All posts tagged: Particles

Pressure from individual particles measured for the first time

Pressure from individual particles measured for the first time

Published by skeptic

The ultra-sensitive pressure sensor features a 100-nanometre silica sphere held in place by laser light Thomas Penny/Yale Wright Laboratory The pressure produced by a single particle can now be measured for the first time, thanks to a device that uses a tiny bead held in place by a laser. It is so sensitive that researchers hope that it could help find elusive new particles, such as those that could make up dark matter. Pressure is caused by particles hitting an object and collectively exerting a force across its area. Researchers typically think of it as an average effect rather than zooming in on each particle, but when pressure is extremely low, such as in experiments conducted in near-perfect vacuum, tracking every particle is needed to properly account for its effects. Yu-Han Tseng at Yale University and his colleagues have now built the first device capable of making such measurements. The central component is a tiny silica sphere, half the size of some viruses, held in place with a laser beam thanks to electromagnetic interactions between …

The particles in the early Universe painted a different picture

The particles in the early Universe painted a different picture

Published by Jenni Sidey

Today’s Standard Model describes our Universe’s particles and forces. Although there are many similarities and differences within the Standard Model: between quarks and leptons, between fermions and bosons, between particles and antiparticles, etc., displaying the Standard Model’s particle content in this fashion is oversimplified. The six quarks can take on three colors each and all have fractional charges. The tau, muon, and electron are charged leptons, while the three neutrinos are uncharged. Quarks and leptons have antiparticle counterparts, but of the bosons (on the interior), only the W comes in two types: W+ and W-, which are each other’s antiparticle. Credit: Symmetry Magazine Six quarks, six leptons, and antiparticles comprise the fermions. The quarks, antiquarks, and gluons of the Standard Model have a color charge, in addition to all the other properties like mass and electric charge. All of these particles, except gluons and photons, experience the weak interaction. Only the gluons and photons are massless; everyone else, even the neutrinos, have a non-zero rest mass. Credit: E. Siegel/Beyond the Galaxy Eight gluons, one photon, …

For the first time ever, scientists create particles out of empty space

For the first time ever, scientists create particles out of empty space

Published by Jenni Sidey

The universe looks like it is mostly empty space. Remove the stars, planets, dust, and gas, and what remains is nothing at all. Physics tells a stranger story. The vacuum is not truly empty. It is filled with restless energy and fleeting quantum fluctuations. These are brief disturbances that can produce virtual particle pairs before they disappear again. These particles cannot be observed directly. However, their effects can shape the behavior of matter in measurable ways. Now physicists working at the U.S. Department of Energy’s Brookhaven National Laboratory and Stony Brook University have found new evidence. Some of those hidden vacuum fluctuations may leave a direct imprint on the particles we can detect. Their study points to a link between short-lived virtual quark-antiquark pairs in the vacuum and real particles produced in high-energy proton collisions. The findings offer a new way to study one of the biggest unresolved problems in physics. Specifically, the question is how quarks become bound into matter. “The vacuum is now understood to have a rich and complex structure, characterized by …

Particles seen emerging from empty space for first time

Particles seen emerging from empty space for first time

Published by skeptic

Particle collisions inside the STAR detector at the Solenoidal Tracker at RHIC, known as STAR Brookhaven National Laboratory A pair of rare particles produced in high-energy proton collisions may be the clearest evidence yet that mass can emerge from empty space. The finding could shed light on one of the biggest puzzles in physics: how particles acquire their mass. According to quantum chromodynamics (QCD) – widely considered to be our best theory for describing the strong force, which binds quarks inside protons and neutrons – even a perfect vacuum isn’t truly empty. Instead, it is filled with short-lived disturbances in the underlying energy of space that flicker in and out of existence, known as virtual particles. Among them are quark-antiquark pairs. Under normal conditions, these fleeting pairs vanish almost as soon as they appear. But if enough energy is injected into a vacuum, QCD predicts they can be promoted into real, detectable particles with measurable mass. Now, the STAR collaboration – an international team of physicists working at the Relativistic Heavy Ion Collider in Brookhaven …

New research discovers quantum particles that exist in one dimension

New research discovers quantum particles that exist in one dimension

Published by Jenni Sidey

A pair of identical particles swapping places sounds like a small move. In quantum physics, it is a defining one. In everyday three-dimensional space, that swap only comes in two flavors. Either the system looks exactly the same after the exchange, or it flips sign in a way that forces the particles to avoid sharing a state. Those two outcomes sit at the heart of the boson and fermion divide that organizes the Standard Model. Lower the number of dimensions, and that clean split starts to fray. Physicists have predicted since the 1970s that a middle ground should exist: anyons, particles that are neither bosons nor fermions. In 2020, experiments observed anyons at the interface of supercooled, strongly magnetized, one-atom-thick semiconductors, a two-dimensional setting. Now two joint papers in Physical Review A describe a one-dimensional system where anyons can exist, and spell out what their behavior should look like. (a) Bosonic-anyon–fermionic-anyon mapping that connects Ψ+, Ψ−, Ψα,+, and Ψα,−. (b) Momentum distributions (top) nα,+(k) and (bottom) nα,−(k) for three identical free-space bosonic anyons and fermionic …

