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 English physicist and mathematician who was born
into a poor farming family. Luckily for humanity, Newton was not a
good farmer, and was sent to Cambridge to study to become a
preacher. At Cambridge, Newton studied mathematics, being especially
strongly influenced by Euclid,
although he was also influenced by Baconian and Cartesian
philosophies. Newton was forced to leave Cambridge when it was
closed because of the plague, and it was during this period that he
made some of his most significant discoveries. With the reticence he
was to show later in life, Newton did not, however, publish his
results.
Newton suffered a mental breakdown in 1675 and was still
recovering through 1679. In response to a letter from Hooke,
he suggested that a particle, if released, would spiral in to the
center of the Earth.
 Hooke
wrote back, claiming that the path would not be a spiral, but an ellipse. 
Newton, who hated being bested, then proceeded to work out the
mathematics of orbits. Again, he did not publish his calculations.
Newton then began devoting his efforts to theological speculation
and put the calculations on elliptical motion aside, telling Halley
he had lost them (Westfall 1993, p. 403). Halley,
who had become interested in orbits, finally convinced Newton to
expand and publish his calculations. Newton devoted the period from
August 1684 to spring 1686 to this task, and the result became one
of the most important and influential works on physics of all times,
Philosophiae Naturalis Principia Mathematica (Mathematical
Principles of Natural Philosophy) (1687), often shortened to
Principia Mathematica or simply "the Principia."
In Book I of Principia, Newton opened with definitions and
the three laws of motion now known as Newton's
laws  (laws of
inertia, action and reaction, and acceleration proportional to
force). Book II presented Newton's new scientific philosophy which
came to replace Cartesianism. Finally, Book III consisted of
applications of his dynamics, including an explanation for tides and
a theory of lunar motion. To test his hypothesis of universal
gravitation, Newton wrote Flamsteed
to ask if Saturn
had been observed to slow down upon passing Jupiter.
The surprised Flamsteed replied that an effect had indeed
been observed, and it was closely predicted by the calculations
Newton had provided. Newton's equations were further confirmed by
observing the shape of the Earth
to be oblate
spheroidal, as Newton
claimed it should be, rather than prolate
spheroidal, as claimed by
the Cartesians. Newton's equations also described the motion of Moon
by successive approximations, and correctly predicted the
return of Halley's Comet. Newton also correctly formulated and
solved the first ever problem in the calculus
of variations which
involved finding the surface of revolution which would give minimum
resistance to flow (assuming a specific drag law).
Newton invented a scientific method which was truly universal in
its scope. Newton presented his methodology as a set of four rules
for scientific reasoning. These rules were stated in the
Principia and proposed that (1) we are to admit no more
causes of natural things such as are both true and sufficient to
explain their appearances, (2) the same natural effects must be
assigned to the same causes, (3) qualities of bodies are to be
esteemed as universal, and (4) propositions deduced from observation
of phenomena should be viewed as accurate until other phenomena
contradict them.
These four concise and universal rules for investigation were
truly revolutionary. By their application, Newton formulated the
universal laws of nature with which he was able to unravel virtually
all the unsolved problems of his day. Newton went much further than
outlining his rules for reasoning, however, actually describing how
they might be applied to the solution of a given problem. The
analytic method he invented far exceeded the more philosophical and
less scientifically rigorous approaches of Aristotle
and Aquinas. Newton refined Galileo's
experimental method, creating the compositional method of
experimentation still practiced today. In fact, the following
description of the experimental method from Newton's Optics
could easily be mistaken for a modern statement of current methods
of investigation, if not for Newton's use of the words "natural
philosophy" in place of the modern term "the physical sciences."
Newton wrote, "As in mathematics, so in natural philosophy the
investigation of difficult things by the method of analysis ought
ever to precede the method of composition. This analysis consists of
making experiments and observations, and in drawing general
conclusions from them by induction...by this way of analysis we may
proceed from compounds to ingredients, and from motions to the
forces producing them; and in general from effects to their causes,
and from particular causes to more general ones till the argument
end in the most general. This is the method of analysis: and the
synthesis consists in assuming the causes discovered and established
as principles, and by them explaining the phenomena preceding from
them, and proving the explanations."
Newton formulated the classical theories of mechanics and optics
and invented calculus
years before Leibniz.
However, he did not publish his work on calculus
until afterward Leibniz
had published his. This led to a bitter priority dispute between
English and continental mathematicians which persisted for decades,
to the detriment of all concerned. Newton discovered that the binomial
theorem was valid for
fractional powers, but left it for Wallis
to publish (which he did, with appropriate credit to Newton). Newton
formulated a theory of sound, but derived a speed which did not
agree with his experiments. The reason for the discrepancy was that
the concept of adiabatic propagation did not yet exist, so Newton's
answer was too low by a factor of  , where  is the ratio of heat
capacities of air.
Newton therefore fudged his theory until agreement was achieved
(Engineering and Science, pp. 15-16).
In Optics (1704), whose publication Newton delayed until
Hooke's
death, Newton observed that white light could be separated by a prism
into a spectrum of different colors, each characterized by
a unique refractivity, and proposed the corpuscular theory of light.
Newton's views on optics were born out of the original prism
experiments he performed at Cambridge. In his
"experimentum crucis" (crucial experiment), he found that the image
produced by a prism
was oval-shaped and not circular, as current theories of
light would require. He observed a half-red, half-blue string
through a prism,
and found the ends to be disjointed. He also observed Newton's
rings, which are
actually a manifestation of the wave nature of light which Newton
did not believe in. Newton believed that light must move faster in a
medium when it is refracted
towards the normal, in opposition to the result predicted
by Huygens's
wave theory.
