this post was submitted on 27 Apr 2026
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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?

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[โ€“] a_gee_dizzle@lemmy.ca 1 points 6 days ago (1 children)

I might be missing something here. Is the doppler effect related to time dilation?

[โ€“] mech@feddit.org 1 points 6 days ago* (last edited 6 days ago)

The actually true explanation is that special relativity only applies to reference frames without acceleration or nearby gravity.
So the fact that your clock runs slow as seen from earth and earth's clocks run slow from your POV doesn't cause a paradox.
There's no way to compare clocks at this time, since information can't travel faster than light.
When you decelerate/accelerate back towards earth, you leave the realm of symmetric time dilation and earth's clocks will appear to jump ahead as you switch reference frames, so it'll show more elapsed time when you're back. But I've yet to find an intuitive illustration for that.