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Auphor_Phaksache t1_j9eb4sh wrote

Reply to comment by Bokbreath in TIL black holes also regurgitate matter such as stars that they suck in by Desolecontra

How did you determine the star was not devoured?

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Bokbreath t1_j9ebrjb wrote

Nothing can escape the event horizon by definition. Not even light. That means anything being ejected from the vicinity of a black hole hasn't yet passed the event horizon.
This includes hawking radiation btw. That does not come from beyond the event horizon either. It happens when a particle/anti-particle pair is spontaneously created just outside the event horizon and before they can recombine, the anti-particle falls into the black hole and the particle escapes.
EDIT: someone correct me here plz. I'm getting flashbacks that the pair creation thing is different from hawking radiation but I don't know enough to be sure.

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Auphor_Phaksache t1_j9ece36 wrote

That's still pretty fascinating. Can particles just spontaneously appear out of nowhere? Do they exist just outside the event horizon for years. Why is the force applied away from the black hole and not towards it?

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kerfitten1234 t1_j9fwspn wrote

Particles are constantly appearing and annihilating, even in front of your face right now. It's called vacuum energy.

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

>Vacuum energy can also be thought of in terms of virtual particles (also known as vacuum fluctuations) which are created and destroyed out of the vacuum. These particles are always created out of the vacuum in particle–antiparticle pairs, which in most cases shortly annihilate each other and disappear. However, these particles and antiparticles may interact with others before disappearing, a process which can be mapped using Feynman diagrams.

The process involving black holes is called hawking radiation.

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

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JediMimeTrix t1_j9hbdvc wrote

I mean time slows down near a black hole due to the extremely strong gravitational field of the black hole. Given the theory of general relativity this is due to the gravity curving literally everything around it in a way that affects our ability to measure time and space.

So I mean technically things exist for a longer period of time than we can truly process because either we accept that there's a distortion and our technology hasn't advanced enough or that time is inherently slower there and things entering a black hole entered it long before we even know it entered.

To answer the latter question (someone else may have already answered it) "As black holes gobble up the matter in their surroundings, they also spit out powerful jets of hot plasma containing electrons and positrons, the antimatter equivalent of electrons. Just before those lucky incoming particles reach the event horizon, or the point of no return, they begin to accelerate. Moving at close to the speed of light, these particles ricochet off the event horizon and get hurled outward along the black hole's axis of rotation."

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Bokbreath t1_j9ecwjx wrote

Yes they can be created spontaneously .. but only for very brief periods while the universe isn't paying attention. Then they recombine and the ledger is balanced. What is possible near the event horizon, is the anti-particle can cross the event horizon leaving the normal particle outside. It can escape (it also might not, but it can). If it does then the books still balance because the anti-particle robs the black hole of the exact mass of the particle.

Not sure what you mean by 'force applied away from the black hole'.

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Auphor_Phaksache t1_j9edz9o wrote

The article suggest that the particles are being ejected away from the black hole. What force cause the particles to drive away from the black hole and not into it? Is it reacting off the anti particle?

Can spontaneous particle creation be replicated using tech?

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Bokbreath t1_j9eed3k wrote

The ones in the article are 'regular' matter that is in the accretion disk. That's ejected by centripetal force. Gets sucked in close and some of it loses angular momentum and falls into the hole. Some of it gains that same momentum and is flung out.
As for replicating particle creation, I don't think so, but I'm not 100% sure of this stuff. I went back and edited the original because your questions are triggering some vague memories that I might be conflating different things.

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LipTrev t1_j9g4wg3 wrote

> Nothing can escape the event horizon by definition. Not even light.

Leonard Susskind made a career of working on that issue. From fixing sinks, to winning a bet with Hawking.

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reversecolonoscopy t1_j9h8fsk wrote

You mean lil black holey didn't have an upset tum tum from too many starry stars?

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