Comment by nextaccountic a day ago
> The current "pop science" (nearly science fiction) statement is that it is possible to fall into a black hole and there is "nothing special" about the event horizon.
How is this not true? From the point of view of whoever is falling, and supposing the black hole is very large
It is absolutely untrue that GR predicts that you would be knocked unconscious crossing the horizon. In fact one of the most fundamental aspects of GR (equivalence) predicts the exact opposite - there is no local experiment you can do as a freely falling observer to detect the horizon.
...and tidal forces may have reduced your body to red goo, so there's that
Nobody knows what happens at the event horizon, but we do know from the perspective of an outside observer things about physics 'break'. It makes sense that there's a flip-side to that 'breakage' (on the inside of the surface, or even "only at" the surface) that isn't just normal space as if nothing happened.
For example there's no mathematics at all that mankind has ever known where an asymptotic approach towards some limit doesn't have a mirror version (usually inverted) on the other side of the asymptote. If we see time stop, at the EH it seems wrong to assume there's nothing "stopped" similarly from the other side too. So this means the surface has to be very special. You don't just pass by it and not notice as you fall in, imo.
> For example there's no mathematics at all that mankind has ever known where an asymptotic approach towards some limit doesn't have a mirror version (usually inverted) on the other side of the asymptote.
That’s a strong statement. 1/sqrt(x), over the reals, doesn’t have an inverted world for x<0. Maybe you could argue that it does exist, weirdly rotated, outside the reals?
In any event, the Schwarzchild metric itself is an actual example of this. From the perspective of a doomed spaceship at the event horizon, the Schwarzchild metric is quite civilized.
The stuff after the horizon is a different story, but that’s not immediately after crossing the event horizon — it might be whole nanoseconds later :)
Go take a GR class. It’s fun and mind-bending.
What I meant to say was "asymptotically approaches infinity" for 'f(x)' at some limiting value 'x' and thus a left/right mirroring of the function. I shouldn't assume people know I mean vertical just because I say asymptotic, so thanks for catching that imprecision in my wording.
As you probably know, horizontal asymptotes are never what we think of as the 'problematic' parts of Relativity, because when something approaches a constant that's never something that breaks the math.
The Schwarzchild metric, being a relationship of 6 different variables I think, has some relationships that go to infinity asymptotically at the EH radius and some things that approach a constant at that radius, so it's an example of the kind of asymptotic I was talking about _and_ one like your "horizontal" example.
Consider that every "surface" inside the event horizon is like a stronger event horizon so passing through you'd certainly notice things like not being able to see your feet any more as the light wouldn't be able to travel out to your eyes! There would be a lot of other stuff happening too so you may not notice exactly, but the event horizon is definitely noticeable!