Hello and Welcome to Western SIV Episode two hundred and seventy two Galleo Part four. Over the years spent in Padua, Galileo had been increasingly drawn into the Medici sphere of influence in Florence. That situation soared exponentially when in sixteen ten Galleo agreed to move to Florence to take up the world's first ever research professorship. In moving to Florence, Galleo was not only getting a better position, it was also moving to one of the most important cities in Western Europe.
And yet there were many in Galileo's inner circle who wanted him to stay in Padua. Why well, The answer is simple. The Inquisition. Italy in the sixteenth and early seventeenth centuries was a patchwork of kingdoms saw under their authority and others subject to the authority of foreign powers, mostly France and Spain.
Some parts of Italy, notably Venice, were estranged from Rome. Venice was in fact often on the verge of war with the Pope, but Florence was allied with Rome, and that meant that the Inquisition was alive and well in Florence. Hence, when Galileo decided to move to Florence. He was placing himself and his Copernican ideas firmly in the crosshairs of the papacy. It was a decision that will come back to haunt him. So what changed that made
Galileo willing to such a move. In February of sixteen oh nine, Ferdinando the First died and Galileo's pupil, now Cosimo the Second, became the Grand Duke of Florence. Galleo immediately let it be known that he would welcome the offer of a position at court, making it clear that he was not after more money. No author was forthcoming, however, presumably because the Grand Duke was reluctant to match Galileo's vast salary, which would have made him one of
the highest paid employees of the Florentine government. Free time, Galileo said, was worth more to him than gold. With gold, one might acquire celebrity, but with free time he could hope to win true fame. The previous summer, the Ducal Secretary had taken Galileo under his personal protection, saying, as they parted, quote Galileo, in all your activities and dealings deal with
me and with no one else end quote. Thus, well before Galileo discovered the telescope, well before he dedicated the Starry Messenger to Cosmo, he had set his heart on transferring from Padua to Florence. Galileo finally arrived in Florence on the twelfth of September sixteen ten. At first, much of his time was taken up by new observations of the heavens, although it was not long before he found himself unintentionally caught up in a bitter debate with local Aristotelian philosophers.
The debate started in the summer of sixteen eleven when Galileo happened to remark that ice floats because it's lighter than water. The Aristotelians, faithfully following Aristotle, were convinced that ice is heavier than water. Ice, they reasoned, is condensed water, and that it floats because of its shape. They claimed flat things float because they're unable to overcome the resistance of water, while spherical
objects sink. Now, of course, it is so obvious to us today that things float because they're lighter than water and sink because they're heavier than water, that it's difficult for us to imagine a world in which the best educated and most sophisticated minds simply denied that this was the case. Galileo, who viewed the subject as we do today, had a number of straightforward responses.
Not only had he already worked on specific gravity in sixteen oh eight, he had got caught up in an argument with the Grand Duke's engineers, who were building a pontoon bridge on the Arno as part of the arrangements for Cosimo's wedding. They had argued that the flat structure of the pontoon's base would give it extra buoyancy, while Galileo insisted that shape had nothing to do with whether or
not something floated. Dal Leo argued that an object whose specific gravity is heavier than water will always sink, although sometimes it will take a very long time to do so. A handful of mud may take hours to sink to the bottom of a large tub of water. The shape of a solid object has no bearing on whether it floats or sinks. It affects only the speed with which it moves through the water. Thus, a small ice cube will float.
