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Category: particle physics – Page 543

A rare earth element that doesn’t get much mention could become the key to upgrading atomic clocks to become even more accurate. This could help us explore space and track satellites, and even keep the world’s time zones in sync.

Atomic clocks use the oscillations of atoms under laser fire as a measurement of time, in the same way a grandfather clock uses the swing of a pendulum. They can lose less than a second over 50 million years, depending on the elements used — but scientists want even greater accuracy.

That’s where lutetium (Lu) comes in. It offers both a higher level of stability and a higher degree of precision than the caesium or rubidium of today’s atomic clocks, according to a team of researchers from the Centre for Quantum Technologies (CQT) in Singapore.

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In general, modelers attack the problem by breaking it into billions of bits, either by dividing space into a 3D grid of subvolumes or by parceling the mass of dark and ordinary matter into swarms of particles. The simulation then tracks the interactions among those elements while ticking through cosmic time in, say, million-year steps. The computations strain even the most powerful supercomputers. BlueTides, for example, runs on Blue Waters—a supercomputer at the University of Illinois in Urbana that can perform 13 quadrillion calculations per second. Merely loading the model consumes 90% of the computer’s available memory, Feng says.

For years such simulations produced galaxies that were too gassy, massive, and blobby. But computer power has increased, and, more important, models of the radiation-matter feedback have improved. Now, hydrodynamic simulations have begun to produce the right number of galaxies of the right masses and shapes—spiral disks, squat ellipticals, spherical dwarfs, and oddball irregulars—says Volker Springel, a cosmologist at the Heidelberg Institute for Theoretical Studies in Germany who worked on Millennium and leads the Illustris simulation. “Until recently, the simulation field struggled to make spiral galaxies,” he says. “It’s only in the last 5 years that we’ve shown that you can make them.”

The models now show that, like people, galaxies tend to go through distinct life stages, Hopkins says. When young, a galaxy roils with activity, as one merger after another stretches and contorts it, inducing spurts of star formation. After a few billion years, the galaxy tends to settle into a relatively placid and stable middle age. Later, it can even slip into senescence as it loses its gas and the ability make stars—a transition our Milky Way appears to be making now, Hopkins says. But the wild and violent turns of adolescence make the particular path of any galaxy hard to predict, he says.

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Inside the proton, there is an immense amount of pressure which is equivalent to a billion, billion times the pressure at the bottom of the Mariana Trench. Scientists at the Thomas Jefferson National Accelerator Facility have measured the pressure inside the proton for the first time. To probe the conditions within the proton, Burkert and his colleagues used an electron beam to probe the inner conditions of a proton. In simple terms, the electrons in the electron beam have energy and this is handed over to one of the quarks. This causes the entire proton to recoil and the quark emits a high-energy photon. By using conservation of momentum and measuring the positions and energies of the photon, proton, and electron in the experiment provides insight into the inner structure of the proton.

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It isn’t always easy to wrap your mind around how light works. It’s a particle, but it’s also a wave, and that wave can be powerful. Photons generally travel en masse — we’re talking densities in the range of quadrillions per square inch if they’re coming from the sun. But what if instead of the whole wave crashing over you, you were only hit by a single drop of light — would you know? In other words, is it possible for the human eye to see a single photon?

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Based on complex simulations of quantum chromodynamics performed using the K computer, one of the most powerful computers in the world, the HAL QCD Collaboration, made up of scientists from the RIKEN Nishina Center for Accelerator-based Science and the RIKEN Interdisciplinary Theoretical and Mathematical Sciences (iTHEMS) program, together with colleagues from a number of universities, have predicted a new type of “dibaryon”—a particle that contains six quarks instead of the usual three. Studying how these elements form could help scientists understand the interactions among elementary particles in extreme environments such as the interiors of neutron stars or the early universe moments after the Big Bang.

Particles known as “baryons”—principally protons and neutrons—are composed of three quarks bound tightly together, with their charge depending on the “color” of the quarks that make them up. A dibaryon is essentially a system with two baryons. There is one known dibaryon in nature—deuteron, a deuterium (or heavy-hydrogen) nucleus that contains a proton and a that are very lightly bound. Scientists have long wondered whether there could be other types of dibaryons. Despite searches, no other dibaryon has been found.

The group, in work published in Physical Review Letters, has now used powerful theoretical and computational tools to predict the existence of a “most strange” dibaryon, made up of two “Omega baryons” that contain three strange quarks each. They named it “di-Omega”. The group also suggested a way to look for these strange through experiments with heavy ion collisions planned in Europe and Japan.

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Scientists at the University of Alberta have applied a machine learning technique using artificial intelligence to perfect and automate atomic-scale manufacturing, something which has never been done before. The vastly greener, faster, smaller technology enabled by this development greatly reduces impact on the climate while still satisfying the insatiable demands of the information age.

“Most of us thought we’d never be able to automate atomic writing and editing, but stubborn persistence has paid off, and now Research Associate Moe Rashidi has done it,” said Robert Wolkow, professor of physics at the University of Alberta, who along with his Research Associate has just published a paper announcing their findings.

“Until now, we printed with about as efficiently as medieval monks produced books,” explained Wolkow. “For a long while, we have had the equivalent of a pen for writing with atoms, but we had to write manually. So we couldn’t mass produce atom-scale devices, and we couldn’t commercialize anything. Now that has all changed, much like the disruption following the arrival of the printing press for those medieval monks. Machine learning has automated the atom fabrication process, and an atom-scale manufacturing revolution is sure to follow.”

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Although Hurricane Patricia was one of the most powerful storms ever recorded, that didn’t stop the National Oceanic and Atmospheric Administration (NOAA) from flying a scientific aircraft right through it. Now, the researchers have reported their findings, including the detection of a beam of antimatter being blasted towards the ground, accompanied by flashes of x-rays and gamma rays.

Scientists discovered terrestrial gamma-ray flashes (TGFs) in 1994, when orbiting instruments designed to detect deep space gamma ray bursts noticed signals coming from Earth. These were later linked to storms, and after thousands of subsequent observations have come to be seen as normal parts of lightning strikes.

The mechanisms behind these emissions are still shrouded in mystery, but the basic story goes that, first, the strong electric fields in thunderstorms cause electrons to accelerate to almost the speed of light. As these high-energy electrons scatter off other atoms in the air, they accelerate other electrons, quickly creating an avalanche of what are known as “relativistic” electrons.

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An Antares rocket launched from Virginia before sunrise this morning and is on its way to the International Space Station. Its 7,400 pounds of cargo include an experiment that will chill atoms to just about absolute zero—colder than the vacuum of space itself.

The Cold Atom Laboratory (CAL) is set to create Bose-Einstein condensates on board the ISS. But what’s a Bose-Einstein condensate? And why make it in space?

“Essentially, it’s going to allow us to do different kinds of things than we’d be able to do on Earth,” Gretchen Campbell, co-director of the University of Maryland’s Joint Quantum Institute, told Gizmodo.

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