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Archive for the ‘cosmology’ category: Page 43

Nov 21, 2022

New superstring theory says black holes may be portals to other universes

Posted by in categories: cosmology, quantum physics

Circa 2021 face_with_colon_three


We don’t know very much about our universe. We’re fairly certain it exists, but we don’t know how it got here, how long it’s been here, or how big it is. Heck, we don’t even know if our universe is unique.

Ever since Albert Einstein came up with the theory of relativity and other scientists realized that classical physics and quantum mechanics don’t really line up, we’ve been trying to reconcile those worlds.

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Nov 21, 2022

Dark Matter as an Intergalactic Heat Source

Posted by in categories: cosmology, particle physics

Spectra from quasars suggest that intergalactic gas may have been heated by a form of dark matter called dark photons.

Dense gas clouds across the Universe absorb light from distant quasars, producing absorption lines in the quasar spectra. A new study shows that the larger-than-predicted widths of these lines from nearby gas clouds could result from a form of dark matter called dark photons [1]. These particles could heat the clouds, leading to a widening of the absorption lines. Other explanations of the broadening—based on more conventional heating sources—have been proposed, but if the dark-photon mechanism is at work, it might also cause heating in low-density clouds from earlier epochs of the Universe. Researchers are already planning to test this prediction.

When viewing the spectrum of a distant quasar, astronomers often observe absorption lines coming from the intervening clouds of gas. The most prominent absorption line is the Lyman-alpha line of hydrogen. Indeed, some quasar spectra have a “forest” of Lyman-alpha lines, with each coming from a cloud at a different distance from our Galaxy (or different epochs). By examining the widths, depths, and other details of the line shapes, researchers can extract information about the density, the temperature, and other features of the clouds. This information can be compared with the results of cosmological simulations that try to reproduce the clumping of matter into galaxies and other large-scale structures.

Nov 20, 2022

Simulations suggest GW190521 merger was the result of non-spinning black holes randomly finding each other

Posted by in categories: cosmology, physics

A team of researchers from Friedrich-Schiller-Universität Jena, Università di Torino and INFN sezione di Torino, has found evidence that the black hole collision that led to an odd gravitational wave detection in 2019 was due to a unique set of circumstances. In their paper published in the journal Nature Astronomy, the group describes modeling and simulating the conditions that could possibly lead to the unique gravitational wave signature.

The development of gravitational wave detectors has led to a better understanding of what happens when collide. In most instances, the data has shown, they occur due to exploding and then slowly spiraling toward one another until they meet at a gravitational center and merge.

But then, on May 21, 2019, were detected from two black holes merging, but the data showed that neither of the black holes appeared to be spinning and the duration of the signal was shorter than all the others that have been detected. The odd signal left astrophysicists scratching their heads. Now, in this new effort, the researchers believe they have come up with a plausible explanation for the observation.

Nov 20, 2022

Researchers simulated a black hole on Earth, and it actually started to glow

Posted by in category: cosmology

A group of researchers recently simulated the event horizon of a man-made black hole in a lab. The new analog could help us learn more about the elusive radiation that is believed to be emitted by real black holes out in space. Black holes are by far one of the most mysterious objects in space.

Nov 20, 2022

Scientists are finally decoding the secrets within the Milky Way’s supermassive black hole

Posted by in categories: cosmology, evolution

The massive object at the galaxy’s center is invisible. But this year’s picture of the swirling plasma around its edges will help to reveal more about the galaxy’s history and evolution.

Nov 19, 2022

JWST’s First Glimpses of Early Galaxies Could Break Cosmology

Posted by in category: cosmology

The James Webb Space Telescope’s first images of the distant universe shocked astronomers. Is the discovery of unimaginably distant galaxies a mirage or a revolution?

Nov 18, 2022

Our universe may have a twin that runs backward in time

Posted by in category: cosmology

An anti-universe running backwards in time could explain dark matter and cosmic inflation.

Nov 18, 2022

Physicists Study How Universes Might Bubble Up and Collide

Posted by in categories: cosmology, quantum physics

Circa 2021 face_with_colon_three


In the cosmological context, space can get similarly stuck in a false vacuum state. A speck of false vacuum will occasionally relax into true vacuum (likely through a random quantum event), and this true vacuum will balloon outward as a swelling bubble, feasting on the false vacuum’s excess energy, in a process called false vacuum decay. It’s this process that may have started our cosmos with a bang. “A vacuum bubble could have been the first event in the history of our universe,” said Hiranya Peiris, a cosmologist at University College London.

But physicists struggle mightily to predict how vacuum bubbles behave. A bubble’s future depends on countless minute details that add up. Bubbles also change rapidly — their walls approach the speed of light as they fly outward — and feature quantum mechanical randomness and waviness. Different assumptions about these processes give conflicting predictions, with no way to tell which ones might resemble reality. It’s as though “you’ve taken a lot of things that are just very hard for physicists to deal with and mushed them all together and said, ‘Go ahead and figure out what’s going on,’” Braden said.

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Nov 18, 2022

Webb telescope finds two of the most distant galaxies ever observed

Posted by in category: cosmology

The James Webb Space Telescope has spied one of the earliest galaxies formed after the big bang, about 350 million years after the universe began.

The galaxy, called GLASS-z12, and another galaxy formed about 450 million years after the big bang, were found over the summer, shortly after the powerful space observatory began its infrared observations of the cosmos.

Webb’s capability to look deeper into the universe than other telescopes is revealing previously hidden aspects of the universe, including astonishingly distant galaxies such as these two finds.

Nov 18, 2022

Black holes could reveal their quantum-superposition states, new calculations reveal

Posted by in categories: cosmology, particle physics, quantum physics, singularity

Quantum superposition is not just a property of subatomic particles but also of the most massive objects in the universe. That is the conclusion of four theoretical physicists in Australia and Canada who calculated the hypothetical response of a particle detector placed some distance from a black hole. The researchers say the detector would see novel signs of superimposed space–times, implying that the black hole may have two different masses simultaneously.

Black holes are formed when extremely massive objects like stars collapse to a singularity – a point of infinite density. The gravitational field of a black hole is so great that nothing can escape its clutches, not even light. This creates a spherical region of space around the singularity entirely cut off from the rest of the universe and bounded by what is known as an event horizon.

An active area of research into the physics of black holes seeks to develop a consistent theory of quantum gravity. This is an important goal of theoretical physics that would reconcile quantum mechanics and Einstein’s general theory of relativity. In particular, by considering black holes in quantum superposition, physicists hope to gain insights into the quantum nature of space–time.

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