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Astronomers have assembled the largest-ever compilation of high-precision galaxy distances, called Cosmicflows-4. Galaxies, such as the Milky Way, are the building blocks of the universe, each comprised of up to several hundred billion stars. Galaxies beyond our immediate neighborhood are rushing away, faster if they are more distant, which is a consequence of the expansion of the universe that began at the moment of the Big Bang. Measurements of the distances of galaxies, coupled with information about their velocities away from us, determine the scale of the universe and the time that has elapsed since its birth.

“Since galaxies were identified as separate from the Milky Way a hundred years ago, astronomers have been trying to measure their distances,” said Brent Tully, astronomer at the University of Hawaii at Manoa. “Now by combining our more accurate and abundant tools, we are able to measure distances of galaxies, and the related expansion rate of the universe and the time since the universe was born with a precision of a few per cent.”

From the newly published measurements, the researchers derived the expansion rate of the universe, called the Hubble Constant, or H0. The team’s study gives a value of H0=75 kilometers per second per megaparsec or Mpc (1 megaparsec = 3.26 million light years), with very small statistical uncertainty of about 1.5 percent.

There are a number of ways to measure galaxy distances. Generally, individual researchers focus on an individual method. The Cosmicflows program spearheaded by Tully and Kourkchiincludes their own original material from two methods, and additionally incorporates information from many previous studies. Because Cosmicflows-4 includes distances derived from a variety of independent, distinct distance estimators, intercomparisons should mitigate against a large systematic error.

Astronomers have assembled a framework that shows the universe’s age to be a little more than 13 billion years old, however, a dilemma of great significance has arisen in the details.

Physics of the evolution of the universe based on the standard model of cosmology predicts H0=67.5 km/s/Mpc, with an uncertainty of 1 km/s/Mpc. The difference between the measured and predicted values for the Hubble Constant is 7.5 km/s/Mpc – much more than can be expected given the statistical uncertainties. Either there is a fundamental problem with our understanding of the physics of the cosmos, or there is a hidden systematic error in the measurements of galaxy distances.

Cosmicflows-4 is also being used to study how galaxies move individually, in addition to flowing with the overall expansion of the universe. Deviations from this smooth expansion arise due to the gravitational influences of clumps of matter, on scales ranging from our Earth and Sun up to congregations of galaxies on scales of a half billion light years. The mysterious dark matter is the dominant component on larger scales. With knowledge of the motions of galaxies in response to the mass around them, we can recreate the orbits that galaxies have followed since they were formed, giving us a better understanding of how the universe’s vast, dark-matter-dominated structures have formed over the eons of time.


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Scientists Recreate Cosmic Ray Physics Using Cold Atom in New Laboratory Study

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Scientists Recreate Cosmic Ray Physics Using Cold Atom in New Laboratory Study

For the first time, researchers have managed to simulate a fundamental process of cosmic particle acceleration in a laboratory: the first series of discoveries that will transform our understanding of cosmic rays. Now, scientists from the Universities of Birmingham and Chicago have created a tiny, 100-micrometre Fermi accelerator, in which mobile optical potential barriers collide with trapped atoms, in a partial replica of how cosmic particles pick up energy in space. The technique not only replicates cosmic ray behaviour but also sets a new benchmark in quantum acceleration technology.

Lab-Built Fermi Accelerator Using Cold Atoms Validates Cosmic Ray Theory and Advances Quantum Tech

As per findings published in Physical Review Letters, this fully controllable setup demonstrated particle acceleration through the Fermi mechanism first proposed by physicist Enrico Fermi in 1949. Long theorised to underlie cosmic ray generation, the process had never been reliably replicated in a lab. By combining energy gains with particle losses, researchers created energy spectra similar to those observed in space, offering the first direct validation of Bell’s result, a cornerstone of cosmic ray physics.

In Fermi acceleration, ultracold atoms are accelerated to more than 0.5 metres per second using laser-controlled barriers. Dr Amita Deb, a coauthor and researcher at the University of Birmingham, mentioned, ‘Our chimney is more powerful than conventional quantum nano-measurements, which are the best acceleration tools in the world so far, and while its simplicity and small size can be compelling, its lack of a theoretical speed limit is the most attractive feature.’ The ultracold atomic jets could be readily controlled with high precision in the subsequent experiments.

