Astronomy, New Philosophy, and Galileo

1. The place of physics and astronomy in Scholasticism (1500s – 1600s)
   • idealized, mathematical Ptolemaic model (Ptolemy’s Almagest):
     • “saving the phenomena” and mathematical models
     • celestial spheres: geometric techniques, epicycles, eccentrics
     • dilemmas of model not fitting observations [retrogression of Mars]
     • lack of unity with Aristotelian philosophy
   • problems for orthodoxy
     • calendar and other technical problems (Papal Commission for reform of the calendar)
     • Reformation & Counter-Reformation (Council of Trent)
   • Copernicus’s On the Revolutions of the Heavenly Spheres (1543):
     • the argument for heliocentrism, summarized in the “Preface”:
       • ancient authority
       • the new model’s accuracy
       • restoration of systematic coherence
       • Hermetic appeal to the role of the sun
   • the reaction to Copernican theory
     • a model for computation, as stated in the anonymous Foreword
     • questions of accuracy and technique in the Copernican model
     • the physical problem of an earth in motion
     • Tycho’s new accuracy and alternative model
   • Kepler’s new model and causes (1595-1608):
     • ideal, mathematical harmony
     • elliptical solution for orbits
     • new physical explanations and anima motrix
2. Galileo’s new physics of motion and substance (1590s-1620s)
   • rejection of Aristotle
   • the new use of Archimedes’s mechanics
   • new geometrical, diagrammatic techniques of analysis: abstract idealization of problems
   • quantitative measurement of physical properties
   • emphasis on dimension, distance, time, and the role of mathematics
   • rejecting causal qualities and “forces”
   • empirical investigations and inventions: “Measure all things, and make measurable what is not.”
   • physics and mathematical demonstrations in The Assayer (1623)
3. Supporting Copernicus with new physical evidence (1610s)
   • Tycho’s measurements of comet and supernova
   • Galileo’s telescope observations and Starry Messenger (1610):
     • rhetoric and style of his demonstration
     • new evidence for the physical nature of moon, planets, heavens
     • contradictions with orthodox model
     • Jupiter as a center of motion for its satellite moons
     • persuasiveness and celebrity
   • the phases of Venus
4. Galileo’s political and legal support and troubles
   • life as a courtier
   • his defense of his views, as explained in “Letter to the Grand Duchess Christina of Tuscany” (1615)
   • the 1616 ban on Copernican astronomy
   • Galileo’s Dialogue concerning the Two Chief World Systems (1632):
     • rhetoric of Galileo’s presentation
     • trial: Admonition and violation, Sentence, and Abjuration
5. Galileo’s unification of earthly and celestial physics
   • uniform circular motion
   • argument for inertia and relative motion
   • Discourses and Mathematical Demonstrations concerning Two New Sciences (1638)
   • new method for physics:
     • empiricism, experimentation, and demonstration
     • natural experiments of confirmation
     • the language of mathematics and “the book of nature”
     • simple mechanical interpretation and language, in opposition to qualities

© 2018 Dr. William Kimler