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Most animations and drawings of Black Holes that I've seen usually depict some kind of funnel which is the "entrance" to the black hole; let's call this the front.

Are there more than one way to enter the Black Hole, such as the back side (180 degrees from the "front" side)?

Can a Black Hole have more than one entry point? (It's kind of difficult viewing a ball {the Black Hole} with multiple entry points around the surface, sucking in matter and light).

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    $\begingroup$ I've never seen such a drawing. Can you provide a link to one? $\endgroup$
    – D. Halsey
    Jul 1 at 21:43
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    $\begingroup$ Search the internet for "black hole wire frame". $\endgroup$ Jul 1 at 21:50
  • $\begingroup$ So like a worm-hole that's got a black-hole in it? $\endgroup$
    – Nat
    Jul 3 at 0:39
  • $\begingroup$ The funnel is like a 2D black hole embedded in 3D; you can enter that black hole from any direction in the 360° of the plane. A real black hole is 3D and you would need 4D to visualize a similar kind of potential energy funnel. $\endgroup$
    – Nayuki
    Jul 3 at 4:34
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    $\begingroup$ Here is a scientifically accurate animation that I created of what it would look like to fall into a black hole: youtube.com/watch?v=z-H-PipYCKc The black disk that you're seeing is the silhouette of the event horizon, which is a sphere. Because it's a sphere, the view would look pretty much the same if you were falling from any direction. The only thing that would change would be the background stars. $\endgroup$
    – user15381
    Jul 3 at 15:54
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What you are talking about is an embedding diagram. These are ways of visualising the curvature of 3D space by projecting it onto a 2D surface. These can be very misleading - for example, the trajectory of something in freefall around a black hole is not simulated by rolling a ball on this surface.

Such diagrams make no attempt to represent the full dimensionality of a real black hole.

Black holes exist in all three spatial dimensions. If we are talking about a non-spinning black hole, it is absolutely spherically symmetric and looks and behaves the same approaching it from any direction

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It depends on what you mean by 180 degrees from the front side. If you mean 180 degrees aroud the mouth in the 2D visualization (which is a good one as long as you don't let balls roll on it because balls are pulled in by gravity already so it won''t serve as a good model in that case but insofar the space structure itself is concerned it serves as a good model without time being involved though) then it seems obvious that you can approach the 2D funnel from all directions in the plane.

Likewise, though harder to imagine, you can approach the 3D hole from every direction in a 3D space. From every direction you move inside a 3d funnel leading to the center of the black hole.

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Black holes are three-dimensional in reality. If you were two-dimensional you can imagine to enter the black hole from all sides. From the left, from the right, from the front, from the back, and everything in between and at different angles.

The same holds for a 3d hole. You can imagine it to be builtt up from an infinity of the funnels in the black hole wire picture. All these funnels are connected with each other to form the 3d space structure. So you can imagine that you enter the hole from the left, from the right,or from the top (which isn't possible for a 2d hole.

The metric for a 2d hole is a 2d Schwarzschild metric with one angle missing.

So you can imagine a 3d black hole as a 3d funnel, consisting of an infinity of angular connected 2d funnels.

The accelerated motion is a natural state so to speak, without forcing a oarticle to change its motion. So if you involve time then a particle would follow the natural path of a geodesic. Inside the horizon all geodesics are inward directed.

This can be seen in the 2d funnel model. The path of all particles, even the ones whose velocity is an outward directed lightspeed, is ending up at the center (as you can see in the model there is not a real center point though as the funnel extends to infinity).

It might seem counterintuitive that an outward direct geodesic is not possible. It is easy enough to draw one. But remeber that also time is involved. If time were reversed all geodesics would be pointing outward! Like in a white hole.

So the 3d black hole can be approached frim all directions in 3d space just as a 2d hole can be approached from all directions in a 2d space.

A black hole can have two mouths though. There are various wormholes of which the Einstein-Rosen bridge is the most known:

More precisely it is a transcendental bijection of the spacetime continuum, an asymptotic projection of the Calabi–Yau manifold manifesting itself in Anti-de Sitter space.

There are more double mouth wormholes. They have in common that the black hole can be approached from two disconnected pieces of space. Though a white hole connected with a black hole cannot be approached from the white hole side where time goes backward and everything can only come out of the hole.

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  • $\begingroup$ Why is this question downvoted? Could someone explain if there is something incorrect in it? $\endgroup$ Jul 12 at 17:39

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