He also became increasingly interested in the application of thermodynamics to relativistic systems, and cosmology; including showing in 1934 that black body radiation in an expanding universe cools but remains thermal-a vital result for the properties of the cosmic microwave background.
He also became increasingly interested in the application of thermodynamics to relativistic systems, and cosmology. Work in that field included establishing the oscillatory universe hypothesis; and showing in 1934 that black body radiation in an expanding universe cools but remains thermal-a vital result for the properties of the cosmic microwave background.