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?
It’s just two objects moving apart. If I drive my car away from yours, it looks exactly the same as if you had driven away from me (once you delete all the frames of reference like the ground, because there is no ground in space). The other person gets smaller at the same rate.
Have you ever been in a car or train where you couldn’t see the ground, only another car or train next to you? And you see the other vehicle moving, but you can’t tell if it’s actually them or you moving? Same thing. It’s all relative.
I’m just confused as to how we could both experience time dilation at the same time. Isn’t our time only dilated in relation to each other? So if both our times were dilated there would be no relative difference and it would look like our clocks were in sync, no?