What nationality was the man who determined that light has a finite speed?
Rømer's determination of the speed of light Rømer's determination of the speed of light was the demonstration in 1676 that light has a finite speed, and so does not travel instantaneously. The discovery is usually attributed to Danish astronomer Ole Rømer (1644–1710), who was working at the Royal Observatory in Paris at the time.
John Lighton Synge John Lighton Synge ( ; 23 March 1897 – 30 March 1995) was an Irish mathematician and physicist, whose seven decade career included significant periods in Ireland, Canada, and the USA. He was a prolific author and influential mentor, and is credited with the introduction of a new geometrical approach to the theory of relativity.