# Newton, Isaac (1642–1727)

SIR ISAAC NEWTON WAS one of the most famous and influential men in the world of science, in both mathematics and natural philosophy. His laws of gravity and motion formed the basis of classical mechanics, principles that are at the heart of modern engineering, physics, and astronomy. His work provided a mathematical mechanism to prove earlier theories of heliocentrism—the sun-centered system—and allowed later scientists to correctly determine the orbits of planets, comets, and even galaxies. Newton is also known in other areas of science and mathematics for his work on optics and differential calculus.

Newton was born in Woolsthorpe, England, in the rural eastern county of Lincolnshire. He was educated at Trinity College, Cambridge, where he continued as a professor from 1667 until his resignation in 1701. The years just prior to this appointment, however, were among his most productive. During this time he formulated his ideas on calculus, as well as his earliest thoughts on gravity and optics. He analyzed the pull of the planets around the sun, the moon around the Earth, and the pull of the Earth on everyday objects, such as Newton’s proverbial apple. From these observations, he was able to calculate the force applied to these bodies or objects, as well as their orbit, velocity, and mass. This eventually led him to conclusions about a universal force applicable to all things, large and small, a force that he named gravity, for the Latin word for weight, gravitas.

The relevance of these laws to geographers in particular lies in Newton’s theories on the shape of spinning spherical objects (like the Earth), and on the tides. For the first time, the tides could be mathematically explained through application of Newton’s law of universal gravitation.

His first publications were in the area of optics, examining the diffusion of white light into colors of the spectrum through a prism. One of his chief contributions to science was not necessarily in the content of these early publications, but in their presentation, which relied on empirical observations and experimentation alone, rather than mixing them with hypothesis, which had been the accepted practice since the days of Aristotle.

Newton developed a more practical telescope and theorized about the nature of light, considering it to be made up of particles, each affected by gravity. Today, we understand light more as a series of waves, not particles, but the material is again worthy as pure observed data. His system for advanced mathematical calculations, known as the calculus, provided the means for scientists to test and prove ideas that until then existed only as hypotheses. The German mathematician Gottfried Wilhelm Leibniz also created such a system, concurrently and independently, and the credit for the initial idea was heatedly disputed by Newton, and clouded his scientific relationships (and creative output) for the rest of his life.

His work in mathematics and optics quickly became popular among the scientific community and he was named a Fellow of the Royal Society in 1672. It was the publication of his major work in 1687, the Philosophiae Naturalis Principia Mathematica, however, that made Newton a household name, not just in England, but across Europe. This was an extension of his first work on the laws of motion, De Motu Corporem (“On the Movement of Bodies”), published in 1684.

The Principia established the three universal laws of motion that would not be improved upon for the next 300 years. In general, the work is a unification of numerous isolated physical facts developed by previous natural philosophers, but codified by Newton into a satisfying system of laws. The work also presents analysis of the speed of sound in air, and preliminary thoughts on the laws of thermodynamics. There were three reprints of the Principia in his lifetime, and numerous others in the centuries to follow. As Newton’s fame spread, he was elected president of the Royal Society in 1703, and associate of the French Academie des Sciences. He was knighted by Queen Anne in 1705, and was buried with full pomp and ceremony in Westminster Abbey, England, in 1727.

In addition to his academic career, Newton was also briefly a member of Parliament for Cambridge (1689 and 1701) and served as master of the Royal Mint (1699), in charge of reorganizing the system of British coinage. Newton’s work as a scientist cannot be entirely separated from his intense, lifelong passions for both religion and alchemy. He believed firmly that gravity explained the motions of the planets but could not explain who got this motion started. Many of his writings later in life were religious tracts dealing with the literal interpretation of the Bible. Secretly a Unitarian, he disbelieved in the Trinity, so much of this work was published posthumously. As an alchemist, he was very interested in matters of the occult and in ideas of the attraction and repulsion of particles.

The life of Newton overall reflects a fundamental shift in values in Western Europe across the 17th century, the period now known as the Scientific Revolution. Whereas Galileo’s work on the movement of celestial bodies had nearly got him burned at the stake in the first third of the 17th century, less than a century later, Newton’s work in the same area earned him universal praise.