History and Philosopy of Science Lecture 3

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History and Philosopy of Science Lecture 3

• Historical views of
• The Scientific Revolution

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The Scientific Revolution

• Period 17th C 50 years, i.e. 1550-1750
• Why revolution?
• Context
• Enlightenment
• Post-feudalism, emergence of nation-state
• Protestant Reformation

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Revolution vs Evolution

• Evolution Normal Science
• Incorporate new findings into existing frameworks
  of belief
• Revisions and adjustments to existing beliefs
• Revolution Paradigm change
• Rejection and replacement of existing frameworks
  of belief
• Incompatibility of new framework with old

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17th C in Science

• Cosmology and Astronomy
• Geocentric to Heliocentric universe
• Brahe, Copernicus, Kepler, Galileo, Newton
• Anatomy and physiology
• Structure of living things, circulation of blood
• Vesalius, Harvey, Leeuwenhoek, Malpighi,
• Mathematics
• Algebra, analytic geometry, calculus
• Vieta, Newton, Descartes, Leibnitz
• Methodology
• From scholasticism to empiricism
• Bacon, Royal Society, Academie des Sciences

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Ancient Problem

• What is the structure of the universe?
• How to account for the observations of the
  celestial objects?
• Sun, moon, planets, fixed stars
• Planet wanderer
• Assume a stationary earth
• Philosophical constraints creation stories

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Copernican Revolution

• Aristotelian Geocentric Universe
• Crystalline Spheres

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Retrograde motion of planets

• Incompatible with circular orbit viewed from a
  centrally located earth
• Mars (2009-2010) relative to the
• constellation cancer

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Ptolemaic Geocentric Universe

• Claudius Ptolemy (90-168 CE)
• Author of The Great Treatise usually called the
  Almagest
• Modification of Aristotelian model by adding
  epicycles to the orbits
• Viewed this conception as a mathematical
  characterization, not necessarily a description
  of reality

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Copernican Heliocentric Universemain virtue
elegance

• Heavenly motions are uniform, eternal, and
  circular or compounded of several circles
  (epicycles).
• The center of the universe is near the Sun.
• Around the Sun, in order, are Mercury, Venus,
  Earth and Moon, Mars, Jupiter, Saturn, and the
  fixed stars.
• The Earth has three motions daily rotation,
  annual revolution, and annual tilting of its
  axis.
• Retrograde motion of the planets is explained by
  the Earth's motion.
• The distance from the Earth to the sun is small
  compared to the distance to the stars.

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Tycho Brahe

• Brahe (1556-1601) made precise astronomical
  measurements to refine the Copernican model along
  Ptolemaic lines!
• Gold Standard data for a long time
• Tychonic System
• Earth at center
• Sun revolves around earth
• Planets revolve around Sun

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Johannes Kepler (1571-1630)

• Defender of Copernican System
• Numerological approach, mystical?
• Mysterium Cosmographicum

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Kepler on orbits

• Search for mathematical elegance and simplicity
  in the world
• Harmonices Mundi (1619)
• Book 5 planetary motions relationships between
  orbital velocity and orbital distance from the
  Sun. Tycho's data and his own theories allowed
  more precision and a new new physical
  significance
• Keplers Laws of planetary motion

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Keplers Laws

• The orbit of every planet is an ellipse with the
  sun at a focus.
• A line joining a planet and the sun sweeps out
  equal areas during equal intervals of time.
• The square of the orbital period of a planet is
  directly proportional to the cube of the
  semi-major axis of its orbit.

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Geo to Heliocentrism

• Problem of Heaven-Earth distinction
• Greek elements earth, water, fire, air plus
  Fifth Essence
• Sun, moon, planets are heavenly and hence without
  imperfection
• Problem of perfection of circular motion
• Circles are perfect, ellipses are not
• Relationship of theory to reality
• Descriptions versus reality

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Two new instruments

• Advances in optics led to the invention of the
  Telescope and the Microscope in the early years
  of the 17th Century

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Galileo Galilei (1564-1642)

• Telescopic observations of the sun sun spots
  (Sun had imperfections !!!)
• Telescopic observations of Venus saw that Venus
  has phases incompatible with Ptolemy but
  explained by Copernicus

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Heliocentrism prevails!

• Copernicus vs Ptolemy about equal precision in
  prediction, but more elegant
• Kepler provided a more elegant mathematics
• Galileo made observations that gave trouble to
  Ptolemy but supported Copernicus

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The structure of the body

• Greek anatomy
• Aristotle (384-322 BCE) History of Animals,
  Generation of Animals, and Parts of Animals
• Galen (129- ca 217 CE) 600 works
• Authority versus Experience
• Scholasticism
• Dissection, Observation, Experimentation
• Microscopic studies

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Andreas Vesalius (1514-1564)

• Interest in reliability of Galen
• Dissections done in person
• Use of drawings in teaching
• De humani corporis fabrica
• Revolutionary qualities
• Reliance on direct observation rather than
  ancient authority
• Knowledge was revisable by investigation

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Printing, Images, and Scientific Revolutions
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The invisible world

• The microscope showed a new level of structural
  detail in the world.

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Social Organization of Science

• 1660 Royal Society of London for the Improvement
  of Natural Knowledge
• 12 natural philosophers, including Robert Boyle,
  John Wilkins and Robert Boyle, John Wilkins, and
  Christopher Wren, decided to form a 'Colledge for
  the Promoting of Physico-Mathematicall
  Experimentall Learning', which would meet weekly
  to view experiments and discuss science
• Nullius in Verba
• 1665 Philosophical Transactions of the RS
• First professional scientist Robert Hooke,
  1664
• 1666 Académie des Sciences organ of French
  government

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Next Time

• Newton, Descartes, Leibnitz, Bacon
• Demise of Scholasticism and rise of empiricism
• Neoplatonism versus The New Mechanical Philosophy
• Hume and Skepticism