ISAAC NEWTON

English scientist, physicist, philosopher, alchemist and mathematician (25 December 1642 – 31 March 1727) 

Author of the PHILOSOPHIAE NATURALIS PRINCIPIA MATHEMATICA, Newton is most known for describing the law of universal gravitation (gravity) and establishing the foundations of classical or Newtonian mechanics.  Also noteworthy is his work concerning the nature of light, optics and the development of mathematical calculus.  

The universe described by Newton and other scientists of the period was made up of solid objects, an enormous mechanical system that functioned along the lines of Newtonian laws of movement.  This belief persisted until the 19th century, when the solid blocks of which everything is composed came to be known as atoms.  Newton’s mechanical model described the movement of the planets, mechanical machines and fluids in perpetual movement.   

Newton was the first scientist to unify apparently disparate things.  He proved that the same laws that govern the movement of celestial bodies, such as the planets or the stars, also govern the movement of planetary bodies, such as an apple falling from a tree.  The result of this discovery was the unification of the heavens and the earth.

It is important to understand that when we say that Newton discovered gravity, what we mean is that he discovered a mathematical formula for calculating the force a planet exerts either on the objects on it or in its celestial proximities (thus an apple of a specific weight falling from a tree, falls and accelerates to maximum velocity toward the ground; the moon maintains its orbit around the earth, the planets around the sun; the greater mass, the greater the gravity).  In other words, when we say that Newton “discovered” gravity, we do not mean he discovered gravity itself or the reason why it acts the way it does.  The fact that we use the forces of electricity and magnetism, and even nuclear forces, for many things and do not use the force of gravity supports this.  This is because we have neither discovered the graviton, the hypothetical particle that mediates the force of gravity, nor do we completely understand how gravity works.   All we know is that it acts.... but this is obvious.