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Category: particle physics – Page 484

Neutrinos Yield First Experimental Evidence of the CNO Energy-Production Mechanism of the Universe

Neutrinos Yield First Experimental Evidence of Catalyzed Fusion Dominant in Many Stars

An international team of about 100 scientists of the Borexino Collaboration, including particle physicist Andrea Pocar at the University of Massachusetts Amherst, report in Nature this week detection of neutrinos from the sun, directly revealing for the first time that the carbon-nitrogen-oxygen (CNO) fusion-cycle is at work in our sun.

The CNO cycle is the dominant energy source powering stars heavier than the sun, but it had so far never been directly detected in any star, Pocar explains.

Antimatter gravity could explain Universe’s expansion

O,.o circa 2011 antigravity? Antimatter gravity equals antigravity: D.

(PhysOrg.com) — In 1998, scientists discovered that the Universe is expanding at an accelerating rate. Currently, the most widely accepted explanation for this observation is the presence of an unidentified dark energy, although several other possibilities have been proposed. One of these alternatives is that some kind of repulsive gravity – or antigravity – is pushing the Universe apart. As a new study shows, general relativity predicts that the gravitational interaction between matter and antimatter is mutually repulsive, and could potentially explain the observed expansion of the Universe without the need for dark energy.

Ever since was discovered in 1932, scientists have been investigating whether its gravitational behavior is attractive – like normal matter – or repulsive. Although antimatter particles have the opposite electric charge as their associated matter particles, the masses of antimatter and matter particles are exactly equal. Most importantly, the masses are always positive. For this reason, most physicists think that the gravitational behavior of antimatter should always be attractive, as it is for matter. However, the question of whether the gravitational interaction between matter and antimatter is attractive or repulsive so far has no clear answer.

In the new study, Massimo Villata of the Osservatorio Astronomico di Torino (Observatory of Turin) in Pino Torinese, Italy, has shown that an answer can be found in the theory of general relativity. As Villata explains, the current formulation of general relativity predicts that matter and antimatter are both self-attractive, yet matter and antimatter mutually repel each other. Unlike previous antigravity proposals – such as the idea that antimatter is gravitationally self-repulsive – Villata’s proposal does not require changes to well-established theories. The study is published in a recent issue of EPL ().

Aerodynamics of Infectious Disease: Airflow Studies Reveal Strategies to Reduce Indoor Transmission of COVID-19

Scientists studying the aerodynamics of infectious disease share steps to curb transmission during indoor activities.

Wear a mask. Stay six feet apart. Avoid large gatherings. As the world awaits a safe and effective vaccine, controlling the COVID-19 pandemic hinges on widespread compliance with these public health guidelines. But as colder weather forces people to spend more time indoors, blocking disease transmission will become more challenging than ever.

At the 73rd Annual Meeting of the American Physical Society’s Division of Fluid Dynamics, researchers presented a range of studies investigating the aerodynamics of infectious disease. Their results suggest strategies for lowering risk based on a rigorous understanding of how infectious particles mix with air in confined spaces.

Decades Old Mystery Solved: A “New Kind of Electrons”

Why do certain materials emit electrons with a very specific energy? This has been a mystery for decades — scientists at TU Wien have found an answer.

It is something quite common in physics: electrons leave a certain material, they fly away and then they are measured. Some materials emit electrons, when they are irradiated with light. These electrons are then called “photoelectrons.” In materials research, so-called “Auger electrons” also play an important role — they can be emitted by atoms if an electron is first removed from one of the inner electron shells. But now scientists at TU Wien (Vienna) have succeeded in explaining a completely different type of electron emission, which can occur in carbon materials such as graphite. This electron emission had been known for about 50 years, but its cause was still unclear.

Strange electrons without explanation.

Dark Matter Candidate Could Generate String-Like Entities in Exotic Materials

Calculations show how theoretical ‘axionic strings’ could create odd behavior if produced in exotic materials in the lab.

A hypothetical particle that could solve one of the biggest puzzles in cosmology just got a little less mysterious. A RIKEN physicist and two colleagues have revealed the mathematical underpinnings that could explain how so-called axions might generate string-like entities that create a strange voltage in lab materials.

Axions were first proposed in the 1970s by physicists studying the theory of quantum chromodynamics, which describes how some elementary particles are held together within the atomic nucleus. The trouble was that this theory predicted some bizarre properties for known particles that are not observed. To fix this, physicists posited a new particle—later dubbed the axion, after a brand of laundry detergent, because it helped clean up a mess in the theory.

Researchers have succeeded in directly observing the formation and interaction of highly ionized krypton plasma

The last decade has been marked by a series of remarkable discoveries identifying how the universe is composed. It is understood that the mysterious substance dark matter makes up 85% of the matter in the universe. Observable matter in the universe consists of ionized particles. Thus, a profound understanding of ionized matter and its interaction with light, could lead to a deeper understanding of the relationships at play that formed the universe. While ionized matter, or plasma, is relatively easy to generate in the lab, studying it is extremely challenging as methods that can capture ionization states and density are virtually non-existant.

In a new paper published in Light Science & Application, a team of scientists has succeeded in directly observing the formation and interaction of highly ionized krypton plasma using femtosecond coherent ultraviolet light and a novel four-dimensional model.

Particle Physicists Continue Empty Promises

The CERN in Geneva has become a sink for public money.

At the same time there’s a lack of funding in other research areas, that would be much more urgent!

In this video I explain why building a next larger particle collider will most likely not tell us anything about dark matter and why, therefore, claims by prominent particle physicists that dark matter would be a “guaranteed result” are misleading.

The piece that I quote in the beginning is this:

https://www.nature.com/articles/s41567-020-01054-6

Continue reading “Particle Physicists Continue Empty Promises” | >

Versatile building blocks make structures with surprising mechanical properties

Researchers at MIT’s Center for Bits and Atoms have created tiny building blocks that exhibit a variety of unique mechanical properties, such as the ability to produce a twisting motion when squeezed. These subunits could potentially be assembled by tiny robots into a nearly limitless variety of objects with built-in functionality, including vehicles, large industrial parts, or specialized robots that can be repeatedly reassembled in different forms.

The researchers created four different types of these subunits, called voxels (a 3D variation on the pixels of a 2D image). Each voxel type exhibits special properties not found in typical natural materials, and in combination they can be used to make devices that respond to environmental stimuli in predictable ways. Examples might include airplane wings or turbine blades that respond to changes in air pressure or wind speed by changing their overall shape.

The findings, which detail the creation of a family of discrete “mechanical metamaterials,” are described in a paper published today in the journal Science Advances, authored by recent MIT doctoral graduate Benjamin Jenett PhD ’20, Professor Neil Gershenfeld, and four others.

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