I’m asking this because there is a scifi book I’m reading, and in the book there’s a scene where someone is communicating with a person in a spacecraft moving at lightspeed. I know their ability to communicate would probably not be possible, but let’s just put that aside for a second. Hypothetically, if you could communicate with someone moving lightspeed, would the time dilation make it so that they would appear to be moving and speaking very slowly relative to you?


Only in comparison to (relative to) others. A photon from the sun experiences no time at all between leaving the sun and landing in your eye but we perceive it as eight minutes.
Oh I see. That makes sense. The fact that it’s experiencing less time is why, relative to us, it’s time seems to be running slower