Nicholas Copernicus 14731543

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Nicholas Copernicus (1473-1543)
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The Heliocentric System In On the Revolutions of
the Heavenly Bodies (published as Copernicus lay
on his deathbed), Copernicus proposed that the
Sun, not the Earth, was the center of the Solar
System. Such a model is called a heliocentric
system.

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The ordering of the planets known to Copernicus
in this new system is illustrated in the
following figure, which we recognize as the
modern ordering of those planets.
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The Copernican Universe
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In this new ordering the Earth is just another
planet (the third outward from the Sun), and the
Moon is in orbit around the Earth, not the Sun.
The stars are distant objects that do not revolve
around the Sun. Instead, the Earth is assumed to
rotate once in 24 hours, causing the stars to
appear to revolve around the Earth in the
opposite direction.
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The heliocentric hypothesis was rejected out of
hand by virtually all.
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Copernicus was an unlikely revolutionary. It is
believed by many that his book was only published
at the end of his life because he feared ridicule
and disfavor by his peers and by the Church,
which had elevated the ideas of Aristotle to the
level of religious dogma. However, this reluctant
revolutionary set in motion a chain of events
that would eventually produce the greatest
revolution in thinking that Western civilization
has seen.
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His ideas remained rather obscure for about 100
years after his death. But in the 17th century
the work of Kepler, Galileo, and Newton would
build on the heliocentric universe of Copernicus
and produce the revolution that would sweep away
completely the ideas of Aristotle and replace
them with the modern view of astronomy and
natural science. This sequence is commonly called
the Copernican Revolution.
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Kepler was forced finally to the realization that
the orbits of the planets were not the circles
demanded by Aristotle and assumed implicitly by
Copernicus, but were instead the "flattened
circles" that geometers call ellipses.
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Galileo Galilei 1564-1624
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Galileo made extensive contributions to our
understanding of the laws governing the motion of
objects.
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Galileo did not invent the telescope (Dutch
spectacle makers receive that credit), but he was
the first to use it to study the heavens
systematically. His little telescope was poorer
than even a cheap modern amateur telescope, but
what he observed in the heavens rocked the
foundations of Aristotle's universe and the
theological-philosophical worldview that it
supported.
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It is said that what Galileo saw was so
disturbing for some officials of the Church that
they refused to even look through his telescope
they reasoned that the Devil was capable of
making anything appear in the telescope, so it
was best not to look through it.
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Galileo observed the Sun through his telescope
and saw that it had dark patches that we now call
sunspots (he eventually went blind, perhaps from
damage suffered by looking at the Sun with his
telescope). Furthermore, he observed motion of
the sunspots indicating that the Sun was rotating
on an axis.
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These "blemishes" on the Sun were contrary to the
doctrine of an unchanging perfect substance in
the heavens, and the rotation of the Sun made it
less strange that the Earth might rotate on an
axis too, as required in the Copernican model.
Both represented new facts that were unknown to
Aristotle and Ptolemy.
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The famous Leaning Tower of Pisa experiment may
be apocryphal.
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It is unlikely that Galileo himself dropped two
objects of very different weight from the tower
to prove that they would hit the ground at the
same time. However, it is certain that Galileo
understood the principle involved, and probably
did similar experiments.
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The realization that, as we would say in modern
terms, the acceleration due to gravity is
independent of the weight of an object was
important to the formulation of a theory of
gravitation by Newton.
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In popular lore, Galileo Galilei (15641642)
dramatically refuted Aristotles laws of motion
by dropping unequal weights from the Leaning
Tower. In the scientists writings, however, he
never claimed to have conducted an experiment
from that tower. Instead, his first biographer,
Vincenzo Viviani, launched the story roughly a
dozen years after the great mans death.
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Galileo's challenge of the Church's authority
through his assault on the Aristotelian
conception of the Universe eventually got him
into deep trouble with the Inquisition.
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Late in his life he was forced to recant publicly
his Copernican views and spent his last years
essentially under house arrest. His story
certainly constitutes one of the sadder examples
of the conflict between the scientific method and
"science" based on unquestioned authority.
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Isaac Newton 1642-1727
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The legend is that Newton saw an apple fall in
his garden, thought of it in terms of an
attractive gravitational force towards the earth,
and realized the same force might extend as far
as the moon.
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Newton's First Law of Motion
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Newton's Second Law of Motion
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Newton's Third Law of Motion
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Alexander Pope on Isaac Newton
"Nature and nature's laws lay hid in night God
said Let Newton be! and all was light."
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Francis Bacon 1561-1626
Bacon's Philosophy Francis Bacon's major
contribution to philosophy was his application of
induction, rather than the a priori method of
medieval scholasticism.
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"There are and can be only two ways of searching
into and discovering truth. The one flies from
the senses and particulars to the most general
axioms this way is now in fashion. The other
derives axioms from the senses and particulars,
rising by a gradual and unbroken ascent, so that
it arrives at the most general axioms last of
all. This is the true way, but as yet untried."
-Francis Bacon
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René Descartes (1596 - 1650)
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When studying human consciousness Descartes
concluded that the human mind was a substance
distinct from the physical brain. However he also
believed that they were linked. The link between
the brain and the mind, according to Descartes,
was the immaterial mind or the soul. Descartes
believed that the soul was a feature unique to
humans who have the ability for sophisticated
social interaction - i.e., language.
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Descartes was of the belief that science should
be grounded, not in observation and prediction,
as Bacon thought, in absolute certainty. He used
three principles to describe his philosophy.
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1. To employ the procedure of complete and doubt
to eliminate every belief that does not pass the
test of indubitability (skepticism)
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2. To accept no idea as certain that is not
clear, distinct, and free of contradiction
(mathematicism).
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3. To found all knowledge upon the bedrock
certainty of self-consciousness, so that "I
think, therefore I am" becomes the only innate
idea unshakable by doubt (subjectivism).
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It is quite evident that existence can no more be
separated from the essence of God than the fact
that its three angles equal two right angles can
be separated from the essence of a triangle It
is a contradiction to think of God (that is, a
supremely perfect being) lacking existence (that
is, lacking a perfection).
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In other words, existence is a property no
perfect being could be without out, and so a
perfect being must exist. Critics claim that
Descartes has effectively defined God into
existence.
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dualism, Cartesian interactionist - The view
that (1) the mental and the material comprise
two different classes of substance and (2) each
can have causal effects on the other.