Tag Archives: Johannes Kepler

On the shoulders of giants; Newton’s vision

Sir Isaac Newton (1642 – 1727) – Lucasian Professor (1669-1702), knighted in 1705, President of the royal society (1703-1727), Warden of the Mint (1696-1699) then Master of the Mint in (1699-1727) – is considered today one of the most influential scientists of all time. His Opus Magnus, the Principia, is the foundation of physics and engineering. However, his words carry a greater weight: “If I have seen further it is by standing on the shoulders of giants.”

Within the Principia are Newton’s three laws of motion. These laws allow us to build airplanes and to explore the universe. They allow us to build unimaginable monuments of engineering. They are the foundations of both classical and quantum mechanics. These laws, according to Newton, came because he stood on the shoulders of giants.

Euclid
Euclid

Newton grew up reading Euclid’s work. He studied number theory, geometry, and irrational numbers. As a hobby he computed logarithms, each time more accurately. His reliance on mathematics and proof separated him from many of his more philosophical peers.

Johannes Kepler
Johannes Kepler

Decades earlier, Johannes Kepler formulated Kepler’s laws of planetary motion. Planets orbited in ellipses, with the speed of each depending on its position on the ellipse. This was confirmed by the vast observations gathered by Tycho Brahe. Nevertheless, Kepler could not explain why the planets revolved this way.

Rene Descartes argued that objects could only affect other objects by touching them. Space according to him was filled with objects called “vortexes” which caused the motion of the planets. Newton would take this one step further. These “vortexes” were replaced by the force of gravity.

Rene Descartes
Rene Descartes

Newton’s laws were simple. First, if there is no force on an object, then the object cannot accelerate. Second, force is equal to mass times acceleration. Third, for every action there is an equal but opposite reaction. Now the planets orbited because of the force of gravity; without it they would fly off in straight lines. Planets were always accelerating and decelerating due to gravity, thus their speed changed throughout their orbit.

With the publication of the Principia, science would now depend on mathematics and rigor. His work provided the framework of the science to come. By innovating the works of previous giants, Newton was immortalized. “What Descartes did was a good step … If I have seen further it is by standing on the shoulders of giants.”

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