Christiaan Huygens

Christiaan Huygens (14 April 1629 – 8 July 1695) was a Dutch physicist, mathematician, astronomer and inventor, who is widely regarded as one of the greatest scientists of all time and a major figure in the scientific revolution. In physics, Huygens made groundbreaking contributions in optics and mechanics, while as an astronomer he is chiefly known for his studies of the rings of Saturn and the discovery of its moon Titan. As an inventor, he improved the design of the telescope with the invention of the Huygenian eyepiece. His most famous invention, however, was the invention of the pendulum clock in 1656, which was a breakthrough in timekeeping and became the most accurate timekeeper for almost 300 years. Because he was the first to use mathematical formulae to describe the laws of physics, Huygens has been called the first theoretical physicist and the founder of mathematical physics.

In 1659, Huygens was the first to derive the now standard formula for the centripetal force in his work *De vi centrifuga*. The formula played a central role in classical mechanics and became known as the second of Newton’s laws of motion. Huygens was also the first to formulate the correct laws of elastic collision in his work *De motu corporum ex percussione*, but his findings were not published until after his death in 1703. In the field of optics, he is best known for his wave theory of light, which he proposed in 1678 and described in 1690 in his *Treatise on Light*, which is regarded as the first mathematical theory of light. His theory was initially rejected in favor of Isaac Newton’s corpuscular theory of light, until Augustin-Jean Fresnel adopted Huygens’ principle in 1818 and showed that it could explain the rectilinear propagation and diffraction effects of light. Today this principle is known as the Huygens–Fresnel principle. *read more*

*Image credit: NASA/JPL, Commons.wikimedia*