And Yet it Moves! Part IV

Galileo before the Inquisition

The whole affair has an air of tragedy about it, with the protagonists cursed by their own abilities and destroyed by their own inherent faults. The Church was initially agreeable to helio-centrism (which is true, just in case people were wondering) but the thought of being questioned on theology terrified them and to be faced with a layman who told them what to believe caused the clerics to strike back to protect the status quo. Galileo was a victim of his own ego. He repeatedly alienated potential allies because they showed signs of ability and he refused to admit the possibility that he was wrong to champion Copernicus' theory.

What turns the tragedy into farce is that, while both sides were wrong, the answer had already been discovered if either side in the trial had bothered to read it. Johannes Kepler, whom we came across earlier, had been obsessing about perfect shapes affecting the planets which had by a convoluted process, allowed him to discover the laws of planetary motion. The flaw in Copernicus' theory was that Copernicus, like the medieval philosophers, had simply assumed that all planetary motions were circular. By introducing elliptical orbits Kepler had saved the day and completed the revolution (if you'll pardon the pun) that Copernicus had started. Kepler had helped Galileo with his work but when he sent a copy of his own book to Galileo, hoping for an endorsement from the great astronomer, Galileo ignored it. Kepler died in 1630 but his theories were already receiving tentative confirmation by 1631.The great showdown between Galileo and the Inquisition was not until 1633 and news travelled fast between scientists.

Johannes Kepler

The church astronomers and Galileo should have been aware of Kepler's ideas and discoveries (Galileo had actually had the book sent to him by the author). Another damning mark against Galileo is that Kepler had also published a theory of the tides, which Galileo viewed as being pivotal to helio-centrism. Kepler had an alternative idea, albeit a crazy one, that the tides were caused by the Moon's movement acting at a distance. Galileo laughed at it as a "useless fiction." Kepler was right. Galileo was wrong.

The Galileo Affair was a clash of science against religion. It was also a clash of bad science against well, bad science. But it was mainly a clash of egos. Galileo was a great man. His work on falling bodies paved the way for Newton and was perhaps his greatest achievement, but he was active in making discoveries in many branches of science. But, by refusing to admit that he could be wrong he drew the anger of the authorities on himself. The Catholic Church behaved poorly as well, and its dogged insistence on treating anything associated with opposition as heresy hurled it from being at the cutting edge of science to being (from a scientific perspective) hundreds of years behind the rest of Europe.

And who was the real hero of the affair? Galileo was not the infallible man of science. There's no real evidence that he ever muttered "Eppur si muove!" (And Yet It Moves!) and his conduct betrayed all too human failings. He was a genius and we can forgive genius a lot. But for a truly extraordinary man of science, one whom we should take as a role model, I believe that Kepler is the real hero of the tale.

The Old Geocentric Model: What we have left behind

Postscript: It should be noted that some people have told this tale with slight variations, some favouring Galileo more, others favouring the Church. I am roughly retelling, in a far inferior form, the historical narrative laid out by Arthur Koestler in his excellent book Sleepwalkers. If you want to read more about the events, times and people involved in the birth of the scientific revolution I would highly recommend it.

And Yet It Moves: Part I
And Yet It Moves: Part II
And Yet It Moves: Part III
And Yet It Moves: Part IV

And Yet it Moves! Part III

Page from Galileo's Book "The Starry Messenger"

Galileo continued to make discoveries about the planets but his writings about heliocentricity were beginning to attract unwanted attention. There are certain verses in the Bible that speak of the Earth remaining still. Galileo, anxious that the Church should endorse his ideas, began to interpret these as speaking in a strictly poetic sense (the verses are taken from books of what are essentially, poems) effectively saying that these verses were merely figures of speech, rather like the way that we continue to speak of sunrises, despite knowing that the sun does not actually rise. St Augustine, the great 5th century theologian of the West had made similar claims about these books so it was a valid interpretation. If Galileo had made these claims in the Middle Ages he would have probably have gotten away with it. But when Galileo wrote, the Counter-Reformation was gaining strength. The Counter-Reformation was the response of the Church to Protestantism and the one thing that they were determined to prevent was individual scriptural interpretation. Even if this had not been ongoing, Galileo was not a theologian and he was told to stick to what he did best and not write about theology when he was unschooled in it.

Cardinal Bellarmine

At this stage Galileo had had an earlier run in with the Inquisition in 1616 but was released after questioning with no ill effects or stain upon his character. The question then had been about the Copernicus himself, who was now long dead. Copernican theory was deemed technically heretical but it was done in such a way that neither the works of Copernicus or Galileo were banned. This was a warning but by 1630 Galileo was on terms of reasonable friendship with the new Pope. The Pope was interested in the heliocentric theory but, with the Church under attack by the Protestants, he was concerned that the Church should only commit to the theory when it was a certainty. The Pope urged Galileo to write a book dealing with the strengths and weaknesses of the different theories and the Pope even put forward some ideas of his own that he thought could contribute to the discussion. Galileo wrote the book.

