments at high-energy particle accelerators like the European Organization for Nuclear Research's Large Hadron Collider (LHC) and Brookhaven National Laboratory's Relativistic Heavy Ion Collider(RHIC).

Accelerators like RHIC and LHC routinely turn energy into matter by accelerating pieces of atoms near the speed of light and smashing them into one another. The 2012 discovery of the Higgs particle at the LHC is a notable example. At the time, the Higgs was the final unobserved particle in the Standard Model, a theory that describes the fundamental forces and building blocks of atoms.
Post Reply