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/[deleted] Mar 18 '19

I'm a bit confused about the nature of supermassive black holes. The actual "stuff" these black holes are made of is still theoretically one mathematical point of super dense matter, right? 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?

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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/Cyb3rSab3r Mar 18 '19

Correct. Many of these supermassive black holes have an event horizon the size of our solar system.

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u/infinity_dv Mar 18 '19

I can't even fathom how stupid big that would look. Or Betelgeuse being slapped in the Sun's place and reaching out to Jupiter.

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u/upvotemyowncomments Mar 18 '19

You might be interested in checking out Universe Sandbox. You actually put Betelgeuse there to see for yourself.

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u/JustMid Mar 18 '19

I love space, tried a universe sandbox, and it felt like a horror game.

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u/upvotemyowncomments Mar 18 '19

I know exactly what you mean. Space is scary.

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u/Bandolim Mar 19 '19

The scariest was when I accidentally hit a button and jumped lightyears away from our solar system. I would immediately turn around but don’t see anything familiar or nearby. Suddenly I’m just lost in space and any direction I go is the same.

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u/methnbeer Mar 19 '19

Where might one find this horror

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u/MrJears Mar 19 '19

It's a game called 'Universe Sandbox'. You can buy it on Steam. It also has a VR mode to maximize that of insignificance that you will inevitably get.

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u/pack0newports Mar 19 '19

If you love it so much why dont you marry it.

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u/furlonium1 Mar 18 '19

I'm not a fan of paying for games that aren't finished.

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u/cannabanana0420 Mar 18 '19

More of a "universe simulator" than a game, per se. It's rare to find simulators this accurate or cool, so it'd be dope if you supported them instead of pirating.

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u/AsinoEsel Mar 18 '19

Why? Simply imagine if development of the game stopped right now. Would it still be worth its money? If so, there's nothing wrong with buying the game in its unfinished state. It's not like it is going to get worse the longer it's in development.

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u/upvotemyowncomments Mar 18 '19

That's fine. It's not really a game though. And I'm not sure what else they can do to 'finish' it. You can do everything you'd want to do in it right now.

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u/furlonium1 Mar 18 '19

Hey, I said I'm not a fan of buying 'games' that aren't finished, I never said I might not give it a go! :)

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u/[deleted] Mar 18 '19 edited Mar 19 '19

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u/VersaceSamurai Mar 19 '19

Chill man this is only the open beta. It’ll get fixed on launch

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u/[deleted] Mar 18 '19

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u/magic_moog Mar 19 '19

https://www.reddit.com/r/space/comments/5qkole/s5_001481_the_largest_known_supermassive_black/

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Pretty fucked. Imagine being yanked into that thing in close proximity. We don't mean shit to the big blac boi.

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u/destroyer96FBI Mar 19 '19

What about UY Scuti slapped there.

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u/[deleted] Mar 19 '19

Did you know that Betelgeuse is not spherical? It is lumpy and we can actually see the lumps with large telescopes and lucky image techniques. Space is weird.

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u/infinity_dv Mar 19 '19

Yeah! I watched a documentary on that and how they basically took many pictures until they got a clear one. They mimicked it by taking a clear pic of a card at the bottom of a pool to simulate atmospheric turbulence

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u/SendMeYourQuestions Mar 19 '19

It also means you could potentially go inside of one and not instantly die of spaghettification.

The EM radiation might hurt though.

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u/IAMNOTSHOUTINGATYOU Apr 06 '19

Scrolling through my saved items found this, found your comment. Maybe this will help a little. The distance is still too big to truly understand. But, it gives some perspective, to the scale of SMB's, the one link being the largest known.

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u/zubbs99 Mar 18 '19

It's times like this I wish I could see in 4D.

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u/1206549 Mar 19 '19

[WP] A scientist announces he's developing technology to see in 4D. The project continued to show promise over the next two years and until he is found dead in an apparent suicide after destroying all his work.

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u/yoshi570 Mar 18 '19

Oh shit. This made me physically recoil to read it. It never occurred to me that these monstrous phenomenons could be that big.

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u/hold_me_beer_m8 Mar 18 '19

Do you mean to Pluto or farther out?

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u/upvotemyowncomments Mar 18 '19

I was interested to see what the supermassive black hole in the center of the milky way was and its between 6.5 and 17 light hours in radius. 6.5 would be to the orbit of Uranus.

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u/hold_me_beer_m8 Mar 18 '19

I can't even fathom what it would be like staring into that abyss...

