Christiaan Huygens

Christiaan Huygens was a Dutch mathematician and physicist, the greatest between Galileo and Newton, who discovered Saturn’s rings and its moon Titan, invented the pendulum clock, worked out the laws of collision and centrifugal force, and founded the theory of probability. The Treatise on Light of 1690 proposes that light is a wave spreading through an ether, each point of the front a new source, and explains reflection, refraction and the double refraction of Iceland spar. Newton’s particles won the argument for a century; then Young and Fresnel showed that Huygens had been right.