Is it possible to difereciate between a expanding universe due to the big bang?, or an expanding universe due to this part of universe coming out of a more compressed stream (like coming out of a 3d venturi tube). I don't know if that makes sense. And if red shifted light is not red due to the expansion, but due to some kind interaction with dark matter?. I suppose this questions are dumb, and surely they have been discarded and replyied lotsof times, but never found that info. Does any body know a place were this kind of thinks are explained?