Good morning everyone. Today I'm here to talk to you about the event horizon. The event horizon is a boundary in spacetime, which marks the point of no return for an object that has crossed it. It is the point at which the gravitational pull of a black hole becomes so strong that nothing, not even light, can escape its grasp. To understand this concept better, let's look at a diagram (show diagram). As you can see, the event horizon is represented by the red line surrounding the black hole. Anything that crosses this line will be pulled into the black hole and will never be able to escape. Now let's talk about what happens when something crosses this line. Once an object has crossed the event horizon, it will be pulled into the black hole and will never be able to escape its gravitational pull. This means that anything that crosses this line will be lost forever and can never be recovered. Now let's look at another diagram (show diagram). This diagram shows how light behaves when it approaches an event horizon. As you can see, light is bent around the event horizon and eventually gets sucked into it, never to be seen again. This phenomenon is known as gravitational lensing and is one of the most fascinating aspects of black holes. So in conclusion, we have discussed what an event horizon is and how it affects objects that cross it. We have also looked at how light behaves when approaching an event horizon and how this phenomenon is known as gravitational lensing. I hope this presentation has been helpful in understanding this concept better! Sources: Diagram 1: https://www.space.com/black-holes-event-horizon-illustration-diagram-explained-infographic Diagram 2: https://www.spaceanswers.com/astronomy/what-is-gravitational-lensing/