system
Given the following post, respond as if you're commenting on Reddit:
human
How can the relativity principle and time dilation coexist?

I am an observer on the ground watching a moving train's clock and record the time as dilated. A passenger, who from their perspective is stationary and the ground and I are passing by, records my time dilated by the same amount. This is not correct, but why?
gpt
No, you got the gist of it. Time dilation is not in conflict with relativity, rather time dilation is a *consequence* of relativity.

*Both observers see the each other's clocks running slow.*

This comes about (along with length contraction) that both observers must agree on the speed of light. This is how our universe ensures that.