His202

Galileo Galilei (1564-1642)

Aims:

Galileo,astronomy, mathematics and physics.

Galileo and the Church.

One cannot come to know and understand the Galileo affair without knowing and properly understanding that he was a mathematician and that his career in Astronomy was forged on mathematics.

We will also look at his career inside the Tuscan court.

Galileo was interested in the mixed (PRACTICAL) mathematics. This sets him apart from Tycho and Kepler, who were more interested in the mystical applications of mathematics.

Catani,Galileo and the Telescope, (c. 1790) Engaged in Mathematics, Physics and Astronomy.
Whatever the myths may be - we do know that he was definitely interested in these studies.

Galileo was accused of being anti-papist for working in Padawa and Venice. Galileo thought there was money to be made in an academic career and he knew that he would only make money if he pitched, sold, ideas correctly. He despised teaching and just wanted to do research. He spent a lot of his time in Padawa working out mathematical equations of practical nature which could be sold for money. Much of this work was based on ancient geometers (Achiomedes for example). Interested in the sciences, in what the ancients had to say about them and interested in new ideas (Typical humanist).
Galileo got 8x magnification (not much). So it's a testament to the guy that he made some pretty impressive calculations with such low magnification.
Before he turned it to the stars he tried to sell it to wealthy merchants and politicians who wanted to see, ahead of their competitors, what cargo merchant traders were carrying into port - so as to make decisions ahead of their competitors. So he was able to sell his instrument to the merchant class.

Published observations - 2 small books: Starry Messenger (1610) Letters on Sunspots (1613).
What it reveals is the dedication to the Medici family in Tuscany - even though he was working in Venice - what this means is that he was doing a little bit more of ass-licking to potential patrons.
In these works he claimed to be rejecting Aristotelian natural philosophy (Galileo was a full blooded natural philosopher - he was interested in physics!)

The first example he sought to prove is that Venus rotated around the sun, internally to Earth. He would argue that the disc size and the phases of Venus account for this.
He also observed craters on the moons surface which he claims refutes the Aristotelian notion about the (eternal, unchanging) universe.
He also observed sunspots - the sun has imperfections (which goes against the Aristotelian notion).

The Medicean stars (four stars) - bodies moving around another planet - so goes against Aristotelian notions - it's also a monument to the Medici family, a tribute.

During the middle of the 16th century the Medici house established a new dynasty of Grand Dukes ruling Tuscany from the 1630's onwards. They sought to regain power by appealing to the social elite of Tuscany. They were trying to revive the glory days of Tuscany and the Medici house.
It's clear that the practical applications of mathematics was helping to establish the position of mathematicians as valuable members of the European elite (courtly life). So it's no surprise that Galileo would seem as a worthy candidate of the Tuscany court. For Galileo, he had to present a gift to the grand duke which would aid the Medici family. (There's a book which explicates the next sentence) A virtuous man needs to bring in something worthwhile to the court which would add to the patron's prestige - Galileo took the telescope.
Grand Duke offered Galileo the position of Court mathematician and philosopher - such was the promise of Galileo's work. The idea that you could have one person expert in both mathematics and philosophy was alien to universities and mostly everywhere. And also, this deal meant that Galileo did not have to teach so much.

One problem about Galileo's pro-copernican interpretations were not as fantastic as he claimed. There was a question about how much theory there was enveloped in his 'observations'. Some questions about the reliability of his telescope. Perhaps it wasn't an instrument that could effectively view the stars. Some used it and couldn't see what he saw. Some did see what he saw but then offered different interpretations.
The claim about Venus doesn't bring down Tycho's philosophy - planets zoom around the sun.
The craters - well they are filled with Ether - so there a bits for the moon that are less dense then others - so still the moon is less dense then others.
Sun spots? NO! They are tiny little planets revolving around the sun.
Besides all this Tycho had already observed a new comet in the 1570's.
So Aristotelian philosophy was a resilient paradigm.
So one or two observations was not going to bring down a whole philosophy.
And here come the Jesuits

Christopher Clavius (1538-1612)

Educated in mathematics and theology (Collegio Romano)
Gregorian calender in 1582
Geocentric interpretation of Galileo's observations.
Clavius was in the game of reviving Mathematics. Tight relationship between the early modern sciences, mathematical sciences and religious authority. Which dismisses the claim that science and religion were at loggerheads at this time.
And what Clavius did was maintain the traditional scholastic tradition that while the mixed mathematics are both revealing about what is out there in nature were still inferior to philosophy. Mathematics won't tell you what causes things.
Galileo couldn't convince the authoritative body (Jesuits) of the veracity of his claims.
Galileo's assertions seemed to run contrary to biblical passages which claim that the Earth is stationary. The protests came from Dominicans. These Dominican theologians were writing to the Pope about this problem pleading an investigation into Galileo's works.
Caccini - nasty fellow - got up on the pulpit denounced mathematicians, philosophers and Galileo as heretics.