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“Nature and Nature’s laws lay hid in night: God said, Let Newton be! and all was light. – Alexander Pope

Sir Isaac Newton remains one of the most prominent physicists and mathematicians from the Enlightenment >. His interest in science began early when, at age 13, he lodged with a local apothecary while attending the grammar school in Grantham. His fascination with the chemicals quickly overruled his mother’s ambition to turn him into a farmer.
Newton’s uncle persuaded his mother that it would be better for Isaac to go to the university, and in 1661 he began his studies at Trinity College, Cambridge. In 1664, he was elected a scholar, guaranteeing four years of financial support. At that time the plague was spreading across Europe and reached Cambridge in the summer of 1665. The university closed and Newton returned home, where he spent two years concentrating on problems in mathematics and physics. He wrote later that this time was “the prime of my age of invention” during which he laid the groundwork for his theory of universal gravitation >, the theory of optics, and the foundations for differential and integral calculus. During these two to three years of intense mental effort, he prepared Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy), commonly known as the Principia.

Although Newton’s findings trumped the current research of the time, Newton was uncomfortable in the public eye and therefore reluctant to publish his results, that is, until it appeared that someone else was about to be credited with his original ideas.

Almost 20 years later, in 1684, three members of the Royal Society – Sir Christopher Wren, Robert Hooke and Edmond Halley – argued about whether the elliptical orbits of the planets could result from a gravitational force toward the sun proportional to the inverse square of the distance. Halley went up to Cambridge and put the problem to Newton, who, despite his discomfort, had since gained attention in the mathematics world through his treatise on infinite series and in the scientific world through his design and construction of the reflecting telescope. Newton claimed he had solved that question years earlier but couldn’t find the proof among his papers. Three months later, he sent an improved version of the proof to Halley and devoted himself full time to developing these ideas, culminating in the publication of the Principia. In addition to Newton’s theory of universal gravitation, the book discussed his laws of motion >. Its importance was fully appreciated very quickly throughout Europe and heavily influenced Émilie > and Voltaire > in their scientific research at Cirey. Newton left Cambridge for London, where he was appointed Master of the Mint in 1699, a role he retained to his death. His next major work, Opticks, appeared in 1704.In Opticks, he reached the revolutionary conclusion that white light could be separated by a prism into a spectrum of different colors. One year following the publication of Opticks, Newton was knighted by Queen Anne.

Newton argued with Hooke about who deserved credit for discovering the connection between elliptical orbits and the inverse square law, until Hooke died in 1703, and he argued with German mathematician and philosopher Leibniz > about which of them invented calculus. Newton then spent the rest of his life working on alchemy experiments. During the exhumation following Newton’s death, it was discovered that the central cause of his death was massive amounts of mercury in his body, probably resulting from his alchemical pursuits.

Despite the controversy he generated among the scientists of his time, Newton was aware of the legacy of his grand discoveries, as evidenced by the inscription on his tombstone: “Mortals! Rejoice at so great an ornament to the human race!”

The term “classical mechanics” was coined during the early 20th century to describe the system of mathematical physics developed by Isaac Newton and his fellow 17th-century scientists. Classical mechanics is also referred to as “Newtonian mechanics” and is associated with the physical concepts employed by and the mathematical methods invented by Newton himself, in parallel with Leibniz > and others.

The basis for Newton’s classical mechanics is his theory of universal gravitation and his laws of motion. In his theory of universal gravitation, Newton claimed that every object in the universe is attracted to another object by a force. The popular legend claims that Newton created his theory of universal gravitation while he was observing an apple tree outside his home. John Conduitt, Newton’s assistant, described the event when he wrote about Newton’s life:
“Whilst he was pensively meandering in a garden it came into his thought that the power of gravity (which brought an apple from a tree to the ground) was not limited to a certain distance from earth, but that this power must extend much further than was usually thought. Why not as high as the Moon said he to himself & if so, that must influence her motion & perhaps retain her in her orbit, whereupon he fell a calculating what would be the effect of that supposition.”

Enjoy “Victim of Gravity” from the Schoolhouse Rock series.

In his three laws of motion, Newton proposed that an object at rest will not move unless an outside force is applied to it (Law No. 1); force moves an object because the force equals mass multiplied by acceleration (Law No. 2); and every force has an equal but opposite force acting on it at the same time (Law No. 3).

Learn more about Newton’s laws of motion through this video, featuring 3-D animation and motion graphics.

Newton’s classical mechanics were groundbreaking during his time. Newton’s findings helped modern-day scientists develop more detailed theories to explain how our universe works, such as string theory > and quantum mechanics >.