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[10ebbor10]

However, time doesn't slow down from the inside perspective. Instead, what happens is that the distance that needs to be travelled approaches infinity.

Edit: I hope I'm not screwing my relativistic mechanics here.

Edit: I am screwing up my relativistic mechanics here.

[Darvi]

From ANY external observers point of view, the first bit of matter never hits the event horizon. The atom right behind the first one is also an "external observer" compared to the first one, therefore goop is going to build up.

But one of the fundamental properties of an event horizon is that nothing can escape from inside of it, not even information. Wouldn't that mean that the atom right behind it would be incapable of observing the first atom?

[Sergarr]

From ANY external observers point of view, the first bit of matter never hits the event horizon. The atom right behind the first one is also an "external observer" compared to the first one, therefore goop is going to build up.

But one of the fundamental properties of an event horizon is that nothing can escape from inside of it, not even information. Wouldn't that mean that the atom right behind it would be incapable of observing the first atom?

The idea is that no atoms actually go through the event horizon from ANY point of view, because there exists at least one outside observer which observes them as not in black hole. And all events must be the same from ALL points of view. The position and timing of these events may be vastly different, but the event which happened from one point of view happens in ALL of them, and visa versa.

[10ebbor10]

IIRC, from the point of view from the object entering the black hole, the event horizon is approaching them at the speed of light. Due to length contraction, this means that the size of the black hole becomes zero.

[Darvi]

The idea is that no atoms actually go through the event horizon from ANY point of view, because there exists at least one outside observer which observes them as not in black hole.

Which, as I said, should be impossible.

[Sergarr]

IIRC, from the point of view from the object entering the black hole, the event horizon is approaching them at the speed of light. Due to length contraction, this means that the size of the black hole becomes zero.

Not the size, but the width IIRC. Only one dimension gets contracted.

The idea is that no atoms actually go through the event horizon from ANY point of view, because there exists at least one outside observer which observes them as not in black hole.

Which, as I said, should be impossible.

Why? Like I said, nothing goes through the event horizon from any point of view, so everything stays observable, just extremely red-shifted.

[Darvi]

Because

one of the fundamental properties of an event horizon is that nothing can escape from inside of it, not even information.

If nothing gets out, there's nothing to be observed by any outside observer.

[Reelya]

Because

one of the fundamental properties of an event horizon is that nothing can escape from inside of it, not even information.

If nothing gets out, there's nothing to be observed by any outside observer.

nothing gets out because nothing got in, in the first place. It's not hard.

[10ebbor10]

In order to get in, it has to disappear from the event horizon. According to outside observers, it can't.

[Darvi]

Because

one of the fundamental properties of an event horizon is that nothing can escape from inside of it, not even information.

If nothing gets out, there's nothing to be observed by any outside observer.

nothing gets out because nothing got in, in the first place. It's not hard.

Now that makes sense. Thanks.

[Sergarr]

The more interesting question is what happens to the stuff that was already inside the event horizon at the moment of collapse.

I presume it involves fractals.

[Putnam]

Interesting stuff. It fits with the relativistic calculations: time dilation should hit infinity as you approach an event horizon. Therefore nothing can actually go beyond the event horizon until infinite external time has passed. What this means is that rather than an empty "hole" you fall through, in practice you get this relativistic sludge which builds up outside the black hole, and resembles a neutron star. At least that's the new theory.

That's not correct, is it? There's no time dilation in the frame of the infalling object. It never reaches the horizon only for outside observers.

(a statement disagreeing with the above). Sounds logical for me.

This is never a good way to think of anything in science. That goes for everyone, too, of course.

[Il Palazzo]

The events must be the same for all observers. From the outside perspective, you don't fall into the black hole, therefore, you don't fall there from any perspective, including your own. Sounds logical for me.

No, of course not. Simultainety is relative. An event that already happened in one frame may not have yet happened in another.

Anyway, I won't pretend to understand GR - I only have a shallow, layman's understanding gained from evesdropping on other people's discussions. However, from what I read about it, the singularity at the event horizon exists only in the so-called Shwarztshild coordinates, which can't be used for the infalling observer.
Nowhere will you find the inability to cross the horizon as an obstacle to BHs' existence. That's why the aforementioned paper(and earlier papers on Planck stars, e.g.: http://arxiv.org/abs/1401.6562 ) start with the information paradox as the problem to be solved.

[iceball3]

Ehh, i might be missing some conversation in this context, but...
Hawking radiation, anyone?
In fact there's some regards to the possibility that hawking radiation could actually be technically a release of information from a black hole. Albeit horribly obfuscated and beyond recovering via observation within the universe, but information nonetheless.

The more interesting question is what happens to the stuff that was already inside the event horizon at the moment of collapse.

I presume it involves fractals.

I always thought material thrown into a black hole contributed to the center of mass even though the whole time-confusion renders them near the event horizon for the longest duration. Wouldn't having material get "stuck" at the event horizon of a black hole make it's gravitational field amorphous, not concentrated around a point? What if the event horizon of a black hole "moves over" an object, due to a black hole with velocity?

[Reelya]

Well moving over and object is the same as "infalling" really. It will still take infinity to hit the event horizon from any external observer. so the stuff should smear over the event horizon surface.