All Questions
4
questions
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3
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182
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Relativity and the age of the Universe
I put my assistant in a spaceship and accelerate it to near the speed of light. 100 years from now (in my time), my assistant is travelling with speed $0.99c$. At that time I put up a super ...
user32023
2
votes
2
answers
241
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What should I consider as an observer to measure the speed of cosmic objects?
I mean for example if earth is the observer, then there might be entire galaxies travelling faster than the speed of light relative to earth. So according to Einstein relativity this shouldn't be ...
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0
votes
0
answers
33
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Is the Hubble parameter different for each observer?
As the universe expands, galaxies disappear beyond the observable universe. So we could calculate the rate of expansion of the universe (the Hubble parameter) by estimating the rate of disappearance.
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- 333
2
votes
2
answers
124
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Is the age of the universe different for a returning space traveller?
When an astronaut returns to the planet he came from, he would then count the exact same number of galaxies as an observer on that planet, but they could have had experienced wildly different amounts ...
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