Dark matter may consist of particles with different masses

Dark matter may consist of particles with different masses

Published by Jenni Sidey

Dark matter keeps getting blamed for the universe’s big patterns while staying stubbornly out of reach. You cannot see it, touch it, or capture it. Yet its gravity helps shape galaxies, and that makes it hard to ignore. For decades, many astronomers have leaned on the cold dark matter model to explain how cosmic structure forms. The model works well on large scales. Trouble starts when you zoom in. As measurements sharpen, a set of small-scale puzzles has piled up that does not sit neatly inside the classic picture. Some dwarf galaxies, for example, seem to have dark matter that spreads out, with surprisingly low density in the center. At the same time, strong gravitational lensing has uncovered dark substructures that look almost too compact, far denser than traditional expectations. These two signals have lived side by side for years, and they pull in opposite directions. Projected dark matter density distribution and the induced strong lensing critical curves in a two-component self-interacting dark matter model. (CREDIT: Science China Press) One Dark Matter, Or More Than …

Milky Way neutrino map predicts how many ghost particles will reach Earth

Milky Way neutrino map predicts how many ghost particles will reach Earth

Published by Jenni Sidey

They slip through your skin, your walls, and the whole Earth without leaving a mark. Neutrinos earn the nickname “ghost particles” because they almost never interact with anything. Yet those rare moments when you do catch them can change what you know about the universe. Now, researchers at the University of Copenhagen say they have built the most complete picture yet of how many neutrinos the stars in the Milky Way make, where those particles come from, and how many should reach Earth. The team combined advanced models of how stars behave with precise star-position data from the European Space Agency’s Gaia telescope. “For the first time, we have a concrete estimate of how many of these particles reach Earth, where in the galaxy they come from, and how their energy is distributed. Because ghost particles come straight from the core of stars, they can tell us things that light and other radiation cannot,” said lead author Pablo Martínez-Miravé, a postdoc at the Niels Bohr Institute. Galactic stellar neutrino and antineutrino flux at Earth for …

‘Stenciling’ tiny gold particles gives them new properties

‘Stenciling’ tiny gold particles gives them new properties

Published by skeptic

application: A particular use or function of something. circuit: A network that transmits electrical signals. In the body, nerve cells create circuits that relay electrical signals to the brain. In electronics, wires typically route those signals to activate some mechanical, computational or other function. computer model: A program that runs on a computer that creates a model, or simulation, of a real-world feature, phenomenon or event. fabric: Any flexible material that is woven, knitted or can be fused into a sheet by heat or compression and drying. metal: Something that conducts electricity well, tends to be shiny (reflective) and is malleable (meaning it can be reshaped with heat and not too much force or pressure). metamaterial: Lab-built materials that develop particularly desirable properties based on the way that they are built, rather than what they’re made from. They have qualities not found in the natural world. model: A simulation of a real-world event (usually using a computer) that has been developed to predict one or more likely outcomes. Or an individual that is meant to display …

Scientists discover new quantum state where electrons stop acting like particles

Scientists discover new quantum state where electrons stop acting like particles

Published by Jenni Sidey

A new study in Nature Physics ties together two ideas that long seemed to live in different corners of condensed matter physics. One is quantum criticality, the restless tipping point where a material cannot settle into a single state. The other is electronic topology, the math-like “twists” in an electron’s wave behavior that can make certain properties unusually robust. The work was co-led by Rice University physicist Qimiao Si and Vienna University of Technology (TU Wien) physicist Silke Bühler-Paschen. Their teams argue that strong electron interactions can create a topological state, rather than destroy it, even in a regime where the usual picture of electrons as particle-like “quasiparticles” breaks down. “This is a fundamental step forward,” said Si, the Harry C. and Olga K. Wiess Professor of Physics and Astronomy and director of Rice’s Extreme Quantum Materials Alliance. “Our work shows that powerful quantum effects can combine to create something entirely new, which may help shape the future of quantum science.” Professor Qimiao Si, graduate student Lei Chen, and the Rice University research team. (CREDIT: …

Ghostly particles might just break our understanding of the universe

Ghostly particles might just break our understanding of the universe

Published by skeptic

Neutrinos rarely interact with normal matter Shutterstock / betibup33 Notoriously ghostly particles called neutrinos may have revealed a crack in our understanding of all the particles and forces in the universe. The standard model of particle physics, which catalogues all the particles and forces we know to exist, is one of the biggest successes of modern physics, but physicists have also spent decades trying to break it. That is because it has enough flaws – notably, it doesn’t connect gravity to any of the three other fundamental forces – for researchers to suspect that they must formulate another, better model. If the standard model cracks under a stress test, that would point to where we should start building this next model. Francesca Dordei at the Italian National Institute for Nuclear Physics (INFN) in Cagliari and her colleagues have now identified one possible crack by studying the enigmatic neutrino. “In all the checks [of the standard model] that we did in the last two decades, every time, stubbornly, they confirmed the standard model, which means that …