Renaissance/Early Modern

Christiaan Huygens

1629–1695

It is inconceivable to doubt that light consists in the motion of some sort of matter.
Treatise on Light, Chapter I

Christiaan Huygens was a Dutch mathematician, astronomer, and inventor who treated natural effects as mechanical motions open to geometric proof. In the he explains reflection and refraction by wave fronts propagating through an ethereal medium. Each point on a front becomes the source of new wavelets. Waves need a medium. He built reliable pendulum clocks and corrected Descartes on the laws of collision. Optics after him had to choose between his waves and Newton's particles for nearly two centuries.

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