The book was a great success in terms of publishing but was not well received by the authorities. Galileo had ignored the Tychonic system and completely favoured the Copernican system over the Ptolemaic one. He had also put the ideas of the Pope into the mouth of a character (the book is a fictional conversation between three characters) called Simplicio, who as the name suggests, is consistently portrayed as an idiot. The Pope was furious and turned against Galileo. Now Galileo had to prove his case once and for all and he had to do it before the Inquisition.

Pope Urban VIII

What about the astronomers of Europe? Intellectuals were given quite a bit of free rein in this age of intolerance. If there was a concerted plea from the learned, possibly Galileo would be spared. But Galileo’s skill at making friends had worked here as well. He would make demands for data from other scientists who by and large would share. But Galileo not only did not share his research, but also would often not even answer his letters. He would also occasionally write nasty papers about other people’s work. This was not uncommon unfortunately, but it didn’t help him make friends. Worst of all he had made a declaration to the effect that only he could discover things using a telescope. So when any astronomer made a discovery Galileo would publish a subsequent paper saying that he had seen it first. This was downright intellectual theft and so when Galileo needed friends he found he had none.

In 1633 Galileo was summoned before the Inquisition and he had to prove his case; firstly that he was in no way involved in independent theological reasoning and secondly that there was good proof for the Copernican theory. Galileo had what he believed to be a perfect proof; that the tides were caused by the motion of the earth as it orbited the sun.

Sketches of Imperfections on the Moon

Thus armed, Galileo faced his accusers. What destroyed Galileo was the fact that some of his adversaries were scientists as well. As you may have guessed, Galileo’s theory of the tides was completely incorrect and his accusers were able to point to glaring inconsistencies. The worst by far was that Galileo’s theory predicted the wrong number of tides. With no explanation for the planetary orbits and his theory of tides and motion in tatters, Galileo (who was now an old man) was hemmed in by the power of the Church, abandoned by his friends and scientists and lacking the crucial theories and proofs that would have cleared his name. Facing uncertain consequences he signed a document abandoning Copernicanism and helio-centrism. Galileo spent the rest of his life under house arrest, in relative comfort it is true, but he was nevertheless confined. His works were banned and helio-centrism was confirmed as heretical. The Catholic Church wavered no longer and judged helio-centrism to be contrary to Scripture and as a consequence was left behind by further progress of science. Galileo died in disgrace some years after.

Galileo Galilei

And Yet It Moves: Part I
And Yet It Moves: Part II
And Yet It Moves: Part III
And Yet It Moves: Part IV

And Yet It Moves! Part II

Copernicus

Copernicus had completed most of his calculations and his work was nearly ready to be published. But Copernicus delayed. One might assume, looking backwards at history with our modern notions, that he was concerned about religious persecution by the Catholic authorities but in actual fact, the papacy were very interested in the document and the cardinals wrote to Copernicus urging him to publish. The main religious opposition came from the Protestant side, with both Luther and Melanchthon (Luther's most notable pupil and a crucial figure in the history of Lutheranism) writing against helio-centrism. But Copernicus was well beyond the reach of any Protestant authorities. So why did he not publish?

As usual, we can't really be sure, but it would seem that Copernicus was unhappy with his own ideas. He didn't have any decent proofs of his own work that would stand up to scientific scrutiny, and, as he was not using any advanced scientific equipment, even by the standards of the day, he was unlikely to find any. If he published a work without proof he would have to defend it to the world and he may not have felt equal to the task. His pupil, Rheticus, took it upon himself to publish the book while Copernicus was on his deathbed and the great secret that everyone already knew, was out.

The Copernican Model

Copernicus' work provoked a great deal of debate in Europe, but did not produce a scientific revolution per se. Astronomers, scientists and theologians all agreed that it was an interesting concept but many disliked the idea and most withheld judgement about it. This was not because the intelligentsia of the time were necessarily bound to tradition but because Copernicus' theory was just, well, a theory. It was a theory without proof, a model of how the heavens moved. The problem was that, while it simplified some of the equations and provided a decent model for celestial movements, it suffered from many of the same defects as the Ptolemaic model.

