Why Do Black Holes Trap Light?

Imagine you are standing on a trampoline with a heavy bowling ball in the center. The fabric dips down, creating a hill around it. If you roll a marble too close to the ball, it falls in. Light acts like that marble, but it moves much faster. Near a black hole, the "dip" in space is so deep that the sides become vertical walls. Light tries to roll up the side, but the wall is too steep. It slides back down into the center. This invisible boundary is called the event horizon. Inside this line, nothing can get out because the slope is effectively vertical. Even though light is the fastest thing in the universe, it cannot climb a vertical wall. Think of it like trying to swim upstream in a river that flows faster than you can swim. The water pulls you back no matter how hard you try. This happens because the black hole is so heavy that it bends the space around it. The more massive the object, the deeper the dip in space. For a black hole, that dip is a bottomless pit. Once light crosses that edge, it is trapped forever.