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?
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?