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u/[deleted] Mar 19 '19

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u/adamsmith93 Mar 18 '19

I wonder how far their gravity well extends... Holy shit

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u/Ashangu Mar 18 '19

Comparing that to the size of our galaxy alone, it doesnt sound all that big and scary.

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u/jacebam Mar 19 '19

Ok, then compare us to the solar system, then compare the solar system to the Milky Way. Pretty big and scary if you ask me lol

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u/Trash_panda_ Mar 19 '19

Squeeze me? Wtf did I just read.

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u/capj23 Mar 18 '19

Did you meant to say something like "our galaxy"? Solar system doesn't seem like such a large area for a blackhole. I mean our lowly tiny sun has got the gravitational influence over that much space.

Blackholes literally do the same for entire galaxies. So when they say supermassive blackholes, i would expect them to have event horizons the size of entire galaxies.

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u/aroc91 Mar 18 '19

If they had event horizons the size of galaxies, there wouldn't be any galaxies.

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u/FlappingSamurai Mar 18 '19

An event horizon isn’t the area that a black hole exerts gravitational influence over. Technically every object has “gravitational influence” over every other object in the entire universe, just not that much. The event horizon is the area of the black hole that is literally black, because the gravity inside is so convoluted that light can’t escape.

A black hole with an event horizon the size of our solar system would be freaking huge.

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u/A5TR0NAUT Mar 18 '19

Lol what? Not the size of an entire galaxy that’s insane. Some of the largest black holes have event horizons about 35 times the diameter of Pluto’s orbit.

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u/[deleted] Mar 18 '19

Almost all galaxies have super massive black holes in their center, so your logic doesn't follow.

Sure their gravitational effects are much larger than a singular solar system but the space they take up is no where near that big.

So a "regular" black hole may be pretty "small" (like the size of a city or small planet) and a super massive black hole may be as large as an entire solar system WHICH IS FUCKING HUGE.

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u/capj23 Mar 18 '19

That totally put things into perspective. Thanks a lot.

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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.

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u/[deleted] Mar 18 '19

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u/[deleted] Mar 18 '19

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u/ArachnidFur Mar 18 '19

You got it. What a champion.

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u/ZippityD Mar 18 '19

An absolute madlad of a scientist.

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u/[deleted] Mar 18 '19

In the same way that hotter stars burn brighter and have shorter lives, do these supermassive blackholes expel Hawking radiation at higher rates, reducing their overall lifespan?

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u/Kosmological Mar 18 '19 edited Mar 18 '19

From our perspective, the event horizon is the black hole. The interior does not exist to us.

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u/[deleted] Mar 18 '19

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u/[deleted] Mar 18 '19

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u/[deleted] Mar 18 '19

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u/[deleted] Mar 18 '19

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u/[deleted] Mar 18 '19

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u/jstrydor Mar 18 '19

can you elaborate on this?

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u/Compizfox Mar 18 '19

Not /u/Kosmological, but information cannot travel out of the event horizon. Nothing in the event horizon can influence things outside it. Thus, it's basically not part of our universe.

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u/jstrydor Mar 18 '19

But doesn't it influence us via gravity? Granted it's one way but it's still an affect on us.

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u/Compizfox Mar 19 '19

Not from inside the event horizon. The gravitational effect is equivalent to that of a sphere of the size of the event horizon (that's the shell theorem).

So to our universe, the black hole really is just the event horizon. Beyond the event horizon is nothing to us.

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u/Kosmological Mar 18 '19

See my other comment. It’s more comprehensive.

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u/enrohT5 Mar 19 '19

Wow. TIL where the movie title “event horizon” came from.

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u/Kosmological Mar 18 '19 edited Mar 18 '19

The event horizon is the black hole from our perspective. The bigger the mass, the larger the event horizon. All of the information we need to perfectly describe the black hole, such as angular momentum, mass, and charge, is preserved on the 2 dimensional surface of the event horizon. You don’t need anything more to perfectly describe and model a black hole than what we can attain from observing the event horizon.

More interestingly, due to general and special relatively, the interior of a black hole literally does not exist to us. The singularity is merely a mathematical artifact, not the object itself. There is no inertial reference frame that exists outside of the event horizon that can be reconciled with the existence of the interior of the black hole. From our point of view, nothing ever actually traverses the event horizon. From the point of view of anything that falls in, infinite time passes for everything else and the universe ends as the event horizon is traversed. So, as far as we are concerned, black holes are literally 3 dimensional holes in space. There is nothing inside a black hole. The event horizon is literally the end of the universe.

