I have a couple of questions about black holes I'm hoping you can answer. One of these questions is if black holes last forever. If they DO eventually fade from existence, how do they and does anything happen to the things they've captured? My other question is about the theory (theories) of what would happen to a human if they were to enter a black hole. I've heard a theory saying that, with how time theoretically flows, one could be stuck in it for countless years and slowly have every atom in their body explode and feel it until an important organ in their body were to rupture. Is this the most logical theory, or are there more? Thank you for your help (if you could give it. I had originally asked another expert, but he did not have an answer), and I apologize for my huge wall of text. I'm pretty thorough.
Well technically, no one really knows (and probably never will- see last 3 sentences of this paragraph)... what happens when a human (or spacecraft or any other matter) passes through the "Event Horizon" of a black hole, where time becomes zero for an outside observer. (The event horizon is that point on a spherical shell surrounding the black hole where the space-time continuum (technical name for just regular outer space)... is entering at light speed, thus any matter and even light itself, can no longer escape the black hole's gravity well. Thus even a radio transmitter would become silent when entering the black hole's event horizon because radio waves travel light speed, and it takes a speed greater than light speed to escape, once the event horizon is crossed. So unless (or until) we humans find something in nature that travels faster than light (??)... we can never know. Of course, going faster than light speed automatically takes you backward in time so that in itself poses another rather impossible situation, but that's another story.
But I've heard it said, due to the gravitational tidal forces imposed on a human body that are theorized to exist inside the event horizon, that you are "spaghettified" - that is stretched to an infinite length head to toe) if a human passes through the event horizon, as viewed by the unfortunate individual. To them, time is passing as "space normal" speed.
Of course, due to the gravitational time effect and general relativity, an outside observer would observe something completely different... a time = zero at the event horizon. Thus an outside observer would see the unfortunate individual frozen in time at the event horizon, taking forever to fall through the event horizon. (Thus information is NOT destroyed by a black hole... the imprint of the in-falling material resides on the event horizon, a bet that Stephen Hawking lost to Saul Perlmutter, see
(Hawking argued that information was destroyed by a black hole, but was wrong and lost the bet!)
Ironically, the first part of your question is solved by Hawking... black holes are not forever as they slowly "evaporate" due to Hawking Radiation. This deals with part of quantum mechanics which gets very complicated very quickly, as the laws at the sub-micro micro atomic level are completely different than our own macro world. To understand all this, you'll have to Google Hawking Radiation and read up on the various laws of quantum physics. But basically it has to do with virtual particles that burst onto the scene near the event horizon... one matter and one anti-matter... say the antimatter virtual particle falls into the black hole and the matter particle does not, and escapes. This "steals" a little energy from the black hole.... and given a long enough period of time, the black hole will evaporate and cease to exist.
But this so called Hawking Radiation has never been observed, so far... so we just don't know as yet. And we still don't know how dark energy (72% of the Universe) and dark matter (23% of the Universe) interact with black holes. (That's right, you, me, stars, planets, and McDonalds... only make up about 5 percent of this Universe, called "normal" matter. The rest is still unknown and as yet, unexplained. (Thus the word "dark" is used).
Hope this helps,