In general relativity, we cannot determine the global structure of the universe (since it is not flat), therefore all measurements and observations are only meaningful locally. In particular, we can observe redshift of light from distant galaxies. And then we have the Expansion of the Universe described by Friedmann–Lemaître–Robertson–Walker metric explaining this redshift. However, I think there are always possibilities that different structures of universe may also give rise to this redshift. Is it true? Is there any kind of experiments that can help us determine the structure of the universe (or at least determine the universe is finite or not)?
However, I think there are always possibilities that different structures of universe may also give rise to this redshift. Is it true?
The redshift is on average the same in every direction and depends on the distance, so if it came not from cosmic expansion but from "structure" (matter, energy distribution) that would mean that we were in the cosmic center because the farther from us the redder objects are, in every direction. Therefore the "structure" would have to increase its redshiftfavoring properties shellwise from our position. That is not very likely.