If you jump into a black hole

If two spacecrafts sail to a spinning black hole before and after space, the first spacecraft is ready to sacrifice itself bravely, and what kind of scene will you see when you observe the performance of the second spacecraft? Imagine that on the first spacecraft is an intelligent robot. When approaching the horizon, that is, the black hole boundary where there is no return point, the robot astronauts walk out of the spacecraft to meet the death. He will be attracted by the gravitational attraction of the nearest part of the black hole, broken into two halves, and then unconsciously swallowed up in the singular point (the center of the black hole) that just disappeared near the space-time. The spacecraft was torn to pieces by the powerful gravitational force before it was engulfed. How big is this attraction? For a black hole with a mass equal to the sun, a 2 meter tall person must bear the acceleration of gravity equivalent to 1 billion times the earth's surface. In order not to fall into a black hole, you must rely on the thrust of a sufficiently large engine to park the spacecraft in a safe distance or around a black hole. It seems to you that the spaceship ready to sacrifice seems to have used endless time to get close to the black hole, and the speed of the spacecraft is slower and slower, changing the color at the same time, but before you can see the spacecraft is still at rest, the spaceship will disappear from the eyes. The reason for this phenomenon is that, according to the theory of relativity, the passage of time depends on the speed of the observer.

In this black hole journey, we see that a rotating black hole is like a rotating disc with holes in it. It has two layers of interface, one of which is the horizon, and the outer layer is called the "static limit" or the infinite redshift surface. Between these two interfaces is a special area called "energy level".On the static boundary, time is "frozen", radiation is redshifted indefinitely, the spacecraft stays at a fixed point, the spaceship that the robot astronaut sees on the spacecraft will no longer change, and the black hole will rotate rapidly under his feet. If we go beyond the static boundary and enter the energy level, the spacecraft will be dragged into the rotating motion.

The energy layer has an amazing characteristic. As the British mathematician Roger Penrose (Roger Penrose) pointed out, the energy entering into it can become negative. We might as well imagine this object as a person with energy debt. When a black hole captures this object, the energy of the black hole is not increasing but decreasing, because the black hole must "repay" the energy debt owed by its prey.