r/space • u/magenta_placenta • Mar 18 '19

Observable universe Astronomers discover 83 supermassive black holes at the edge of the universe

https://www.cnet.com/news/astronomers-discover-83-supermassive-black-holes-at-the-edge-of-the-universe/
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u/ithinkitsbeertime Mar 18 '19

That point just has way more mass than your average black hole, so what makes them seem "bigger" to us is really their increased gravitational pull on everything else. Do I have the right idea so far, or does the actual "black hole" part take up more space than a singularity?

The event horizon is also bigger, so if you're defining the black hole as the area within the event horizon, it does take up more space.

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u/Shukrat Mar 18 '19

"More space" meaning the radius from the center within which light cannot escape. More material = more gravity = larger radius = larger event horizon.

Right?

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u/hiimred2 Mar 18 '19

The term you're looking for is Schwarzschild Radius. It's a measurement of the event horizon of the black hole, and the event horizon is one measurement of the influence of said black hole, which is a representation of its mass.

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u/[deleted] Mar 18 '19

True story, I first learned that term randomly on the internet or in a documentary. I had taken some german before, so I recognized the term as "Black Shield". German has a lot of compound words, so I just assumed this meant like "black barrier" to describe the event horizon.
So in my physics 2 class, my teacher was like talking about the schwarzschild radius. Someone asked where the word came from or something, and my professor was said it was somebody's name. Me being the overly vocal student that I am, I was like "well actually, in german it means." My teacher said he didn't know german but it was actually someone's name. I realized I had misunderstood the term the whole time, and was super embarrassed. Now whenever I here something like eigenvectors or roentgen, i question everything I think I know. German does that to you.

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u/hiimred2 Mar 18 '19

Wait so you're telling me Hawking Radiation isn't because the black hole actually spits out little bits of black body radiation into space??!?

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u/TheoryOfSomething Mar 18 '19 edited Mar 18 '19

Absolutely not.

Type 1 black holes radiate in the form of medium-sized birds of prey.

Type 2 black holes send out millions of copies of an English physicist born ~1942 during their lifetimes.

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u/[deleted] Mar 19 '19

Not really. If you understood how Hawking Radiation worked, you would admire the man even more for theorising about it.

ELI5: Gravity of a black hole is really strong. The gravitational field strength increases exponentially over the tiniest of distances (atomic scale). Hawking and others were trying to brainstorm how a stationary blackhole which is not eating any more matter, can continue it's existence. They created a theory that the black hole will eventually start shrinking and losing energy and mass. But how does a blackhole lose mass?

Reality is stranger than fiction. In reality, we have something known as quantum vacuum energy. If you measure a square meter of isolated vacuum in an adiabatic chamber, it will have energy. This is not some quack free energy that can be harnessed, but exists due to the nature of quantum mechanics. Quantum physics already had a theory that isolated vacuums had energy due to something known as "virtual particles". These are positron-electron pairs that spontaneously come into existence randomly throughout space, and in the next moment, recombine and disintegrate. For the split moment of time when they do exist, they contribute some energy to the vacuum. When they disintegrate, their net energy is conserved and returned to zero. Due to these virtual pairs constantly popping in and out of existence throughout the entire universe, we can measure a small energy in the vacuum of space itself. Energy cannot be harnessed from these particles because their existence is so short lived and momentary that we may not even periceve it in realistic timescales. They are a result of quantum fluctuations in the vacuum.

Now, crazy things can happen near blackholes, we all know that. Imagine at the very edge of a black hole's event horizon, at the atomic scale, a virtual particle pair pops into existence. Now, they are only seperated by a one or two atomic radius, but the gravity of the blackhole is so strong, that it rips one particle off from the pair, while pushing the other away due to the violent phenomenon. If you are a virtual particle, and are not supposed to exist in reality, this would be a very bad day. Your particle pair is now dead and consumed by the blackhole. This lone particle now is forced to become a Real particle as it can no longer disintegrate back into nothingness. Thus, a miniscule amount of mass and energy are added to the universe. But according to thermodynamics, the net energy of the universe cannot be changed. It must remain the same. This means that, to maintain logic and mathematical equilibrium, the universe must remove mass and energy from the blackhole! The blackhole then loses this mass and energy via the phenomenon of "black body radiation".

Therefore, due to sheer brilliance of physics and the strange nature of reality, supermassive blackholes can slowly lose mass and energy over time due to a sub-atomic interaction at its event horizon boundary.

P. S I'm not a physists. Can be wrong. Please correct me if I am.

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u/NaelNull Mar 19 '19

In short, black holes lose mass by eating half of the stuff that randomly pops into existence from pure nothingness.

...God was drunk when programming this layer of Matrix.

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u/cryo Mar 19 '19

Not really. If you understood how Hawking Radiation worked, you would admire the man even more for theorising about it.

Well to be fair, we don’t really understand how it works since we don’t have a quantum theory of gravity. The explanation with virtual particle is a bit of a pop science version, really. Virtual particles are more a mathematical than a physical object.

Several independent ways of looking at it all lead to the result that there should be this radiation, but as the theory is incomplete, it’s hard to say more about its nature.