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Category: particle physics – Page 367

What is time? What is humankind’s role in the universe? What is the meaning of life? For much of human history, these questions have been the province of religion and philosophy. What answers can science provide?

In this talk, Sean Carroll will share what physicists know, and don’t yet know, about the nature of time. He’ll argue that while the universe might not have purpose, we can create meaning and purpose through how we approach reality, and how we live our lives.

Sean Carroll is a Research Professor of theoretical physics at the California Institute of Technology, and an External Professor at the Santa Fe Institute. His research has focused on fundamental physics and cosmology, especially issues of dark matter, dark energy, spacetime symmetries, and the origin of the universe.

Recently, Carroll has worked on the foundations of quantum mechanics, the emergence of spacetime, and the evolution of entropy and complexity. Carroll is the author of Something Deeply Hidden, The Big Picture, The Particle at the End of the Universe amongst other books and hosts the Mindscape podcast.

Continue reading “The Passage of Time and the Meaning of Life | Sean Carroll” | >

JÜLICH, Germany, May 28, 2021 — Quantum systems are considered extremely fragile. Even the smallest interactions with the environment can result in the loss of sensitive quantum effects. In the renowned journal Science, however, researchers from TU Delft, RWTH Aachen University and Forschungszentrum Jülich now present an experiment in which a quantum system consisting of two coupled atoms behaves surprisingly stable under electron bombardment. The experiment provide an indication that special quantum states might be realised in a quantum computer more easily than previously thought.

The so-called decoherence is one of the greatest enemies of the quantum physicist. Experts understand by this the decay of quantum states. This inevitably occurs when the system interacts with its environment. In the macroscopic world, this exchange is unavoidable, which is why quantum effects rarely occur in daily life. The quantum systems used in research, such as individual atoms, electrons or photons, are better shielded, but are fundamentally similarly sensitive.

“Systems subject to quantum physics, unlike classical objects, are not sharply defined in all their properties. Instead, they can occupy several states at once. This is called superposition,” Markus Ternes explains. “A famous example is Schrödinger’s thought experiment with the cat, which is temporarily dead and alive at the same time. However, the superposition breaks down as soon as the system is disturbed or measured. What is left then is only a single state, which is the measured value,” says the quantum physicist from Forschungszentrum Jülich and RWTH Aachen University.

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How materials behave depends on the interactions between countless atoms. You could see this as a giant group chat in which atoms are continuously exchanging quantum information. Researchers from Delft University of Technology in collaboration with RWTH Aachen University and the Research Center Jülich have now been able to intercept a chat between two atoms. They present their findings in Science on May 28, 2021.

Atoms, of course, don’t really talk. But they can feel each other. This is particularly the case for magnetic atoms. “Each atom carries a small magnetic moment called spin. These spins influence each other, like compass needles do when you bring them close together. If you give one of them a push, they will start moving together in a very specific way,” explains Sander Otte, leader of the team that performed the research. “But according to the laws of quantum mechanics, each spin can be simultaneously point in various directions, forming a superposition. This means that actual transfer of quantum information takes place between the atoms, like some sort of conversation.”

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What does quark-gluon plasma—the hot soup of elementary particles formed a few microseconds after the Big Bang—have in common with tap water? Scientists say it’s the way it flows.

A new study, published today in the journal SciPost Physics, has highlighted the surprising similarities between , the first matter thought to have filled the early Universe, and water that comes from our tap.

The ratio between the viscosity of a , the measure of how runny it is, and its density, decides how it flows. Whilst both the viscosity and density of are about 16 orders of magnitude larger than in water, the researchers found that the ratio between the viscosity and density of the two types of fluids are the same. This suggests that one of the most exotic states of matter known to exist in our universe would flow out of your tap in much the same way as water.

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Step aside, Nikon P1000, the new king of zoom is here. It’s an electronic microscope, though, but it can zoom in 100 million times and still keep the subject clear. It’s so impressive, in fact, that it earned a spot in the Guinness World Records.

