Galileo's Battle for the Heavens

Galileo's Battle for the Heavens

PBS Airdate: October 29, 2002

NARRATOR: It was a time of discord in the Christian world. Threatened by the Protestant Reformation, the Roman Catholic Church demanded strict adherence to its dogma, enforced by the violent threat of Inquisition. Fear of heresy was in the air.

In this turbulent era, Galileo Galilei would become Europe's most celebrated scientist.

JULIAN BARBOUR (Theoretical Physicist): He was so confident. He was such a brilliant writer. He was a tremendous wit. If there is any one single person who can be said to have created modern science, it's got to be Galileo.

NARRATOR: His early experiments laid the foundation for modern physics, and his observations revealed new truths about the universe.

ALBERT VAN HELDEN (Utrecht University): What we have in Galileo is a package then, of somebody who is mechanically and practically very good, somebody who is a great philosopher about nature and somebody who is ambitious.

NARRATOR: But ambition drove Galileo to question the Church's view of the world and revolutionize our understanding of astronomy. Ironically, Galileo himself was a faithful Catholic and gave his daughter, Virginia, to the Church.

Joining the sisters of St. Clare, she wrote letters to him, many of which survive today. They reveal a daughter's concern for the anguish of her father, whom the Church had silenced as a heretic and imprisoned in his own home. But Galileo would never lose his passion for explaining the natural world.

GALILEO: I wanted people to understand that Nature gave them eyes to see her works, but also brains to make them capable of understanding them.

NARRATOR: Who was this man who saw further than others into the far reaches of the universe? What does his suffering tell us about the recurring clash between religion and science?

DAVA SOBEL (Author, Galileo's Daughter): Galileo was honest when he said that the Bible was the true word of God. He just didn't think it was a good astronomy textbook.

NARRATOR: Galileo's works were banned by the Church for centuries, and not until our own time would his rift with the church be healed. Galileo would pay a terrible price, but his discoveries would change the world.

NARRATOR: Galileo was born into a world where each morning reaffirmed the common view that the Sun moved around the Earth. This belief was confirmed as the sun appeared to pass overhead each day. It was a view of the universe originally set out by the ancient philosopher Aristotle. In the center sat the static earth, the home of man. The Sun was just one of many heavenly bodies which circled endlessly around it.

Dissenting from this accepted worldview could prove hazardous. A statue of Father Giordano Bruno marks the site in Rome where he was burned alive for a host of unorthodox beliefs.

The Vatican considered astronomy to be an investigation of God's work.

GUY CONSOLMAGNO (Vatican Observatory): The Church's universities had seven basic subjects that you had to pass before you could go onto philosophy and theology. One of those subjects was astronomy. Studying the stars was a way of getting themselves out of the mundane world, into a world that was more transcendent, a world that was beautiful, a world that was eternal.

NARRATOR: For the Church, there was also a practical reason to study the heavens. The sky was both a clock and a calendar.

Behind the walls of convents, sunrise and sunset defined the cycle of morning and evening prayer. Each spring, the planting of the gardens would commence with the coming of the Equinox. The Winter Solstice foreshadowed Christmas, and the phases of the moon fixed the exact dates of Lent and Easter. The Church used the calendar to give spiritual significance to Aristotle's earth-centered astronomy.

GUY CONSOLMAGNO: The images were very useful for teaching theology. The earth is not the center of the universe in that it's in a privileged place. It's at the bottom of the universe. Only hell is lower. And there's a chain of creation reaching up to heaven.

As a young man, Galileo toyed briefly with the idea of becoming a priest. Instead he entered the University of Pisa as a medical student in 1581. The curriculum at Pisa was prescribed by the Jesuit authorities in Rome.

Even the anatomy diagrams in Galileo's textbooks had to be approved by the Jesuits. Galileo left medicine behind after only a few months and began, instead, to study mathematics. Among the many writings he left behind is an eloquent tribute to the power of mathematics to illuminate the world.

GALILEO: This grand book, the universe, could only be understood if one learned to comprehend the language and the alphabet in which it is composed. That is, the language of mathematics—triangles and circles, geometric figures—without which it was impossible, humanly impossible, to understand a word of it. Without it, one wandered as in a dark labyrinth.

JULIAN BARBOUR: It's so confusing, the world. Where do we find truth? Where is the real truth?

And there was a sort of consensus, which Galileo felt very deeply, that in mathematics you had real truth. If there was anywhere where human beings could think like God, it was when they were thinking about mathematics.

