Who was Isaac Newton?
Sir Isaac Newton (1643–1727) was an English mathematician, physicist, and astronomer whose Principia Mathematica (1687) established the laws of motion and universal gravitation, unifying terrestrial and celestial physics. He also co-invented calculus and made foundational contributions to optics. His work defined the Scientific Revolution and dominated physics until Einstein.
Isaac Newton was arguably the most influential scientist in human history — the man who demonstrated that the physical universe operates according to mathematical laws that can be discovered through observation and reason. Born on Christmas Day 1642 in Woolsthorpe, England, he was a difficult, reclusive, and sometimes vindictive genius whose discoveries reshaped human understanding of the cosmos.
Newton's annus mirabilis (miracle year) was 1665–1666, when the plague closed Cambridge University and he retreated to his family's farm. During this period, working alone and in his early twenties, he developed the foundations of calculus, his theory of optics (showing that white light was composed of a spectrum of colors), and his initial insights into gravitation. The famous story of the falling apple, while probably embellished, captures the essence of his insight — that the same force pulling an apple to the ground also keeps the Moon in orbit around Earth.
The Principia Mathematica (1687), arguably the most important scientific work ever published, formalized these insights. Newton's three laws of motion and his law of universal gravitation provided a mathematical framework that could explain and predict an enormous range of phenomena — from the tides to the orbits of comets to the precession of the equinoxes. For the first time, a single set of equations described both terrestrial and celestial mechanics.
Newton also co-invented calculus (independently of Leibniz, leading to a bitter priority dispute), built the first practical reflecting telescope, and made important contributions to number theory and the study of power series. Later in life, he served as Warden of the Royal Mint and President of the Royal Society, spending more time on alchemy and Biblical chronology than on physics.
Newton's impact on subsequent thought was immense. The philosopher Alexander Pope captured the sentiment: 'Nature and nature's laws lay hid in night; God said "Let Newton be" and all was light.' His demonstration that the universe followed discoverable mathematical laws inspired the Enlightenment's confidence that reason could unlock all of nature's — and society's — secrets. Newtonian physics remained the foundation of science until Einstein's relativity in the 20th century.