Lifeboat Foundation: Safeguarding Humanity
Toggle light / dark theme

Blog

Category: particle physics – Page 3

Crystal melting and the glass transition obey the same physical law

The melting of crystals is the process by which an increase in temperature induces the disruption of the ordered crystalline lattice, leading to the disordered structure and highly fluctuating dynamic behavior of liquids. At the glass transition, where an amorphous solid (a glass) turns into a liquid, there is no obvious change in structure, and only the dynamics of the atoms change, going from strongly localized dynamics in space (in the glass state) to the highly fluctuating (diffusive) dynamics in the liquid.

The search for the atomic-scale mechanism of 3D crystal melting has a long history in physics, and famous physicists such as Max Born, Neville Mott and Frederick Lindemann proposed different ways to look at it. I have always had the impression that we still do not understand the melting of 3D crystals, which is a highly complicated cooperative process involving nonlinearly coupled dynamics of a huge number of atoms. This complexity I always found very fascinating.

Comparatively, the melting of 2D solids, mediated by dislocations-unbinding, is much better understood, and the theory that describes it led to the 2017 Nobel prize in physics for Kosterlitz and Thouless.

Simulation reveals emergence of jet from binary neutron star merger followed by black hole formation

Binary neutron star mergers, cosmic collisions between two very dense stellar remnants made up predominantly of neutrons, have been the topic of numerous astrophysics studies due to their fascinating underlying physics and their possible cosmological outcomes. Most previous studies aimed at simulating and better understanding these events relied on computational methods designed to solve Einstein’s equations of general relativity under extreme conditions, such as those that would be present during neutron star mergers.

Researchers at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute), Yukawa Institute for Theoretical Physics, Chiba University, and Toho University recently performed the longest simulation of binary neutron star mergers to date, utilizing a framework for modeling the interactions between magnetic fields, high-density matter and neutrinos, known as the neutrino-radiation magnetohydrodynamics (MHD) framework.

Their simulation, outlined in Physical Review Letters, reveals the emergence of a magnetically dominated jet from the , followed by the collapse of the binary neutron star system into a black hole.

A Fifth Force of Nature May Have Been Discovered Inside Atoms

Every action in physics is governed by some kind of push or pull. As far as we know, these all fall into one of just four categories; electromagnetism, gravity, and two kinds of nuclear force.

Yet there could well be forces hidden deep within the tiny storms of particle dynamics that have been simply too subtle to easily detect.

Physicists from Germany, Switzerland, and Australia have now placed new restrictions on where one example of a ‘fifth’ force may be hiding in the hearts of atoms, exchanging whispers between electrons and neutrons.

Physicists record the most precise neutrino mass measurement ever

The Standard Model of particle physics, our best guide to the building blocks of nature, once claimed neutrinos were massless. But that turned out to be wrong. Neutrinos do have mass—just an incredibly tiny one. So far, though, no experiment has measured that mass directly. That’s where the KATRIN experiment comes in.

KATRIN stands for the Karlsruhe Tritium Neutrino Experiment. It’s based in Germany and stretches nearly 70 meters, or about 230 feet—longer than a Boeing 747. Published in the journal, Science, the experiment uses a radioactive form of hydrogen called tritium, which naturally decays into helium. When this happens, it releases an electron and a neutrino.

By measuring the energy of the electron, scientists can figure out how much energy the neutrino took away. This helps them estimate the neutrino’s mass. The trick is, this has to be done with extreme accuracy. That’s why KATRIN includes one of the world’s most advanced spectrometers, which is 10 meters wide and filters out unwanted particles with precision.

Semi-heavy water ice detected around young sunlike star for first time

A team led by astronomers at Leiden University in the Netherlands and the National Radio Astronomy Observatory in Virginia (U.S.) have, for the first time, robustly detected semi-heavy water ice around a young sunlike star. The results strengthen the case that some of the water in our solar system formed before our sun and the planets.

Their findings are published in The Astrophysical Journal Letters.

One way that astronomers trace the origin of water is through measuring its deuteration ratio. That is the fraction of water that contains one deuterium atom instead of one of the hydrogens. So instead of H2O, it’s HDO, which is also called semi-heavy water. A high fraction of semi-heavy water is a sign that the water formed in a very cold place, such as the primitive dark clouds of dust, ice, and gas from which stars are born.

