*Editor* at **The Secrets of the Universe**, I am a science student pursuing Master’s in Physics from India. My interests include Cosmology, Condensed Matter Physics and Quantum Mechanics.

Exactly 332 years ago on this day, on July 5, 1687, the most revolutionary work in the history of science was published. Simply known as Principia, It is basically a comprehensive work of 3 books by Sir Isaac Newton in the 17th Century.

### The Contributors :

The author of this revolutionary work was Sir Isaac Newton, whom we widely recognise as one of the most influential scientists of all time.Though early in his career, Newton was often reluctant to publish his work. But eventually with support from his peers, he started compiling his ideas, Eventually, publishing his work in form of Principia Mathematica. The work also involved some contributions from Newton's contemporaries and forebears. This includes German scientist Johannes Kepler who found that planets had elliptical orbits. He made observations about the radii of orbits and how long revolutions took. But he couldn't come up with a mathematical justification of why and how. This is where Newton accomplished. Using Kepler's observations, Newton conceived a universal theory of gravitation that could apply to all celestial bodies, from the smallest moon to the largest star.

### What does Principia consist of?

Newton's Principia Mathematics consists of total three books, written in Latin. Principia is well known for The Newton's laws of motion. These form the foundation of classical mechanics and Newton's law of universal gravitation. It also contains a derivation of Kepler's laws of planetary motion which were earlier obtained by Kepler empirically. Book I concerns with the motion of objects in the absence of any resisting medium. It contains some proofs with little connection to real world dynamics. But there are also sections with far reaching application to the solar system and universe. Book II mainly deals with motion through resisting mediums. Whereas, Book III is mainly an explanation of many consequences of universal gravitation, especially its consequences for astronomy.

### Why is Principia Mathematica so important?

The legendary work of Newton in the form of Principia is one of the most important works in the history of science. It not only introduced the theory of gravity, but also defined the principals of modern physics. It represents a transformational work. Though the content was considered difficult to understand, but, it played a fundamental role for Newton to receive the elite rank of Scientific theorists. The Principia provided a physical and mathematical basis for how the basic elements of the universe work and how celestial bodies move and interact with each other. In philosophical contexts, people usually regard the Principia Mathematica as a demonstration of a logical system.

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### The controversy and success :

No doubt, Principia contained some revolutionary content. But, Scientists found the Principia very difficult to understand. Many of the era's scholars couldn't perceive it. These includes Leibniz and Huygens, two of Newton's great contemporaries. There were few people in the world studying mathematics at such a high level at that time. And the work seemed very theoretical, difficult to apply in the real world. However, over the time, Principia has withstand and passed several tests of its fidelity, especially the first and third book.

The illustrious explanations provided by Sir Newton helped in spreading the light of mathematics on Science which up to then had remained in the darkness. Hence, without any doubt, Principia is one of the most important and revolutionary work in the history of Science.