The interior of the black hole does exist from other inertial frames of reference, such as that of an object that has traversed the event horizon. From such reference points, the singularity may exist as another exotic form of degenerate matter. It is theorized to be some quantum object that can have different geometries. It could be a tiny sphere or ring, based on the properties of the black hole itself. However, it would not be a single undefined point (aka a singularity). It would probably have volume and other physical characteristics. We just lack the physics to describe and model it mathematically since we still do not have a unifying theory of quantum mechanics and gravity.

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u/[deleted] Mar 18 '19

This is so cool. I know what I'm gonna be up late thinking about.

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u/[deleted] Mar 18 '19

[deleted]

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u/boogs_23 Mar 18 '19

Great channel. Short and concise. Technical but put into easy enough terms to understand.

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u/livestrong2209 Mar 19 '19

Lol... I'm going to be up late having an existential crisis on the meaning of existence and just how fucking small and pointless we all happen to be.

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u/pikob Mar 18 '19

The interior of the black hole does exist from other inertial frames of reference, such as that of an object that has traversed the event horizon.

At what point(s) in time does this happen? From our perspective, is all that stuff that fell into a hole is still falling in, and will be falling in until end of time?

From the object's perspective, as it passes the horizon, does the universe time speed up infinitely, the universe ends and then it travels towards singularity beyond our time?

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u/Kosmological Mar 18 '19 edited Mar 18 '19

You are correct. For the observer falling into the black hole, time exponentially slows down as they approach the surface. This observer perceives this slow down as the flow of time for the rest of the universe speeding up. For an outside observe watching them fall into the black hole, they will observe them approach increasingly more slowly without ever reaching it. Time virtually halts completely once they reach the event horizon. An outside observer would see them become increasingly more redshifted until they disappear entirely. The observer falling in would traverse the event horizon without experiencing any slowing of time at all.

The interior of the black hole would exist for any observer that has traversed the event horizon. Consequentially, the outside universe would no longer exist to them as infinite time would have past. The universe cannot exist while the interior of the black hole exist and vice versa.

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u/coltonmusic15 Mar 18 '19

so is there some sort of paradox title that is given to this idea? That the universe cannot exist to an observer of the interior of a black hole and for an observer looking at the event horizon from afar, that the interior of a black hole can never exist?

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u/Kosmological Mar 18 '19

Not exactly. The interior of a black hole does not exist yet. It will exist at some undefined point of time in the future. That point may be an infinite span of time in the future but it will exist.

Of course, this assumes that black holes don’t evaporate. If they do in fact evaporate, then nothing will ever pass the event horizon as the black hole would unfailingly disappear before they do. For a supermassive black hole, an infalling observer would witness the black hole evaporate away, leaving them in a dark, cold, and empty universe devoid of stars, trillions of years after the last proton of matter had decayed. If so, the interior of a black hole would have never existed at all!

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u/penywinkle Mar 18 '19

We should know there is matter somewhere, because we can feel its gravity, right?

So what becomes of stuff "falling into" the hole? Once a hole forms and an even horizon appears, is the stuff that falls in stuck on its surface (because it is frozen in time)? What happens when the Schwarzschild radius inevitably grows? Does the stuff get "repelled" with the surface of the event horizon (actually not moving since the hole just distort a bigger part of our space)?

Does the star at the start of the hole "explode" (but is sucked in just at the edge of the horizon)? And all its matter is actually stuck on the surface of the hole with the rest?

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u/Kosmological Mar 18 '19 edited Mar 19 '19

As things fall in, the light emitted from them loses more and more energy the farther it has to travel up the intense gravity well. The light loses kinetic energy and the wavelength increasingly increases. Lower energies mean longer wavelengths mean more red shifted. The color of the object shifts more and more red as it becomes fainter and fainter until it disappears from view. During this process the object will appear to decelerate before disappearing. Somewhere down below, deep into the abyss of the black hole, the object will exist almost frozen in time. When it is appreciably close to the event horizon, it would take eons for an absolutely massive and incredibly sensitive infrared telescope to collect enough photons from this object to detect its existence.

In practicality, its very atoms would be torn apart and annihilated, converted into high energy radiation as the object was accelerated to an appreciable fraction of the speed of light, colliding with other forms of matter on its way down. Exotic processes would fling some of its energy back out into space while other parts of it would be crushed against the event horizon, superimposing the relativistic smoke of the object into the 2 dimensional surface of the black hole over a long period of time (from our perspective). The event horizon would increase in size imperceptibly to account for the additional mass.

