1. Aristotle, Galileo, Kepler and Company Attempts to describe heavenly motion

2. Realism vs. Instrumentalism Instrumentalism: an idea is judged bases on it’s usefulness, regardless of it’s ultimate correctness Instrumentalism: an idea is judged bases on it’s usefulness, regardless of it’s ultimate correctness Id, Ego and Superego Id, Ego and Superego Realism: an idea is judges based on the accuracy of its description of reality Realism: an idea is judges based on the accuracy of its description of reality

3. Paradigm Set of background beliefs that govern allowable ideas Set of background beliefs that govern allowable ideas Can change over times in “revolutions” Can change over times in “revolutions” Renaissance: God made and governs universe. God is all powerful and miracles are possible. Universe in unpredictible. Renaissance: God made and governs universe. God is all powerful and miracles are possible. Universe in unpredictible. Modern Paradigm: Natural Laws make for a predictable universe, no miracles, only natural causes Modern Paradigm: Natural Laws make for a predictable universe, no miracles, only natural causes

4. Aristotle’s Basic Ideas Aristotle constructed his view of the Universe based on a intuitive feeling of holistic harmony. Aristotle constructed his view of the Universe based on a intuitive feeling of holistic harmony. Central to this philosophy was the concept of teleology or final causation. Central to this philosophy was the concept of teleology or final causation. Objects, being solid like earth, would tend to clump together with other solids (earth), so objects tend to fall to earth, their natural place. Thus, falling is a natural motion. Objects, being solid like earth, would tend to clump together with other solids (earth), so objects tend to fall to earth, their natural place. Thus, falling is a natural motion.

5. Aristotle’s Basic Ideas Universe is perfect and unchanging. Contrast with imperfect, changing earth

6. Aristotle’s Universe Now all is in harmony, the earth is at the center of the universe and the cosmos revolves around us in perfect contentment Now all is in harmony, the earth is at the center of the universe and the cosmos revolves around us in perfect contentment Geocentric Cosmology and the Earth is Immobile. Geocentric Cosmology and the Earth is Immobile. Stars and planets on perfect crystalline spheres that rotate around the Earth. Stars and planets on perfect crystalline spheres that rotate around the Earth. Universe is perfect and Changeless Universe is perfect and Changeless

7. Pythagorean Constraints Mathematics shows universal design and express perfection of god Mathematics shows universal design and express perfection of god Universe must follow mathematical Constraints Universe must follow mathematical Constraints All motion is in Circles, the perfect shape All motion is in Circles, the perfect shape All motion must take place at a constant rate, a reflection of unchanging Heavens All motion must take place at a constant rate, a reflection of unchanging Heavens All motion around a common point All motion around a common point

8. Problems in Describing Heavenly Motion Motion of the Sun Motion of the Sun Daily east to west Daily east to west Monthly relative to stars and moon Monthly relative to stars and moon What time does the moon rise? What time does the moon rise? Yearly from north to south and back (seasons) Yearly from north to south and back (seasons) Motion of the planets Motion of the planets Nightly East to west Nightly East to west Retrograde motion and variation in brightness Retrograde motion and variation in brightness Temporary backwards motion Temporary backwards motion

9. Sense Observations to support Geocentrism Stationary earth- no rotation Stationary earth- no rotation we don’t feel it move we don’t feel it move No constant wind from east to west No constant wind from east to west Arrow goes up and comes down in same place Arrow goes up and comes down in same place

10. Stationary earth – no revolution around sun Stationary earth – no revolution around sun No parallax: apparent shift in position due to motion of observer No parallax: apparent shift in position due to motion of observer Could be explained if Universe is very large, or if the earth didn’t move Could be explained if Universe is very large, or if the earth didn’t move “waste of space” “waste of space”

11. Early Greek Models-- Geocentric Earth at the Center – immobile Sun and all heavenly bodies circle the earth Simple circles do not explain retrograde motion

12. Early Greek: Circles and more circles Epicycles and Equants: circles revolving around an invisible revolving point Epicycles and Equants: circles revolving around an invisible revolving point

13. Greek Models: Heliocentric Heraclitus – partial heliocentric (sun at center, earth revolves around sun, all else aroudn the earth Aristarchus – completely heliocentric

14. Summary of Greek Models All were seen instrumentally All were seen instrumentally Aristotle supported geocentric as more reasonable Aristotle supported geocentric as more reasonable Geocentric improved by Ptolomy Geocentric improved by Ptolomy Used over 80 circles Used over 80 circles Gave predictions (sunrise, seasons, etc) accurate to about 1% Gave predictions (sunrise, seasons, etc) accurate to about 1%

15. Situation in the Renaissance Ptolomy is still dominant model Ptolomy is still dominant model St. Thomas Aquinas worked to unify Catholic theology with Aristotle St. Thomas Aquinas worked to unify Catholic theology with Aristotle Earth (man) at center of the universe: logical spots for heaven and hell Earth (man) at center of the universe: logical spots for heaven and hell Columbus and Magellan navigated oceans using Ptolomy Columbus and Magellan navigated oceans using Ptolomy

16. Situation in the Renaissance Copernicus (1475-1543) reintroduces Heliocentricism Copernicus (1475-1543) reintroduces Heliocentricism

17. Added Information for Copernicus Copernicus was Polish cannon (religious man) Copernicus was Polish cannon (religious man) Thought Ptolomy was too awkward; God wouldn’t make such a system Thought Ptolomy was too awkward; God wouldn’t make such a system Neo-Platonism: Wanted physical symbol (sun) to represent God as the center of the universe Neo-Platonism: Wanted physical symbol (sun) to represent God as the center of the universe Calculations were Easier: System used 48 circles instead of 80, accuracy was no better than for Ptolomy Calculations were Easier: System used 48 circles instead of 80, accuracy was no better than for Ptolomy Book published posthumously. Preface stated it was to be seen instrumentally, but Copernicus probably though it was real Book published posthumously. Preface stated it was to be seen instrumentally, but Copernicus probably though it was real

