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Vacuum energy in alt black hole model as source of dark energy's acceleration role

#1
C C Offline
This so-called vacuum energy type of black hole isn't really new (Gliner, 1965-PDF), though the relationship with the universe's expansion might be. (Popular expressions like "black hole", etc weren't coined yet in 1965.)

This same camp was dispensing an early taste in 2019:
Are black holes made of dark energy?

EXCERPT: Croker and Weiner demonstrated that the growth rate of the universe can become sensitive to the averaged contribution of such compact objects. Likewise, the objects themselves can become linked to the growth of the universe, gaining or losing energy depending on the objects' compositions. This result is significant since it reveals unexpected connections between cosmological and compact object physics, which in turn leads to many new observational predictions.



https://www.science.org/content/article/...dical-idea

EXCERPTS: . . . What they are proposing makes no sense to me,” says Robert Wald [...] Other theorists were more receptive to the radical claim—even if it ends up being wrong. “I’m personally excited about it,” says astrophysicist Niayesh Afshordi...

[...] At first blush, black holes and dark energy seem to have nothing to do with each other ... So how could the two be connected?

Quantum mechanics suggests that the vacuum of empty space should contain a type of energy known as vacuum energy. This is thought to be spread throughout the universe and exert a force opposing gravity, making it a prime candidate for the identity of dark energy. In 1966, Soviet physicist Erast Gliner showed that Einstein’s equations could also produce objects that to outside observers look and behave exactly like a black hole—yet are, in fact, giant balls of vacuum energy.

If such objects were to exist, it would mean that rather than being uniformly spread throughout space, dark energy is actually confined to specific locations: the interiors of black holes. Even bound in these particular knots, dark energy would still exert its space-stretching effect on the universe.

One consequence of this idea—that supermassive black holes are the source of dark energy—is that they would be linked to the constant stretching of space and their mass should change as the universe expands [...] “If the volume of the universe doubles, so does the mass of the black hole,” he added.


https://aasnova.org/2023/02/15/black-hol...rk-energy/

EXCERPT: The most common model predicts a spinning black hole containing a singularity — a point of hypothetically infinitely curved spacetime where our equations describing gravity break down — hidden by the black hole’s event horizon.

However, this common black hole model is in tension with the overall expansion of the universe, leading some scientists to propose alternative models. In one such model, black holes do not contain a singularity, but are instead filled with vacuum energy. These vacuum-energy black holes are intriguing because their growth is coupled to the expansion of the universe: as the universe expands, these black holes gain mass.


https://www.eurekalert.org/news-releases/979797

EXCERPTS: Searching through existing data spanning 9 billion years, a team of researchers [...] uncovered the first evidence of "cosmological coupling" –a newly predicted phenomenon in Einstein's theory of gravity, possible only when black holes are placed inside an evolving universe.

[...] The first paper found that these black holes gain mass over billions of years in a way that can't easily be explained by standard galaxy and black hole processes, such as mergers or accretion of gas.

The second paper finds that the growth in mass of these black holes matches predictions for black holes that not only cosmologically couple, but also enclose vacuum energy—material that results from squeezing matter as much as possible without breaking Einstein's equations, thus avoiding a singularity.

With singularities absent, the paper then shows that the combined vacuum energy of black holes produced in the deaths of the universe's first stars agrees with the measured quantity of dark energy in our universe.

“We're really saying two things at once: that there's evidence the typical black hole solutions don't work for you on a long, long timescale, and we have the first proposed astrophysical source for dark energy [...] this is the first observational paper where we're not adding anything new to the universe as a source for dark energy: black holes in Einstein's theory of gravity are the dark energy.''

[...] The researchers found that the further back in time they looked, the smaller the black holes were in mass, relative to their masses today. These changes were big: The black holes were anywhere from 7 to 20 times larger today than they were 9 billion years ago—big enough that the researchers suspected cosmological coupling could be the culprit.

[...] In the second study, the team investigated whether the growth in black holes measured in the first study could be explained by cosmological coupling alone.

"Here's a toy analogy. You can think of a coupled black hole like a rubber band, being stretched along with the universe as it expands," said Croker. "As it stretches, its energy increases. Einstein's E = mc2 tells you that mass and energy are proportional, so the black hole mass increases, too."

How much the mass increases depends on the coupling strength, a variable the researchers call k.

"The stiffer the rubber band, the harder it is to stretch, so the more energy when stretched. In a nutshell, that's k," Croker said.

[...] The conclusion is profound: Croker and Weiner had already shown that if k is 3, then all black holes in the universe collectively contribute a nearly constant dark energy density, just like measurements of dark energy suggest.

[...] According to the researchers, their studies provide a framework for theoretical physicists and astronomers to further test—and for the current generation of dark energy experiments such as the Dark Energy Spectroscopic Instrument and the Dark Energy Survey—to shed light on the idea.


RELATED TOPIC (scivillage): Collective cosmolgists/astophysicists insanity?
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