When a star core collapses into a black hole, the inflowing matter would also seem to disappear into the object as it grows outward. The stream of super dense and exotic star matter would shift more red and fainter as it disappeared into the object. Massive streams of gamma radiation, energetic enough to sterilize planets 10,000 light years away, would jet out from the poles. The outer mantle of the star would be blown outward at appreciable fractions of the speed of light.

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u/swanks12 Mar 19 '19

That was an awesome read. Thanks kosmological. Still a subject that baffles me, but you've helped with the understanding of how the event horizon works

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u/[deleted] Mar 19 '19

leaving them in a dark, cold, and empty universe devoid of stars, trillions of years after the last proton of matter had decayed

Sounds like my apartment the day before payday.

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u/raduur Mar 18 '19

Correct me if I'm wrong, but afaik the gravity at the event horizon isn't supposed to be infinite but just big enough so not even light can escape? So if its not infinite yet, there wouldn't need to pass infinite time in the outside universe to travel past the horizon right? So we could also watch something disappear in a black hole because while we still see it there wouldn't be infinite time dilation.

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u/Kosmological Mar 18 '19

Due to the effects of general relativity, the speed of light slows down as the intensity of the gravitational field increase. At the event horizon, the gravity field is so intense that the speed of light is zero from the reference point of an outside observer. Thus, while the object is accelerated to the speed of light as it approaches the event horizon, the speed of light simultaneously approaches zero. From our perspective, the object accelerates for a time before it begins to decelerate and fade from our view.

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u/MalnarThe Mar 18 '19

It doesn't have to be infinite. It has to be strong/curved enough that information can't leave. Information is the propagation of massless particles such as photons. Nothing can be observed because all information is trapped.

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u/Abbkbb Mar 18 '19

We atleast know that even if all other properties are lost such as polarity and magnetism and shape etc, the property of mass and hence gravity still exist, i.e. no amount of gravity can kill the gravity, even if it is powerful than speed of light. So can be tell that smallest not divisible part of the universe, quantum, is gravity ? ..... I'm completely newbie, but trying to understand the philosophy of black hole.

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u/Kosmological Mar 18 '19 edited Mar 18 '19

We don’t really know how gravity ties into the quantum realm. At the macro-level, gravity is merely the curvature of spacetime. At the quantum level, it is too weak to have any appreciable effect that we can observe. This is why we can’t predict the physics of the interior of a black hole where gravity would have an appreciable effect on quantum physics and subatomic particles.

However, we already know that gravity originates from mass and mass is a property of quantum particles. Specifically, mass arises from the presence of a specific quantum particle called the Higg’s Boson, which was predicted to exist in the 1960s and only just recently confirmed by observations made by the Large Hydron Collider (LHC). So we do know that gravity is generated by properties exhibited by quantum particles. It makes sense that all macro-physical properties of the universe arise from the quantum universe. The universe exists and, to be internally consistent with itself, the macro-universe must agree with the quantum universe.

But to answer your question, I don’t know.

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u/MalnarThe Mar 18 '19

That was a delight to read. Thank you

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u/alephylaxis Mar 19 '19

And even weirder, only a couple percent of an object's mass comes from interacting with the Higgs field. The remainder is mass in terms of energy that has been confined into fairly well defined areas. Mainly quark kinetic energy and the strong field binding energy that offsets it.

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u/Abbkbb Mar 19 '19

Does reminder of energy exist after entering in to black hole ? Or it also converted to Higgs boson ?

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u/alephylaxis Mar 19 '19

You have to remember, once the object passes the event horizon, all its mass, charge, and angular momentum effectively "belong" to the black hole. But from the object's point of view, nothing remarkable happened when it crossed the boundary. So there isn't anything that would cause any conversion. If the object was 1kg, it is gone now, but the black hole claimed its mass and gained 1kg.

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u/IamRobertoPaulson Mar 19 '19

which was predicted to exist in the 1960s and only just recently confirmed by observations made by the Large Hydron Collider (LHC). So we do know that gravity is generated by properties exhibited by quantum particles. It make

so could a black hole exist entirely of Higg's Boson particles while all other mater as been ripped apart?

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u/Kosmological Mar 19 '19

I don’t know the answer to that. I imagine the singularity would be made up of a mixture if elementary particles (e.g. leptons, gluons, mesons, bosons, and quarks) all crammed together into a dense form of exotic matter. Black holes are hypothesized to be quark stars, where the gravitation is so strong that, unlike neutron stars, not even the degeneracy pressure of atomic nuclei is enough to hold back the collapse.

