Saturday, January 30, 2021

Extreme black holes probably have 'hair' | Space

According to a leading idea known as the "no hair" or "black hole uniqueness" theorem, black holes can be fully characterized using just three data points — their mass, spin and electric charge. There's no other observable information to be had about these light-gobbling behemoths, which therefore seem to be sleekly and uniquely "bald."

But a new study casts doubt on the no-hair idea , or at least its universal application: Computer simulations suggest that "extreme" black holes — the ones whose spin or electrical charge is fully maxed out — do sport a few wispy hairs here and there.

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Publisher: Space.com
Date: 2021-01-28T12:17:27 00:00
Author: https www facebook com spacecom
Twitter: @SPACEdotcom
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Humans Can Theoretically Harness Energy From Black Holes

Wait, they can accelerate plasma particles to . . . negative energy? That’s right. The scientists compare it to the idea of eating candy that somehow removes calories from your body instead of adding them—black holes “eat” particles with negative energy that then pulls out a discharge of energy. The black holes are, to follow the analogy, losing proverbial “weight” in the form of energy.

As magnetic fields disconnect and reconnect, like an unfathomably large cosmic version of regular refrigerator magnets, energy accumulates and is smashed out both against the black hole’s spin and with it. The energy that travels with the black hole’s spin is accelerated, and it’s this portion of energy that can clear the black hole to be gathered by some keen-eyed future builders.

Publisher: Popular Mechanics
Date: 2021-01-29 08:02:00
Twitter: @PopMech
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Alternatives to black holes are scarce and strange | Science
Publisher: Science
Date: 2021-01-08
Author: Copyright 2021 The Authors some rights reserved exclusive licensee American Association for the Advancement of Science No claim to original U S Government Works
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New Black Hole Merger Simulations Could Power Next-Gen Gravitational Wave Detectors

Color map of the curvature on the large black hole horizon generated by the near merging small black hole. Credit: Nicole Rosato

Rochester Institute of Technology scientists have developed new simulations of black holes with widely varying masses merging that could help power the next generation of gravitational wave detectors. RIT Professor Carlos Lousto and Research Associate James Healy from RIT’s School of Mathematical Sciences outline these record-breaking simulations in a new Physical Review Letters paper.

Publisher: SciTechDaily
Date: 2021-01-28T21:52:09-08:00
Author: Mike O
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Many things are taking place:

Are primordial black holes really giant gravitinos? | Space

Astronomers don't understand the origins of the biggest black holes in the universe. These black holes appear so early in the cosmological record that we might have to invoke new physics to explain their appearance.

New research proposes an intriguing origin story: the first black holes didn't come from stars but from clumps of super-exotic, super-hypothetical particles known as gravitinos that managed to survive the first chaotic years of the Big Bang .

Publisher: Space.com
Date: 2021-01-06T12:08:45 00:00
Author: https www facebook com spacecom
Twitter: @SPACEdotcom
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Extreme black holes have hair that can be combed

This quantity constitutes "gravitational hair" and potentially measurable by recent and upcoming gravitational wave observatories like LIGO and LISA. The structure of this new hair follows the development of a similar quantity that was found by Angelopoulos, Aretakis, and Gajic in the context of a simpler "toy" model using a scalar field and spherical black holes, and extends it to gravitational perturbations of rotating ones.

"This new result is surprising," said Burko, "because the black hole uniqueness theorems are well established, and in particular their extension to extreme black holes. There has to be an assumption of the theorems that is not satisfied, to explain how the theorems do not apply in this case.

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Black Holes Could Get So Humongous, Astronomers Came Up With a New Size Category

There are supermassive black holes . There are ultra massive black holes. How large can these strange objects grow? Well, there could be something even bigger than ultramassive: stupendously large black holes, according to the latest research.

Such hypothetical black holes - larger than 100 billion times the mass of the Sun - have been explored in a new paper which names them SLABs, an acronym that stands for "Stupendously LArge Black holeS".

"We already know that black holes exist over a vast range of masses, with a supermassive black hole of 4 million solar masses residing at the centre of our own galaxy," explained astronomer Bernard Carr of Queen Mary University London.

Publisher: ScienceAlert
Author: Michelle Starr
Twitter: @ScienceAlert
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Galaxies Hit Single, Doubles, and a Triple (Growing Black Holes) | NASA
Publisher: NASA
Date: 2021-01-13T19:31-05:00
Twitter: @NASA
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