system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: The current theories of time traveling

Isn't the word "time" just a perception of something we can't really grasp? I remember seeing some video of two atomic clocks and one was put on an airplane and somehow they ended up telling different times. How is that possible?
gpt
The faster you go, the slower time appears TO YOU.  So, put a clock on Earth and a clock on a spaceship.  Send the spaceship out travelling near the speed of light.  When it returns, the earth clock says the ship was gone 10 years (or whatever), the spaceship clock says it was only gone 2 years (or whatever, depending on the speed it was going).  They're both right!

edit: Time travelling will never be invented.  If it ever were to be invented at any point in the future, then we'd be seeing visitors from the future today.  We don't see visitors from the future today, so that means nobody will figure out a way to do it.