So, let's combine precise observation of nature, and let's apply that one technique of thought which we know God will share with us, which is mathematics, and let's put the two together and then we will have a really secure foundation on which we can study things.

NARRATOR: Galileo brought his mathematical studies to the University of Padua, 40 miles from Venice, far enough from Rome to be beyond the influence of the Jesuits and their officially approved curriculum.

INGRID ROWLAND (American Academy in Rome): In Padua itself was a university. It was founded in 1222 by breakaway students. It wasn't chartered by a king or by a pope. It was absolutely free and had the free Republic, as Venice, as its supervisor. So getting a job in Padua was as close to getting academic freedom as you could want, certainly in Italy and probably, rather uniquely, in Europe.

NARRATOR: The city of Venice was just a ferry ride from Padua, and it was here that the young professor spent many holidays. Galileo began a liaison with a Venetian woman named Marina Gamba. Little is known about her, but she was far from Galileo's social equal. The affair made his life complicated, but was not unusual even among faithful Catholics.

DAVA SOBEL: Yes, he loved to have a good time. He enjoyed his wine. He enjoyed many forms of pleasure. But that didn't make him a bad Catholic, especially at a time when even the popes had illegitimate children.

NARRATOR: Galileo himself had three illegitimate children. The eldest, Virginia, was born in 1600.

DAVA SOBEL: The birth records in Padua say that she was "born of fornication," because Galileo was not married to her mother. They didn't live together. I suppose he might have lived with her if he'd wanted to, but his house was full of students, and he worked at odd hours, so he didn't really keep his mistress or his children in the house where he lived.

NARRATOR: Despite these complications, Galileo thrived in the free air of Padua, becoming an ambitious scholar.

Always fascinated by new devices, Galileo heard that a craftsman from the Netherlands had found a new use for common eyeglass lenses. The first telescope to reach Venice was a toy, a novelty built to amuse partygoers.

ALBERT VAN HELDEN: Spectacles, compared to telescopes, are very low tech. But they had been around for several hundred years. It was only when lenses became available in certain ranges of strengths that one could take the weakest convex lens and combine it with the strongest concave lens and get an appreciable magnifying effect.

NARRATOR: Galileo set out to turn the Dutchman's toy into a useful device.

GALILEO: Hearing reports of a new invention from a lens maker in Holland, I determined to fashion a device for myself and was able to make considerable improvements in it.

ALBERT VAN HELDEN: Galileo realized that spectacle makers could not give him the lenses that he needed in order to make this device more powerful. They just weren't good enough and they weren't the right strength. And so, in order to improve the instrument, he had to teach himself to grind lenses. And that is extremely difficult, and it certainly was in 1610.

NARRATOR: At first, Galileo was only interested in the optics of the telescope. With his improved lenses he increased its power tenfold. But his lenses did more than magnify. By reshaping these pieces of glass, Galileo would eventually reshape our view of the world.

With his telescope, Galileo first set out to make some money. The Naval Arsenal of Venice was the greatest in all of Europe. What if the Arsenal had a way to spot enemy ships hours before they appeared in the harbor? Wouldn't this give the Navy a distinct advantage?

Installing his new device at the top of St. Mark's Tower, Galileo arranged persuasive, real-life demonstrations.

GALILEO: Numerous gentlemen and senators, more than once, climbed the stairs of the highest bell towers of Venice to observe vessels so far away at sea that two hours or more were required before they could be seen by naked eye without my spyglass.

NARRATOR: From within the Venetian senate came a handsome order for Galileo to supply the arsenal with spyglasses. Galileo was given a generous lifetime salary for his service to the republic. Part scientist and part self-promoter, for now, his future seemed bright. But soon his telescope would launch a dispute which would threaten to destroy its creator.

Galileo's daughter was just nine years old on a November night in 1609. That was the evening when Galileo first pointed his new spyglass at the moon setting behind the hills of Padua and began to sketch what he observed. It was the start of eight weeks of sleepless nights spent in his tiny courtyard, suddenly transformed into the world's premiere, astronomical observatory.

GALILEO: From my observations, I've been led to the opinion that the surface of the moon is not smooth, uniform, as a great number of philosophers believe it and the other heavenly bodies to be, but is uneven, rough and full of cavities and prominences, being, not unlike the face of the earth, relieved by chains of mountains and deep valleys.

NARRATOR: The moon Galileo saw was Earth-like, and he sketched its features with Earth-like detail. If the surface of a heavenly body resembled the Earth, perhaps the heavens and earth were not as different as everyone thought.

