Part 3/9:
A significant concept in the discussion of black holes is the event horizon, which serves as the boundary surrounding a black hole. Once an object crosses this invisible line, it is irrevocably drawn into the black hole; no amount of propulsion or force can allow it to escape. The term "event horizon" is apt since it defines the limit of what we can observe—any events occurring beyond this line remain shrouded in mystery, forever hidden from our view.