Isaac Newton Invents Physics in 1687

Isaac Newton created the modern concept of planetary astronomy through his publication of “Mathematical Principles of Natural Philosophy” or “Principles” (“Principia”, in Latin). He provided the physical and mathematical underpinnings (gravitation) of Keplers “laws”, which up to that time had been regarded suspiciously by scholars. After Newton, the planets moved in near-ellipses because of mutual gravitational forces acting between all mater. There were no “crystal spheres” guiding the planets.

It can be hard for us today to appreciate the magnitude of the discoveries Newton described in Principia because so much of it is now taken for granted, but many of the things he described seemed unlikely (or even absurd) to educated people of his time. In the process, Newton invented a whole new field of mathematics – The Calculus – allowing us to perform precise calculations on systems undergoing constant change. Like the most profound scientific advances, it predicted previously unnoticed phenomena which, upon investigation, where found to be true. (The Calculus could also be said to have been developed by Gottfried Leibniz, another genius working at the same time as Newton.)

Newton proposed that matter attracted matter by a force determined only by the mass of the items in questions and the distance of their separation – regardless of what lay in between. Just a few months earlier it was clear that Newton himself did not grasp this central aspect of the motion of planets. But once discovered, the new mathematics and the new ideas seemed to apply to more and more observations about the nature of the world. Principia declares that the same “gravity” that determines the motions of the planets is at work on the objects we see and use each day on Earth. 

It’s hard to overstate the scale of Newton’s contribution or his genius. On the other hand, Newton was living in a period of absolute ferment of scientific ideas. Some of those contributing ideas, partial solutions and unproven intuition were Edmund Halley, Christopher Wren, Christiaan Huygens, Gottfried Leibniz and Robert Hook. Newton integrated the varied ideas of others, along with his own, into a cohesive model of the cosmos and the Earth – and backed it up with the mathematical tools needed to prove, understand and apply the model. But it is unlikely he would have gotten so far so fast without the influence of those he respected (like Halley), those he envied (like Leibniz) and those he despised (like Hook).