Newton, Isaac (1642-1727)Isaac Newton (1642-1727) - The man who is virtually universally credited with advancing the field of science by leaps and bounds is Isaac Newton.  With basically only three Renaissance scientists from which to draw (Copernicus, Kepler and Galileo), Newton more or less laid the foundation for our understanding of the physical world and the laws which govern it.  His magnum opus is the Philosophiæ Naturalis Principia Mathematica (Mathematical Principles of Natural Philosophy) which famously outlined the laws of motion and universal gravitation.  One of his lesser known achievements is that he was able to finally put the heliocentrism issue to rest.  His observations and discoveries demonstrated beyond a shadow of a doubt that the earth does in fact revolve around the sun, and not vice-versa.  The controversy that got Galileo into trouble only a couple generations earlier (Newton was born in the year Galileo died) was over.  Newton was a keen observer, which served him well.  Always wanting to understand how things worked, he studied the accepted model of the universe (known as the Aristotelian or Ptolemaic model) and then compared it to the more recent theories of Galileo and Kepler.  Through observation and testing, he was able to discredit the old model and replace it with the new one, and leave no doubt as to its reliability.  He also shares credit with Gottfried Liebniz for formulating the field of math known as calculus.  This led to a controversy within their lifetimes (which continued even after their deaths) that was only settled by concluding that they each had developed the math independent of one another.  Newton did a lot of work in optics and studied the spectrum of light refracted through a prism and discovered that light's properties do not change regardless of whether it is bent, reflected or transmitted.    He was able to apply this knowledge by inventing the reflecting telescope which was superior to the existing refracting telescopes of the day.  Probably the most famous event associated with Isaac Newton is the "apple tree" moment which supposedly contributed to his formulation of universal gravity.  It's pretty clear that he was never actually struck on the head by a falling apple, but according to the writings of more than one of his colleagues, he was intrigued by the action of an apple falling to the ground from the branch of a tree.  William Stukeley, an English antiquarian, wrote:


"We went into the garden and drank tea under the shade of some apple trees; only he and myself.  Amongst other discourse...the notion of gravitation came into his mind.  'Why should that apple always descend perpendicularly to the ground,' thought he to he sat in a contemplative mood.  'Why should it not go sideways or upwards, but constantly to the earth's center?'  Assuredly, the reason is, that the earth draws it.  There must me a drawing power in matter, and the sum of the drawing power in the matter of the earth must be in the earth's center, not in any side of the earth.  Therefore does this apple fall perpendicularly, or toward the center.  If matter thus draws matter, it must be in proportion to its quantity.  Therefore the apple draws the earth, as well as the earth draws the apple."


Newton received widespread acclaim for his work within his own lifetime, but he himself was relatively modest about his own accomplishments.  In a letter to Robert Hooke in 1676, he wrote: "If I have seen further, it is by standing on the shoulders of giants." (an apparent reference to the likes of the three aforementioned scientists).  From a personal standpoint, it's my opinion that only Archimedes and Einstein deserve to be in the same league with Isaac Newton.