Newton also formulated a system of chemistry in Query 31 at the
end of Optics. In this corpuscular theory, "elements"
consisted of different arrangements of atoms, and atoms consisted of
small, hard, billiard ball-like particles. He explained chemical
reactions in terms of the chemical affinities of the participating
substances. Newton devoted a majority of his free time later in life
(after 1678) to fruitless alchemical experiments.
Newton was extremely sensitive to criticism, and even ceased
publishing until the death of his arch-rival Hooke.
It was only through the prodding of Halley
that Newton was persuaded at all to publish the Principia
Mathematica. In the latter portion of his life, he devoted much
of his time to alchemical researches and trying to date events in
the Bible. After Newton's death, his burial place was moved.
During the exhumation, it was discovered that Newton had massive
amounts of mercury in his body, probably resulting from his
alchemical pursuits. This would certainly explain Newton's
eccentricity in late life. Newton was appointed Warden of the
British Mint in 1695. Newton was knighted by Queen Anne. However,
the act was "an honor bestowed not for his contributions to science,
nor for his service at the Mint, but for the greater glory of party
politics in the election of 1705" (Westfall 1993, p. 625).
Newton singlehandedly contributed more to the development of
science than any other individual in history. He surpassed all the
gains brought about by the great scientific minds of antiquity,
producing a scheme of the universe which was more consistent,
elegant, and intuitive than any proposed before. Newton stated
explicit principles of scientific methods which applied universally
to all branches of science. This was in sharp contradistinction to
the earlier methodologies of Aristotle
and Aquinas,
which had outlined separate methods for different disciplines.
Although his methodology was strictly logical, Newton still
believed deeply in the necessity of a God. His theological views are
characterized by his belief that the beauty and regularity of the
natural world could only "proceed from the counsel and dominion of
an intelligent and powerful Being." He felt that "the Supreme God
exists necessarily, and by the same necessity he exists always and
everywhere." Newton believed that God periodically intervened to
keep the universe going on track. He therefore denied the importance
of Leibniz's
vis viva as nothing more than an interesting quantity which remained
constant in elastic collisions and therefore had no physical
importance or meaning.
Although earlier philosophers such as Galileo
and John
Philoponus had used experimental procedures, Newton was the
first to explicitly define and systematize their use. His
methodology produced a neat balance between theoretical and
experimental inquiry and between the mathematical and mechanical
approaches. Newton mathematized all of the physical sciences,
reducing their study to a rigorous, universal, and rational
procedure which marked the ushering in of the Age of Reason. Thus,
the basic principle of investigation set down by Newton have
persisted virtually without alteration until modern times. In the
years since Newton's death, they have borne fruit far exceeding
anything even Newton could have imagined. They form the foundation
on which the technological civilization of today rests. The
principles expounded by Newton were even applied to the social
sciences, influencing the economic theories of Adam Smith and the
decision to make the United States legislature bicameral. These
latter applications, however, pale in contrast to Newton's
scientific contributions.
It is therefore no exaggeration to identify Newton as the single
most important contributor to the development of modern science. The
Latin inscription on Newton's tomb, despite its bombastic language,
is thus fully justified in proclaiming, "Mortals! rejoice at so
great an ornament to the human race!" Alexander Pope's couplet is
also apropos: "Nature and Nature's laws lay hid in night; God said,
Let Newton be! and all was light."
Several interesting Newton quotes are given by Misner et al.
(1973, pp. 40-41).
 Halley,
Hooke,
Leibniz
Additional biographies: MacTutor
(St. Andrews), Dublin
Trinity College, Bonn
References
--. Engineering and Science, Caltech, No. 2,
pp. 15-16, Winter 1991.
Andrade, E. N. da C. Sir
Isaac Newton. Greenwood Pub., 1979.
Bell, E. T. "On the Seashore: Newton." Ch. 6 in Men
of Mathematics: The Lives and Achievements of the Great
Mathematicians from Zeno to Poincaré. New York: Simon and
Schuster, pp. 90-116, 1986.
Christianson, G. E. In
the Presence of Creation: Isaac Newton and His Times. New
York: Free Press, 1984.
De Gandt, F. Force
and Geometry in Newton's Principia. Princeton, NJ: Princeton
University Press, 1995.
Fauvel, J.; Flood, R.; Shortland, M., and Wilson, R. (Eds.). Let
Newton Be! New York: Oxford University Press, 1988.
Gjertsen, D. The
Newton Handbook. London: Routledge, 1986.
Guicciardini, N. Reading
the Principia: The Debate on Newton's Mathematical Methods for
Natural Philosophy form 1687 to 1736. Cambridge, England:
Cambridge University Press, 1999.
Hall, A. R. Isaac
Newton: Adventurer in Thought. Cambridge, England: Cambridge
University Press, 1996.
Lines, M. E. On
the Shoulders of Giants. Philadelphia: Inst. of Phys., 1994.
Manuel, F. E. A
Portrait of Isaac Newton. Da Capo Press, 1990.
Misner, C. W.; Thorne, K. S.; and Wheeler, J. A.
Gravitation.
San Francisco, CA: W. H. Freeman, 1973.
Newton, I. The Principia: Mathematical Principles of Natural
Philosophy (Trans. I. B. Cohen and A. Whitman).
Berkeley, CA: University of California Press, 1999.
Turnbull, H. W. The Mathematical Discoveries of
Newton. London, England: Blackie and Sons, 1945.
Westfall, R. S. The
Life of Isaac Newton. Cambridge: Cambridge University Press,
1994.
Westfall, R. S. Never
at Rest: A Biography of Isaac Newton. New York: Cambridge
University Press, 1988.
White, M. Isaac
Newton: The Last Sorcerer. Reading, MA: Addison-Wesley,
1997.
Author: Eric W. Weisstein
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