 We can use tipping light cones to show how all objects, unfortunate enough to cross the event horizon, are captured forever. Here's a light cone far from the black hole. The horizontal axis represents distance from the singularity. As we saw earlier, when space-time is curved by the presence of mass energy, the light cone structure gets distorted. When the mass is a black hole, the tilting reaches 45 degrees at the event horizon. This means that all events beyond the horizon are no longer in the future light cone for any object that has gone past it. No possible world line gets you out. All remaining world lines lead to the singularity. Distance from the singularity decreases inside the black hole's horizon as surely as time increases outside the horizon. In Interstellar, Cooper flies his ship into the black hole while Brand watches from a higher orbit. We can use our space-time diagram along with light cone bending again to illustrate what each of them would have seen. First we'll take a look at it from Cooper's point of view. As he heads directly into Gargantua, he sees periodic signals from Brand. She is far enough away from the horizon for her light signals to all travel in a parallel manner at 45 degrees along her light cone boundary. Cooper crosses the event horizon without even noticing it as signals continue to arrive at regular intervals. Eventually, he will feel the tidal forces of the singularity. Now things are quite different from Brand's point of view. As Cooper approaches the event horizon, his light cone tips towards the singularity. This means that his light signals back to Brand are taking longer with each kilometer traveled. The effect is hyperbolic and the light signal he sends from the horizon itself will never get to Brand. She sees his clock slowing down to the point that it stops. She never sees him enter the black hole. What's more, because of gravitational redshift, the image of Cooper and his ship shift to the red. At the horizon, it has shifted into the infrared and can no longer be seen by Brand. For her, Cooper grinds to a halt and goes invisible. Quite different from what Cooper sees.