Time paradox usually refers to logically contradictory conclusions that can be derived due to time travel or time travel. It assumes that two or more premises cannot be established at the same time, which is a common feature of all paradox problems.
Time paradoxes were first mentioned in science fiction novels. The necessary premise of this paradox is that human beings can control the "fourth dimension" after the three-dimensional space - time at will, and can travel to the past or the future.
As far as serious physical theory is concerned, it is indeed possible to change time without violating the known physical laws. But it's more of a science fiction. In order to solve the "time paradox", there are also many hypotheses, such as the more popular "parallel universe" hypothesis, which believes that our world has many similar "clone worlds" in the universe. When someone goes back to the past, he He entered another parallel world (that is, a world that has changed in the future due to his actions) [2] It may also be that many other sub-worlds were created in the main world, and the sub-world was created at a certain moment (maybe you returned to (a moment in the past), it may collapse and disappear, or it may remain unchanged, but the laws and situations in each world may not be the same.
A went back in time and killed A's grandfather before A's father was born. Since A's grandfather is dead, there would be no A's father; without A's father, there would be no A. Since A does not exist, it is impossible to go back in time and kill A's grandfather.
Time is a developing thread, and everything you do has cause and effect. Following example 1, when you first want to travel back in time and kill your grandfather, it makes sense to go here. After you successfully kill your grandfather, everything related to your grandfather will change the moment your grandfather dies. People your grandfather knew, and friends or relatives of people your grandfather knew will no longer exist. , then according to the butterfly effect, this world will also disappear because you killed your grandfather.
Someone arrives in the future and learns that unfortunate outcome A will occur. He returned to reality and took actions to avoid the result, resulting in result B. Then result A will not happen at all in the future, and it is impossible for him to know result A.
A went back in time and tried to avoid B's car accident, but it was A's advice that made B insist on driving, and then a car accident occurred. This paradox is similar to a self-fulfilling prophecy.
A drank a cup of poisonous coffee, and as time went by, the poison in the coffee took effect. He sent a message to his past self and told his past self not to drink that cup of coffee. In the past, he did not drink that cup of coffee. , then the question is, since you didn’t drink that cup of coffee, how could you send that message
After the birth of the time paradox, there was once a very interesting and difficult problem - the twin paradox. A pair of twins A and B, A is on the earth, and B takes a rocket to travel among the stars, and returns to the earth after a long time. Einstein asserted from the theory of relativity that two people experienced different times, and B will be younger than A when they meet again. Many people have questions, thinking that A sees B moving, and B sees A moving. Why can't A be younger than B? Since the earth can be approximated as an inertial frame, B has to experience acceleration and deceleration processes, and it is a variable acceleration reference frame. , the real discussion is very complicated, so this issue that Einstein has discussed clearly has been mistaken by many people as a self-contradictory theory of relativity. It would be much easier to discuss this issue using the concepts of space-time diagrams and world lines, but a lot of mathematical knowledge and formulas would be required. Here we only use language to describe the simplest situation. However, words alone cannot explain the details in more detail. If you are interested, please refer to some relativity books. Our conclusion is that B is younger than A in any frame of reference.
In order to simplify the problem, we will only discuss this situation. The rocket accelerates to sub-light speed in a very short time, flies for a period of time, turns around in a very short time, flies for another period of time, and decelerates to meet the earth in a very short time. The purpose of this processing is to ignore the effects of acceleration and deceleration. It is easy to discuss in the earth's reference system, the rocket is always moving clock, and B is younger than A at the reunion. In the rocket reference frame, the earth is moving at a constant speed, and the time process is slower than that in the rocket, but the most critical point is the process of the rocket turning around. During the U-turn, the Earth travels across half a circle from far behind the rocket to far in front of the rocket in a very short time. This is a "super-light" process. But this super-light speed does not contradict the theory of relativity. This "super-light speed" cannot transmit any information, and it is not super-light speed in the true sense. Without this U-turn process, the rocket and the Earth cannot meet. Since there is no unified time in different reference systems, their ages cannot be compared. They can only be compared when they meet. After the rocket turns around, B cannot directly receive A's information because the information transmission takes time. The actual process that B saw was that during the U-turn, the earth's time progress suddenly accelerated. From B's perspective, A is actually younger than B, and then ages rapidly when turning around. When returning, A ages slower than himself. When we met again, I was still younger than A. In other words, there are no logical contradictions in the theory of relativity.
If time travel is possible, why aren’t we surrounded by time travelers from the future? The subtext of this question is: Time travelers have not come around us. The most likely reason is that time travel has never been realized in the entire time - that is, forever.
Doomsday scientists do not regard this question as a serious theoretical challenge to time machines. However, his question still caused some physicists to think, and they found a possible answer: that is, among the theoretical models we currently know that may realize time travel, there is one that is likely to be universal. The common feature is that time travelers are not allowed to return to the era before the existence of time machines.
Now that Lin Feng has solved the crisis in the world of death, all that is left is to find another hidden base. This means that there was a phenomenon of space distortion a long time ago, and the former Naiya believers used space distortion to travel to the present time. Carry out destruction.
Although Lin Feng had read about the time paradox in the science magazine in his supermarket, he still couldn't figure it out. Perhaps this is a bottleneck of time energy. When Lin Feng understood the order and correctness of time travel, his time ability There will be a big improvement.
When thinking about it again, Lin Feng regretted one thing. If he could get Kunajie's energy, could he get the ability to travel through space from him
(End of chapter)