Although electron microscopes allow scientists to see individual atoms, zooming all that far will not result in a sufficiently clear image. It’s due to the aberrations in the lenses which are corrected with special aberration correctors. But the problem is that you can’t stack those correctors forever.

David Muller and Sol Gruner, physics professors of Cornell University, came up with a new approach that they first introduced back in 2018. Their electron microscope achieves high resolution using a high-powered detector and a technique called ptychography. Thanks to this technique, they could capture in sharp detail even particles that measure down to 0.39 ångströms or 0.039 nanometers (one-billionth of a meter).

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Transmission electron microscopy (TEM) is a technique that involves beaming electrons through a specimen to form an image. This enables the generation of significantly higher resolution than traditional optical microscopes. While the latter devices are typically limited to around 1000x magnification due to the resolving power of visible light, TEM can provide zoom capabilities that are orders of magnitude greater – surpassing even a scanning electron microscope (SEM).

In recent years, TEM instruments have begun to reach extraordinary levels of detail. Spatial resolutions are now edging into the realm of individual atoms, measuring less than 0.0000005 millimetres (mm).

However, TEM is prone to lens aberrations and multiple scattering, limiting its use to samples thin enough to let electrons pass through. The process is technically challenging and requires additional tools to perform. In 2018, researchers at Cornell University offered a potential solution. They built a high-powered detector combined with a new algorithm-driven process called ptychography. This achieved a new record for microscopic resolution, tripling the previous state-of-the-art.

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## SCIENCE ADVANCES • MAY 24, 2021 # *by Vienna University of Technology*

In everyday life, phase transitions usually have to do with temperature changes--for example, when an ice cube gets warmer and melts. But there are also different kinds of phase transitions, depending on other parameters such as magnetic field. In order to understand the quantum properties of materials, phase transitions are particularly interesting when they occur directly at the absolute zero point of temperature. These transitions are called "quantum phase transitions" or a "quantum critical points."

Such a quantum critical point has now been discovered by an Austrian-American research team in a novel material, and in an unusually pristine form. The properties of this material are now being further investigated.

It is suspected that the material could be a so-called Weyl-Kondo semimetal, which is considered to have great potential for quantum technology due to special quantum states (so-called topological states). If this proves to be true, a key for the targeted development of topological quantum materials would have been found.

This surprising result is probably related to the fact that the behavior of electrons in this material has some special features. "It is a highly correlated electron system. This means that the electrons interact strongly with each other, and that you cannot explain their behavior by looking at the electrons individually.

Continue reading “New quantum material discovered” | >

Circa 2016 o.o!

The theory used to be that hydrocarbons were created in “shocks,” or violent stellar events that cause a lot of turbulence and, with the shock waves, make atoms into ions, which are more likely to combine.

The data from the European Space Agency’s Herschel Space Observatory has since proved that theory wrong. Scientists at Herschel studied the components in the Orion Nebula, mapping the amount, temperature and motions for the carbon-hydrogen molecule (CH), the carbon-hydrogen positive ion (CH+) and their parent molecule: the carbon ion (C+).

They found that in Orion, CH+ is emitting light instead of absorbing it, which means that it is warmer than the background gas. This was surprising to scientists because the CH+ molecule is incredibly reactive and needs a high amount of energy to form, so when it interacts with the background hydrogen in the cloud it gets destroyed.

Continue reading “Scientists find ultraviolet light may create life-essential chemicals” | >

Cosmic rays are high-energy atomic particles continually bombarding Earth’s surface at nearly the speed of light. Our planet’s magnetic field shields the surface from most of the radiation generated by these particles. Still, cosmic rays can cause electronic malfunctions and are the leading concern in planning for space missions.

Researchers know cosmic rays originate from the multitude of stars in the Milky Way, including our sun, and other galaxies. The difficulty is tracing the particles to specific sources, because the turbulence of interstellar gas, plasma, and dust causes them to scatter and rescatter in different directions.

In AIP Advances, University of Notre Dame researchers developed a to better understand these and other cosmic ray transport characteristics, with the goal of developing algorithms to enhance existing detection techniques.

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