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Black Holes
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2022-01-01 at 9:16 PM UTCHAHA...TRICKED YOU!
You thought this was going to be about African-American sluts, didn't you?
Live Science
We may finally be able to test one of Stephen Hawking's most far-out ideas
Paul Sutter
In the 1970s, Hawking proposed that dark matter, the invisible substance that makes up most matter in the cosmos, may be made of black holes formed in the earliest moments of the Big Bang.
Now, three astronomers have developed a theory that explains not only the existence of dark matter, but also the appearance of the largest black holes in the universe.
"What I find personally super exciting about this idea is how it elegantly unifies the two really challenging problems that I work on — that of probing the nature of dark matter and the formation and growth of black holes — and resolves them in one fell swoop," study co-author Priyamvada Natarajan, an astrophysicist at Yale University, said in a statement. What's more, several new instruments — including the James Webb Space Telescope that just launched — could produce data needed to finally assess Hawking's famous notion.
Black holes from the beginning
Dark matter makes up over 80% of all the matter in the universe, but it doesn't directly interact with light in any way. It just floats around being massive, affecting the gravity within galaxies.
It's tempting to think that black holes might be responsible for this elusive stuff. After all, black holes are famously dark, so filling a galaxy with black holes could theoretically explain all the observations of dark matter.
Unfortunately, in the modern universe, black holes form only after massive stars die, then collapse under the weight of their own gravity. So making black holes requires many stars — which requires a bunch of normal matter.Scientists know how much normal matter is in the universe from calculations of the early universe, where the first hydrogen and helium formed. And there simply isn't enough normal matter to make all the dark matter astronomers have observed.
Sleeping giants
That's where Hawking came in. In 1971, he suggested that black holes formed in the chaotic environment of the earliest moments of the Big Bang. There, pockets of matter could spontaneously reach the densities needed to make black holes, flooding the cosmos with them well before the first stars twinkled. Hawking suggested that these "primordial" black holes might be responsible for dark matter. While the idea was interesting, most astrophysicists focused instead on finding a new subatomic particle to explain dark matter.
What's more, models of primordial black hole formation ran into observational issues. If too many formed in the early universe, they changed the picture of the leftover radiation from the early universe, known as the cosmic microwave background (CMB). That meant the theory only worked when the number and size of ancient black holes were fairly limited, or it would conflict with measurements of the CMB. .
The idea was revived in 2015 when the Laser Interferometer Gravitational-Wave Observatory found its first pair of colliding black holes. The two black holes were much larger than expected, and one way to explain their large mass was to say they formed in the early universe, not in the hearts of dying stars.
A simple solution
In the latest research, Natarajan, Nico Cappelluti at the University of Miami and Günther Hasinger at the European Space Agency took a deep dive into the theory of primordial black holes, exploring how they might explain the dark matter and possibly resolve other cosmological challenges.
To pass current observational tests, primordial black holes have to be within a certain mass range. In the new work, the researchers assumed that the primordial black holes had a mass of around 1.4 times the mass of the sun. They constructed a model of the universe that replaced all the dark matter with these fairly light black holes, and then they looked for observational clues that could validate (or rule out) the model.
The team found that primordial black holes could play a major role in the universe by seeding the first stars, the first galaxies and the first supermassive black holes (SMBHs). Observations indicate that stars, galaxies and SMBHs appear very quickly in cosmological history, perhaps too quickly to be accounted for by the processes of formation and growth that we observe in the present-day universe.
"Primordial black holes, if they do exist, could well be the seeds from which all supermassive black holes form, including the one at the center of the Milky Way," Natarajan said.
And the theory is simple and doesn't require a zoo of new particles to explain dark matter.
"Our study shows that without introducing new particles or new physics, we can solve mysteries of modern cosmology from the nature of dark matter itself to the origin of supermassive black holes," Cappelluti said in the statement.
So far this idea is only a model, but it's one that could be tested relatively soon. The James Webb Space Telescope, which launched Christmas Day after years of delays, is specifically designed to answer questions about the origins of stars and galaxies. And the next generation of gravitational wave detectors, especially the Laser Interferometer Space Antenna (LISA), is poised to reveal much more about black holes, including primordial ones if they exist.
Together, the two observatories should give astronomers enough information to piece together the story of the first stars and potentially the origins of dark matter.
"It was irresistible to explore this idea deeply, knowing it had the potential to be validated fairly soon," Natarajan said. -
2022-01-01 at 11:13 PM UTCNobody else finds this cool???
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2022-01-01 at 11:26 PM UTCfake, the hawking radiation & dark matter is just convenient explanations they use to smooth over modern theories as they beat around the bush
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2022-01-01 at 11:32 PM UTCI find the article in OP about indicipherable, since it's obvious the journalist doesn't have a fucking clue.
It seems to be a paper arguing that early universe (primordial) black holes could attribute for the excess gravitational force which is currently ascribed to "dark matter".
Wouldn't this cause a massive increase in the weight of the universe, and would it also cause a re-evaluation in the ratio of matter to anti-matter in the early universe?
All good questions, and questions the article writer seems unqualified to answer.
I'll wait for scientists, not journalists, to weigh in. One has merely a bad track record, the other has the absolute worst track record.The following users say it would be alright if the author of this post didn't die in a fire! -
2022-01-02 at 6:33 PM UTCScienceAlert
The Tiny Dots in This Image Aren't Stars or Galaxies. They're Black Holes
Michelle Starr
The image above may look like a fairly normal picture of the night sky, but what you're looking at is a lot more special than just glittering stars. Each of those white dots is an active supermassive black hole.