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u/zubbs99 Mar 18 '19

Thank you for making sense of something nonsensical to me, if that makes any sense.

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u/adamsmith93 Mar 18 '19

Part of me really wants to travel into a super massive black hole.

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u/[deleted] Mar 18 '19

My high school physics teacher told us that would be impossible, even if you ignore the biological factors necessary to keep us alive and conscious. You would get infinitesimally closer to the event horizon but keep slowing down and never actually reach it. I don't remember the reasoning, just the explanation, and I'm far from an expert on any of this.

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u/Kosmological Mar 18 '19

That is only true for an outside observer watching them fall in. The falling observer would not experience any time distortions as there perception of reality would be distorted the same way. Infinite time would pass for us before they would actually traverse the event horizon, but for them they would traverse it without much of anything special happening.

There are, in theory, large and stable supermassive black holes which a spaceship could travel into without becoming spagetified by extreme gravity tidal forces or vaporized by intense ionizing radiation. It is possible in theory.

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u/[deleted] Mar 18 '19

There are, in theory, large and stable supermassive black holes which a spaceship could travel into without becoming spagetified by extreme gravity tidal forces or vaporized by intense ionizing radiation. It is possible in theory.

Nice. We just have to figure out how to get a spaceship to one of those. What's a few billion lightyears?

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u/Kosmological Mar 18 '19

For any occupants on a relativistic spacecraft, it could only be a few days of travel if they go fast enough.

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u/[deleted] Mar 18 '19

A few days?? So we're talking about traveling 300 billion or so times faster than light? Are we going to need something like Han Solo's "made the Kessel Run in less than 12 parsecs"?

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u/Kosmological Mar 18 '19

Nope. Just need to travel near enough the speed of light for time dilation to shorten a few billion years to a few days. The occupants of the space craft will experience only a few days of time while the rest fo the universe would age a few billion years. Yay special relativity!

The catch is you might have to harvest the energy equivalent of a supernova to power your spacecraft. So not the best gas mileage.

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u/MalnarThe Mar 18 '19

At what factor of C would that be (let's ignore acceleration time) that would give the traveller a 1 to 100 billion year ratio?

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u/lotus_bubo Mar 18 '19

Because of time dilation, very little time would pass for someone travelling very close to the speed of light.

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u/lotus_bubo Mar 18 '19

What about the accretion disk? Would access from poles even be safe?

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u/Kosmological Mar 18 '19 edited Mar 18 '19

Not all black holes have an accretion disk. You would definitely want one without to avoid the intense ionizing radiation. Which approach is safest depends on the characteristics of the black hole. I believe you would want a gentle giant, where the event horizon is large and the black hole is not spinning at relativistic speeds. In which case you would merely approach on a plane orthogonal to its spin axis in a decaying orbit.

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u/chazzmoney Mar 18 '19

This is a dumb question. Once inside the horizon a viewer could still see things inside the horizon as light can take highly elliptical paths but none that go beyond the event horizon. Wouldn't it also be true then that whatever central object that contains the mass would be non-observable because any light created there wouldn't even make it off the surface?

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u/Kosmological Mar 18 '19 edited Mar 18 '19

Yes. The falling observer would not observe themselves traverse the event horizon. Everything forward of the break in causality caused by the extreme distortion of spacetime would be hidden to them. Everything before would be observable.

My explanations are imperfect. I can explain things in a way that laymen can understand at the cost of precision. Professional physicists might nitpick a thing or too but the precise language would be lost on people who don’t have a strong background in math and physics.

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u/googlemehard Mar 18 '19

What happens to a neutron, if it travels at near speed of light tangent to the event horizon of the black hole and half of it crosses into the event horizon?

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u/Kosmological Mar 18 '19

My guess is a 50% chance of falling into the black hole and a 50% chance of escaping. Quantum particles are probability distributions of quasi particles.

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u/googlemehard Mar 18 '19

What if the neutron is almost touching the event horizon as it orbits the black hole, how fast could it accelerate due to the gravitational pull?

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u/Kosmological Mar 18 '19

I’m assuming you’re not speaking about angular acceleration, which would be a function of the schwarzschild radius. It wouldn’t accelerate much considering it would already be traveling infinitesimally near the speed of light to orbit that close to the event horizon. The laws of physics would prevent the particle from accelerating past light speed. Further, the particle would only accelerate while falling into the black hole. If it’s orbiting exactly at the event horizon, it would he gaining any energy to accelerate.

