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Black hole feeding bursts may explain JWST’s Little Red Dots in early universe

A new theoretical study may have cracked one of the most puzzling discoveries of the James Webb Space Telescope (JWST): Little Red Dots, spotted across the early universe. The paper, posted to the arXiv preprint server on May 29, argues that these objects could be black holes caught in rare, violent bursts of feeding at a rate exceeding theoretical limits.

Since JWST began its survey of the deep universe, astronomers have been puzzled by a class of tiny, faint objects appearing in the early universe in far greater numbers than expected. They have a distinctive V-shaped spectrum—bright in both ultraviolet and optical light, but with a dip in between—along with broad emission lines hinting at active black holes. They also show an absence of X-ray, radio and infrared emission.

They don’t look like ordinary galaxies, and they don’t completely look like quasars, either. What they are has been an open question. Some researchers argue that Little Red Dots may need some outside-the-box physics to explain their origin and nature.

Neutron star merger simulations gain new precision with AI-driven r-process heating

Using a novel simulation model based on machine learning, an international research team at GSI/FAIR has succeeded in gaining a deeper understanding of element formation in stellar events such as neutron star mergers. For the first time, the scientists used deep learning with a neural network to model the energy release during r-process nucleosynthesis in hydrodynamic simulations. The results are published in the journal Physical Review D.

Many of the chemical elements we know are created in massive stellar events such as exploding stars or neutron star mergers. These events release incredible amounts of energy, allowing for the production of heavy nuclides. One key nuclear production process is the so-called rapid neutron-capture process, or r-process, in which free neutrons are captured by existing nuclei and converted into protons—thus creating larger, heavier atomic nuclei.

“Researchers around the world strive to make these complex reactions understandable through theoretical simulations. However, modeling all parameters requires incredible computing power, which is why the models often have to be simplified,” said Dr. Oliver Just, first author of the publication and a researcher in the Nuclear Astrophysics & Structure Department at GSI/FAIR. “Our new model, RHINE, which uses artificial intelligence, offers an efficient alternative.”

China’s Thorium Reactors

Every commercial nuclear reactor in the world runs on uranium. Uranium brings three undeniable problems. It creates weapons-grade plutonium. It melts down under pressure. Its radioactive waste lasts for tens of thousands of years.

Thorium solves all three.
Physicists have known this since the 1960s. The United States actually built a working thorium reactor. They proved the technology was viable. Then they deliberately abandoned it.

Milky Way black hole’s missing wind finally found after a half-century-long search

The hunt is over. After more than 50 years of searching, astrophysicists at Northwestern University have finally discovered evidence of a powerful wind blowing from the Milky Way’s central supermassive black hole, Sagittarius A* (Sgr A.

According to theoretical physics and a long-accepted understanding of galaxies’ evolution, as black holes consume materials, they should produce wind or jets. Even a small amount of gas falling into a black hole should generate enough energy to push material outwards. Without wind, Sgr A* would be a unique outlier.

But, until now, no one could find it.

Physicists discover attractive forces between molecular condensates may cause running off

Inside cells, certain functions are carried out by locally adjusting molecular composition. This condensation of material results in the formation of dense droplets that can dynamically rearrange. Because of this, interactions between such dense regions determine the shaping of condensates. Scientists from the Department of Living Matter Physics at MPI-DS recently developed a model that can describe such phase separation dynamics based solely on attraction. The work is published in the journal Physical Review Letters.

“It’s natural to think that a system with only attractive forces would form one large, stationary condensate,” explained Jacopo Romano, first author of the study.

“However, instead we observed an unexpected emergent property of chasing dynamics resulting in movement and propulsion,” he said.

We’ve Been Searching for Aliens the Wrong Way. That’s All About To Change

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We’ve been looking for messages from the stars ever since Frank Drake pointed the Green Bank radio telescope at Tau Ceti and Epsilon Eridany 65 years ago. He saw nothing that couldn’t be explained by natural causes. Nor have the much more extensive SETI surveys conducted since. So, maybe there are no alien signals to see. Or maybe we need to update how we search for them. We have, after all, learned an awful lot since 1960—both about the galaxy and about observing the galaxy.

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Measuring gravitational waves in a humming universe with a coordinate-free approach

Gravitational waves are tiny ripples in spacetime. Their first direct detection in 2015 marked a revolutionary moment in astronomy. Today, we have a thorough understanding of signals that travel far from their sources through quiet, nearly empty space, such as those emitted when black holes merge. In this case, the wave can be considered a minor disturbance on a silent background. The distinction between “background” and “wave” is clear, and the quantity measured by the detector—a tiny stretching and squeezing—is clearly determined.

In cosmology, however, things are more subtle. The focus shifts to the universe in its entirety—encompassing spacetime and everything contained within it, such as stars, black holes and galaxies. The background itself is dynamic. Small fluctuations in density and velocity gently stir spacetime everywhere, blurring the boundary with the wave.

But what exactly does a gravitational-wave detector measure when the entire universe is gently vibrating? Previously, theoretical predictions were entirely dependent on the choice of mathematical coordinates. However, the only meaningful quantity is what a real instrument records, which must be coordinate-independent.

AI paired with tiny optical device corrects distorted light for sharper imaging

Blurry light from lens imperfections is a problem everywhere, from microscopes to telescopes to smartphone cameras. Using a tiny yet carefully engineered optical element and artificial intelligence, University of California San Diego engineers have built a way to spot and correct those distortions from a single image—a step that could make advanced optical systems faster, smaller and easier to use.

“We used a combination of fundamental physics, nanofabrication and machine learning to make hidden distortions easier to detect and correct,” said senior author Abdoulaye Ndao, an electrical and computer engineering faculty member in the Jacobs School of Engineering and an affiliate of the Qualcomm Institute at UC San Diego.

“Our fast, robust solution is tiny and easy to integrate into different optical systems,” he continued. “The weight is almost nothing, because the size of the sample can be one by one centimeter and half a millimeter thick.”

Portable UV spectrometer can detect air pollutants across 2.5 km with high precision

Birgitta Schultze-Bernhardt and her team at the Institute of Experimental Physics at Graz University of Technology (TU Graz) have developed a new type of UV dual-comb spectrometer that detects gaseous air pollutants with unrivaled accuracy and sensitivity. Using ultraviolet double laser light, the device measures the concentration of harmful gases such as formaldehyde within half a second.

Thanks to its compact design and a measuring range of up to two and a half kilometers, the spectrometer is not only suitable for laboratory analyses, but also for mobile measurements in cities, industrial areas and agricultural regions.

The work is published in the journal PhotoniX.

Violating the 3rd law of black hole mechanics in vacuum gravity

Black holes, regions in space where gravity is so strong that nothing can escape, have been widely studied over the past decades, due to their unique and intriguing properties. Einstein’s theory of general relativity predicts that black holes obey a set of rules, known as the laws of black hole mechanics. These rules somewhat resemble the laws of thermodynamics, which delineate how energy, heat, and entropy behave in our universe.

The 3rd law of black hole mechanics states that an extremal black hole, or in other words, a black hole that is spinning or charged to its absolute theoretical limit, cannot realistically form in a finite amount of time.

Extremal black holes are predicted to have a surface gravity of zero, thus they do not emit standard Hawking radiation and would not evaporate in a vacuum. This specific characteristic of extremal black holes is known as “zero temperature.”

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