system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 How does time slow down when traveling near the speed of light?

Just can't get my head around it.
gpt
It doesn't. Time passes normally for you even when you're moving quickly past things.

But when you see someone else travelling quickly past you, it looks to you as though time is moving normally for you and slower for them.

And actually, it's exactly the other way around for them - it looks to them as though time is moving slowly for you and normally for them. 

This seems surprising, but it's no more so than many other things we experience every day - consider the fact that you look small to them from a distance even though they also look small to you.