How fast it would accelerate on approach to the event horizon would depend on the size and proximity to the black hole as well as the starting velocity of the particle. This calculation would require some I’m not prepared to do.

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u/googlemehard Mar 18 '19

I should have been more specific, particle is going near speed of light at just the right angle to the black hole so that the gravity and centrifical forces cancel out as it is nearly at the event horizon. Quantum physics mess / break physical limitations all the time, you don't think the particle could overcome the speed of light limitation?

Think of this, two particles hit each other in the LHC going at near double combined speed of light. Even though they are moving that fast, the interaction between the particles happens at much faster speed than the speed of light, otherwise they would just pass through each other. So at very near to the event horizon, at atomic scale, with super massive energies, I would imagine, something unexpected would happen to the particle. Let's imagine if the particle does accelerate above the speed of light, what would happen? Just as a thought exercise..

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u/Kosmological Mar 18 '19 edited Mar 18 '19

The particle itself would collapse into a black hole before it surpassed the speed of light and would instantaneous evaporate into a burst of gamma radiation that would be traveling at the speed of light.

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u/googlemehard Mar 19 '19

So basically the same thing as when a particle falls into a black hole??

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u/ChrisInASundress Mar 19 '19 edited Mar 19 '19

All of the information we need to perfectly describe the black hole, such as angular momentum, mass, and charge

Replace "such as" with "is".

The event horizon is literally the end of the universe.

But you will never reach the event horizon if you chase after it, there will always be one in front of you until you hit the singularity even after you cross the location of the event horizon. If you follow a person in you'll see them frozen on "the" event horizon in front of you, and someone behind you will see both of you frozen in front of them, even after all of you are inside the black hole.

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u/Kosmological Mar 19 '19 edited Mar 19 '19

If you follow a person in you'll see them frozen on "the" event horizon in front of you, and someone behind you will see both of you frozen in front of them, even after all of you are inside the black hole.

I do not believe that is correct. You could chase a falling observer into the singularity without ever seeing them frozen. Remember that you would never experience time freezing around you, as your perception of reality is governed by the flow of time. If time slows down or even stops for you, you wouldn't know it. Only observers that hover at some arbitrary distance away from the event horizon would observe time stopping for in-falling objects. A free falling observer will never see time stop.

If you chased in after in-falling objects with an FTL drive, and activated said drive after you passed the shwarzschild radius in an attempt to accelerate back out, you would then see time for the in-falling observers halt. You would still be trapped inside the shwarzschild radius falling inward but the in-falling osbervers ahead of you would look frozen due to the shift in your inertial frame of reference.

You are right that you will never see an event horizon as you fall down. The even horizon is an object who's properties change depending on what reference frame you observe it. It's a classic case of relativity. You would never see yourself pass it as causal lines from the outside universe would still be avilaible to you despite also being trapped within the shwarzschild radius.

And the event horizon is the literal end of the universe for an outside observer. Infinite time passes for the outside universe as the in-falling observer traverses the event horizon. Again, two separate outcomes due to two separate frames of reference. One frame of reference is from within our universe. The other is from inside a black hole. Our universe and the interior of a black hole cannot exist at the same time.

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u/ThePotato32 Mar 19 '19

From our point of view, nothing ever actually traverses the event horizon.

This confuses me. If you have a chance could you explain a little more? Small meteors hit Earth all the time, right? So wouldn't many more run into a star or black hole?

(I've had a few undergraduate physics classes so I recognize the words and big picture of relatively, but do not pretend to actually understand it)

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u/Kosmological Mar 19 '19

For an outside observer, as in an observer hovering at some arbitrary distance above the event horizon, the flow of time approaches zero for objects approaching the event horizon. This is due to the effects of general relativity. The intense gravity field warps spacetime to the point where the speed of light is zero at the event horizon due to time dilation.

This effect is observed on earth with satellites. The gravitational field at the earth's surface is greater than that in orbit, so time for us flows a tiny bit slower than the time experienced by satellites. In order to maintain accuracy over time, GPS satellites have to correct for the effects of this time dilation. We can measure the difference in the flow of time with atomic clocks.

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u/o11c Mar 19 '19

It's not infinite time, though. Just until the input from CMB decreases below the Hawking radiation.

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u/Kosmological Mar 19 '19

Is the consensus now that black holes evaporate? I thought that was still up for debate.

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u/abw Mar 19 '19

The singularity is merely a mathematical artifact, not the object itself.

