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For the first time, the “inertial range connecting large and small eddies in accretion disk turbulence” was reproduced.

Black holes cannot be directly detected by ground or space-based telescopes. But the accretion disks of gas, plasma, and dust that orbit them emit detectable electromagnetic radiation, allowing astronomers to infer the presence of black holes.

Continue reading “Supercomputers expose hidden inner disk dynamics of a black hole” »

After its formation, the moon may have been the scene of such immense volcanic activity that its entire crust melted several times and was completely churned through. At that time, the moon orbited significantly closer to Earth than today. The resulting tidal forces heated up its interior and thus powered the violent volcanism. Only Jupiter’s moon Io, by far the most volcanically active body in the solar system, offers comparable conditions.

These new considerations published today in the journal Nature by an international team of researchers from the University of California Santa Cruz, the Max Planck Institute for solar system Research (MPS) and the Collège de France resolve previous contradictions and inconsistencies regarding the age of the moon. According to the researchers, the moon was formed between 4.43 and 4.51 billion years ago. Its crust, however, appears around 80 to 160 million years younger.

The moon is apparently quite reluctant to reveal its age. Attempts to uncover its secret have yielded estimates that lie several hundred million years apart: While some researchers suggest that our cosmic companion was formed 4.35 billion years ago, others date its birth to 4.51 billion years ago.

How do you find and measure nuclear particles, like antineutrinos, that travel near the speed of light?

Antineutrinos are the antimatter partner of a neutrino, one of nature’s most elusive and least understood subatomic particles. They are commonly observed near nuclear reactors, which emit copious amounts of antineutrinos, but they also are found abundantly throughout the universe as a result of Earth’s natural radioactivity, with most of them originating from the decay of potassium-40, thorium-232 and uranium-238 isotopes.

When an antineutrino collides with a proton, a positron and a neutron are produced—a process known as inverse beta decay (IBD). This event causes scintillating materials to light up, making it possible to detect these antineutrinos; and if they can be detected, they can be used to study the properties of a reactor’s core or Earth’s interior.

Caltech researchers have developed a new method to map the positions of hundreds of DNA-associated proteins within cell nuclei all at the same time. The method, called ChIP–DIP (Chromatin ImmunoPrecipitation Done In Parallel), is a versatile tool for understanding the inner workings of the nucleus during different contexts, such as disease or development.

The research was conducted in the laboratory of Mitchell Guttman, professor of biology, and is described in a paper that appears in the journal Nature Genetics.

Nearly all cells in the human body contain the same DNA, which encodes the blueprint for creating every cell type in the body and directing their activities. Despite having the same genetic material, different cell types express unique sets of proteins, allowing for the various cells to perform their specialized functions and to adapt to conditions within their environments. This is possible because of careful regulation within the nucleus of each cell and involves thousands of regulatory proteins that localize to precise places in the nucleus.

At night, charged particles from the sun caught by Earth’s magnetosphere rain down into the atmosphere. The impacting particles rip electrons from atoms in the atmosphere, creating both beauty and chaos. These high-energy interactions cause the northern and southern lights, but they also scatter radio signals, wreaking havoc on ground-based and satellite communications.

Scientists would like to track electrical activity in the ionosphere by measuring the distribution of plasma, the form matter takes when positive ions are separated from their electrons, to help better predict how communications will be affected by electromagnetic energy.

But analyzing plasma in the ionosphere is a challenge because its distribution changes quickly and its movements are often unpredictable. In addition, collisional physics makes detecting true motion in the lower ionosphere exceedingly difficult.

A team of researchers has identified a unique phenomenon, a “skin effect,” in the nonlinear optical responses of antiferromagnetic materials. The research, published in Physical Review Letters, provides new insights into the properties of these materials and their potential applications in advanced technologies.

Nonlinear optical effects occur when light interacts with materials that lack inversion symmetry. It was previously thought that these effects were uniformly distributed throughout the material. However, the research team discovered that in antiferromagnets, the nonlinear optical response can be concentrated on the surfaces, similar to the “skin effect” seen in conductors, where currents flow primarily on the surface.

In this study, the team developed a self-designed computational method to investigate the nonlinear optical responses in antiferromagnets, using the bulk photovoltaic effect as a representative example. Their results showed that, while the global inversion symmetry was broken, the local inversion symmetry deep inside the antiferromagnet was almost untouched.

Imagine if we could take the energy of the sun, put it in a container, and use it to provide green, sustainable power for the world. Creating commercial fusion power plants would essentially make this idea a reality. However, there are several scientific challenges to overcome before we can successfully harness fusion power in this way.

Researchers from the U. S. Department of Energy (DOE) Ames National Laboratory and Iowa State University are leading efforts to overcome material challenges that could make commercial fusion power a reality. The research teams are part of a DOE Advanced Research Projects Agency-Energy (ARPA-E) program called Creating Hardened And Durable fusion first Wall Incorporating Centralized Knowledge (CHADWICK). They will investigate materials for the first wall of a fusion reactor. The first wall is the structure that surrounds the fusion reaction, so it bears the brunt of the extreme environment in the fusion reactor core.

ARPA-E recently selected 13 projects under the CHADWICK program. Of those 13, Ames Lab leads one of the projects and is collaborating alongside Iowa State on another project, which is led by Pacific Northwest National Laboratory (PNNL).

In the quest for ultra-precise timekeeping, scientists have turned to nuclear clocks. Unlike optical atomic clocks—which rely on electronic transitions—nuclear clocks utilize the energy transitions in the atom’s nucleus, which are less affected by outside forces, meaning this type of clock could potentially keep time more accurately than any previously existing technology.

However, building such a clock has posed major challenges—thorium-229, one of the isotopes used in nuclear clocks, is rare, radioactive, and extremely costly to acquire in the substantial quantities required for this purpose.

Reported in a study published in Nature, a team of researchers, led by JILA and NIST Fellow and University of Colorado Boulder Physics professor Jun Ye, in collaboration with Professor Eric Hudson’s team at UCLA’s Department of Physics and Astronomy, have found a way to make nuclear clocks a thousand times less radioactive and more cost-effective, thanks to a method creating thin films of thorium tetrafluoride (ThF₄).

MIT physicists have created a new and long-lasting magnetic state in a material, using only light.

In a study that appears in Nature, the researchers report using a terahertz laser —a light source that oscillates more than a trillion times per second—to directly stimulate atoms in an antiferromagnetic material. The laser’s oscillations are tuned to the natural vibrations among the material’s atoms, in a way that shifts the balance of atomic spins toward a new magnetic state.

The results provide a new way to control and switch antiferromagnetic materials, which are of interest for their potential to advance information processing and memory chip technology.