Barely a day goes by without my making some use of the Milne model, the vacuum, curvature-only FLRW solution. It’s a useful standard for comparing supernova distance modulus curves with. But Edward Arthur Milne was much more than the father of a handy reference model. Throughout the 1930’s and 40’s he worked on a radical, non-general-relativistic cosmology, deduced purely from two basic axioms. Those were the Cosmological Principle – that everything is the same everywhere in the Universe – and the principle that observers could mutually agree on some universal standard of measuring time.
Milne’s theory is a beautiful attempt to deduce cosmological theory axiomatically, without recourse to empirical input. It received a substantial amount of attention in the first half of the 20th Century but, through a series of conceptual difficulties, it ultimately failed, yielding to the more practical relativistic theories. Nevertheless, it seems to have left a lasting mark on the field, and many of Milne’s ideas remain common currency, even if the original theory has slipped into obscurity.
I’m giving a talk on this subject at an OUSAS meeting tomorrow.