If I ask anyone, a primary school student or a doctoral student, to name a few scientists they have heard about extensively, I’m sure no one’s list would be complete without naming Newton in it. Born on the pious day of Christmas in 1642, Sir Isaac Newton was an English mathematician, physicist, astronomer, theologian, and author who played a remarkable role in bringing a scientific revolution.

Mostly known for the famous apple incident that led to the discovery of Newton’s interpretation of Gravity, Newton contributed vigorously in different fields, including optics and calculus. So today, on Newton’s 378th birth anniversary, let’s have a look at his most significant contributions one by one!

**Newton’s Laws of Motion**

Newton is well known for his three laws of motion that describe the relationship between an object’s motion and the forces acting on it. According to the first law, an object either remains at rest or continues to move at a constant velocity unless it is acted upon by an external force. The second law states that the rate of change of momentum of an object is directly proportional to the force applied to it. The third law states that every action has an equal and opposite reaction.

Newton compiled these laws and used them to explain and investigate the motion of many physical objects and systems, thus laying the foundation for Newtonian mechanics.

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**Gravity**

Everyone knows the apple incident that drove Newton to discover gravity. It is said that once while sitting under a tree, he saw an apple falling on the ground. Newton worked out that if the force of gravity pulled the apple from the tree, then it was also possible for gravity to exert its pull on objects much, much further away. Newton’s theory helped prove that all objects, as small as an apple and as large as a planet, are subjected to gravity, which remained the basis of classical mechanics until Albert Einstein’s theory of relativity in the 20th century.

**Calculus**

Although Newton is generally remembered for his contributions to physics, however little do people know that he also laid the foundation stone of one of the most beautiful branches of mathematics, ie. Calculus. Newton created his new and specialized form of mathematics to explain his theories of gravity and motion. Today, calculus has widespread uses in science, engineering, and economics. Not only calculus, but Newton also contributed to mathematics by discovering the generalized Binomial theorem, which describes the algebraic expansion of powers of a binomial and has a wide range of applications.

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**Planetary Sciences**

Newton used his mathematical description of gravity to prove Kepler’s laws of planetary motion. He also employed them to account for tides, comets’ trajectories, the precession of the equinoxes, and other phenomena and eradicated doubt about the Solar System’s heliocentricity. Newton also postulated that the Earth is an oblate spheroid. This inference was later confirmed by the geodetic measurements of Maupertuis, La Condamine, and others.

**Optics**

Newton didn’t fail to make major contributions to optics as well. He developed a sophisticated theory of color based on the observation that a prism separates white light into the visible spectrum’s colors. His work on light was collected in his highly influential book Opticks, which was published in 1704. Apart from this, Sir Isaac was also responsible for building the first-ever practical reflecting telescope.

**Newton’s Philosophiae Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy):**

The Principia Mathematica is considered one of the most important single works in modern scientific history. Newton’s Principia Mathematics consists of a total of three books written in Latin. Principia is well known for Newton’s laws of motion. These laws form the foundation of classical mechanics and Newton’s law of universal gravitation. It also contains a derivation of Kepler’s planetary motion laws, which were earlier obtained by Kepler empirically.

The book I concerns with the motion of objects in the absence of any resisting medium. It contains some proofs with little connection to real-world dynamics. But there are also sections with far-reaching applications to the solar system and universe. Book II mainly deals with motion through resisting mediums. Whereas, Book III is mainly an explanation of many consequences of universal gravitation, especially its consequences for astronomy.

Newton’s legendary work in the form of Principia is one of the most important works in the history of science. It not only introduced the theory of gravity but also defined the principles of modern physics. It represents a transformational work. Though the content was considered difficult to understand initially, it played a fundamental role for Newton to receive Scientific theorists’ elite rank. The Principia provided a physical and mathematical basis for how the basic elements of the universe work and how celestial bodies move and interact with each other. In philosophical contexts, people usually regard Principia Mathematica as a demonstration of a logical system.

Apart from the above-mentioned contributions, Newton also formulated an empirical law of cooling, made the first theoretical calculation of the speed of sound, and introduced a Newtonian fluid notion.

Newton was not only a scientist but also spent a major part of his life investigating religious issues. Considering his groundbreaking revelations about nature, Newton was elected a Fellow of the Royal Society in 1672. It has been claimed that as devoted as he was to his work, he remained single throughout his life and died in his sleep in London on 20 March 1727. Isaac Newton was really one of the finest brains this humanity has ever witnessed, and it would not be wrong to say that his contributions have changed the way we see and understand the world around us.

I don’t know what I may appear to the world,

Sir Isaac Newtonto myself I am only a child playing on the beach, while vast oceans of truth lie undiscovered before me.

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