1656–1690Reputable sourceWell documented
Huygens, the Pendulum Clock, and the Wave of Light
On the timeline · around 1656–1690 ·
What happened
The Dutch scientist Christiaan Huygens invented the pendulum clock in 1656, giving the world its first accurate timekeeper, and worked out the mathematics of pendulums and circular motion. In his Treatise on Light he argued that light travels as a wave, explaining reflection and refraction — a direct challenge to Newton's view that light was a stream of particles.
Why it matters
Huygens's precise clocks made exact measurement possible, and his wave theory of light was a powerful rival to Newton's — a debate not settled for two centuries. He was arguably the greatest physicist between Galileo and Newton.