Copernicus had represented the Sun as being in the centre of the Universe around which the planets moved in perfectly circular orbits. From this one could work out the positions in which the planets should appear in the night sky. After all, this was in an age when space exploration was undreamt of and the night sky was all that the astronomers had to go on. And the helio-centric theory was wrong. Interestingly, the word planet derives from the Greek word for “wanderer” due to their unusual tracks in the sky. The planetary positions did not fit at all and Copernicus had to introduce epicycles to try and make it work. But even with these, the orbit of Mars meandered aimlessly and until a theory could be found to reconcile these anomalies, the thinkers of Europe withheld judgement. Copernicus was now passed away and now the challenge had been laid down to either refine and prove the ideas of Ptolemy or Copernicus or come up with a third theory.

Tycho Brahe

A Danish scientist called Tycho Brahe took up the challenge. He came up with a theory where the Earth was at the centre of the Universe and the Sun revolved around the Earth but where the planets revolved around the Sun, rather than the Earth in the Ptolemaic sense. This theory had problems as well but Tycho Brahe made an effort to solve them by setting up a small island full of machines and observation towers to map the sky with unparalleled clarity and prove his theory. There is a modern tendency to ignore Tycho Brahe's work (we now know that he was incorrect) but it should be remembered that Tycho's measurements were probably the finest measurements ever carried out without the aid of telescopes and large volumes of data were collected with the help of his assistant, Johannes Kepler. But still the theory didn't quite work. Tycho Brahe died hoping that his assistant would continue to work on perfecting the Tychonic theory but it was not to be. Kepler became obsessed with the mystical notion of perfect shapes (circles, triangles, etc.) that, if their radii and lengths of sides held a certain proportion, could give the right figures for the orbits of the planets in a Copernican system. This sounds like a pretty silly notion to us, and it is actually nonsense, but it was to have important consequences.

Tycho Brahe's island

The political situation of the time was changing. The rapid spread of Lutheranism had pretty much stopped and the second wave of Protestantism (Calvinism) had begun. The Catholic Church had reasserted doctrinal points in the Council of Trent and had begun to combat the spread of Protestantism effectively. The Inquisition in Italy and Spain and the newly founded order of the Jesuits were crucial in this retrenchment of Catholicism. The old haphazard tolerance of the Middle Ages and the Renaissance disappeared as the champions of Reformation and Counter-Reformation kept watch for any deviation from the doctrines of their particular church.

There are certain passages in the Bible that seem to suggest that the Earth remains in place. When Copernicus' work was first published no one in the Catholic Church objected to it, but after a few years minor clerics began to question whether Copernicus could be reconciled with Scripture. The Protestants, who had no central authority anyway, became more amenable to the doctrine but it wasn't considered important enough to really merit discussion from the pulpit. The Catholic Church made no official decision regarding Copernicus and whether his text was heretical but the Inquisition was examining any belief that deviated from the norm and it was possible that helio-centrism might be a cover for heresy. This uneasy situation, where helio-centrism was tolerated but could attract suspicion, lasted for a number of years.

Kepler's Initial Vision of the Universe

Meanwhile, an Italian scientist by the name of Galileo Galilei (finally, we get to Galileo) heard of a Dutch invention, which we now refer to as the telescope. Galileo is often credited with the invention of the telescope but in fact he merely refined it. However, he was probably the first person to use it to look at the sky. Galileo discovered the larger moons of Jupiter fairly quickly and became enamoured of the heliocentric theory. If the planets had moons then possibly the earth, which had a moon, was also a planet. At the time philosophers believed (from Aristotle) that the celestial bodies were perfect and almost of a different order of being from earthly objects. Galileo discovered the imperfections on the Moon's surface and speculated that the heavenly objects were in fact of the same order as the earthly ones.

These were important discoveries but still very far from proofs. Galileo had become a strident advocate of Copernican theory. Unfortunately this confidence in his ideas was to bring the Church authorities against Galileo and trigger possibly the most famous confrontation of science and faith in history.

And Yet It Moves: Part I
And Yet It Moves: Part II
And Yet It Moves: Part III
And Yet It Moves: Part IV

And Yet It Moves! Part I

Galileo Galilei

Galileo Galilei was a great man, a brilliant thinker and a pioneer of astronomy, physics and science in general. He was described by Stephen Hawking as "… responsible for the birth of modern science," and by Einstein as the "father of modern science." He has also become an icon for the struggle of science against faith. The tale told is of his conflict with the Church; of how he was indicted by the Church for the heresy of claiming the earth moved and brought before the Inquisition to answer for his beliefs. The tale recounts the fearless disputation where Galileo pitted science against blind dogmatic faith but was forced to silence the truth after the aged astronomer was faced with the torture. The final scene in the saga tells of the scientist, who has been forced to gainsay his conscience and say that the earth remains the motionless centre about which the celestial objects move, hobbles out of the court, murmuring under his breath in a whisper that echoes throughout history "Eppur si muove" (translation from the Italian "And yet it moves").