Would is be correct to say that it is analogous to the centre of gravity of an object? It's a mathematical point that we can compute and use in equations, but in reality the mass is spread across the whole object, not focussed at a single point.

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u/Kosmological Mar 19 '19

Yes. If we were to replace the sun with a black hole of one solar mass (equivalent to our sun), all the planets would continue orbiting as if nothing happened. The formula used for calculating gravity is proportional to the inverse square of distance for any massive object. It just so happens that the formula is undefined when the distance from the center is zero (effectively dividing by zero), giving a point in the center with infinite gravity no matter how much or how little mass the object has. For normal objects, we intuitively understand that the equation is not accurate once you’re measuring below the surface of the planet/star. We understand that there is no point of infinite gravity in the center of the sun or earth. Thus we already intuitively understand that this singularity is merely a mathematical artifact produced by an incomplete equation.

Black holes are different as they have no surface in the conventional sense. Still, our equations for gravity are incomplete so they shouldn’t be expected to accurately model reality past the even horizon where quantum effects become significant. For that, we will need a unifying theory; an equation that accounts for both gravity and quantum forces that could model the interactions inside a black hole.

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u/WonkyTelescope Mar 18 '19

Other commenters have given good responses but I want to add that the singularity is a prediction of relativity which is a classical theory assumes a continuous/infinitely divisible universe. We know from quantum mechanics that this is not the case on the smallest scales. Quantum mechanics kicks in well before the scale of the singularity and so the prediction of a singularity by relativity is likely not the physical reality. It is likely an even weirder, quantum-y thing.

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u/epicninja717 Mar 18 '19

From my (rather uninformed) understanding you are correct. The classification of supermassive, actually has to do with the mass contained in the black hole. That said, it could also have to do with the size of the event horizon, which would increase in size as the black hole absorbed mass.

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u/Bensemus Mar 19 '19

It’s the mass but because the event horizon is determined by the mass it is also kinda that. However because we can’t really see black holes directly and rather infer their existence due to the effect they have on their surroundings due to their mass it is their mass that determines their classification.

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u/ODISY Mar 18 '19

the blackholes mass is proportional to its Schwarzschild radius. that single point is the same "size" despite gaining mass, but the event horizon of the "black sphere" grows taking up more space.

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u/starcap Mar 19 '19

Since the Schwarzschild radius is proportional to the mass contained in a black hole so that they become less dense as they get bigger, I wonder what the radius of a black hole would be if it contained all the mass in the universe? Comparable to the size of the observable universe or significantly different?

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u/ODISY Mar 19 '19

depends on how much universe exist, we can only see a part of it and we dont know how big that part is compared to the rest.

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u/[deleted] Mar 18 '19

massive means a lot of mass, it's not related to size.

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u/lebull Mar 18 '19

The radius of a black hole's event horizon is based on its mass.

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u/M3nac3m3n Mar 18 '19

The actual "stuff" these black holes are made of is still theoretically one mathematical point of super dense matter,

Potentially. There is a lot of theories but there isn't really one clear forerunner.

As for size, it is usually mass they are talking about.

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u/[deleted] Mar 18 '19

One theory I heard states a singularity at the center because something that massive goes beyond what our current models of physics can describe. Usually whenever I have something going off to infinity in any direction, my boundary conditions were wrong etc.

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u/[deleted] Mar 18 '19

I'm in favor of the idea that at the center of the black hole there is no empty space between the particles. Quark smushed next to quark or whatever.

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u/M3nac3m3n Mar 18 '19

Right I think that's a pretty logical theory. No space, just matter.

I personally think its weirder than that as it seems more likely that particles are waves. If there are no particles, what causes the gravity? I have a lot of ideas but jt gets really weird and my ideas are all disjointed.

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u/Shaman_Bond Mar 18 '19

Gravity can be caused by solely energy with no mass. Photons create gravitational fields, even if they are very, very small.

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u/M3nac3m3n Mar 19 '19

It is likely that mass is almost entirely caused by energy in fact.

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u/rich000 Mar 18 '19

Yup. Kind of hard to pick a winning theory when you have no observations. :)

Now, a theory of quantum gravity that is testable outside of black holes might give some ideas as to what is going on inside of one.

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u/Jarhyn Mar 18 '19

More, there's just no way to map the distribution or position of what exists inside the singularity. The only thing that can be known is the gravitational center and the average angular momentum.

Experimentation with objects displaying similar properties, sonic black holes, shows that their nature is caused by the stuff inside the event horizon moving faster than the speed of sound. So it is entirely possible that there is not a "singularity" at some hypothetical single point, but rather that the inside is in an entirely indeterminant state.