ALBERT VAN HELDEN: Galileo had observed the Moon through a series of phases, and he apparently made some adaptations to his instrument, and, uh, began exploring the planets.

Now, Jupiter was the one that was in the most favorable position for observation. It was closest to the Earth at that particular point. And when Galileo looked at Jupiter he saw three very bright little stars, invisible with the naked eye, on a line with Jupiter, and he remarked on that.

He had no idea what they were. I mean, he thought that, of course, they were what they used to call "fixed stars"—in other words, the things that we call stars.

But then, since there's such a remarkable configuration, he came back to it the next night. And well, yes, there were still three stars, but their relative position to Jupiter had changed. And so, within a week, he realized that, "What we have here are moons of Jupiter. Like the Moon goes around the Earth, these moons go around Jupiter, and there are four of them."

GALILEO: Four planets, never seen from the beginning of the world right up to our present day. These wandering little stars make their journeys around the planet Jupiter with a marvelous speed and with mutually different motions, like children of the same family.

NARRATOR: In a little more than a week, Galileo had found the first new astronomical bodies to be discovered since ancient times. This discovery clashed with the common belief that the heavens revolved around the earth alone. Eventually it would bring him head to head with church dogma, but for now Galileo was exuberant.

ALBERT VAN HELDEN: He rushed into print because he knew he could get scooped. If we date the discovery from the first observation of Jupiter's satellites until he realized they were moons, uh, January the 7^th to January 15^th, he was in print...by March the 12^th the book was out.

NARRATOR: Sidereus Nuncius, The Starry Messenger was an enthusiastic announcement of telescopic astronomy. The first printing sold out within days, and news spread across Europe of Galileo and his amazing telescope. Galileo became an advocate for his new astronomy and for scientific observation. But as his fame spread, so did his reputation for arrogance.

GALILEO: Sir, your ignorance of astronomy confounds me. I think, if you spat on the ground you'd see a new star in the shine of your own saliva. And as for you, my lord, I'm astonished that you persist in trying to prove something to me with the testimony of expert witnesses that I can perfectly well find out for myself with a simple experiment. See, witnesses...witnesses have...have the useful, of course, in difficult matters in the past, eh...I mean, a judge might, for example, call a witness to establish whether Luigi stabbed Giovanni. But he's not going to call a witness to establish that Giovanni was stabbed at all, because he's got the wound in front of him. Do you, do you see? He can see it with his own eyes.

NARRATOR: Modesty never came easily to the young professor.

GALILEO: I render grace to God that it has pleased him to make me alone the first observer of an admirable thing kept hidden all these ages.

NARRATOR: By making the invisible now visible, the telescope was starting to revolutionize astronomy. From ancient times, astronomers had tried to account for the observed motions of heavenly bodies by assuming that they were attached to transparent crystal spheres, rotating sphere within sphere. The Greek astronomer Ptolemy worked out the system in great detail to explain the motions of the Sun, the Moon, the stars, and the planets, all that could be seen with the naked eye. At the center of Ptolemy's intricate system sat the Earth, solid and unmoving.

OWEN GINGERICH (Harvard-Smithsonian Astronomer): The Ptolemaic system was filled with ingenious geometrical devices. It made it possible for people to compute where the planets were to be, and this was useful, let us say, for astrology. It was useful if you just wanted to keep track of where things were in the sky, but it wasn't perfect.

NARRATOR: Sixty years before the telescope, a Polish clergyman, Nicholas Copernicus, noticed that the calculations needed to predict the positions of the planets in the sky would be simplified if he assumed that the Sun, rather than the Earth, were at the center of the Universe.

OWEN GINGERICH: Copernicus described the Sun as though on a royal throne, ruling the planets that circled around it. It was a wonderful system aesthetically. For decades after his book, most astronomers simply suspended judgment. The reason was that there was no observational evidence that the Earth moved. In fact, it seemed almost silly that the Earth moved.

NARRATOR: In the Copernican system the Earth was never still. It had two separate motions, revolving around the Sun each year and spinning on its axis once each day.

OWEN GINGERICH: Copernicus was a little bit reluctant even to publish his system, because he figured there would be a lot of criticism of it.

