SCIENTIFIC REVOLUTION of 17th C.
I. Thomas Kuhn, The Structure of a Scientific Revolution (1962)
1) paradigm:
universally recognized model from which a coherent tradition
of scientific research originates; set of rules or assumptions guiding
ordinary science: e.g. any basic textbook account of a science
2) data:
organized and given meaning by paradigm;
without paradigm, data gathering is random procedure
3) anomalies:
data which does not fit current paradigm;
growth of anomalies leads to search for new paradigm
II. Old World View
Aristotelian
Physics: explanations of motion
natural motion of matter (up: fire, air; down: earth, water)
acceleration of falling bodies (jubilancy, homecoming)
projectile motion: impossibility of vacuum, rush of air
distinction between earthly & heavenly (perfect) motion
Ptolemaic
universe: (Ptolemy, 2cd century AD Greece)
geocentric, crystalline spheres which require mover,
angels turn spheres; music of the spheres
finite universe: boundary is primum mobile
boundary between sphere of earth (corruptible)& heavens (incorruptible)
celestial motion is uniform & circular
problem
of motion of planets in Ptolemaic astronomy
observation of retrograde motion = anomaly, not uniform or circular
solution: epicycles, deferents, eccentric orbits
result: loss of "conceptual economy" (Kuhn)
Copernican Revolution: Nicolas Copernicus, Polish monk
Major
work: De revolutionibus orbium caelestium 1543
Revolutionary proposals: (On the revolutions of the heavenly sphere)
heliocentrism: rejects motion of sun
motion of earth, no longer central to universe
retrograde motion of planets is optical illusion
Conservatism
of Copernicus
insistence on circular motion as more perfect
religious motivation: to display divine order
desire for single all encompassing explanation
Opposition
to heliocentrism: common sense (sun rises & sets)
Scripture: condemned by both Protestants & Catholics
threatens entire Christian cosmology, world view (see Donne poem, over)
III. Post-Copernican Astronomy
Tycho Brahe (1546-1601)
careful observation & recording of planetary motions;
observation of comet & supernova in l570's: end of crystalline
spheres
publishes 1st printed tables of observations: standardized, repeatable
data available to all astronomers; anomalies become more apparent
Tychonic system: compromise between Copernicus & Ptolemy
earth at center of rotating stellar sphere
moon & sun in old Ptolemaic orbits around earth
other planets orbit around sun
Joannes Kepler (1571-1630) mechanical, mathematical approach
three mathematical laws describe planetary motion, but do not explain
it
1. elliptical orbits (two foci of motion)
2. planets do not move at uniform speeds
3. line from planet to sun describes equal areas in equal times
Kepler's laws confirmed by Newton, explained as the effects of gravity;
Galileo Galilei (1584-1642)
Astronomy:
popularizer of Copernican system
1609 telescope: qualitatively new data made visible; views new stars,
sun spots (corruptibility), moons of Jupiter, phases of Venus
1616 "Copernicanism" condemned as heresy by Roman Catholic Church
1625 Dialogue on Two Chief World Systems: attack on Ptolemy &
Aristotle;
first major public defense of Copernican system; written in vernacular
debate between Salviati (Galileo), Sagredo (man of the world), and
1630-33 trial by Roman Inquisition, required to abjure Copernican
heresy,
sentenced to house arrest in Florence; reported to say under his breath
after recanting: "Eppure si muove." -- "Yet it
(the earth) does move."
Physics:
mathematics as "language of nature," need to read book of universe
mathematical descriptions of types of motion, without explanation:
falling bodies: writes equation describing acceleration of
falling bodies
but cause of pattern not understood; no theory of gravity until Newton
inertial motion: explains planetary motion by circular inertia;
wrong
(inertial motion is linear), but important for concept of inertia
Rene
Descartes: inventor of analytical geometry (Cartesian coordinates)
geometrical shapes, math'l equations express relationships between bodies
Issac
Newton (1642-1727) student at Cambridge, then Fellow 1667-97; lectures on
mathematics and physics (especially optics & mechanics); also chemistry
Platonic view of universe as mathematical in structure
Principia
Mathematica 1687 (Mathematical Principles of Natural Philosophy)
central work of classical physics: defines mass, momentum, inertia, force;
gravity posited as common principle underlying earthly and heavenly motion
and force that keeps universe intact (in absence of crystalline spheres)
Newton's Three Laws of Motion:
I. Inertia
-- Every body continues in its state of rest or of uniform recti-
linear motion unless compelled to change its state by action of forces.
II. Acceleration or any change of motion is proportional to the force acting,
and takes place along the straight line along which the force acts.
III. To every action there is an equal and opposite reaction; or the
actions of two bodies on each other are always equal and opposite.
The
calculus: technique for mathematical description of motion (measuring speed and
changes in rates of speed); independently discovered by Newton and Leibniz
Religion:
God as author of laws of universe, omniscient, eternal, perfect;
origins of Deist concept of God as "clockmaker" who winds
up universe
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John Donne, An Anatomy of the World 1611
And new
philosophy calls all in doubt,
The element of fire is quite put out;
The sun is lost, and the earth, and no man's wit
Can well direct him where to look for it.
And freely men confess that this world's spent,
When in the planets, and the firmament
They seek so many new; then see that this
Is crumbled out again to his atomies.
'Tis all in pieces, all coherence gone;
All just supply, and all relation:
Prince, subject, father, son, are things forgot,
For every man alone thinks he hath got
To be a phoenix, and that then can be
None of that kind, of which he is but he.