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Physicists at the Max Planck Institute of Quantum Optics have tested quantum mechanics to a completely new level of precision using hydrogen spectroscopy, and in doing so they came much closer to solving the well-known proton charge radius puzzle.

Scientists at the Max Planck Institute of Quantum Optics (MPQ) have succeeded in testing quantum electrodynamics with unprecedented accuracy to 13 decimal places. The new measurement is almost twice as accurate as all previous hydrogen measurements combined and moves science one step closer to solving the proton size puzzle. This high accuracy was achieved by the Nobel Prize-winning frequency comb technique, which debuted here for the first time to excite atoms in high-resolution spectroscopy. The results are published today in Science.

Physics is said to be an exact science. This means that predictions of physical theories – exact numbers – can be verified or falsified by experiments. The experiment is the highest judge of any theory. Quantum electrodynamics, the relativistic version of quantum mechanics, is without doubt the most successful theory to date. It allows extremely precise calculations to be performed, for example, the description of the spectrum of atomic hydrogen to 12 decimal places. Hydrogen is the most common element in the universe and at the same time the simplest with only one electron. And still, it hosts a mystery yet unknown.

Physicists use a Bose-Einstein condensate to study phase transitions in an iron pnictide superconductor.

Physicists have deployed a Bose-Einstein condensate (BEC) as a “quantum microscope” to study phase transitions in a high-temperature superconductor. The experiment marks the first time a BEC has been used to probe such a complicated condensed-matter phenomenon, and the results – a solution to a puzzle involving transition temperatures in iron pnictide superconductors – suggest that the technique could help untangle the complex factors that enhance and inhibit high-temperature superconductivity.

A BEC is a state of matter that forms when a gas of bosons (particles with integer quantum spin) is cooled to such low temperatures that all the bosons fall into the same quantum state. Under these conditions, the bosons are highly sensitive to tiny fluctuations in the local magnetic field, which perturb their collective wavefunction and create patches of greater and lesser density in the gas. These variations in density can then be detected using optical techniques.

Continue reading “Ultracold atoms put high-temperature superconductors under the microscope” »

The discovery “reinforces our confidence that we understand how stars work.”

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Scientists had already found neutrinos given off when the Sun fuses hydrogen into helium, a hallmark process of lighter stars that gives off 99 percent of the sun’s energy. The new discovery not only extended the lifespan of the Borexino detector — which was scheduled to be decommissioned next month — but also revitalized scientists’ understanding of the cosmos.

Continue reading “Scientists Decipher the Sun’s Nuclear Fusion for the First Time” »

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.

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 antimatter 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.

Continue reading “Antimatter gravity could explain Universe’s expansion” »

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.

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.

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.

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.