So I came across an interesting idea: we think we are real now, but we have a future in front of us. For them, we have become the past, and people in the future may have mastered the technology of the space shuttle, so they have come back to us through technology and watched us quietly. We can't detect them, and they can't do anything about our lives. Looking at us, some people are happy and some people are worried, and some people are dying. But nothing can be done. Therefore, after mastering the technology of time travel, we can grasp every detail of history, but we can't make any changes because of the rules of time and space. I really don't know whether this ability is a human gift or a human sorrow.
So even in the past, you can't buy lottery tickets. To you, the world is like a 4D movie. Can you buy things from movies?
Maybe when you are reading this reply I gave you, there is a traveler from 3000 years standing behind you. Why, you would say, no! I am now, the future hasn't happened yet, they can't exist! But, think about it, what would Li Bai think if we mastered the technology of time travel and returned to the Tang Dynasty and came to Li Bai? He will think that his words and deeds will affect the future. We don't exist, but we don't know that we are always by his side, watching his life, rejoicing for him and worrying about him. For Li Bai, he doesn't know what his next step will be, but we know that watching him go to every step he thinks is caused by countless coincidences. What about us? Isn't it the same for future people?
In fact, the study of time travel reached its climax after the birth of Einstein's theory of relativity. Relativity puts forward the "time shortening" effect, that is, it introduces the relationship between speed and time and space, and opens up a new era of physics. As we all know, you are sitting on a speeding train. For the world outside the train, the inside of the train is a brand-new time and space, because the train has another speed relative to the outside world. At this speed, the time and speed in the train are slower than those in the outside world, and the objects in the train are shorter to outsiders. Of course, to produce this effect, the speed of the train must be at least many times faster than that of the satellite to be clearly perceived. But for you sitting in the train, everything in the train is no different from when you are outside. If the train is traveling near the speed of light, suppose you only stayed in the train for a few seconds. Of course, you thought it was only a few seconds, but when you got off the train, you found that things outside had changed. This is relative to time, and speed has caused this change. So this leads to the following inference, what happens when the train speed is infinitely close to the speed of light? In this way, the time inside the train is infinitely close to zero relative to the outside world, so when the train reaches the speed of light, the train and everything inside will fall into absolute stillness, that is, time will stop relative to the outside world, so some physicists think that when it exceeds the speed of light, time can return to the past relative to the outside world. This is the mainstream theory of time travel in physics. But Einstein pointed out that the speed of light is absolute. When an object approaches the speed of light infinitely, its mass will be infinite and will eventually disintegrate, so nothing can reach the speed of light and surpass it. So Einstein thought it was impossible to go back in time. But everyone thinks that great men sometimes make mistakes, so Einstein's view does not affect scientists' interest in time travel.
Well, I'm going to end this long narrative. The theoretical research mentioned in the first paragraph is also the latest theory abroad, and its authenticity needs to be verified, but it does successfully explain the grandmother paradox, that is, nothing can be done. As long as the physics discipline enters the space-time field, it will fall into many contradictions, so my reasoning in paragraphs 2, 3 and 4 will be uncertain, so you don't have to be afraid that future scientists will always spy on your history and privacy. Perhaps the space-time shuttle will never be born, because only in this way will the world evolve in a stable state, and our present is the real present. There will be no existing problems in the future, and there will be no future in the future, and so will the future. . . This repeated contradiction.
This kind of problem itself has insoluble contradictions. Grasp your present life and be truly happy!