# Weird question on black hole formation **URL:** \ **Category:** Factual Questions\ **Created:** [June 11, 2003, 2:07am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019 "2003-06-11T02:07:11Z")\ **Posts on this page:** 9\ **Page:** 1
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 11, 2003, 2:07am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/1 "2003-06-11T02:07:11Z")
Suppose you were in the exact center of a sphere of mass large enough and dense enough to undergo gravitational collapse. Someone releases whatever’s been holding it and the sphere collapses, with you inside. Since you’re not falling into a singularity that’s already there, what exactly would you observe (before your presumed annihlation)? ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [June 11, 2003, 2:20am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/2 "2003-06-11T02:20:20Z")
You would see nothing of the formation of the Black Hole. Your extinction is assured LONG before the black hole singularity forms (even supposing some sci-fi gizmo to keep you alive longer than necessary). The densities at the center would be staggering. Remember the mass would pass through densities of a Neutron star and Quark star on its way to singularity. However, you can ask what the view is like from the inside of a black hole (that is inside the event horizon). For a sufficiently large black hole you could easily survive passing that threshold (although you are now ultimately doomed). Unfortunately I don’t know the answer to this but I suppose someone will be along soon who does. ---
**Author:** ![iaboy12](https://avatars.discourse-cdn.com/v4/letter/i/ccd318/32.png) [@iaboy12](https://boards.straightdope.com/u/iaboy12)\ **Post date:** [June 11, 2003, 2:43am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/3 "2003-06-11T02:43:27Z")
nobody knows what it looks like inside a black hole. according to relativity, if the center is actually a singularity, then the laws of physics and probability would completely break down. you wouldn’t get much of a glimpse anyway. once you pass the event horizon the gravitational difference between your head and your feet will turn you into human spaghetti! ---
**Author:** ![Whack-a-Mole](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/whack-a-mole/32/141_2.png) [@Whack-a-Mole](https://boards.straightdope.com/u/Whack-a-Mole)\ **Post date:** [June 11, 2003, 7:50pm UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/4 "2003-06-11T19:50:19Z")
Ok…here’s a page with an animated ride into a black hole…all the way to just before the singularity. It’s crude but there are explanations. [http://casa.colorado.edu/~ajsh/singularity.html](http://casa.colorado.edu/~ajsh/singularity.html) ---
**Author:** ![Shade](https://avatars.discourse-cdn.com/v4/letter/s/2bfe46/32.png) [@Shade](https://boards.straightdope.com/u/Shade)\ **Post date:** [June 12, 2003, 12:02am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/5 "2003-06-12T00:02:12Z")
Come on guys, lets try and answer. The obvious answer is “nothing, but you’d be crushed,” so let’s suppose that: 1. You are in an incompressable shell. 2. The matter arround it is transparent. Then either: 1. This prevents a singularity forming. 2. A singularity forms at some point on the edge of the shell 3. A singularity forms at all points round the edge, ie. it gets infinitely thin. 2 would just be you next to a singularity (being crushed against the edge of the shell) and probably within the event horizon. 3 sounds very cool but very unstable and would probably become 2. But you’d experience no gravity (some calculus shows a uniform mass round you cancels out), and nothing could get in as it would be absorbed by the singularity. In 1, you’d still be stuck in a black hole. Any physicists want to weigh in with a clearer explanation, and explain any time-dilation effects? ---
**Author:** ![Hari\_Seldon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/hari_seldon/32/5173_2.png) [@Hari\_Seldon](https://boards.straightdope.com/u/Hari_Seldon)\ **Post date:** [June 12, 2003, 12:26am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/6 "2003-06-12T00:26:44Z")
If you were in a sufficiently massive black hole, you would feel nothing special and there is no reason to think you would be crushed. In fact, the density of a black hole is IIRC inversely proportional to its mass. As far as I know, there is no way we could know that our observable universe is not a black hole. On the other hand if somehow the sun could be compressed into a black hole it would be incredibly dense. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [June 12, 2003, 12:27am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/7 "2003-06-12T00:27:01Z")
> [@](#): > > \*Originally posted by Whack-a-Mole \* > You would see nothing of the formation of the Black Hole. Your extinction is assured LONG before the black hole singularity forms (even supposing some sci-fi gizmo to keep you alive longer than necessary). The densities at the center would be staggering. Remember the mass would pass through densities of a Neutron star and Quark star on its way to singularity. That’s only for a stellar-mass black hole. For bigger ones, not necessarily so. A body of water the mass of the galaxy is dense enough to be a black hole. ---
**Author:** ![Achernar](https://avatars.discourse-cdn.com/v4/letter/a/e274bd/32.png) [@Achernar](https://boards.straightdope.com/u/Achernar)\ **Post date:** [June 12, 2003, 12:28am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/8 "2003-06-12T00:28:07Z")
Darn you beat me to it. The only thing is… > [@](#): > > \*Originally posted by Hari Seldon \* > In fact, the density of a black hole is IIRC inversely proportional to its mass. should be “inversely proportional to the square of its mass.” ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [June 12, 2003, 12:34am UTC](https://boards.straightdope.com/t/weird-question-on-black-hole-formation/181019/9 "2003-06-12T00:34:48Z")
> [@](#): > > \*Originally posted by Whack-a-Mole \* > \*\*You would see nothing of the formation of the Black Hole. Your extinction is assured LONG before the black hole singularity forms (even supposing some sci-fi gizmo to keep you alive longer than necessary). The densities at the center would be staggering. Remember the mass would pass through densities of a Neutron star and Quark star on its way to singularity. \*\* Sorry, I should have been clearer. I meant a spherical hollow shell, so that none of the matter reaches you until after (from an outside observer’s viewpoint) the shell has fallen past the event horizon. I know that calculated strictly Newtonian, someone inside a spherically symmetrical shell feels no net gravitational pull, but presumably you need to take General Relativity into account. My own intuitive guess was that the inrush of matter would generate a tremendous gravity wave that would exert enough pressure on you to crush you into a singularity. BUT: what if the “shell” was a stupendously dense sphere of photons? If it collapsed at lighspeed, then the gravitational force couldn’t reach you untill the wall of photons hit you. But I admit that my grasp of “when” events inside an event horizon can be said to have happened is pretty shaky.