Sorcerer Posted July 26, 2014 Author Posted July 26, 2014 (edited) Relativity doesn't say anything like that. It defines the geometric background of time and distance. How is there any distance if there isn't any two points? How is there any time if there isn't a third point to observe the changing distance between two points? "Even though the Milne model as a special case of a Friedmann-Robertson-Walker universe is a solution to General relativity, the assumption of zero energy content limits its use as a realistic description of the universe. Besides lacking the capability of describing matter Milne's universe is also incompatible with certain cosmological observations. In particular it makes no prediction of the cosmic microwave background radiation nor the abundance of light elements which are hallmark pieces of evidence that cosmologists agree support Big Bang cosmology over alternatives." Edited July 26, 2014 by Sorcerer
Strange Posted July 26, 2014 Posted July 26, 2014 How is there any distance if there isn't any two points? How is there any time if there isn't a third point to observe the changing distance between two points? It defines the metric, or coordinate system; the way measurements would be made (if you had a ruler, except you don't have one because you have excluded matter). Points are a mathematical abstraction and can exist in an empty universe. Even in an empty universe, the spatial metric will expand over time (which is a bit surprising).
Mordred Posted July 27, 2014 Posted July 27, 2014 probably the easiest way to visualize Milne is an empty universe that expands at the speed of light, its a bottom up toy model. its handy to show the Dl-z relations here is one of my favourite papers on it http://arxiv.org/ftp/physics/papers/0510/0510170.pdf
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