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Ok, so after I've read a few (around 50 :P ) articles on subject of black holes. There are a few gaps in my understanding of it. Please follow my reasoning, I bet there is a mistake in there, and I need to know where is it.

So, First thing, black hole has an event horizon, and a singularity which is supposed to be something really small at the center of it. But an event horizon has a certain measurable radius, and singularity is practically a dot. So there is some space between it.

Second thing, time inside a black hole goes slower. Lets say a guy Vic (victim) is falling into a black hole (traveling towards event horizon) and a guy named Obs (observer) is... well observing.

Here is the question finally: When Vic passes the event horizon, he gets stretched, starts decomposing ('n such things), but for Obs, he does so very slowly. And that slowliness increases. Now, after Vic crosses the event horizon, he still has some space to travel between event horizon and singularity (because e. horizon has radius, and I bet my mistake is somewhere around here). Since time is slowing down from Obs point of view, Vic will not reach singularity for Obs lifetime, and possibly many Obs lifetimes. He will just keep slowly moving towards it. At least that is my understanding. This means that most matter that fell into a black hole (in recent times), still hasn't reached the center of it. So is this true?

Add rotation of a black hole to a whole thing (from our perspective of passage of time), and I'm dumbfounded.

P.S. for better ilenter image description herelustration, I've made a small picture of what I mean.

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  • $\begingroup$ You are right that there is a finite spatial distance between the singularity and horizon. For the observer at infinity, the victim's motion will seem to get slower as the victim approaches the horizon. At the moment the victim touches the horizon, the signals sent by the victim to the observer will take infinite time to reach the observer. But in the reference frame of the victim, he takes a finite time to cross the horizon and travel the remaining distance inside the horizon until he hits the singularity. $\endgroup$
    – Avantgarde
    Commented Jun 20, 2017 at 0:10

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Obs will not even see Vic going below the horizon- that would mean light is coming out of the black hole and we know that doesn't happen (putting aside Beckenstein-Hawking radiation for a different discussion).

What will actually (theoretically) happen, is that Obs will see his friend Vic ever slowing his fall but never passing the horizon, eventually freezing on the horizon and than red-shifted until Vic will not be visible (in the visible light) for Obs anymore. if Obs had a very good camera that can see infinitely large wave-lengths, he will see Vic ever slowing his endless fall towards the horizon, without ever crossing it.

as far as Vic is concerned though, he fell into the black hole in a finite time.

I would highly recommend reading "Exploring Black Holes: Introduction to General Relativity" by E.F. Taylor and J.A. Wheeler, it delves deep into space-times and black holes without heavy-duty mathematics being used (no tensors and the like)-if you understand special relativity and know how to differentiate you should understand most of it. it deals with these exact problems and analyzes them mathematically and physically in a way that gives intuition to the subject- I really enjoyed it and I think if you are into black holes, you might too.

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  • $\begingroup$ "Obs will not even see Vic going below the horizon..." My bad. I understand that part. But Vic still exists (in some way) after he passes event horizon. My question was is it true that for our lifetime, and many years more, from our perspective, Vic moves very slowly toward the center of black hole? Its not just about Vic. If this is correct, than anything that has passed event horizon "recently", from our perspective still isn't near the center of the black hole. Its going slowly towards it, and it rotates with BH (if BH is rotating). $\endgroup$
    – Coco
    Commented Jun 20, 2017 at 1:37
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    $\begingroup$ @Coco The last part of your question is perhaps addressed in this post before: How can anything ever fall into a black hole as seen from an outside observer?. A minor comment on the diagram though: it shouldn't be assumed that stretching (or spaghettification) begins only after something has crossed the event horizon. That's not necessarily true. A stellar mass black hole could spaghettify the objects well before they even reach the event horizon. $\endgroup$
    – Dhruv Saxena
    Commented Jul 7, 2017 at 23:37
  • $\begingroup$ Yeah, my bad on that one $\endgroup$
    – Coco
    Commented Jan 15, 2018 at 23:52

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