Why can't time go back?

He: "There is a saying that if the speed of an object exceeds the speed of light, time will go back, right?" Me: "This is not a misunderstanding, is it? According to the theory of relativity ... "He:" Stop, I ask you, do you know the theory of relativity? This understanding is not only memorized, but can explain part of it. " Me: "I won't, and few people in the world can explain it clearly, right?" He: "Of course, few people can explain everything, but there are still many people who can explain part of it. What I want to do here is not to give you a basic lesson, but to tell you: when you don't really understand a theory, don't quote it easily, or use it to prove it or refute it. You have to figure it out first, or you will probably become a joke, because you are doing something you are not good at. And when you don't understand some problems, don't explain them at random, which will only make you look ridiculous and stupid. Suppose you have to explain quantum teleportation with radio wave theory and look at quantum teleportation with wireless transmission loss, then you are ridiculous and can only prove your ignorance and self-righteousness. Although they are all transmission, the concept is different. You need a postal system to write letters, but you don't need a postal system to write emails. Although they are all called emails. Do you understand? " Me: "OK, I see. I take back the sentence of relativity. " He said, "Tell me the time. In fact, superluminal is also a manifestation of speed, rather than what strange things will happen beyond that limit. Suppose you see the earth a light-year away, then you actually see the earth a year ago. I don't need to explain this foundation? " Me: "No, light years are units of length." He: "Right, so what you saw was a year ago. Suppose your speed is 365 times the speed of light, or 3650 times. You came to the earth not long ago, so you came to the earth a year ago? Right? The earth you see is now, not a year ago. " Date: 2009-10-1421:01:00 I said, "I seem to understand something." He: "In fact, you can use archery as an example. A man shoots an arrow at you, and the arrow comes to your eyes. If you move fast, at most, you will see an arrow hanging in the air. If you reach the archer at superluminal speed, which arrow will return to the bow? Right? That arrow, no longer on the bow, has been fired at where you were just now. Your high speed, at best, leads you to see a static world, not a countercurrent. " Me: "I see, you mean: suppose there is superluminal, in fact, superluminal also consumes time, even if it is only one tenth of a second, it is consumed and there is no way to reverse it." He: "Yes, the so-called superluminal reversal time is just an illusion that the public likes very much. In fact, the concept of superluminal inversion can be seen even by philosophical analysis. Is it that a person's speed exceeds the speed of light and the whole world is upside down? This idea is too subjective. In fact, relativity, as a theory, should explain that if there is speed, the time problem can be ignored, which is only a physical hypothesis. " Agree 0| Comment