Now this is obvious to us, but it wasn't in seventeenth century Florence, they would have seen ice only in two forms, in thin sheets on the surface of ponds in the winter, and as large brocks brought down from
the Apennine Mountains in summer to keep their fish fresh. This disagreement involved a straightforward clash between the followers of Aristotle, who once again simply parroted what he said and held that ice is condensed water, and Galileo, who was applying the principles of Archimedes, who maintained that since ice floats, it has evidently expanded water. To contemporaries, Galileo's view, which seems so straightforward to us,
was quizzical. Matters became more interesting when a philosopher called Ludovico de le Combe announced that he had an experiment that would prove Galileo wrong. De le Combe was a strict Aristotelian. He had also written about the New Star of sixteen oh four and suspected, surely correctly, that Galileo had something to do with the mysterious Second Pamphlet from Mari, which, of course Galleo had written. Del Combe's experiment was simple. He placed an ebony chip and an ebony
ball gently onto the surface of a bowl of water. The chip floated, the ball sank. Aristotle was vindicate. Dela Coombe was supposed to meet with Galleo to debate his experiment, but it never turned up. Instead, he just kind of went around the city, demonstrating his ability to float ebonyon water in the public squares and crying out that he had defeated the Great Galileo. In September sixteen eleven, the whole question was discussed at the Grand Duke's dinner
table. The discussion grew heated, and in this atmosphere, the Grand Duke told Galleo to stop trying to arrange a confrontation with Della Combe, and to just put his arguments in writing, as this was the best way to ensure that good sense would triumph. Galileo acknowledged the Grand Duke's advice. Galileo had thus learned, or believed he had learned a valuable lesson. Debates on intellectual topics conducted in the court, in the open air, or in the houses
of leading citizens rapidly degenerated into shouting matches. Moreover, in such circumstances, matic reasoning was impossible. Indeed, when entered a sort of nightmare world in which the meaning of words and the subjects discussed were constantly changing. It was better, he agreed now, to write down one's arguments. That way others couldn't twist them and misrepresent them. Better to abandon the court in the city squares and retire to one's study. Now, Galileo was very good in debate.
His admirers believed he could out argue anyone. One of his most infuriating tricks was to offer ways of improving his opponent's case before comprehensively demolishing it. But he no longer had confidence that out arguing his opponents was enough. The retreat from public and court life that's already in apparent when he wrote Discourse on Floating Bodies was soon to be carried further. By January of sixteen twelve,
Galileo was effectively living in a villa in the countryside outside Florence. He had abandoned the house he had rented in the center of Florence and had moved in with his friend. Eventually, what started out as a letter to the Grand Duke about floating bodies turned into a book. This was published in May of sixteen twelve, and it is in this book that Galileo offered a solution to dela Combe's puzzle. He showed that it wasn't because of this shape that the
ebony chip floated. He could, he discovered, float a needle on the top of the water. How could objects float that were heavier than the water, well, Galileo claimed that they floated slightly below the surface of the surrounding water. What was really floating was not the ebony chip alone, because this would always sink if you immersed it fully in the water, but an open sandwich of the ebony chip and a layer of air, the average weight of
the two combined being less than that of the water they displaced. In other words, the ebony chip was a bit like a boat, even though there were no planks holding the water back. Galileo had thus recognized that, in moving into his own territory that of experimental evidence, de la Combe had indeed identified an interesting puzzle. He had no idea why air would stick to the surface of an ebony chip, or why water would not flow into cover the
chip. Galileo knew only that this is what happened. Galileo's small book provoked considerable comment. Four books appeared attacking it, while Galileo's disciple Benedito Castelli published a substantial work defending it. Yet it's an important book because in it Galileo
seems to make a major transition. He begins to concede that you can only discover causes through experiments, and this new way of thinking obliged him to give up his belief in astrology, which he was still defending as late as sixteen
eleven. For all the elegance of Galleo's arguments, which his opponents could scarcely ignore, the debate overfloating bodies confirmed his growing conviction that he would never persuade Aristotelian professors of philosophy to agree with his views, even if he persuaded them to adopt an approach that recognized the central significance of facts. In the whole of his lifetime, not a single professor of philosophy in even one university supported
him on any topic. Mere force of argument would never do the job. Now, with the benefit of hindsight, we might say that Galleo was too impatient an Aristotelian philosophy was to retain a secure position in European universities for more than another one hundred years. In fact, it was still being taught when Newton was a professor of mathematics at Cambridge. If Galileo was going to defeat the Aristotelians, he needed not just new arguments, he needed new allies.