It is a compelling tale and is undeniably based on historical reality. But whenever we come across a wonderful tale from history, with clearly defined heroes and villains, we must suspect that the reality is more complex.

Martin Luther

In the early 1500’s the Renaissance was in full swing. The Catholic Church, far from prohibiting the new learning and arts was in fact the largest patron of them. However, political tensions and concerns about the increasing corruption within the church meant that when Martin Luther wrote the Ninety-Five Theses and started a revolution against the church, the church was unable to stop him. The German princes, concerned about the growing power of the Habsburg Emperor (who was supposedly their overlord) sheltered the fugitive from papal and imperial power and the Reformation began. Europe now became a virtual and, in many cases, a literal, battleground of ideologies and religious beliefs. This time of struggle (like most times of struggle in actual odd fact), combined with the new learning of the Renaissance, proved a backdrop for a major increase in learning.

Aristotle

Science was in an interesting state at that time. For hundreds of years, all across Europe and the Middle-East, the works of Aristotle had been held to be almost entirely true and the sheer brilliance of the Greek thinker had fooled many scholars into thinking that between Aristotle and the other Greek philosophers, most things worth discovering had been discovered. Thomas Aquinas, the greatest philosopher of the Middle Ages, had codified Aristotelian learning in such a way that it had become (and still is) the official philosophy of the Catholic Church, and one of the things Aristotle had said was that the earth was the centre of the Universe.

Previous Greek thinkers had speculated that the Earth might revolve around the Sun but Aristotle had "disproved" them with a simple thought experiment. I’ll give a version of it here. Imagine you are driving at speed in an open top convertible and you throw an object directly up in the air. Does it land behind you or back in the car? (Aristotle used a chariot for his example but the principle is the same.) Common sense says that it lands behind you. Yet when we stand still upon the surface of the earth and throw an object straight up into the air it reaches its zenith and then falls directly downwards. Aristotle reasoned that if the earth was moving then the object should fall hundreds of feet (or maybe even miles away) because of the speed of the earths rotation, therefore, the earth cannot move. I should mention that this example is taken from my dodgy memories of undergraduate college, so if there are any experts on Aristotle out there who feel that this is inaccurate, I would welcome any clarifications or corrections.

Claudius Ptolemy

There were a number of other astronomical arguments against heliocentrism as well. For the earth to be in constant motion, the stars should be observed to shift position according to the Earth's rotation. The Greek conception of the Universe found it difficult to imagine that the stars could be located at such immense distances from the earth as to make these shifts indiscernible to the naked eye. I should take a brief moment to clarify that Aristotle was very clear about the earth being a sphere. In fact the Greeks had clear knowledge of the spherical nature of the earth from around 240 BC when Erastosthenes provided an empirical proof. The whole notion of people fearing Columbus would fall off the edge of the world is total nonsense.

The problem with the Earth being at the centre of the Universe is that it makes astronomy very awkward but Claudius Ptolemy, a Greek mathematician, had provided a model that allowed the Moon, Sun, Planets and Stars to rotate around the Earth on basically circular orbits. Simple circular orbits would require the planets to move in perfect, regular orbits in the night sky but instead, they "regress" or appear to track back on themselves in their orbits. This was explained by using "epicycles" which were conceived as mini-spins that the planets would do at a certain period of their orbit that would explain their apparent backwards motion.

Copernicus

The Ptolemaic system (i.e. the system first invented by Ptolemy) was refined throughout the Middle Ages and Renaissance. As astronomy improved it became clear that more epicycles were needed and that in fact, the centre of the orbits was not the earth but some point in space near the earth. The system was based on notions that the celestial bodies moved in perfect circles and yet had to have odd spins at seemingly random points of their rotations. The Earth was at the centre and yet not at the centre. The system was extremely complicated and complex and yet it provided a very poor model for predictions about planetary motions. As the brilliant minds of the Renaissance thinkers pored over the data, a new theory that would better explain the appearances was sought and the stage was set for a scientific revolution.

Enter Copernicus. Copernicus was an astronomer from what is now Poland. He became convinced that there was a simpler way to explain the data. For a variety of reasons he believed that the Sun, not the Earth, was at the centre of the Universe. He began work on a book entitled "On the Revolution of the Celestial Spheres" where he argued his point. At that time writers and thinkers all over Europe communicated closely through letters, so even though Copernicus refused to publish his work, the secret could not be kept and soon all the world of the intelligentsia was abuzz to hear that (as the Protestant theologian Melanchthon put it) there was an "astronomer who moves the earth and stops the sun."

And Yet It Moves: Part I
And Yet It Moves: Part II
And Yet It Moves: Part III
And Yet It Moves: Part IV