The Tiny Dots in This Image Aren't Stars or Galaxies. They're Black Holes
https://www.msn.com/en-us/news/technology/the-tiny-dots-in-this-image-aren-t-stars-or-galaxies-they-re-black-holes/ar-AASmbof?ocid=msedgdhp&pc=U531
And each of those black holes is devouring material at the heart of a galaxy millions of light-years away – that's how they could be pinpointed at all.
Totaling 25,000 such dots, astronomers created the most detailed map to date of black holes at low radio frequencies in early 2021, an achievement that took years and a Europe-sized radio telescope to compile.
"This is the result of many years of work on incredibly difficult data," explained astronomer Francesco de Gasperin of the University of Hamburg in Germany. "We had to invent new methods to convert the radio signals into images of the sky."
When they're just hanging out not doing much, black holes don't give off any detectable radiation, making them much harder to find. When a black hole is actively accreting material – spooling it in from a disc of dust and gas that circles it much as water circles a drain – the intense forces involved generate radiation across multiple wavelengths that we can detect across the vastness of space.
What makes the above image so special is that it covers the ultra-low radio wavelengths, as detected by the LOw Frequency ARray (LOFAR) in Europe. This interferometric network consists of around 20,000 radio antennas, distributed throughout 52 locations across Europe.
Currently, LOFAR is the only radio telescope network capable of deep, high-resolution imaging at frequencies below 100 megahertz, offering a view of the sky like no other. This data release, covering four percent of the Northern sky, was the first for the network's ambitious plan to image the entire Northern sky in ultra-low-frequencies, the LOFAR LBA Sky Survey (LoLSS).
Because it's based on Earth, LOFAR does have a significant hurdle to overcome that doesn't afflict space-based telescopes: the ionosphere. This is particularly problematic for ultra-low-frequency radio waves, which can be reflected back into space. At frequencies below 5 megahertz, the ionosphere is opaque for this reason.
The frequencies that do penetrate the ionosphere can vary according to atmospheric conditions. To overcome this problem, the team used supercomputers running algorithms to correct for ionospheric interference every four seconds. Over the 256 hours that LOFAR stared at the sky, that's a lot of corrections.
This is what has given us such a clear view of the ultra-low-frequency sky.
"After many years of software development, it is so wonderful to see that this has now really worked out," said astronomer Huub Röttgering of Leiden Observatory in the Netherlands.
Having to correct for the ionosphere has another benefit, too: It will allow astronomers to use LoLSS data to study the ionosphere itself. Ionospheric traveling waves, scintillations, and the relationship of the ionosphere with solar cycles could be characterized in much greater detail with the LoLSS. This will allow scientists to better constrain ionospheric models.
And the survey will provide new data on all sorts of astronomical objects and phenomena, as well as possibly undiscovered or unexplored objects in the region below 50 megahertz.
"The final release of the survey will facilitate advances across a range of astronomical research areas," the researchers wrote in their paper.
"[This] will allow for the study of more than 1 million low-frequency radio spectra, providing unique insights on physical models for galaxies, active nuclei, galaxy clusters, and other fields of research. This experiment represents a unique attempt to explore the ultra-low frequency sky at a high angular resolution and depth." -
2022-01-02 at 7:05 PM UTCSo this is just a useless thread then
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2022-01-02 at 7:08 PM UTC
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2022-01-02 at 8:50 PM UTC
Originally posted by Donald Trump It seems to be a paper arguing that early universe (primordial) black holes could attribute for the excess gravitational force which is currently ascribed to "dark matter".
It has been a proposed solution for the galaxy rotational velocity/mass discrepancy for a while now. If a population of primordial blackholes exists in any given galaxy they need to have a particular distribution to account for something that's called dark matter halos. While not directly observed, there is indirect evidence for dark matter halos. As with all sorts of things that emit little to no radiation you infer it's attributes by looking at the gravitational effects on baryonic(normal) matter. And with dark matter halos you can also see how much the galaxy that is being observed lenses the light from luminous background objects. Since we know X amount of mass should be lensing Y amount of background objects at Z distance as observed from Earth. If i recall correctly observations seem to support dark matter halos and thus dark matter more than primordial black holes. Partly due to the equal spherical distribution of the mass in question required for it to account for the rotational velocity that is observed in spiral galaxies.
Originally posted by Donald Trump Wouldn't this cause a massive increase in the weight of the universe, and would it also cause a re-evaluation in the ratio of matter to anti-matter in the early universe?
No, the mass budget for galaxies would stay the same if you substitute Dark Matter with Primordial Black Holes. Anti-matter to matter ratio would remain unaffected.
Originally posted by Donald Trump All good questions, and questions the article writer seems unqualified to answer.
I'll wait for scientists, not journalists, to weigh in. One has merely a bad track record, the other has the absolute worst track record.
More an engineer than a scientist in terms of formal education but i do enjoy the study of astrophysics and cosmology. I can only talk about these things in terms of what i think i know, i am not qualified to state anything as science fact but i do think my understanding of the subject matter is more sophisticated than some rando journalist.The following users say it would be alright if the author of this post didn't die in a fire! -
2022-01-02 at 9:43 PM UTC
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2022-01-02 at 10:05 PM UTCThe mass if my balls will reverse cosmic inflation
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2022-01-02 at 10:47 PM UTCWill that be a Catholic Mass?
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2022-01-02 at 11:02 PM UTC
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2022-01-02 at 11:37 PM UTClol at OP talking about a subject he had no knowledge or understamding of beyond african american holes are sooooooo cooollll.
sooóo amazingggg. -
2022-01-08 at 7:42 PM UTCreported this thread for being in the wrong subforumThe following users say it would be alright if the author of this post didn't die in a fire!