The publication of The Starry Messenger in March of sixteen ten was followed by a carefully managed campaign to win acceptance for Galleo's discoveries, which were so far at odds with everything that had went before that they had first met with nothing but its skepticism. The campaign, depending on mobilizing the resources of the Medici government for the honor of the Medici, was now linked to the success of Galleo's
publication. But most of Galleo's Venetian friends would have been astonished if they had seen the first letter, or at least surviving letter, that Galileo wrote arriving in Florence in September. It's addressed to the leading Jesuit mathematician, a man by the name of Christopher Clavius, whom he had visited in Rome all the way back in fifteen eighty seven, and with whom he had corresponded in fifteen eighty eight. Clavius had written to Galileo in sixteen oh four seeking to renew
their friendship, but it seems evident that Galileo had not replied. It is time Galileo wrote that I broke the long silence, a silence of my pen rather than my thoughts with regard to you, most reverend Sir. I break my silence now that I find myself repatriated to Florence by the grace of a most serene grand Duke, whom it has pleased to call me back to serve as his philosopher and mathematician. The cause of my lengthy silence throughout the time
that is that I was living in Padua. There is no need for me to specify when writing to someone as wise as yourself and quote. Both the Venetian political establish and the University of Padua were hostile to the Jesuits, and for eighteen years Galileo had no written communication with the Jesuits, although we know
he had conversed on mathematical subjects with Jesuits teaching in their Paduan college. Now he writes that he plans to come at once to Rome to show Clavius and his colleagues the moons of Jupiter in order to dispel any doubts that Clavius may have. The evidence provided by this letter is decisive. Galleo did not move to Florence, thinking that the influence there of the counter Reformation Church, though something of a disadvantage, was worth putting up with in order to seize other
opportunities. The key advantage of moving to Florence was that it would enable him to travel to Rome as an intellectual in good standing, one in the service of a respectable Catholic ruler, and then to renew contact with the Jesuits. There are many reasons Galileo was right to focus on the Jesuits. The Jesuit Order, as I'll talk more about when we get to the Inquisition, was rapidly becoming the educators of Europe's elite. By the end of the sixteenth century,
there were two hundred and forty five Jesuit colleges. Now look today, the Jesuits get a bad reputation as old sticks in the mud who refused to accept new ideas. That perspective, however, ignores the very real battle going on within the order in the early seventeenth century. On the one hand, the Jesuits prided themselves on being the cutting edge of this new science, while on the other hand, the Church remained firmly committed to upholding the traditional learning
of the Church, primarily that of Thomas Aquinas. Frankly, it was only the coming crisis within the Order itself that Galileo played a large part in sparking that would see the triumph of the traditionalist wing over the new science. Galileo wasn't wrong to try and ally himself with the Order. Indeed, there were many within the Order who privately supported him. However, hindsight is twenty twenty and we know with its value that by sixteen thirty two the Jesuit Order would
be one hundred percent opposed to Galileo. That being said, and I hope I don't have to remind you of this. Galleo did not know that at the time. Galleo returned to Florence in September of sixteen ten, about six months after the publication of The Starry Messenger. At the same time, in Prague, Johannes Kepler, mathematician to the Emperor, a rarity given that Kepler was both a Copernican, and a Protestant received a copy of the book.
He decided immediately to write a public response a show of support. Kepler quickly realized that no one who was not a Compernican would be able to accept the ramifications of Galileo's work. He wrote that these moons of Jupiter, which he hadn't seen yet, were conclusive proof that there was much more to the heavens than Ptolemy or Aristotle believed, And he wrote that weeks before himself observing said moons again. Kepler wanted to promote Copernicanism, and he saw through Galileo a
great opportunity to do it. This was great news for Galileo because other mathematicians were not in support of his claims. In fact, many men claimed they could not see these supposed moons of Jupiter. They said Galileo had made it all up. Galileo was now in a bit of a pickle. In the Starry Messenger, he had provided only the most basic information about the telescope. He had used not enough to make it easy for other astronomers to build replicas.
