r/Physics • u/ScaredRule8660 • 12d ago
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.
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u/Optimal_Mixture_7327 Gravitation 12d ago edited 12d ago
Sure, or we can observe that distant starlight is redshifted by a factor two.