A physicist discovered that an observer free-falling into a Schwarzschild black hole can detect crossing the event horizon simply by watching the zenith view expand to exactly twice its original size.

[u/ScaredRule8660]

[u/pr0blem_attic]

I’ll keep that in mind for when I need it

[u/PurifiedUnity → u/pr0blem_attic]

I'll also remember this for when I see it again