He had, for example, withheld probably deliberately information about the diagram, and greatly improved the clarity of the image. His motive, of course, was straightforward. He wanted to maintain his lead and telescope construction for as long as possible in the hope of making further discoveries. And this was a sound strategy. But he had assumed that there would be no difficulty in convincing people that the moons of Jupiter really existed. He would show them by letting them
look through his telescope. His mistake here was probably he didn't do it before publishing. As far as historians can tell, he did not show the moons of Jupiter to anyone before The Starry Messenger was published, and so Galilea was now committed to giving ten new telescopes to influential rulers and cardinals. This would both raise the prestige of astronomy and allow more people to see what he had
seen. The most obvious thing for Galileo to do here would have been to send the Emperor a telescope, who could then pass it along to Kepler. Galileo did not do this. But why Well, the reason is more obvious than you think. Galileo lived in Florence well under the authority of the Inquisition he needed confirmation of his discoveries by a Catholic scientist, not a Protestant one. Kepler wouldn't do him any good. Indeed, I mean Kepler had already
vouched for him, and it hadn't made a difference. Galileo was thus caught in a double bind. He urgently needed a respectable astronomer to confirm that Jupiter had moons, but there was no astronomer here dared trust with a first rate telescope of his own. Manu factor. What he needed was for other astronomers to make their own telescopes. Kepler tried, but his wasn't very good. By the end of sixteen ten, only two people other than Galileo, as
far as he knew, had made telescopes of the required quality. One was a Jesuit in Rome, while the other was Galileo's friend in Venice, Antonio Santini. Santini was surprised at how slow others were, and Galileo probably shared his puzzlement. On September the fifth, Johannes Kepler confirmed the existence of the moons. He received a telescope from the Elector of Colon several days prior,
so Galileo had his confirmation, but again it didn't help him. Reports simultaneously came in from Paris, and worst of all, from Rome that other astronomers had tried to find the moons and had failed. Galileo had gotten nowhere. On hearing in September of the failure of Clavius's efforts to see the moon, Galileo immediately wrote to him, saying that he was about to come to Rome and would show him the planets himself. The technique of using the telescope was
not straightforward. He acknowledged that even one's pulse could make it shake, rendering the planets invisible, and it was too easy to mess up the lens simply by breathing. But instead of leaving for Rome, Galileo grew increasingly anxious and depressed, and then he got sick. One can imagine his anxiety that a visit to Rome might turn out as badly as another one of his visits to Bologne. By early November, however, Clavius, who had by now received
two telescopes from Sanantini, had seen four small stars moving around Jupiter. He was not immediately convinced that they were planets, but he expressed no reservations. When he wrote to Galileo on the seventeenth of December praising him for his wonderful discoveries. Santini had thus solved Galileo's replication problem for him. He had supplied first rate telescopes to the two key Catholic scientists, and had done so without
increasing the risk Galileo was running. Since Galileo and Santini were on very good terms, it seems likely that Santini was acting as Galileo's agent. Certainly, he doesn't seem to have been acting on his own behalf, as he demanded neither money nor fame as recompense. Now, Galileo practically jumped out of bed when he read Clavius's letter. This was the news he had been waiting for. Two months later, in February sixteen eleven, Galileo wrote, there could
be no more doubt about the existence of the moons. When in April he went to Rome, the Roman College greeted him with applause. He now had a small group of allies in Rome, not large, but enough to give him some hope. By this point, Galileo had made two new discoveries. First, he noticed that there seemed to be two blurs around Saturn. He didn't know that these were rings, but he knew that he saw something that On December the eleventh, he discovered that Venus, like the Moon, had
a varied appearance. It was not, in fact a perfectly round orb. The second discovery, the phases of Venus, was a fundamental importance. It was actually discovered mostly by chance between September twelfth and All Saints Day, which is the first of November. Galileo was living in temporary rented accommodations. There.
