About Doraemon Time Machine

This question is very profound. Time travel is just a hypothesis, and no one can do it now, so all the information now is just a hypothesis.

The first reason is that changing the past will not change the present, because the world is different. Our present world is just one of countless world lines, and changing other world lines will have nothing to do with our world.

The second reason is that I was inspired by the cartoon Doors of Destiny. Changing the past will create another world line. The protagonist has a special memory ability, but he is not on the original world line. He crossed the world line several times, but he wanted to return to the original world line, cancel the changes and merge the world line, just like a fan folded one by one. Back to the original world line, the final point of animation is to change the result without changing the facts. This change can turn real death into suspended animation, thus saving lives. This change will not affect the world line. If you are interested, you can see how the protagonist "changes the result without changing the facts". The meaning of this sentence is the same as that of Doraemon.

"It's like going from place A to place B, except by car, you can also fly and take a boat." In fact, this sentence is problematic. So you took a bus, and then you crossed back to the previous plane. If you change, people will have different understandings, and the facts and results will also change. Taking a bus and flying are two different things. The simplest thing is that you go shopping, buy candy for the first time, then come back on time and buy popsicles for the second time. It's as simple as changing the result without changing the fact.