Interesting Facts about Galileo

I listen to Galileo by John L. Heilbron.

Some interesting facts from the book are below together with links that I have found in Internet.

Galileo about Inferno

Galileo has started his scientific career with a speech about how Inferno looks like where he has applied his mathematical genius to find out which theory was the correct one.

Two Lectures to the Florentine Academy On the Shape, Location and Size of Dante’s Inferno by Galileo Galilei, 1588

Galileo against clothes

Galileo has a poem poem “Against the Donning of Gown”

I now conclude, and turn to you, signor,
And force you to confess, against your will,
The Greatest Good will be all clothes to abhor

His First Heresy
Marvin Frandsen, Nude & Natural

Military Compass as Calculator

Galileo has invented a military compass (sector) to use it as a calculator. This was Galileo’s big business.

Galileo’s compass, Institute and Museum of the History of Science

Throughout the Renaissance, many attempts were made to develop a universal instrument that could be used to perform arithmetical calculation and geometric operations easily. This need was felt especially in the military field, where the technology of firearms called for increasingly precise mathematical knowledge. To satisfy these requisites, the first proportional compasses were developed in the second half of the sixteenth century, among them some singular instruments known as the “radio latino” and the “proteo militare”. The geometric and military compass of Galileo (1564-1642) belonged to this class of instruments.”

Inquisition and Galileo: Venice Episode

p. 104 “On 21 April 1604, Silvestro Pagnoni, who had worked for Galileo for a year and a half as a copyist, presented himself ‘spontaneously’, which often meant, as in this case, on the urging of his confessor, before the nearest inquisitor.  His conscience forced him to disclose that his former employer casts horoscopes.”

p. 104 “Pagnoni then enriched his testimony with some precious details about Galileo’s dealing with his mistress and his mother. During visit to Galileo in 1603/4, Guilia had enlisted Pagnoni to spy on his son. He duly relayed her confidences to the inquisitor:

I have understood from his mother that he never takes confession or takes communion, and she asked me to find out whether he went to mass on feast days. I observed that instead of going to mass he went to the house of his Venetian prostitute Marina.”

p. 105 “The Venetian authorities had no trouble to seeing that Pagnoni acted through spite and that his charges were ‘very frivolous and of no importance’. Galileo had to teach astrology; there was no reason that he should not practice it also; and Pagnoni certainly had not shown that Galileo interpreted the charts fatalistically. Galileo’s private life was no business for inquisition.”

Galileo: Body cannot leave the rotating Earth

According to Galileo by John L. Heilbron (Galileo’s extrusion argument):

p. 272 “Ptolemy had agrued that objects not fastened to the Earth would be thrown off if the glove spun. Galileo countered that irrespective of the speed of rotation, no such extrusion can occur.”

p. 273 “He [Galileo] could not think himself away from the Earth anymore, than  Simplicio could imagine himself on the planet.”

I have searched about this issue in Internet and have found a good historical overview of the problem.

P Palmieri – Journal for the History of Astronomy, Nov 2008, Vol. 39 Issue 4, p425
Galileus Deceptus, Non Minime Decepit: A Re-appraisal of a Counter-argument in Dialogo to the Extrusion Effect of a Rotating Earth

‘As we shall see, Galileo basically wishes to prove that no matter how fast the Earth rotates daily on its polar axis, objects on its surface would never be extruded, i.e., they would never fly off toward the sky. That this should be the case was a rather common objection raised by anti-Copernicans at that time. Thus, in the late 1930s, Alexandre Koyré pointed out that “Galileo’s argument … is extremely subtle and seductive. Unfortunately it is incorrect; and what is worse, it is manifestly incorrect”. Others followed Huygens and Koyré in their negative assessment of Galileo’s argument.’

Galileo: Comet is not a Planetary-Like Body

According to the book Galileo by John L. Heilbron, Galileo was convinced that a comet is not a planetary-like body and he has defended such a view in his book Assayer.

I have found in Internet a paper about this controversy.

O Gal, R Chen
The Spectre of the Telescope
Radical Instrumentalism from Galileo to Hooke

What the interpretation of the Assayer as the great manifesto of the New Science has usually passed in silence, however, is that the positions Galileo takes in the essay concerning its explicit subject matter—the nature and position of comets—are extremely conservative, not to say reactionary.”

What he [Galileo] does make completely clear, however, is that he would not allow that the comet is a planetary-like body, residing above the moon:

A comet is not one of the wandering stars which become visible in a manner similar to that of some planet.”

‘Galileo does not have a strong position of his own as to what comets really are and his trust in the Aristotelian theory is tentative and qualified at best. Why, then, should he rely on this theory to cast doubt on the parallax technique and vehemently reject Tycho and Jesuits’ breakthrough that comets are “not sublunar but clearly celestial”? It is not the case that Galileo some deep aversion to parallax considerations, or that he was always so committed to Aristotelian meteorology or convinced in the errors of Tycho’s way. In a series of public lectures following the super nova of 1604 he took a clear Tychonic position and used the lack of parallax to argue that the new star was super lunar. And it is worth stressing again that the curious concept of frictionless motion in a medium is a small part of the price that Galileo has to pay for this rejection. Insisting that the comets should not be placed above the moon, Galileo is undermining an important mathematical empirical tool, the parallax calculation, and adopting a qualitative and analogical mode of explanation, Aristotelian in essence if not fully Aristotelian in details. Most surprising: both in declining to accept Tycho’s demonstrations for the changes in the heavens and in employing the notion of “elemental sphere” in his own account, Galileo re-embraces the sharp distinction between the sub- and super-lunar realms.’

Galileo, Inchofer, and Popper

p. 318 ‘However, false is not useless. The motion supposed by Copernicus can be employed in calculations, and might even be useful to the faith if mathematicians emphasized their falsity along with their utility. Here Inchofer had in mind the minor truth later rediscovered  by Karl Popper: “mathematicians [should] … work more and more toward trying to falsify theories rather than to defend them“. To this anticipation of modern epistemology Inchofer added a pinch of ancient wisdom, Urban’s Simple in the words of the Preacher: “no man can find out the work that God maketh from beginning to end.”‘