He couldn't mount the grinding wheels he needed to make new lenses for his telescopes, and his view to the east, where Jupiter was seen in the morning, was poor, so he naturally just kind of turned his telescope to the west, where you could see Venus in the evening sky. When he moved to the house which he intended to make his home, which had good views in every direction, he continued this program of observation. Thus Galileo had seen both that Venus had phases, and, like the Moon, the planet's
apparent size varied greatly over time. No astronomer before sixteen ten had predicted that Venus would have phases because it was first necessary to be sure that the planet shown only by light reflected from the Sun. This idea was one that had previously been discussed as a possibility, but the evidence seemed to be against it. The light coming from Venus, as seen by the naked eye did not
seem to vary as much as one might expect if it had phases. Kepler, for example, took it for granted that Venus shown by its own light. Still, Galleo came a major step towards this prediction in The Starry Messenger by arguing that the light of the Moon was entirely reflected light, and that the Earth too, shone by reflected light. The implication of all this was earth shattering and obvious, namely that none of the bodies that orbited the Sun
shown by their own light. Given this assumption, it became possible to predict that, if both Copernicus and Ticobrahe were right, Venus did in fact orbit the Sun. In that case, Venus would have phases, which, like the moons, would extend all the way from crescent to full, while if Ptolomey was right, the phases would be limited to either between full and half
or between half crescent. The discovery of the phases of Venus, which in fact, of course do extend all the way from crescent to full could thus correctly be presented as evidence that Venus must orbit the Sun and not the Earth. This was the first observation that was directly incompatible with ptolemy and Ptolemaic cosmology. Unfortunately, for Galleo, it was perfectly compatible with Ticobrahi's geoheliocentric system,
and unlike with the moons of Jupiter. Both of these discoveries were confirmed by the Jesuits in April of sixteen eleven. Throughout all this time period, Galleo kept up his correspondence with Clavius in Rome. This reflects a deliberate choice to rest his credibility on the Roman Church and not on someone who was willing to give it, like Johannes Kepler in the court of the Emperor. It was a deliberate choice whose consequences were to become clear only many years later. I
want to pause here and note two things. First, Galileo was preoccupied with making his priority in telescopic discovery. This is why he had rushed the starry Messenger through the press and why he had announced his discoveries to Kepler. Science had not previously been a competition, and we talked about this when we started to talk about the scientific revolution. Certainly not in this way. Galleo had
invented the scientist as the person who makes discoveries. And since all you need in order to make these discoveries was a good telescope, and Galileo himself was distributing good telescopes around the world, he knew he only had a very small window in which to claim a priority. Second, I want to note a peculiar feature of Galleo's behavior. He was releasing his discoveries to the words in sort of like drips, using Kepler to publish his findings as if he were
running a sort of rudimentary scientific journal. In doing so, Galileo was stepping away from an alternative model of scientific activity. As soon as The Starry Messenger was published, he started talking of an expanded, elegant version to be published in Tuscan, with accompanying dedicated poems, a book of which a prince such as Cosimo and a philosopher such as Galileo could be proud. He even hoped to publish twenty eight engravings of the Moon showing its changing appearance day by day
through the lunar month. Cosmo had advanced him the money to fund such a publication, and Galleo still had it in mind in sixteen eleven. Still, the emphasis on a serial like publication changed the way that science was to progress throughout roughly the next one hundred to two hundred years, because the emphasis became on a priority becoming the first person to discover something. You had to release
a discovery literally the moment that you made it. Galileo recognized this, and in doing his publications in this way, he set the standard for European scientists going forward. But there was more in the night sky than distant planets. During the same period, Galileo also noticed sun spots. Now, sun spots can sometimes be seen with the naked eye. In fifteen ninety, for example, an English ship's captain off the coast of West Africa saw a spot about
the quote bigness of a shilling on the sun end quote. Johannes Kepler saw a spot in sixteen oh seven when looking at the Sun through cracks between shingles in the loft of his house in order to observe a transit of mercury. Galleo was probably the first person to see sunspots with a telescope. In July sixteen ten, after the publication of The Starry Messenger, but before he left
for Florence, he showed them to a number of people in Venice. In the spring of sixteen eleven, he showed them to several people in Rome, and a friend of his wrote to him in the autumn of that year reporting what someone else had seen. In England, a different astronomer, Thomas Harriet, independently observed sunspots in December of sixteen ten. Galileo detailed his observations of sunspots in a series of letters to a gentleman by the name of Mark Wessler.
