Why the clock on the sports train is not the same as the clock on the platform.
First, the velocity decomposition is replaced by the decomposition of time and space, that is, the time and velocity are the orthogonal coordinate axes of the current year in three-dimensional space. Now the time is an exploded coordinate axis, the velocity is a coordinate axis, and all information transmission speed in the universe. All of them are light speed c, all reference systems are in your angle. The next situation can be simply understood as that you have a speed on the train relative to the platform. This speed is a component of the speed of light c in space, your time subtracting this component is naturally slower than on the platform.
To sum up, no matter what, you or the people on the platform, even the train and the platform, and the air, are moving in the sky and the sky at the speed of light. The faster you are in space, the slower the time, and vice versa.
You may ask, then the reference system becomes a person on the platform? Whose table is slower? This question is very interesting. I can only say that it is slow. If you stand on your own point of view, the people on the platform think that you are moving relative to you.
What?! Isn't that ridiculous? The problem is that if you want to know what the real situation is like, you have to slow down and then reverse the acceleration back to the platform. At this time, the situation has changed, and your behavior has affected. The result of the matter, while also explaining one thing, the speed of information transmission can not exceed c, more and more interesting, if you and I just want to have a glimpse of the theory of relativity and do not have deep professional knowledge:
I recommend you look at the shape of time. This book is much better than me. I also explained it with reference to his thoughts.
