Before revision: 1675 – Isaac Newton delivers his theory of light 1676 – Olaus Roemer measures the speed of light by observing Jupiter's moons 1678 – Christiaan Huygens states his principle of wavefront sources and demonstrates the refraction and diffraction of light rays.
After revision: 1675 – Isaac Newton delivers his theory of light 1676 – Ole Rømer proves thatis finite, speed of light by observing Jupiter's moons 1678 – Christiaan Huygens states his principle of wavefront sources and demonstrates the refraction and diffraction of light rays.