Caterpillar factories produce fluorescent nanocarbons

Researchers led by Kenichiro Itami at the RIKEN Pioneering Research Institute (PRI) / RIKEN Center for Sustainable Resource Science (CSRS) have successfully used insects as mini molecule-making factories, marking a breakthrough in chemical engineering. Referred to as “in-insect synthesis,” this technique offers a new way to create and modify complex molecules, which will generate new opportunities for the discovery, development, and application of non-natural molecules, such as nanocarbons.

Molecular nanocarbons are super tiny structures made entirely of carbon atoms. Despite their minuscule size, they can be mechanically strong, conduct electricity, and even emit fluorescent light. These properties make them ideal for use in applications like aerospace components, lightweight batteries, and advanced electronics. However, the precision required to manufacture these tiny structures remains a major obstacle to their widespread use. Conventional laboratory techniques struggle with the fine manipulation needed to put these complex molecules together atom by atom, and their defined shapes make it especially difficult to modify them without disrupting their integrity.

“Our team has been conducting research on molecular nanocarbons, but along with that, we’ve also developed molecules that act on mammals and plants,” says Itami. “Through those experiences, we suddenly wondered — what would happen if we fed nanocarbons to insects?”

Ultrafast spin-exchange in quantum dots enhances solar energy and photochemical efficiency

Quantum dots are microscopic semiconductor crystals developed in the lab that share many properties with atoms, including the ability to absorb or emit light, a technology that Los Alamos researchers have spent nearly three decades evolving. Through carrier multiplication, in which a single absorbed photon generates two electron-hole pairs, called excitons, quantum dots have the unique ability to convert photons more efficiently to energy.

“Our work demonstrates how purely quantum mechanical spin-exchange interactions can be harnessed to enhance the efficiency of photoconversion devices or ,” says Victor Klimov, the team’s principal investigator at the Lab. “This not only deepens our fundamental understanding of quantum mechanical phenomena but also introduces a new paradigm for designing advanced materials for energy applications.”

In this latest research, published in the journal Nature Communications, Los Alamos researchers improved this ability by introducing magnetic manganese impurities into quantum dots. This novel approach to highly efficient carrier multiplication leverages ultrafast spin-exchange interactions mediated by manganese ions to capture the energy of energetic (hot) carriers generated by incident photons and convert it into additional excitons.

World’s first non-silicon 2D computer developed

Silicon is king in the semiconductor technology that underpins smartphones, computers, electric vehicles and more, but its crown may be slipping, according to a team led by researchers at Penn State.

In a world first, they used two-dimensional (2D) materials, which are only an atom thick and retain their properties at that scale, unlike , to develop a computer capable of simple operations.

The development, published in Nature, represents a major leap toward the realization of thinner, faster and more energy-efficient electronics, the researchers said.

First quantum-mechanical model of quasicrystals reveals why they exist

A rare and bewildering intermediate between crystal and glass can be the most stable arrangement for some combinations of atoms, according to a study from the University of Michigan.

The findings come from the first quantum-mechanical simulations of quasicrystals—a type of solid that scientists once thought couldn’t exist. While the atoms in quasicrystals are arranged in a lattice, as in a crystal, the pattern of atoms doesn’t repeat like it does in conventional crystals. The new simulation method suggests quasicrystals—like crystals—are fundamentally , despite their similarity to disordered solids like glass that form as a consequence of rapid heating and cooling.

“We need to know how to arrange atoms into specific structures if we want to design materials with desired properties,” said Wenhao Sun, the Dow Early Career Assistant Professor of Materials Science and Engineering, and the corresponding author of the paper published today in Nature Physics. “Quasicrystals have forced us to rethink how and why certain materials can form. Until our study, it was unclear to scientists why they existed.”

New approach reversibly configures single and heteronuclear dual-atom catalysts on MoS₂ substrate

Single-atom catalysts (SACs) are materials consisting of individual metal atoms dispersed on a substrate (i.e., supporting surface). Recent studies have highlighted the promise of these catalysts for the efficient conversion and storage of energy, particularly when deployed in fuel cells and water electrolyzers.