18. Reaction to Copernicus “Then spake Joshua to the Lord... and said in the sight of Israel, Sun, stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon. “Then spake Joshua to the Lord... and said in the sight of Israel, Sun, stand thou still upon Gibeon; and thou, Moon, in the valley of Ajalon. “And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies... So the sun stood still in the midst of heaven, and hasted not to go down about a whole day.” “And the sun stood still, and the moon stayed, until the people had avenged themselves upon their enemies... So the sun stood still in the midst of heaven, and hasted not to go down about a whole day.” Joshua 10: 12-13 KJV Joshua 10: 12-13 KJV

19. Augustine’s Axiom When a demonstrated scientific fact contradicts a literal interpretation of scripture, the scripture should be interpreted metaphorically Was the Copernican Cosmology a “demonstrated fact”?

20. Galileo Galilei (1564-1642) 1592 Professor of Mathematics at Padua Did studies in Astronomy and Engineering Designed and built best telescope of the time

21. What Galileo Saw With His Telescope Mountains and valleys on the moon, not a sphere of perfect crystal Mountains and valleys on the moon, not a sphere of perfect crystal Sunspots on the sun: inconsistent with unchanging heavens Sunspots on the sun: inconsistent with unchanging heavens Four moons orbiting Jupiter showed that all things didn’t orbit around the earth Four moons orbiting Jupiter showed that all things didn’t orbit around the earth

22. Galileo’s Findings All these were consistent with Copernicus, and not with Aristotle – but they were not conclusive All these were consistent with Copernicus, and not with Aristotle – but they were not conclusive Conclusive evidence would have been showing parallax– his telescope wasn’t good enough. Conclusive evidence would have been showing parallax– his telescope wasn’t good enough. Parallax would have proven that “the earth moved” Parallax would have proven that “the earth moved” Parallax wasn’t shown until over 200 years later, when better telescopes were developed Parallax wasn’t shown until over 200 years later, when better telescopes were developed

23. Giordano Bruno (1548-1600) Giordano Bruno (1548-1600) Dominican monk in Naples Bruno defended the heliocentric theory of Copernicus. He argued that the universe was infinite, that it contained an infinite number of worlds, and that these are all inhabited by intelligent beings. 1592-1600 –”questioned” by inquisition Refused to recant, burned at the stake

24. Tycho Brahe (1546-1601) Danish Royal Astronomer Danish Royal Astronomer Assembled most accurate data on heavenly motion Assembled most accurate data on heavenly motion Revised and proposed partial heliocentric (heraclitus) model Revised and proposed partial heliocentric (heraclitus) model

25. Brahe’s model about as easy to use as Copernican Brahe’s model about as easy to use as Copernican Didn’t go against Scripture or reason Didn’t go against Scripture or reason Earth still didn’t seem to be moving Earth still didn’t seem to be moving Brahe didn’t worry about Neoplatonic ideals Brahe didn’t worry about Neoplatonic ideals Brahe was a protestant, so inquisition wasn’t an issue Brahe was a protestant, so inquisition wasn’t an issue

26. Johannes Kepler (1571-1630) Worked with Tycho Brahe, and inherited his data Protestant mystic and neoplatonist Considered all theories to crude for a perfect God Found Galileo’s astronomy “uninteresting”

27. Kepler’s System Rejected Pythagorean Constraints of circular motion and constant speed Rejected Pythagorean Constraints of circular motion and constant speed Planets move at varying speed in elliptical orbits around the sun Planets move at varying speed in elliptical orbits around the sun

28. Elliptical vs Circular Motion

29. Summary of Models Ptolomy: Earth at center, 80 circles, epicycles etc. and accurate to about 1%. Very difficult to use Ptolomy: Earth at center, 80 circles, epicycles etc. and accurate to about 1%. Very difficult to use Copernicus: Sun at center, 48 circles, epicycles etc. and accurate to about 1%. Easier to use. Copernicus: Sun at center, 48 circles, epicycles etc. and accurate to about 1%. Easier to use. Kepler: Sun at center, 7 ellipses (one for each planet), much more accurate and easier to use than others. This one is “real” Kepler: Sun at center, 7 ellipses (one for each planet), much more accurate and easier to use than others. This one is “real”

30. Church and the Astonomers Aristotle fit traditional theology, place for heaven and hell..unchanging celestial heavens Aristotle fit traditional theology, place for heaven and hell..unchanging celestial heavens Theology: man made in God’s image, so we’re in the center of the universe Theology: man made in God’s image, so we’re in the center of the universe Protestant Reformation: Protestant Reformation: Attack on authority Attack on authority Priesthood of all believers Priesthood of all believers Authority comes from “God’s Word”, not passed down through Popes, so words very important Authority comes from “God’s Word”, not passed down through Popes, so words very important

31. Council of Trent: April 1546 Council of Trent: April 1546 No private interpretation of Scripture No private interpretation of Scripture (watch out Galileo) Siege Mentality – see enemies where there are none Siege Mentality – see enemies where there are none Jesuits founded to defend the Faith Jesuits founded to defend the Faith Result: most Catholics and Protestants chose conservative approach, resisted heliocentricism Result: most Catholics and Protestants chose conservative approach, resisted heliocentricism Many scientists also were conservative and resisted Copernician ideas Many scientists also were conservative and resisted Copernician ideas