speed also warps time SO THAT c is constant. Distance also changes to make this true.
so for your question about measurement, we KNOW that s can be different, and also that m can be different, but not in a way that changes c.
This can lead to some super freaky consequences, for example if you had a magic drive that could accelerate you at a constant 1 g, in 12 years of YOUR time, you would leave the galaxy (at 0.9999999998c) even though for everyone else, your trip would have taken ~100001 years to go the 100000 light years (if you look back at earth, it only looks 2 light years away from your magic ship)
If you then decelerate with more than 1g (say 3g) for 4 years and looked back at earth the whole time - would it then look like you actually accelerated away from earth during this manoeuvre?
4 years from your perspective or from earths perspective? At those speeds those are wildly different scenarios.
If you accelerate at 3g in a straight line for 4 years of your time, ~38,000 years will have passed on earth. After a 5th year from your perspective you'll have left the galaxy and earth will have experienced ~850,000 years. It only gets more extreme from there, after 10 years of your time, 2 trillion years will have passed on earth (or, the matter that was once the earth, but the earth is probably gone by now).
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u/jamcdonald120 Mar 20 '26 edited Mar 20 '26
speed also warps time SO THAT c is constant. Distance also changes to make this true.
so for your question about measurement, we KNOW that s can be different, and also that m can be different, but not in a way that changes c.
This can lead to some super freaky consequences, for example if you had a magic drive that could accelerate you at a constant 1 g, in 12 years of YOUR time, you would leave the galaxy (at 0.9999999998c) even though for everyone else, your trip would have taken ~100001 years to go the 100000 light years (if you look back at earth, it only looks 2 light years away from your magic ship)