Why is there no one who has traveled from the future to the present?

Five hundred years ago, mankind was still in the period of agricultural civilization, and even the shadow of the industrial revolution had not appeared. These scientific and technological products we use now are just like those used by "immortals" at that time, and we will never think of these things in our minds.

1903, man invented the first plane that could fly into the sky. Although it only stayed in the air for about a minute at that time, and the structure of this plane was very simple, there was almost no safety design, but it did let mankind see the hope of flying in the air!

At the beginning of the 20th century, Einstein published the theory of relativity, Bohr put forward the theory of quantum mechanics, and human science and technology officially took off and entered an era of rapid development of science and technology. Then, human beings created atomic bombs, artificial satellites and manned spacecraft, and all the things called "Arabian Nights" before the 20th century were displayed before human eyes.

With the development of science and technology today, people's imagination of the future is more abundant. Many people hope that scientists can invent commercial controlled nuclear fusion, general quantum computers and time machines, and the most anticipated one is a time machine that can make people go back to the past.

People who want the time machine to be invented include ordinary people and theoretical physicists. Some theoretical physicists even put forward the dream of using Einstein's wormhole theory to travel in time and space. But this theory is not perfect, it is still in the hypothetical stage, and it can't really help us create a time machine that goes back to the past.

Therefore, many people think that we may have to wait until future physicists put forward a higher-level physical system before we can realize our dream of time travel.

Then there is an obvious question here, that is, why have we never met anyone who came back from the future? Didn't people in the future think of going back to the past to have a look? Moreover, in the long history of human civilization, it has never been recorded that a person came back from the future. Does this mean that no one can successfully build a time machine even in the future world? Let's open a brain hole together and discuss this problem!

A time machine can never be made. One reason why it can't be done is that time for humans, the earth, the sun and even the Milky Way is limited. Even if humans can emigrate to other planets, they will disappear one day. In some cosmological theories, it is mentioned that at a certain moment, the whole universe will be silent.

So, maybe even if people who live in the future disappear, they can't create a time machine that travels back to the past, and naturally there is no record from future people.

The time machine can't go back to the time when it doesn't exist. Although human beings have begun to prepare the physical theory related to the time machine, we should also realize that we can't make the time machine yet, and the possibility of inventing it after 100 years is very low.

Another reason why we think we can't do it is that even if we make a time machine, we can't use it to go back to the time without it.

That is to say, if humans invented the time machine in 222 1 year, then humans can only go back to the time after the invention in 222 1 year, not earlier.

The time machine can only return to the parallel world. After the invention of the time machine, people in the future can travel in time and space with it, but the time and space they return to is not their original world, but a parallel world.

This assumption is more realistic. After all, if someone really takes a time machine back to his ancestors' time, the world he lives in will change greatly, and maybe he will disappear in the future. So, is it contradictory?

Why do people in the future never come back? Do you have any other answers to this question? Welcome to leave a message for discussion!