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?
Bad news: If a person was moving at the actual speed of light, from their own perspective they would arrive at their destination instantly. This means they wouldn’t have time to send or receive a message at all!
Assuming a velocity close but not quite as fast as C, yes, you would see severe differences in the speed of the communication. One party would be super slowed down and the other would be super sped up.
Another commenter here asked about an interesting set-up where the person moving lightspeed is circling around the stationary person. This is of course super impractical but it might allow them to communicate without catching up to one another instantly
Okay I guess that answers my question then
the angular momentum you would feel from circling someone at light speed would probably tear your limb from limb.
Assume a spherical cow in a vacuum
An infinite, frictionless vacuum?
Is there any other kind for spherical cows to populate?
Now I’m trying to image how spherical cows, or really anyone, can reproduce in a frictionless vacuum.
Limb from limb? Either those limbs are massless, or you’ve just given yourself infinite mass traveling at c with an infinite energy. You’d probably tear the fabric of reality limb from limb.
I’d probably just assume the traveler and receiver aren’t experiencing any maleffects in this situation. Else the traveler would be cooked by all of the radiation that they would be receiving all at once.
Not with a big enough circle. But I’m assuming we’re talking cosmic-scale circles here, with the circle covering an appreciable portion of the observable universe in order to make the g-forces bearable.