system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why time theoretically stops at the Speed of Light

Also, do objects travelling at the speed of light simply perceive other things around it as not moving?  Or does time literally pass slower for these objects?
gpt
what you need to understand is that "time" and "space" are not separate things. They exist in one 4 dimensional space called "spacetime"

in spacetime, everything is always moving at "the speed of light" through the 4 dimensional space. Usually, this is almost fully expressed in the "time" dimension.

As your speed increases as movement through the 3 "space" dimensions, your speed in the "time" dimension must decrease, since the vector sum of all 4 dimensions must always be a vector with speed "c". In other words: the faster you move through space, the slower you move through time.

If you move at the speed of light, this means your movement in through spacetime lies fully in the 3 space dimensions. The vector length in the "time" dimension is 0. Thus, if you travel at the speed of light through space, time stands still for you.