Time travel is actually possible when your speed reaches or exceeds (note that it can be achieved! ), the time around you will lag until it stops. Black holes provide conditions for time travel. Astronomers have found that a black hole is a celestial body with huge mass and extremely fast rotation speed (the greater the mass, the higher the temperature, the faster the rotation speed and the greater the celestial gravity), and light cannot escape from its gravitational field. Due to the huge gravity of the black hole, the celestial body is constantly adsorbed and compressed on its surface, becoming a particle on the surface of the black hole. After absorbing countless celestial bodies, the black hole will become bigger and bigger, and its mass and rotation speed will also rise, so the gravity will become stronger and stronger, so that the black hole can attract celestial bodies from farther places, and then form a celestial belt on its side (the celestial bodies inside are flying to the black hole at a very high speed, and the exact speed cannot be determined, because these celestial bodies are accelerating infinitely, and the farther away they are, the faster they reach the black hole). If you rush into a black hole in a spaceship at the speed of light, once you can rush into it at the speed of light (provided that you can survive in the celestial sphere, the probability is just like you can see an ant you saw before you circled the earth after you made a 747 passenger plane. The two ants are exactly the same in size, sex and DNA, and to put it bluntly, it is the same ant). You will enter the wormhole in the black hole (I don't know the relationship between this thing and the black hole), and then you will reach the white hole (black hole, wormhole and white hole will granulate your body, and only twisting can minimize the influence of gravity, and from the perspective of onlookers, you will be stretched horizontally). As long as you can survive the twisting granulation of the black hole, wormhole and white hole, you won't lose your arms and legs or put you and the spacecraft in a reorganization. You are likely to cross it perfectly and successfully! The destination of this crossing is unknown, which may be a completely mechanized parallel world (that is, a space that will not intersect with other time and space, see "Parallel World" Baidu Encyclopedia for details), a parallel world with only single-celled organisms, and another possibility that the same parallel world has different time points! (If a parallel world is regarded as a number axis, if your original era is the origin, that is, the zero point, then you may not be at the zero point after crossing ... it can be a plus point, a minus point or other points) So ... you have successfully crossed time and space!