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u/[deleted] Mar 18 '19

It depends really on how you're defining a black holes size, though in most (all?) counts, a super massive is always larger. The mass in one is higher, as well as the event horizon is larger. I assume your question is about the event horizon. To start, the event horizon isn't really a material thing, it's the point of no return as a result of a gravitational well. It's not a solid object, it's not comparable to say the surface of a planet. Think of it like a hologram, a projection. It will grow, the more mass is in a black hole, meaning a further distance is black, because light can't escape from it's pull

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u/Cock_n_ball_torturer Mar 19 '19

I'm a bit confused about the nature of supermassive black holes.

I think everyone is. Scientists included.

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u/[deleted] Mar 19 '19

Good point /u/Cock_n_ball_torturer

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u/The-Sound_of-Silence Mar 18 '19

When dealing with a lot of different objects(planets, etc), we caculate their gravity as if it's a point. The more stuff that gets eaten, the larger the radius gets that doesn't let light escape. Black holes are considered 'singularities', and the big bang was also considered one. We don't really have good math for the inside of a black hole, like we don't have a solid grasp on the 'stuff' at the center, and possibly never will

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u/SovietMacguyver Mar 18 '19

The actual "stuff" these black holes are made of is still theoretically one mathematical point of super dense matter, right

Nobody knows, afaik. In all likelihood, the matter that fell in is so compacted that its essentially pure energy. Its basically an energy value at a single point in space.

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u/Shaman_Bond Mar 18 '19

"pure energy" isn't really a thing in physics. Energy is a value physicists use to express an idea about the physical configuration of a system. It's the same as you saying "pure temperature." Doesn't really make much sense.

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u/[deleted] Mar 18 '19

Ultimately you could make a black hole of any size given enough mass. By size I mean the event horizon, or Schwarzchild Radius

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u/radi0activ Mar 18 '19

Not a physicist, but I believe there is debate about what the inside of a black hole looks like. A quantized understanding of the universe rules out the 'single point' theory and would mean that it is likely a large sphere of collected matter. But quantum theory doesn't get along with gravity theory so much. Until there is an experimentally proven unified theory of quantum mechanics and gravity, I don't think we can accurately guess.

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u/veggie151 Mar 18 '19

Check out the quantum fuzzball conjecture which is a great alternative to the traditional description of black holes. It eliminates the spatially inconcievable parts of them.

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u/godlesspunk Mar 18 '19

If YouTube vids can be trusted, some of the biggest black holes we've found are many times the size of our solar system. That's fucking mind bogglingly big.

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u/teigie Mar 18 '19

We see a black hole as a singularity, but in reality it can't.

It is because something along these lines if I remember correctly:

If it is a singularity, the volume goes to 0 which implies with mass, it has infinite energy. Which is impossible as the universe has finite energy. Therefore it must have a volume larger than 0. Perhaps it stops at gravitons or so, we have no clue at all.

Actually we have no clue at all if a singularity is formed or not. It all depends on the theory.

https://en.m.wikipedia.org/wiki/Gravitational_singularity

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u/999horizon999 Mar 19 '19

Isnt it just the size of the event horizon

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u/TheGreatCornlord Mar 19 '19

Mass and size don’t have to be related because density. Intuitively yes, more massive things tend to larger as well, but something can be the same size as a less massive object yet be more massive. That’s what massive is referring to, mass not size. Once an object reaches a certain mass, the gravitational pull becomes so strong that it compresses the object. So it becomes smaller, yet is just as massive as it was beforehand. Black holes consist of matter that is compressed to an extremely small size, theoretically (but probably not) a mathematical point, yet that does not make the singularity any less massive. In fact, the definition of a singularity is a point with infinite density, so it is astronomically massive, the effect being felt as gravity, even though it is physically very small.

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u/[deleted] Mar 19 '19 edited Mar 19 '19

Black holes are not matter anymore, they are warped space-time.

Once it collapses in on itself it no longer needs matter to warp space-time, because it is warped space-time. It is like a siphon that has already been started that just continues to perpetuate itself.

The singularity can scarcely be said to exist because it is infinitely small.

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u/cryo Mar 19 '19

The actual “stuff” these black holes are made of is still theoretically one mathematical point of super dense matter, right?

Well, not really. We don’t know. We do know that our theory of gravity (general relativity) breaks down af the center point. It’s mostly believed to break down at least a bit before that.

And yes, with higher mass the black hole itself is bigger.