system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If you were in a space ship traveling at the speed of light (or extremely close to it) could you walk or even move in the direction of the space ship's motion?
gpt
Yes. From your perspective, it would appear to work normally.

Let's say light speed was 60 mph just to make it simpler.
Say you also have Alice standing still outside the ship watching it go (with a telescope, so she can still see it when it's really far away), and Bob standing still inside the ship.

Alice sees your ship going at 59 mph. You walk forward. From Bob's perspective you're going forwards at 3 mph. Nothing weird. You keep walking for an hour and go 3 miles (it's a big ship!).

From Alice's perspective, you're going forwards at 0.3 mph\* inside the ship. You keep walking for 10 hours and go 3 miles. From what Alice can tell, your time is going slower - this applies not just to walking, but also the clocks inside your ship, your ship's computer, everything in the ship. This is time dilation.

\* Not a calculation, but a made up number in the right range.