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dastardly740 t1_j277nf7 wrote

Reply to comment by Impossible_Pop620 in Black hole question by Impossible_Pop620

So, once the object dips below the event horizon there is no forcethat can make any part of the object below the event horizon move "up". I think that might be your confusion, thinking that a cable can somehow apply a force and thus an acceleration that a rocket or other form of propulsion cannot. Yes, in a sufficiently large black hole, the difference in force between the top and bottom of the object might be not be enough to rip it apart, but there is still no force that will allow the object to climb towards the event horizon.

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Impossible_Pop620 OP t1_j2780hv wrote

See...maybe I am confused, but the event horizon itself is not anything physical, just an arbitary boundary where inside it requires an escape velocity faster than light...

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dastardly740 t1_j279m7j wrote

You are thinking like space elevator where something pulls just a little harder than gravity can make its way up. Basically, if you apply a force of 1.0001g constantly from the earth's surface you move up from the earth's surface. There is no x.000001g that allows any object to move up inside a black hole event horizon.

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Impossible_Pop620 OP t1_j279sec wrote

If this were true...hmmm...then ALL black holes would have the same mass?

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dastardly740 t1_j27acwa wrote

More massive black holes have larger event horizons.

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Impossible_Pop620 OP t1_j278arc wrote

...and of course, this is impossible. But this is from the POV of a rocket or similar, trying to escape the EH from inside, not something with outside connections.

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Impossible_Pop620 OP t1_j278e35 wrote

...ie, a space elevator on Earth would not need to travel at escape velocity, right?

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Quarkchild t1_j27a49p wrote

You’re under a presumption this fictional cable and camera still exist past the event horizon.

They stop existing physically. They’re gone. And if you’re stationary and not orbiting to be able to lower this in, you’re about to be gone too bro.

Orbiting and lowering this in, it would “spaghettify” perceptually.

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Cold_Zero_ t1_j278bhl wrote

Hmmm. Interesting. So, how do particles escape from inside the event horizon, as in black hole shrinking?

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dastardly740 t1_j2797vf wrote

They don't. Hawking radiation doesn't come from inside the event horizon. I am trying to paraphrase Matt O'Dowd here, but the short short version as I understand, an event horizon causes certain frequencies in quantum fields to no longer cancel. The effect is that, for an observer far away from the black hole, the black hole emits radiation. The energy comes from the mass of the black hole, I don't think anyone really knows how that happens since we don't really know what a black holexs mass is made of (if anything),

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urmomaisjabbathehutt t1_j27ka5n wrote

Just over the event horizon are strong vacuum fluctuations caused by the strong gravitational field around the black hole, those fluctuation generate particule pairs

for pairs generated at the edge of the event horizon for example an electron positron pair one particule will fall back into the black hole but its anti particule will escape because particule and the anti particule are pointing to opposite directions

The energy for this is supplied by the black hole gravitational potential

this result in bh mass loss

Edit, out of curiosity why downvotes?

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