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Category: particle physics – Page 446

A top goal in cosmology is to precisely measure the total amount of matter in the universe, a daunting exercise for even the most mathematically proficient. A team led by scientists at the University of California, Riverside, has now done just that.

Reporting in the Astrophysical Journal, the team determined that matter makes up 31% of the total amount of matter and energy in the , with the remainder consisting of dark energy.

“To put that amount of matter in context, if all the matter in the universe were spread out evenly across space, it would correspond to an average mass density equal to only about six per cubic meter,” said first author Mohamed Abdullah, a graduate student in the UCR Department of Physics and Astronomy. “However, since we know 80% of matter is actually , in reality, most of this matter consists not of hydrogen atoms but rather of a type of matter which cosmologists don’t yet understand.”

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Astrophysicists at the University of Jena (Germany) prove that dust particles in space are mixed with ice.

The matter between the stars in a galaxy – called the interstellar medium – consists not only of gas, but also of a great deal of dust. At some point in time, stars and planets originated in such an environment, because the dust particles can clump together and merge into celestial bodies. Important chemical processes also take place on these particles, from which complex organic – possibly even prebiotic – molecules emerge. However, for these processes to be possible, there has to be water. In particularly cold cosmic environments, water occurs in the form of ice. Until now, however, the connection between ice and dust in these regions of space was unclear. A research team from Friedrich Schiller University Jena and the Max Planck Institute for Astronomy has now proven that the dust particles and the ice are mixed. They report their findings in the current issue of the research journal Nature Astronomy.

Better modelling of physico-chemical processes in space.

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Researchers in Singapore have built a refrigerator that’s just three atoms big.

This quantum fridge won’t keep your drinks cold, but it’s cool proof of physics operating at the smallest scales. The work is described in a paper published in Nature Communications (“Quantum absorption refrigerator with trapped ions”).

Researchers have built tiny ‘heat engines’ before, but quantum fridges existed only as proposals until the team at the Centre for Quantum Technologies at the National University of Singapore chilled with their atoms.

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O,.o.

Through a one-of-a-kind experiment at the Department of Energy’s Oak Ridge National Laboratory, nuclear physicists have precisely measured the weak interaction between protons and neutrons. The result quantifies the weak force theory as predicted by the Standard Model of Particle Physics.

The team’s weak observation, detailed in Physical Review Letters, was measured through a precision experiment called n3He, or n-helium-3, that ran at ORNL’s Spallation Neutron Source, or SNS. Their finding yielded the smallest uncertainty of any comparable weak force measurement in the nucleus of an atom to date, which establishes an important benchmark.

The Standard Model describes the basic building blocks of matter in the universe and fundamental forces acting between them. Calculating and measuring the weak force between protons and neutrons is an extremely difficult task.

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Nanoscale vortices known as skyrmions can be created in many magnetic materials. For the first time, researchers at PSI have managed to create and identify antiferromagnetic skyrmions with a unique property: critical elements inside them are arranged in opposing directions. Scientists have succeeded in visualizing this phenomenon using neutron scattering. Their discovery is a major step towards developing potential new applications, such as more efficient computers. The results of the research are published today in the journal Nature.

Whether a material is magnetic depends on the spins of its atoms. The best way to think of spins is as minute bar magnets. In a where the atoms have fixed positions in a lattice, these spins can be arranged in criss-cross fashion or aligned all in parallel like the spears of a Roman legion, depending on the individual material and its state.

Under certain conditions it is possible to generate tiny vortices within the corps of spins. These are known as skyrmions. Scientists are particularly interested in skyrmions as a key component in future technologies, such as more efficient data storage and transfer. For example, they could be used as memory bits: a could represent the digital one, and its absence a digital zero. As skyrmions are significantly smaller than the bits used in conventional storage media, data density is much higher and potentially also more energy efficient, while read and write operations would be faster as well. Skyrmions could therefore be useful both in classical data processing and in cutting-edge quantum computing.

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Data from Southwest Research Institute-led instruments aboard ESA’s Rosetta spacecraft have helped reveal auroral emissions in the far ultraviolet around a comet for the first time.

At Earth, auroras are formed when charged particles from the Sun follow our planet’s to the north and south poles. There, solar particles strike atoms and molecules in Earth’s atmosphere, creating shimmering curtains of colorful light in high-latitude skies. Similar phenomena have been seen at various planets and moons in our and even around a distant star. SwRI’s instruments, the Alice far-ultraviolet (FUV) spectrograph and the Ion and Electron Sensor (IES), aided in detecting these novel phenomena at 67P/Churyumov-Gerasimenko (67P/C-G).

“Charged particles from the Sun streaming towards the comet in the solar wind interact with the gas surrounding the comet’s icy, dusty nucleus and create the auroras,” said SwRI Vice President Dr. Jim Burch who leads IES. “The IES instrument detected the electrons that caused the aurora.”

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The following is adapted from Lewis’ The Rise: Creativity, the Gift of Failure, and the Search for Mastery, published by Simon & Schuster.

“It says, ‘No entrance,’ but you just enter,” physicist Andre Geim told me about the graphite mines in the mountains where he often hikes. His comment embodied the insouciance behind his Nobel Prize–winning physics experiment and his habit of experimenting deliberately outside of his area of expertise.

Geim, a Russian-born Dutch and British citizen and a professor at the University of Manchester, and his colleague Konstantin Novoselov won the 2010 Nobel Prize in physics for their experiments involving the single-atom-thick material called graphene—the thinnest, strongest, most conductive material in existence. It is predicted to replace silicon and transform the electronics industry as we know it.

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