black holes

[taylrl]

If a black hole is a point in space from which nothing can return, does this mean that space itself is lost, and a black hole is actually a genuine point of nothingness, not even vacuum. I know that black holes originate from collapsed stars, and are a very high concentration of mass, but has this collapsed mass has actually fallen through the fabric of space-time. I have heard the question asked, “ since the big bang, what is the universe expanding into?” to which I heard somebody suggest the answer “nothing, absolute nothingness, not even vacuum.” Could black holes therefore be a link to whatever it is that is outside of our universe. Even if that happens to be pure nothing.

Over the course of time, wont black holes go about hovering up all of the matter from the universe. Is it ever possible over trillions of trillions of years that all of the black holes will have absorbed everything. Will the universe still exist then? as the black hole has to be in something. Is there a maximum size a black hole can reach? I am sure I have made some terrible mistakes in my reasoning, but if somebody could set me straight, it would be most appreciated.

[Maddad]

Outside Mainstream Science Warning

 

I think of an intense gravitational field, such as you would would see near a black hole, as a region where space-time is decreasing. Around a massive object, there is less space-time now than there was a second ago. The effect is greater closer to the massive object, so more space-time disappears closer to the massive object than further away.

[taylrl]

i think thats what i am saying. so does that mean that as you approach a black hole, space itself shrinks. As space is expanding, could this be driven by the opposite of a black hole, e.g a white hole.

[Daecon]

I thought Black Holes eventually "evaporated" anyway?

[5614]

Yes Transdecimal, black holes can evaporate through quantum tunnelling in this specific case known as Hawking Radiation.

 

taylrl: Blackstars have not fallen through space-time. They are very dense bodies with a large gravitational field, so strong that it causes space-time itself to warp upon itself. Is that clear? I'll try and explain some more using an example.

 

Light follows the contours of space-time, which is why light will bend around bodies with a large mass. You know that no light escapes a black hole, that is because light follows space-time and around a black hole space-time itself is soo warped that it bends back on itself, so light will do the same, doubling back on it's route past the black hole and go straight into the black hole.

[taylrl]

so if black holes eventually evaporate away, where do they evaporate to? I am sorry, i dont really know much about hawking radiation, what does it consist of and how is able to escape the gravity of a black hole?

[Daecon]

From what I understand (I'm sure someone can correct me if I'm wrong)...

 

Near the event horizon of a Black Hole, like elsewhere in the vacuum of space - particle/antiparticle pairs are constantly being created and destroyed.

If one of these pairs occurs near enough to the event horizon, then one of the pair falls into the hole, and the other one doesn't, so it can fly off into space.

 

The energy needed to create the matter of these particle and antiparticle pairs is "borrowed" from reality, and so when that energy can't be "paid back" because one of the pair no longer has access to the other one of the pair - the energy for the matter has to "come" from somewhere - and so it comes from the Black Hole, which essentially means that an Electron or an antiElectron's worth of matter is "removed" from the Black Hole to consist the makeup of the particle that is now travelling through space away from the Black Hole. Of course there may be other Quarks and such, not just Electrons I believe?

 

One question I have - is Hawking radiation supposed to consit of matter, antimatter or energy?

[taylrl]

where do the particle/anti-particle pairs come from?

[5614]

Hawking radiation is just meant to be stuff. Matter and antimatter are very similar (just different forms of each other) and they're both a form of energy, so one could ask what is the difference? I'm dodging the question because I don't really know!

 

The idea that particles are close enough to the edge of a blackhole so can escape (because they're on the edge) is a simplification. Quantum tunnelling is the real, but more complicated, explanation.

 

I read (probably reliable) that speed needed to overcome the gravity of a blackhole was greater than the speed of light, as nothing can achieve this nothing can escape a blackhole just because it is moving fast.

 

Transdecimal: I don't see any reason why it couldn't be any particle or form of energy, doesn't have to be an electron.

 

taylrl: To answer simply you could say that the particles come from the blackhole. In reality virtual particles will also come into it.

 

Virtual particles are kind of confusing to explain. Basically they are particles which just randomly appear from nowhere, then disappear again, before the universe notices that the particle which shouldn't exist did exist.

[Severian]

Of course there may be other Quarks and such' date=' not just Electrons I believe?

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Since this is supposed to be a gravitational effect, the only consideration is the mass, so it should affect other things too.

 

One question I have - is Hawking radiation supposed to consit of matter, antimatter or energy?

 

All three. It just depends which one falls in.

 

You should bear in mind though that we do not have a working quantum theory of gravity, so all this is speculation (including Hawking radiation).