/sci/ - Science & Math

>>10181655
>Are there any good visualizations of the geometry inside the event horizon of a black hole?
A penrose diagram.

>>10181765
That doesn't give much of an intuitive sense of what it looks like in there.

>>10181655
It looks like this

just think of the curves in this picture as the line of the event horizon

>>10181780

>>10181776
Try closing your eyes, maybe that will help you visualize the region pas the event horizon.

>>10181797
I realize it must be pitch black inside, but objects that haven't yet reached the singularity should still be physically located in particular places and should move in certain ways that can be artificially visualized to give a sense of what it's like

>>10181776
>intuitive sense of what it looks like in there.
Intuitive doesn't really apply when you're talking about the extreme curvature inside the event horizon.
Timelike coordinates become spacelike and vice versa. The reason why you "fall" into the singularity inside the event horizon is because the only way to move forward in time is to close the distance to the singularity. You can't "escape" from inside because "backwards" is not a direction you can go in anymore because it means going backwards in time.
>>10181804
Nope. As you pass the event horizon you are going to catch up to all outward traveling light that can never escape (like trying to run up a down escalator).

>>10181655
https://www.youtube.com/watch?v=zd_HGjH7QZo

>>10181832
>watching videos 4chan gave me with knot in the title
Fool me once...

>>10181836
What you don't like knots? What are you gay?

>>10181820
>As you pass the event horizon you are going to catch up to all outward traveling light that can never escape (like trying to run up a down escalator).
So then you really can see something in there. All the more reason to make a cool visualization.

>>10181780
>>As you
Yep they look like Calabi-Yau manifolds in the inside

>>10181843
>https://youtu.be/mht-1c4wc0Q
If you looked "down" you would see all the light that has been trying to escape since the surface of the star collapsed into the event horizon and beyond. If you looked "up" you would see light that came into the black hole after you entered it.

>>10181855
Ok, so even though all timelike directions now point toward the singularity, there's till a distinction between pointing directly toward the singularity, and in the opposite extreme, pointing as far away as possible from the singularity, even though that direction still ends in the singularity but after a larger distance?

If you look "down", wouldn't most of the light that entered since the black hole formed have already reached the singularity, so that you'd only "catch up" with light that fell in relatively recently? Or does light from the very beginning get "stuck" in there forever somehow? It's hard to wrap my head around the way time is affected by black holes.

Fuck, all this "visualizing" is giving me a headache. I'm gonna need some Christoffel symbols to cure this.

>>10181864
Also, one thing that's interesting to me about this is that it seems like space literally turns "inside out", in the sense that normally if you look 360 degrees around you, you observe an infinite set of physical locations expanding out into the distance, whereas your current location can be thought of as a single point. Whereas inside the black hole, if you look 360 degrees around you, what you see in the distance in all directions is actually a single point.

Exactly at the event horizon, you should see the entire remainder of all possible directions and locations compressed to a single line perpendicular to the event horizon, accessible to you only if you move in that direction at the speed of light.

It's not exactly a perfect inside outness though, since there doesn't seem to be any sense in which your current location, which is normally a single point, is spread out in all possible directions?

>>10181864
>already reached the singularity
Light propagates in all directions, it can no longer make any headway going radially outward because it can't go backwards in time.
It's an escalator that's going down at the speed of light. If you run up it at the speed of light, you will never reach the top. The best you can do is stay in place.
As you are going down this escalator you're catching up to, and passing everything running up the escalator at the speed of light.
If you look "up", you see light that is traveling radially inward, so light that entered the horizon after you is overtaking you because its running DOWN the escalator.

>>10181912
Is the metaphorical escalator moving downward at the speed of light, or effectively faster than the speed of light? The event horizon is the point at which light moving perpendicularly outward still can't get out, but just a bit further inside the curvature should be even greater, so even if the light ray were moving perpendicularly outward at the speed of light it would still be effectively moving toward the singularity, but very slowly I guess? So exactly at the event horizon there would be something like a frozen "shell" of photons aimed radially outward but held in place, and then as you go farther in there'd be something like a gradually accelerating "waterfall" of photons aimed radially outward but still falling in at increasing speed? Though I guess this would only be the case if there were light-emitting objects falling into the black hole in the first place.

That view of it still seems like looking at it "from the outside" though. If you were actually in there, it seems like the curvature would make it look very different somehow, but I still can't quite wrap my head around it.

>>10181951
Consider that you would catch up to the light leaving your own feet and everything on your horizon would be a funhouse mirror of your own reflection.

>>10181655

>>10181972
>Consider that you would catch up to the light leaving your own feet
That's normal though, if you're not in a black hole don't you also catch up with the light leaving your feet in order to see them? It seems like in terms of light, the only thing that would be different is that light that's farther away would reach you more slowly. If the black hole is big enough for the delay to be noticeable and for you to survive long enough to notice it, that could have some strange optical effects. What I'm really having a hard time figuring out is the single point at the center geometrically "wrapping around" you somehow, and what that implies for what the structure of space nearer to you looks like.