In physics, Descartes applied his coordinate geometry to the study of optics, and proved the law of refraction in theory for the first time in Refractive Optics. In the second chapter of his Principles of Philosophy, the law of inertia is completely expressed in the form of the first law and the second law of nature for the first time, and the law of conservation of momentum is clearly put forward for the first time. All these laid a certain foundation for the later research of Newton and others.

Rene descartes (rene descartes,1March 3, 5961-1February 0650+0, 65438),1March 3, 5961was born in Dulan (now Descartes). He made an important contribution to the development of modern mathematics, and was known as the father of analytic geometry because he formulated the geometric coordinate system.