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?
Yes. Distant galaxies that are moving away from us at relativistic speeds exhibit measurable time dilation in their inner workings.
How would you even measure time dilation in a distant galaxy? Consider standard candles like 1a supernova, which explode with near uniform power. These supernova can be observed from intergalactic distances. Gather data and record the times for various supernova explosions. You’ll find that the same types of explosions take longer in more distant galacies, and that the extra time is exactly what relativity predicts.
That’s incredibly cool. From a point of view of a being near that supernova, would we be moving a lot faster?
From the point of view being near the distant supernova, we are moving away from them at relativistic speed, so as much slower as they appear to us, we should appear that much slower to them.
I’m struggling to wrap my brain around this