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If you were stationary, and talking to someone moving at lightspeed, would they appear to be speaking in slow motion due to time dilation? (lemmy.ca)
submitted 1 day ago by a_gee_dizzle@lemmy.ca to c/askscience@lemmy.world
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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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[-] a_gee_dizzle@lemmy.ca 3 points 1 day ago* (last edited 1 day ago)

If an object broadcasting a signal moving at the speed light away from you, I would further assume you experience a severe Doppler effect.

In principle you could have equipment that cancels out any doppler effect, no?

I also did some communcations work for a time. So, this is tickling my brain and I might spend the rest of my evening in my books.

That's awesome, let me know if you find anything interesting

[-] Onomatopoeia@lemmy.cafe 6 points 1 day ago* (last edited 1 day ago)

To cancel the effect of someone moving away from you, the equipment would simply hold the transmission until you received the whole thing.

Like waiting for someone to finish leaving a message on an amswerimg machine before hitting play.

this post was submitted on 27 Apr 2026
37 points (100.0% liked)

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