Isaac Newton: from the apple to the law of gravitation

By Flore Mouchet

Isaac Newton (4 January 1643 – 31 March 1727) was an English mathematician, physicist, and astronomer, one of the most famous scientists, best known for his law of universal gravitation.

Isaac Newton

Isaac Newton, from dunce to top of the class

Isaac’s father died when he was born. His mother brought him up alone before entrusting him to his grandmother. A few years later, his mother returned with a new husband and children. Isaac does not like his new stepfather. He is unhappy with his situation. So he takes refuge in his passion: the workings of things in nature, such as light, the stars, the elements. At first, Isaac is a student who does not pay much attention, always sitting at the back of the class. But one day, after a fight with a classmate and winning, he also wants to assert himself intellectually. “I want to be at the top of the class,” he says to himself. This desire to be the best followed him endlessly. After school, he decided to go to university, encouraged by friends and family who saw his intelligence and gift for science.

Newton at Cambridge, the place of all discoveries

Unable to afford his school fees, Newton did housework in exchange for free tuition at Cambridge University. Curious, he tried many experiments, especially on white light and alchemy. Unfortunately, when the plague broke out in England, Isaac had to interrupt his studies and return to his mother’s house for a while. During this time, he was able to deepen his knowledge of mathematics, optics, and physics. When Isaac resumed his studies, he made a name for himself at the university: he became a professor of mathematics and made many fundamental discoveries. Above all, he formulated the law of universal gravitation.

How did Isaac Newton discover the law of universal gravitation?

Legend has it that Newton was sitting under an apple tree when an apple fell on his head one day. Newton asked himself: “But why does the apple fall to the ground instead of flying up to the sky? We don’t know if this legend is true, but what we do know is that he was right.

For the apple to be drawn down, it must be attracted by force.

The apple is subject to a force called gravity. What exactly does the law of gravity say? It explains that objects are attracted to the Earth by gravity. Any object in free fall is subject to the Earth’s attraction. This law also states that all things with mass are attracted to each other. The greater the masses involved, the greater this force.

The conflict surrounding the discovery of the law of gravity

For the record, London scientists had been working on this issue for a long time. Halley, who gave his name to a comet, realized that the planets in the solar system orbit the sun in an elliptical path. That was thanks to the work of Kepler. But he did not understand the force responsible for these movements around the sun. He wanted to explain it with mathematical formulas. He submitted the problem to the famous mathematician Robert Hook, a member of the Royal Society, an English Academy of Sciences. Hook, a great scientist, tried to explain it but failed. Halley then went to Cambridge to submit the problem to Newton. To his surprise, Newton had solved the question five years earlier. All the movements of the Earth, Moon, and planets are explained in a treatise. He had shown that this force, called the gravitational force, decreased with the square of the distance. Isaac had kept his research secret, however. For several years before, Hook had stolen his work on light. He was taking all the credit. To avoid further humiliation, Newton excluded himself from society and worked alone. However, Halley was aware of Newton’s genius and the revolutionary nature of his discoveries, so he decided to publish his results in manuscript form on his account.

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Gravity on Mars

Why doesn't the Moon fall to the Earth like apples?

The Moon, like the apple, is attracted to the Earth. So why doesn’t it fall to Earth like an apple? Because our natural satellite has a high speed that allows it to escape the gravitational force. Moreover, with the distance that separates it from the Earth, the force applied to the Moon is weaker but sufficient to maintain it in orbit. Therefore, it is always mobile around the Earth. The force of attraction keeps it moving; otherwise, it would simply float in space, moving away from the Earth.

The Moon also exerts an attractive force on Earth. Its action can be observed, for example, on the tides.

What Newton's laws have brung?

Isaac Newton was a legend in Britain during his lifetime and became a significant figure in the history of science. He was given a title of nobility by the Queen and made a Sir. A scientist among scientists, Isaac Newton, brought about a scientific revolution. He died in 1727 in London.

When he was born, the world saw God’s work in celestial mechanics. Newton’s work shows that the only conductor in the universe is gravitation, where every celestial movement is explained by mathematics. Matter obeys mathematical laws, not the Bible. Newton’s laws laid the foundation for the conquest of space, as it was finally understood how to escape the pull of the Earth.

Where is Isaac Newton buried?

Isaac Newton laid in London. His grave is now in Westminster Abbey, next to that of the astrophysicist Stephen Hawking.

Isaac Newton

4 january 1643

31 March 1727