system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: how is time relative? I understand the human aspect of it but how can time pass slower near the speed of light?

Wouldn't assuming time passes slower near the speed of light be assuming that time and light are related? That assumption seems wrong as time still passes in the complete dark.
gpt
You are always moving at the speed of light in 4 dimensional spacetime. Your speed in the 3 space directions plus your speed in the time direction always add up to c. Normally all of that speed is in the time direction, but if you move really really fast you take some speed from the time direction to go in one of the space directions so you slow down in the time direction.