Gravity, time, and spacetime near a black hole

Verification: Supported by general relativity, with an observer-dependent qualification. Massive bodies curve spacetime, and a clock deeper in a gravitational field accumulates less time relative to one far from the black hole. A local observer does not feel their own clock “slowing”; the difference appears when clocks or signals are compared. Near the event horizon, the effect can become very large.

Conclusion: Gravitational time dilation and strong spacetime curvature are predictions of general relativity near black holes.