[dahart]

> Because we found no better analogy, we named them "holes"

Are you sure about that? This sounds specious. This requires knowing who named them and why. It sounds like a logical explanation, but history and human events don't follow logic and can't be derived.

> We talk about [...] "light cannot escape the black hole"

So, light not escaping certain "dark stars" was observed and was a concept before "black hole" was a term. "Dark stars" is one term they were called before the term "black hole".

http://curious.astro.cornell.edu/about-us/86-the-universe/bl...

Wikipedia says the name black hole was adopted because it was catchy, which is not because of the value of the analogy. "Dark star" might be a better analogy, and it existed before black hole.

https://en.m.wikipedia.org/wiki/Black_hole#Etymology

Having said that, black holes are actually black, and they are literally gravity holes in space. A hole in the ground on earth is only a hole because of gravity, it's a thing you can fall into. Because black holes are things you can fall into if you get too close, because it's doing the exact same thing as a hole in the ground, I'd argue that black hole is not a very good example of a cognitive metaphor.

Note also that the best way to demonstrate the intuitive effect of gravity is to show how it acts like a hole. A black hole visualized the same way is a very, very deep pit.

https://youtu.be/MTY1Kje0yLg

[InclinedPlane]

Neither dark star nor black hole are apt "models" for the objects. These are phenomena of space-time, not just of gravity. Light cannot escape a black hole because escaping a black hole is impossible. And it's impossible because the space-time inside an event horizon has no trajectories that go forward in time which go farther away from the singularity. Black holes are like pocket universes with one-way roads connecting them to our Universe, this is why light doesn't leave the inside of the event horizon, the path between there and here only goes one way, unlike the rest of space-time.

"Dark star" is also a misleading term in that it implies the object is a star or something physical at all. In fact to us it doesn't matter what the object is inside the black hole, and its structure is essentially unknown to us (at present), because we can't interact with it. We can only interact with the space-time phenomenon that it created, the event horizon.

[dahart]

Agree with all of this, and I appreciate the explanation, but "black hole" is just a name and not a model. We need a shortcut and not a thesis to talk about it efficiently, right? The name really only needs to identify, and not convey perfect and complete understanding, no? It's nice that the analogy is decent, but there is no name that could capture and communicate the complete meaning, that requires further explanation. True for most/all scientific subjects and physical phenomena, I think.

Given your description, "hole" still seems like a great and very literal analogy to me, if we had to pick a single word. It's capturing a sense of going in but not out, and it's also capturing a sense of darkness, and of going into or down via gravity as well. A one-way road that you can drive in but not out, and is downhill, and dark from the outside, sounds like a 'hole'.

We could call it a pocket universe, or a spacetime existence prison, or a one-way road to infinity, but I'd have to agree with John Wheeler, that "black hole" is brief and catchy, captures the essence of what we know about them in 9 letters, in a way that is accessible to non-physicists.

BTW, isn't gravity a phenomenon of spacetime? I don't understand your differentiation.

[coryfklein]

> escaping a black hole is impossible

Except for Hawking Radiation [1]

"black holes that do not gain mass through other means are expected to shrink and ultimately vanish. Micro black holes are predicted to be larger emitters of radiation than larger black holes and should shrink and dissipate faster."

[1] https://en.wikipedia.org/wiki/Hawking_radiation

[InclinedPlane]

Hawking Radiation comes from outside the event horizon.

[Retra]

Hawking radiation takes energy away from the inside of a black hole.

[InclinedPlane]

Certainly, but the radiation still comes from outside the event horizon.

[coryfklein]

Sounds like the confusion here comes from labeling matter outside the event horizon as "not the black hole". With this wording you can say that nothing escapes the black hole by forever shrinking the region of what constitutes the black hole.

In the end, matter/energy that was inside the black hole can eventually exist in a region that is no longer referred to as part of the black hole.

^ This being my non-physicist layman interpretation, I'm happy to be enlightened if I'm wrong.