Wesler was both bilingual and had studied in Italy. He was also powerful and wealthy, and was a member of the ruling Catholic city of Augsburg and a banker to the Emperor. In his three letters to Westler, which were between May and December of sixteen twelve, Galileo made three critical advances. First, all recent observations of sunspots had involved looking straight at the sun through a telescope. At dawn or dusk, or when there was a light haze.
One could stare at the sun for short periods of time, particularly if using a color glass filter, but one still needed ended up being temporarily blinded, and it was very difficult to record what you had seen. Galleo's friend Castelli, however, discovered that one could project the image of the sun onto a piece of paper held behind the telescope's lens. The resulting image had the top and bottom reversed, but it was large and clear, so now you could
study sunspots without you know, going blind. Moreover, you could record exactly what you had seen if you drew a circle on the paper onto which the image of the sun was projected. You could adjust the distance of the paper from the lens until the image of the sun exactly filled the circle. You could then mark the sun spots on the page simply by painting over the spots
as they appeared. The process is a little bit trickier than it sounds, as the sun moves pretty rapidly through the sky, so you have to aim the telescope periodically. But the result was that Galileo could now make beautifully exact
records of his sunspot observations. Second breakthrough evidently occurred as a result of studying these images, because on the twelfth of May he wrote another correspondent to Rome saying that he could rigorously demonstrate his opinion that the spots were on and not above the surface of the Sun. This is again a massive argument because according
to ptolomy, the heavenly bodies don't change. So if the heavenly bodies don't change, then there shouldn't be any change to the surface of the Sun. If something appeared to be different on top of the surface of the Sun, well, me know, that was perfectly explainable. But if there was some change to the Sun itself, well, I mean that just again shouldn't be. It didn't make any sense. Finally, in December, Galleo also announced
a technical advance that was to lead to his third breakthrough. In the Starry Messenger, he had provided fairly crude images showing the relationship between Jupiter and its moons day by day. The images were based on simple estimates. Galleo looked through his telescope and made a judgment as to how far each moon was from Jupiter using his unit of distance, Jupiter's own diameter. But in January of
sixteen twelve he began to employ a new method. He had attached a grid of lines to a plane which stuck out from the side of his telescope, or so we believe, because the object doesn't survive. With a little adjustment, he could arrange the grid so that if he opened both eyes, when one was applied to the telescope, it appeared to float over the image of
Jupiter, and its center exactly coincided with Jupiter itself. He had constructed a very crude micrometer and could dismiss the rough estimates of others as mere hallucinations. Now, in modern astronomic telescopes, micrometers are mounted within the telescope itself. This is possible in the type of telescope invented by Kepler, but not in
a Gallean telescope. So Galileo did the best he could. He now simply had to count the lines in the grid between Jupiter and any one of its satellites to obtain an exact measurement of the distance, which he could then express in terms of diameters of Jupiter. Galileo could now solve a problem that had been bothering him for the past two years. He could accurately predict and calculate the periods of Jupiter's satellites, and having done this, he could predict their
location in the future. He put all this together in March of sixteen thirteen. There Galileo supplied for the press not only his letters on sunspots, but also tables predicting the positions of the moons of Jupiter over the course of the next few months. He thus put the accuracy of his measurements and calculations to the test. While the publication was delayed, there was still enough time left. Once the publication was complete for people to look at the book, look
at the moons of Jupiter, and realize Galileo had been exactly right. Galleo, in the span of several years, had taken European science and made it more exact than it had been in over one thousand years. He was becoming the world's first scientist. Now next week we're going to start to get into the predictions and the arguments that are going to set Galleo on a collision course with the Inquisition and the Roman Catholic Church. Now, as always, if
you'd like additional content between now and then. You can check out the website link in the show notes, or you can check out Western CIV two point zero, available both through glow dot com and through the Patreon feed. Both offer a seven day free trial, and the links are in the show notes. As always, appreciate Henny and all support that you're able to give. It keeps this crazy show going