theorem and began to develop a mathematical theory that would later
become calculus.
However, his most important discoveries were made during the
two-year period from 1664 to 1666, when the university was closed
due to the Great Plague. Newton retreated to his hometown and set
to work on developing calculus, as well as advanced studies on optics
and gravitation. It was at this time that he discovered the Law of Uni-
versal Gravitation and discovered that white light is composed of all
the colors of the spectrum. These findings enabled him to make fun-
damental contributions to mathematics, astronomy, and theoretical
and experimental physics.
Arguably, it is for Newton’s Laws of Motion that he is most revered.
These are the three basic laws that govern the motion of material
objects. Together, they gave rise to a general view of nature known as
the clockwork universe. The laws are: (1) Every object moves in a
straight line unless acted upon by a force. (2) The acceleration of an
object is directly proportional to the net force exerted and inversely
proportional to the object’s mass. (3) For every action, there is an equal
and opposite reaction.
In 1687, Newton summarized his discoveries in terrestrial and
celestial mechanics in his Philosophiae naturalis principia mathematica
(Mathematical Principles of Natural Philosophy), one of the greatest
milestones in the history of science. In this work he showed how his
principle of universal gravitation provided an explanation both of
falling bodies on the earth and of the motions of planets, comets, and
other bodies in the heavens. The first part of the Principia,devoted to
dynamics, includes Newton’s three laws of motion; the second part to
fluid motion and other topics; and the third part to the system of the
world, in which, among other things, he provides an explanation of
Kepler’s laws of planetary motion.
This is not all of Newton’s groundbreaking work. In 1704, his dis-
coveries in optics were presented in Opticks, in which he elaborated his
theory that light is composed of corpuscles, or particles. Among his
other accomplishments were his construction (1668) of a reflecting
telescope and his anticipation of the calculus of variations, founded by
Gottfried Leibniz and the Bernoullis. In later years, Newton consid-
ered mathematics and physics a recreation and turned much of his
energy toward alchemy, theology, and history, particularly problems of
chronology.
Newton achieved many honors over his years of service to the
advancement of science and mathematics, as well as for his role as war-
den, then master, of the mint. He represented Cambridge University(25)
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