This progress means that, for the first time, complicated astrophysical events like shocks and turbulence can be studied in a laboratory, lead author Dr Vera Guarrera stated. This opens new avenues for high-energy astrophysics and also for applications in quantum wavepacket control and quantum chemistry.

Researchers plan to find out how different behaviour affects energy cutoffs and acceleration rates. A compact Fermi accelerator of this type could be a cornerstone for studies of fundamental physics and also connect to emerging technologies such as atomtronics.

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Scientists Say Dark Matter Could Turn Failed Stars Into ‘Dark Dwarfs’

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Scientists Say Dark Matter Could Turn Failed Stars Into ‘Dark Dwarfs’

Astronomers now propose that “failed stars” known as brown dwarfs could be powered by dark matter. Dark matter makes up about 85 percent of the universe’s matter but does not shine; it interacts only via gravity. Brown dwarfs form like stars but lack enough mass to ignite fusion. The theory suggests brown dwarfs in galaxy centers might trap dark matter in their interiors. When that dark matter annihilates, it releases energy that heats the star, turning the dwarf into a brighter “dark dwarf.” If such objects exist, finding them would give scientists a new clue to the nature of dark matter.

Dark Matter in Failed Stars

According to the new model, dense brown dwarfs at the centers of galaxies act like gravity wells that accumulate dark matter. Because dark matter interacts only via gravity, it naturally drifts to galactic cores, where it can be captured by star. As University of Hawai‘i physicist Jeremy Sakstein explains, once inside a star dark matter can annihilate with itself, releasing energy that heats the dwarf. The more dark matter a brown dwarf collects, the more energy it outputs. Crucially, this effect only works if dark matter particles self-annihilate (as with heavy WIMPs); lighter or non-interacting candidates like axions would not create dark dwarfs.

They propose using a chemical signature: a dark dwarf should hold on to lithium-7 that normal brown dwarfs burn away. The researchers say powerful telescopes like NASA’s James Webb Space Telescope might already be sensitive enough to spot cool, dim dark dwarfs near the Milky Way’s center. Detecting even one would strongly suggest that dark matter is made of heavy, self-interacting particles (like WIMPs).

In related work, Colgate astrophysicist Jillian Paulin coauthored studies of ancient “dark stars” fueled by dark matter, while SLAC physicist Rebecca Leane and collaborators have shown that dark matter capture could heat brown dwarfs and exoplanets – a process called “dark kinetic heating”. Together, these ideas highlight how even dim, unusual stars could illuminate the nature of dark matter.

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New Gel-Based Robotic Skin Feels Touch, Heat, and Damage Like Human Flesh

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New Gel-Based Robotic Skin Feels Touch, Heat, and Damage Like Human Flesh

Researchers have created a novel electronic “skin” that could let robots experience a sense of touch. This low-cost, gelatin-based material is highly flexible and durable and can be molded over a robot hand. Equipped with electrodes, the skin detects pressure, temperature changes, and even sharp damage. In tests it responded to pokes, burns and cuts. Unlike conventional designs that use separate sensors for each stimulus, this single “multi-modal” material simplifies the hardware while providing rich tactile data. The findings, published in Science Robotics, suggest it could be used on humanoid robots or prosthetic limbs to give them a more human-like touch.

Multi-Modal Touch and Heat Sensing

According to the paper, unlike typical robotic skins, which require multiple specialized sensors, the new gel acts as a single multi-modal sensor. Its uniform conductive layer responds differently to a light touch, a temperature change or even a scratch by altering tiny electrical pathways. This design makes the skin simpler and more robust: researchers note it’s easier to fabricate and far less costly than conventional multi-sensor skins. In effect, one stretchy sheet of this material can replace many parts, cutting complexity while maintaining rich sensory feedback.

Testing the Skin and Future Applications

The research team tested the skin by casting the gel into a human-hand shape and outfitting it with electrodes. They put it through a gauntlet of trials: blasting it with a heat gun, pressing it with fingers and a robotic arm, and even slicing it open with a scalpel. Those harsh tests generated over 1.7 million data points from 860,000 tiny conductive channels, which fed into a machine-learning model so the skin could learn to distinguish different types of touch.

UCL’s Dr. Thomas George Thuruthel, a co-author of the study, said the robotic skin isn’t yet as sensitive as human skin but “may be better than anything else out there at the moment.” He noted that the material’s flexibility and ease of manufacture as key advantages. Moreover, the team believes this technology could ultimately help make robots and prosthetic devices with a more lifelike sense of touch.

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