#these misconceptions need to die

The final comic I had planned for that planetarium show. It’s mostly there to lead up to what a black hole is by stating clearly what it is not.

A black hole is not…

A vacuum cleaner—Unless you get close to a black hole (say within 3 radii of a non-rotating black hole’s radius of circumference) orbiting it works mostly the same as any other celestial body.

A very dense object – The physical scales of stellar black holes are similar to neutron stars, but unlike a neutron star, a black hole is a space-time region, not a solid object with a density and definite volume.

A 2D hole or funnel – black holes are space-time objects and so are more properly thought of as 4D objects*.

A portal to another realm – only idealized black holes that have existed forever and have no matter anywhere in them can have wormholes that lead to other places. A real black hole you try to jump through would 1) have formed at some point and 2) have matter in it because you just jumped into it.

*As an aside, this why those people who tell you “a black hole event horizon never forms” or “events inside a black hole never happen” are wrong. The event horizon isn’t just a spatial surface, it’s a space-time hypersurface. You might not see it from an infinitely far distance away, but it is real, and it is still there. It’s just that you’re occupying a 3D slice of the 4D space-time that doesn’t include it. You go into a black hole and you will find it there, and see the events that happen inside a black hole, just as you can’t see Tokyo from NYC, but cross over the horizon far enough and there it will be.**

**Oh dope, did I just explain what an event horizon is using the example of the perspective horizon? Well, actually that’s why it’s called an event horizon, silly.