Philosophiæ Naturalis Principia Mathematica

Portrait of Sir Isaac Newton, 1689

Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), often referred to as simply the Principia, is a work in three books by Isaac Newton, first published on 5 July 1687. The Principia states Newton's laws of motion, forming the foundation of classical mechanics; Newton's law of universal gravitation; and a derivation of Kepler's laws of planetary motion (which Kepler first derived empirically). The Principia is considered one of the most important works in the history of science.

Background

The Principia was written in Latin and was initially published with a full title of Philosophiæ Naturalis Principia Mathematica, translating to "Mathematical Principles of Natural Philosophy". In it, Isaac Newton formulated the laws of motion and universal gravitation that dominated scientists' view of the physical universe for the next three centuries. By deriving Kepler's laws of planetary motion from his mathematical description of gravity, and using the same principles to account for the trajectories of comets, the tides, the precession of the equinoxes, and other phenomena, Newton removed the last doubts about the validity of the heliocentric model of the cosmos.

Contents

The Principia is divided into three books:

• Book I focuses on the foundations of the science of motion, known as classical mechanics. It introduces the laws of motion and the principle of universal gravitation.
• Book II presents Newton's new scientific philosophy which contrasts with Descartes' mechanics. It explores the motion of fluids and the theory of medium resistance.
• Book III is entitled "The System of the World" and applies the laws of motion and gravitation to the astronomical bodies. It demonstrates their application to a wide range of phenomena, including the orbits of comets, the tides, and the precession of the equinoxes.

Impact

The publication of the Principia is considered a seminal event in the history of science, laying the groundwork for most of classical mechanics. Newton showed that the motions of objects on Earth and of celestial bodies are governed by the same set of natural laws. This led to the conclusion that the universe is a unified system, governed by a single set of rules. The Principia also set the stage for the Enlightenment by promoting a rational approach to understanding the universe.

The methodologies and strategies Newton employed in the Principia, such as the use of mathematics to explain and predict natural phenomena, have become standard in the scientific method. Moreover, the Principia's success in providing a coherent and unified description of the universe would inspire future scientists to seek similar descriptions in other areas of science.

Legacy

The Principia's influence on the development of science, mathematics, and philosophy cannot be overstated. It not only introduced the theory of gravity but also laid the groundwork for the field of classical mechanics. The work influenced generations of scientists, including Albert Einstein, who would later build upon Newton's ideas to develop the theory of general relativity. The Principia remains relevant today, not only as a historical document but also as a model of scientific reasoning and problem-solving.