Friday, June 29, 2018

general relativity - Why doesn't a global frame of reference exist for GR?


I only have at best a layperson's familiarity with GR, so forgive me if I am asking a basic question, but I have heard that in GR, we cannot have a global frame of reference, that is a frame of reference that is applicable to the entire universe. Can anybody explain why this is?


I have heard that it has something to do with the expansion of the universe, since we can still define it locally. At the same time I have also heard that it is due to our understanding of space-time as being curved. Can anybody expand on that?





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