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Category: particle physics – Page 312

Physicists have long struggled to explain why the universe started out with conditions suitable for life to evolve. Why do the physical laws and constants take the very specific values that allow stars, planets and ultimately life to develop? The expansive force of the universe, dark energy, for example, is much weaker than theory suggests it should be—allowing matter to clump together rather than being ripped apart.

A common answer is that we live in an infinite multiverse of universes, so we shouldn’t be surprised that at least one has turned out as ours. But another is that our universe is a computer simulation, with someone (perhaps an advanced alien species) fine-tuning the conditions.

The latter option is supported by a branch of science called information physics, which suggests that space-time and matter are not fundamental phenomena. Instead, the physical reality is fundamentally made up of bits of information, from which our experience of space-time emerges. By comparison, temperature “emerges” from the collective movement of atoms. No single atom fundamentally has temperature.

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Superconducting materials are characterized by the fact that they lose their electrical resistance below a certain temperature, the so-called transition temperature. In principle, they would be ideal for transporting electrical energy over very long distances from the electricity producer to the consumer.

Numerous energy challenges would be solved in one fell swoop: For example, the electricity generated by on the coast could be channeled inland without losses. However, this would only be possible if materials were available that have superconducting properties at normal room and ambient temperatures.

In 2019, an unusually high transition temperature of minus 23 degrees Celsius was measured in experiments coordinated by the Max Planck Institute in Mainz. The measurement took place at a compression pressure of 170 gigapascals—1.7 million times higher than the pressure of the Earth’s atmosphere. The material was a lanthanum (LaH10+δ), a compound of atoms of the metal lanthanum with atoms. The report on these experiments and other similar reports remain highly controversial. They have internationally aroused great interest in research on lanthanum hydrides with different compositions and structures.

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The fine structure constant is one of the most important natural constants of all. At TU Wien, a remarkable way of measuring it has been found—it shows up as a rotation angle.

One over 137: This is one of the most important numbers in physics. It is the approximate value of the so-called fine structure constant—a physical quantity that is of outstanding importance in atomic and .

There are many ways to measure the fine structure constant—usually it is measured indirectly, by measuring other physical quantities and using them to calculate the fine structure constant. At TU Wien, however, an experiment has now been performed, in which the fine structure constant itself can be directly measured—as an angle.

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The James Webb Space Telescope (JWST) has just scored another first: a detailed molecular and chemical portrait of a distant world’s skies.

The telescope’s array of highly sensitive instruments was trained on the atmosphere of a “hot Saturn”—a planet about as massive as Saturn orbiting a star some 700 light-years away—known as WASP-39 b. While JWST and other space telescopes, including Hubble and Spitzer, have previously revealed isolated ingredients of this broiling planet’s atmosphere, the new readings provide a full menu of atoms, molecules, and even signs of active chemistry and clouds.

“The clarity of the signals from a number of different molecules in the data is remarkable,” says Mercedes López-Morales, an astronomer at the Center for Astrophysics | Harvard & Smithsonian and one of the scientists who contributed to the new results.

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NASA’s Imaging X-ray Polarimetry Explorer allowed scientists to probe a distant blazar, shedding new light on the cosmic giants.

Scientists made observations of bright, shining jets of particles shooting out of a supermassive black hole and they published their findings in a paper in Nature.

Investigating a blazar with state-of-the-art instruments.

Pablo Garcia (NASA/MSFC)

The observations shed new light on the high-energy mechanisms of black holes and will help to improve existing computer models of the cosmic giants at the center of most of the galaxies in the observable universe. They also shed new light on the energy mechanisms of blazars, some of the most mysterious objects in the cosmos.

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According to the Standard Model of Particle Physics, the Universe is governed by four fundamental forces: electromagnetism, the weak nuclear force, the strong nuclear force, and gravity. Whereas the first three are described by Quantum Mechanics, gravity is described by Einstein’s Theory of General Relativity. Surprisingly, gravity is the one that presents the biggest challenges to physicists. While the theory accurately describes how gravity works for planets, stars, galaxies, and clusters, it does not apply perfectly at all scales.

While General Relativity has been validated repeatedly over the past century (starting with the Eddington Eclipse Experiment in 1919), gaps still appear when scientists try to apply it at the quantum scale and to the Universe as a whole. According to a new study led by Simon Fraser University, an international team of researchers tested General Relativity on the largest of scales and concluded that it might need a tweak or two. This method could help scientists to resolve some of the biggest mysteries facing astrophysicists and cosmologists today.

The team included researchers from Simon Fraser, the Institute of Cosmology and Gravitation at the University of Portsmouth, the Center for Particle Cosmology at the University of Pennsylvania, the Osservatorio Astronomico di Roma, the UAM-CSIC Institute of Theoretical Physics, Leiden University’s Institute Lorentz, and the Chinese Academy of Sciences (CAS). Their results appeared in a paper titled “Imprints of cosmological tensions in reconstructed gravity,” recently published in Nature Astronomy.

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9 nov 2022.

The challenge of fabricating nanowires directly on silicon substrates for the creation of the next generation of electronics has finally been solved by researchers from Tokyo Tech. Next-generation spintronics will lead to better memory storage mechanisms in computers, making them faster and more efficient.

As our world modernizes faster than ever before, there is an ever-growing need for better and faster electronics and computers. Spintronics is a new system which uses the spin of an electron, in addition to the charge state, to encode data, making the entire system faster and more efficient. Ferromagnetic nanowires with high coercivity (resistance to changes in magnetization) are required to realize the potential of spintronics. Especially L 10-ordered (a type of crystal structure) cobalt-platinum (CoPt) nanowires.

Conventional fabrication processes for L 10-ordered nanowires involve heat treatment to improve the physical and chemical properties of the material, a process called annealing on the crystal substrate; the transfer of a pattern onto the substrate through lithography; and finally the chemical removal of layers through a process called etching. Eliminating the etching process by directly fabricating nanowires onto the silicon substrate would lead to a marked improvement in the fabrication of spintronic devices. However, when directly fabricated nanowires are subjected to annealing, they tend to transform into droplets as a result of the internal stresses in the wire.

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Chemists have created nanorobots propelled by magnets that remove pollutants from water. The invention could be scaled up to provide a sustainable and affordable way of cleaning up contaminated water in treatment plants.

Martin Pumera at the University of Chemistry and Technology, Prague, in the Czech Republic and his colleagues developed the nanorobots by using a temperature-sensitive polymer material and iron oxide. The polymer acts like tiny hands that can pick up and dispose of pollutants in the water, while the iron oxide makes the nanorobots magnetic. The researchers also added oxygen and hydrogen atoms to the iron oxide that can attach onto target pollutants.

The robots are about 200 nanometres wide and are powered by magnetic fields, which allow the team to control their movements.

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