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Would it be reasonable to summarise the question as "how do we know that a red-shifted star is red-shifted because the Universe has expanded between us and it, rather than the star moving rapidly away to start with?"
a time clock would be slower now than at big bang
everything would be common mode
Why is the light from the far stars red?
Quote from: jerrygg38a time clock would be slower now than at big bangAccording to Special Relativity, time progresses more slowly in a region of high density, when viewed by an observer outside that gravitational potential well.In the past, the universe was denser than it is today, so would that imply that time was slower in the distant past than it is today? Quoteeverything would be common modeI don't understand this term when applied to cosmology. What is "common mode", and how would it differ from an "uncommon mode"?
Quote from: jerrygg38 on 24/07/2016 13:43:32Why is the light from the far stars red?Not all stars appear red to us. Do they?