What nationality was the man who determined that light has a finite speed?
Ole Rømer Ole Christensen Rømer (] ; 25 September 1644 – 19 September 1710) was a Danish astronomer who in 1676 made the first quantitative measurements of the speed of light.
Abraham Zelmanov Abraham Zelmanov (May 15, 1913 – February 2, 1987), was a prominent scientist working in the General Theory of Relativity and cosmology. He first constructed, in 1944, the complete mathematical method to calculate physical observable quantities in the General Theory of Relativity (the theory of chronometric invariants). Applying the mathematical apparatus, in the 1940s, he established the basics of the theory of inhomogeneous anisotropic universe, where he determined specific kinds of all cosmological models — scenarios of evolution — which could be theoretically conceivable for a truly inhomogeneous and anisotropic Universe in the framework of Einstein's theory.