1. Faith and Reason The Trial of Galileo

2. Galileo’s Accomplishments Called the Father of Modern Science First developed idea of mathematical basis for natural laws Ground-breaking experiments on mechanics – acceleration, friction, motion of pendulums, etc. Helped develop the telescope Discovered moons of Jupiter and rings of Saturn Observed phases of planet Venus and geographic features of the moon One of first western astronomers to discover sunspots

3. Galileo’s Legal Problems Galileo facing the Roman Inquisition Cristiano Banti, 1857 1633 – Galileo put on trial for suspicion of heresy for ideas expressed in his book Dialogue Concerning The Two Chief World Systems Found “vehemently suspect of heresy” and ordered to recant his ideas Placed under house arrest until his death in 1642 Offending book banned and further publications forbidden

4. So Why Is The Church Involved? Jesuit astronomer Christoph Scheiner The question of Galileo’s heresy involves the heliocentric model of the solar system The heliocentric model directly contradicts certain scriptural passages that refer to an unmoving earth – e.g. "the world is firmly established, it cannot be moved." (Psalm 93:1, Psalm 96:10, and 1 Chronicles 16:30 ) Church also heavily involved in scholarship of the day Most universities were ecclesiastical institutions, and students and professors were in minor orders Many key astronomers of the day were clergymen – e.g. Christoph Scheiner, with whom Galileo entered into a bitter controversy over primacy for the discovery of sunspots – some scholars say Galileo’s disputes were as much to blame as his ideas for his troubles

5. Heliocentrism In 17 th century, geocentric model of the solar system is the dominant one – dating back to Ptolemy (2 nd century CE) 1453 – Nicolaus Copernicus publishes On The Revolutions of the Heavenly Spheres outlining a heliocentric theory. 1605 – Johannes Kepler improves the theory by suggesting the planets follow elliptical orbits Galileo’s telescopic observations of Jupiter’s moons and the phases of Venus further improve the theory

6. The Problem of Proof Church demands tangible proof before accepting any model that contradicts Scripture Real proof is hard to come by Copernicus defended his model on its “elegance” – because he used circular orbits, his calculations were no better at predicting celestial motion than Ptolemy Phenomenon of star parallax (motion of stars relative to earth) not addressed until 1725 (Bradley) and not proven until 1838 (Basel) Other models (Brahe) also account for Galileo’s observations – these do not contradict scripture So – Galileo’s insistence on a Copernican model was problematic Tycho Brahe’s geohelio model

7. The Problem of Galileo Galileo Before the Holy Office Joseph Nicholas Robert-Fleury, 19 th c. Embroiled in scholarly controversies that alienate him from potential supporters With Christian Scheiner (as noted above) Over comets with Jesuit astronomer Orazio Grassi Over tides as a proof of heliocentrism (his theory does not hold up to physical reality – multiple tides in Venice, for example, contradict his predictions – he rejects Kepler’s accurate theory that the moon causes tides as “useless fiction”) Overall, Galileo acerbic and unpleasant in these disputes – from a letter to Kepler in 1610 “My dear Kepler, I wish that we might laugh at the remarkable stupidity of the the common herd.”

8. To What Extent Did Galileo Contribute to his Problems? Pope Urban VJII 1616 – Galileo’s scholarly enemies turn him in to the Inquisition, accusing him of heresy Cardinal Bellarmine adjudicates, ruling that Galileo may not “hold or defend” the heliocentric theory. But he can still discuss it as a hypothetical. Galileo meets with Pope Paul V, who reassures him that he is safe from further prosecution Later, in 1521, Cardinal Barberini becomes Pople Urban VII – as a cardinal he opposed Galileo’s prosecution, and was an admirer of the scientist. In 1532 he encourages Galileo to write a dialogue presenting the chief arguments for geocentrism and heliocentrism. The result – A Dialogue Concerning the Two Chief World Systems is a polemic clearly advocating heliocentrism and mocking geocentrism. The geocentrist advocate is named “Simplicio” and mocked accordingly – and Galileo puts some of Urban VII’s published words into his mouth. Galileo is accused and put on trial the following year.

9. Galileo’s Fate View of Duomo, Sienna Found “vehemently suspect” of heresy and forced to recant (which he does) His Dialogue is banned along with any future work on heliocentrism he might produce. First lives with his friend the archbishop of Sienna Then in 1634 moves back to his own villa outside Florence where he stays, receiving friends and working on his masterpiece of material science Two New Sciences with the assistance of his friend and pupil Fernando II de Medici, Grand Duke of Tuscany Arcetri. Site of Galileo’s villa