An object approaching the event horizon of a black hole appears to slow down from the perspective of an outside observer. This phenomenon occurs due to the arrangement of light cones near the event horizon, which causes the information from the infalling object to take increasingly longer to reach the observer. Consequently, the object never actually crosses the event horizon in finite time as perceived by the observer.
PREREQUISITESAstronomy students, physicists, and anyone interested in the effects of gravity on time and space, particularly in relation to black holes.