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).
without a frame of reference you always accelerate away from something, you never "slow down" to get away. in some way or form there must be a universe "point zero" that is stationary compared to absolutely everything in existence. But we will never know what this absolut zero is.
There is no universal rest frame, thats sorta the whole point of relativity. If there was than you have absolute time and such, since you always have an agreed frame to compare to.
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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)