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Archive for the ‘cosmology’ category: Page 85

Sep 26, 2023

Two Black Holes Masquerading as One

Posted by in categories: cosmology, information science, quantum physics

Black holes may be less unique than previously thought, as the expansion due to a cosmological constant can hold apart a pair of holes and allow them to mimic a single black hole.

Black holes are astonishing objects that can pack the mass of Earth into a space the size of a pea. A remarkable attribute is their stunning simplicity, which is encapsulated in the celebrated uniqueness theorems [1]. Briefly stated, these theorems say that there is only one solution to Einstein’s equations of general relativity for a fully collapsed (nonevolving) system having fixed mass and angular momentum [2]. The implication is that all black holes that have settled down to equilibrium with the same mass and rotation are precisely the same: their entire behavior described by a single equation—the so-called Kerr solution—filling only a few lines of paper!

But there is a catch. The uniqueness theorems make a number of assumptions, the key one being that the space around the black hole is “empty”—in other words, there is no energy that might influence the black hole. Such energy can arise from fields, for example, those of the standard model, or from a “cosmological constant,” which is a form of dark energy that might be behind the accelerated expansion of our Universe today. In a fascinating study, Óscar Dias from the University of Southampton, UK, and colleagues demonstrate that uniqueness is violated in the presence of a positive cosmological constant [3]. Specifically, they show that a pair of black holes whose mutual attraction is balanced by the cosmic expansion would look the same to a distant observer as a single isolated black hole. The results may lead to a rethinking of how simple black holes really are.

Sep 26, 2023

Combustion powers bug-sized robots to leap, lift and race

Posted by in categories: chemistry, cosmology, robotics/AI

Call it the big bang for bug-sized robots.

Cornell researchers combined soft microactuators with high-energy-density chemical fuel to create an insect-scale quadrupedal robot that is powered by combustion and can outrace, outlift, outflex and outleap its electric-driven competitors.

Sep 25, 2023

Neutrinos & Dark Matter: How Ultra-Pure Cables Can Unlock Secrets of Physics

Posted by in categories: cosmology, particle physics

Imagine trying to tune a radio to a single station but instead encountering static noise and interfering signals from your own equipment. That is the challenge facing research teams searching for evidence of extremely rare events that could help understand the origin and nature of matter in the universe. It turns out that when you are trying to tune into some of the universe’s weakest signals, it helps to make your instruments very quiet.

Around the world, more than a dozen teams are listening for the pops and electronic sizzle that might mean they have finally tuned into the right channel. These scientists and engineers have gone to extraordinary lengths to shield their experiments from false signals created by cosmic radiation. Most such experiments are found in very inaccessible places—such as a mile underground in a nickel mine in Sudbury, Ontario, Canada, or in an abandoned gold mine in Lead, South Dakota—to shield them from naturally radioactive elements on Earth. However, one such source of fake signals comes from natural radioactivity in the very electronics that are designed to record potential signals.

Sep 24, 2023

James Webb just Found a Supernova That Could Break the Laws of Physics

Posted by in categories: cosmology, physics

In this episode, we explore how a triple-lens supernova observed by the James Webb Space Telescope could help solve the mystery of the Hubble tension, which is the discrepancy between different measurements of the expansion rate of the Universe. We also learn about the details of the supernova and the galaxy cluster that caused the gravitational lensing effect, and how JWST and other telescopes can use this supernova to test various cosmological models and parameters.

Paper Link:
https://arxiv.org/abs/2309.

Continue reading “James Webb just Found a Supernova That Could Break the Laws of Physics” »

Sep 24, 2023

Astronomers weigh ancient galaxies’ dark matter haloes for 1st time

Posted by in categories: cosmology, evolution

The measurement of the mysterious form of matter around these quasar galaxies could have profound implications for our understanding of how the cosmos has evolved.

Sep 24, 2023

Dark stars: Have we finally found a weird sun powered by dark matter?

Posted by in categories: cosmology, particle physics

Astronomers say they have spotted evidence of stars fuelled by the annihilation of dark matter particles. If true, it could solve the cosmic mystery of how supermassive black holes appeared so early.

By Jonathan O’Callaghan

Sep 23, 2023

Theoretical study shows that Kerr black holes could amplify new physics

Posted by in categories: cosmology, physics

Black holes are regions in space characterized by extremely strong gravity, which prevents all matter and electromagnetic waves from escaping it. These fascinating cosmic bodies have been the focus of countless research studies, yet their intricate physical nuances are yet to be fully uncovered.

Researchers at University of California–Santa Barbara, University of Warsaw and University of Cambridge recently carried out a theoretical study focusing on a class of known as extremal Kerr black holes, which are uncharged stationary black holes with a coinciding inner and outer horizon. Their paper, published in Physical Review Letters, shows that these black holes’ unique characteristics could make them ideal “amplifiers” of new, unknown .

“This research has its origin in a previous project started during my visit to UC Santa Barbara,” Maciej Kolanowski, one of the researchers who carried out the study, told Phys.org. “I started discussing very cold (so called, extremal) black holes with Gary Horowitz (UCSB) and Jorge Santos (at Cambridge). Soon we realized that in fact, generic extremal black holes look very different than it was previously believed.”

Sep 20, 2023

Recoiling black holes could move at nearly one-tenth the speed of light

Posted by in categories: cosmology, physics

Knowing black holes’ speed after being kicked by gravitational waves can reveal how much energy converging black holes can release.

Sep 20, 2023

How dark matter-powered stars could solve a huge cosmological puzzle

Posted by in categories: cosmology, particle physics

Astronomers say they have spotted evidence of stars fuelled by the annihilation of dark matter particles. If true, it could solve the cosmic mystery of how supermassive black holes appeared so early.

By Jonathan O’Callaghan

Sep 20, 2023

JWST’s first triple-image supernova could save the Universe

Posted by in categories: cosmology, futurism

With future observations and as more time passes — both from new data and from data that’s still being analyzed and prepared by this collaboration — we may obtain the most precise and accurate measurement for the expansion rate of the Universe using the cosmic distance ladder method of all-time.

This triply-imaged supernova was not named “Supernova H0pe” in vain, as it really does give us hope that the answer to today’s greatest cosmic puzzle may indeed be written on the face of the Universe. With JWST going strong, we may have already found the galaxy cluster, and the gravitationally lensed system, that will resolve what’s been puzzling astronomers for the entirety of the 21st century.

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