Category Great Personalities

Newton was a mathematics professor at Trinity College, Cambridge. But he was not a successful teacher. Newton preferred to spend his time alone in the laboratory, which he built himself, or in the small garden outside his rooms.

Only a few students attended his classes and fewer still understood what he said. A secretary later commented that often, Newton ended up teaching his walls with no students in front of him!

Not even one student who studied mathematics under Newton in the thirty years of his teaching career dedicated himself to the study of mathematics.

Newton’s absent-mindedness was also well known. He would sometimes stay in bed an entire day pondering upon a particular problem. If he received visitors while he was immersed in a new idea, Newton would simply walk into another room to continue thinking; completely forgetting that somebody was awaiting him in the other room.

By the 1670s, Trinity College became a lonely place for him. He enjoyed the brotherhood of similar minds and hence, he eagerly accepted the offer to join the Royal Society.

The English version of Opticks: or A Treatise of the Reflexions, Refractions, Inflexions and Colours of Light was published in 1704. A Latin translation of the book appeared in 1706. This is Newton’s second major book on physical science. It analyses the fundamental nature of light.

The book covers discoveries and theories concerning light and colour made by Newton in 33 years. It deals with ideas ranging from the spectrum of sunlight to the invention of the reflecting telescope. It also includes the first workable theory of the rainbow and the first colour circle in the history of colour theory. Newton also discusses various other subjects such as metabolism, blood circulation and a study of the haunting experiences of the mentally ill.

One of the major impacts of Opticks was that it overthrew the idea that ‘pure’ light (such as sunlight) is white or colourless, and it becomes coloured by mixing with darkness caused by interactions with matter. Newton showed that this assumption from the time of Aristotle and Theophrastus was wrong.

Newton also illustrated that colour is a result of the physical property of light, as each hue is refracted at a characteristic angle by a prism or lens. He also added that colour is a sensation within the mind and not an inherent property of material objects or of light itself. Considering the impact of the book on science, it is astonishing to think that it was initially published anonymously with just the initials I.N. at the end of an advertisement at the front of the book.

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Astronomer Edmond Halley persuaded Newton to expand his studies. Halley was the driving force behind the publication. He acted as a critic as well as supporter for this work.

Edmond Halley even convinced Newton to allow him to edit the Principia. Halley covered the various expenses, corrected the proofs himself, and ultimately got Philosophiae Naturalis Principia Mathematica printed in 1687.

Newton was famously reluctant to publish his works. Without Edmond Halley’s compulsion to publish Principia, Newton may have never become an outstanding figure in the history of science.

Newton would probably be known only for his mathematics and optics, and remain a relatively obscure professor in Cambridge.

Philosophiae Naturalis Principia Mathematica (Latin for Mathematical Principles of Natural Philosophy) is often simply referred to as Principia. This work in three books, written by Isaac Newton in Latin was first published on 5 July 1687. In retrospect, its publication was a landmark event in the development of modern physics and astronomy.

Newton published two more editions in 1713 and 1726 after annotating and correcting his personal copy of the first edition. Principia contains the laws of motion, law of universal gravitation and a derivation of Kepler’s laws of planetary motion (Kepler originally obtained these empirically). The work also forms the foundation of classical mechanics. Principia is considered as one of the most important works in the history of science.

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The significance of the Newtonian reflector does not lie in the discovery of new celestial bodies or celestial phenomena. Newton neither discovered the moons around Jupiter like Galileo nor did he plot the return of a comet – like Halley. However, the Newtonian reflector and Newton’s theory of universal gravitation made an invaluable contribution: they tied together Mathematics, Astronomy, and our understanding of the universe.

He mathematically established that gravitation was a two-way operation. While the Earth pulled on a falling apple, the apple too pulled on Earth. This was seen, calculated and confirmed in the motions of heavenly bodies. It was made possible by the science of the reflector telescopes which can be credited to Newton. The work of Copernicus and Galileo were carried through by Newton and his telescope.

While it is commonly assumed that Newton invented the first reflector telescope, claims to the contrary are also there. The Italian monk Niccolo Zucchi claimed to have experimented with the idea as far back as 1616. It is possible that Newton read James Gregory’s 1663 book Optica Promota which contained designs for a reflecting telescope using mirrors. Gregory had been trying to build such a telescope, but he did not succeed. Ultimately, Newton’s telescope was the one that worked well and brought reflectors to the scientific world.

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The first successful practical reflecting telescope was built by Newton. Until then telescopes were large unwieldy instruments. The design of the telescope was recast by Newton on the basis of his theory of optics. He used mirrors instead of lenses and the result was a new telescope 10 times smaller than the traditional ones.

Earlier also many efforts were made to make more powerful telescopes using larger lenses. They were unsuccessful as the lens kept producing coloured rainbows around bright objects like the Moon and the planets. The coloured fringes formed due to the unequal refraction of colours by the lens were unavoidable in simple telescopes.

Newton was under the assumption that no lens could rectify this issue. Though this was a mistaken assumption, it led him to use a mirror to form an image and thereby to build a reflecting telescope. This is now called the Newtonian reflector. A curved mirror brings rays of light to a focus and forms an image by reflection (whereas a lens does it by bending or refraction). Some of the largest telescopes used today are based on the telescope made by Newton in 1668.

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