Final answer:
The event horizon is a boundary in spacetime that marks the edge of a black hole and separates it from the rest of the universe. Inside the event horizon, nothing can escape, including both sound and light. Sound waves cannot travel through the vacuum of space, and light is bent inward by the strong gravitational pull of the black hole, making it impossible to see anything inside.
Step-by-step explanation:
The event horizon is a boundary in spacetime that separates the region around a black hole where the curvature of spacetime no longer provides any way out. It is the edge of the black hole, and anything that crosses it can no longer interact with the rest of the universe. The event horizon is determined by the size of the star at the moment when the escape velocity becomes equal to the speed of light.
For sound, the event horizon represents a point where no sound can escape. Sound waves need a medium to travel through, and in space, there is no medium for sound to propagate. Therefore, if something were to happen inside the event horizon, it would be completely silent and undetectable through sound.
Similarly, for light, the event horizon marks the point at which no light can escape. Once light crosses the event horizon, its path is bent inward, and it will eventually be pulled into the black hole. This means that any light emitted from within the event horizon cannot reach observers outside, making it impossible to see or detect anything happening inside.