JULIAN BARBOUR: The thing that Copernicus suggested just made him really the laughing stock of Europe, because he was saying here is the Earth—is actually whizzing around at a huge speed about seven or eight hundred miles an hour—that's just going round on its axis. And in addition, it's going round the Sun at about 30 miles a second. I mean, they were saying, "this is just absolutely ridiculous. I mean, look at the ground. It's as solid as you can see. Clearly the Earth is not moving. Nothing could be more obvious than the fact that the earth isn't moving. If it was moving everything would be flying off it. I mean church steeples would fall down. Birds couldn't keep up with it. Clouds would go disappearing over the Western horizon," and things like this.

NARRATOR: Galileo had read Copernicus and already suspected that the Copernican system was correct, but even with his telescope he did not see a way of proving that the Earth moved around the Sun.

First, he would make a move himself, back to Tuscany, the land of his birth. Florence, the Tuscan capital, held a great attraction for the rising young star. The exalted home of Dante and Michelangelo, Florence had been ruled for centuries by the Medici family. A source of great wealth and power, the family dominated banking and commerce, and was influential in church matters. The spheres of the Medici coat of arms adorned palaces throughout the city. For Galileo there could be no greater honor than to have as a patron Duke Cosimo de Medici.

ALBERT VAN HELDEN: Galileo is looking for social improvement. And he has tried several times to get patronage from de Medici, and here he sees his ticket. The Grand Duke of Tuscany is one of four brothers; Galileo has discovered four moons around Jupiter. Shrewdly, he wants to name them after his prospective Medici patrons.

NARRATOR: A copy of the Starry Messenger, Galileo's finest telescope, and a personal plea are dispatched to Florence.

GALILEO: It is up to our sovereign whether I spend the rest of my days here in Venice or return to Florence. If I'm to return, I desire that your Highness shall give me leave and leisure without my being occupied in teaching. Finally, I desire of his Highness that, in addition to the title of mathematician, he will annex the title of philosopher.

ALBERT VAN HELDEN: Galileo points out how bad his position is at Padua, how he doesn't have any time for research, how he's overrun by students, and what he would like would be to serve a great ruler and to do research.

NARRATOR: A few weeks later a letter was issued from the Medici offices at the Uffizi inviting Galileo to join the Medici Court as mathematician and philosopher. Here he would be at the center of Florentine intellectual and social life.

DAVA SOBEL: Florentines were known for arguing about everything, having lively discussions, and that's what Galileo was about. And there was tremendous appeal for him and even more status in being attached to the Court of the Grand Duke. And there were friends of Galileo's who warned him that he wouldn't be as safe in his radical beliefs in Tuscany, that, that Venice had, had more of a sense of independence from the Pope than Tuscany had.

NARRATOR: The Medicis were rich and cultured, but they were also beholden to Rome. With strong ties to the Vatican, the family had produced many popes and cardinals. They could not have known the difficulties their new philosopher would bring upon himself.

Leaving behind his mistress and his young son, Galileo placed his daughter Virginia and her younger sister, Livia, in the Convent of San Matteo at Arcetri, outside Florence.

DAVA SOBEL: It was not unusual in Italy at that time to put young girls in a convent for safekeeping, to make sure they remained virgins, although it was no guarantee. But, because Virginia was illegitimate, her chances for marriage were more complicated than they might have been. She would have needed a large dowry and the proper husband. And Galileo was not a wealthy man.

NARRATOR: Young nuns like Virginia were expected to loosen their ties to the outside world. Even their families would be kept at a distance.

DAVA SOBEL: To look at what happened to the father/daughter relationship once Virginia had taken her vows gives one a sense of terrible loss, almost a living death. There's a physical barrier between them in this grille and, yet, that again overlooks the tremendous pride of the typical Italian Catholic family then, of having a priest in the family, a nun. You were putting that child in the service of God, and what could be more important?

OWEN GINGERICH: I would not say that his placing his daughters in the convent was in any sense an act of faith on his part. In fact, it was an avenue of something to do with them because, after all, uh, their mother had only been his mistress. They were illegitimate, hence, presumably, not marriageable. Uh, so, so what to do? He supported them but not very lavishly.

NARRATOR: Over the course of 20 years, daughter Virginia would write dozens of private letters to her father from behind the convent walls. Galileo's servants carried the letters in baskets of food or clothing. Many of Virginia's letters survive, although all of her father's responses have been lost. Her letters suggest an enduring bond between the two despite the harsh conditions of convent life.

MARIA CELESTE: Most illustrious lord, Father, my room is terribly cold now. And I cannot see how I will be able to stand it, Sire, unless you help me by lending me one of your bed hangings, one that you will not need to use. I am returning the rest of your collars, which I have sewn. I pray that the Lord grant you the greatest possible wellbeing. From San Matteo in Arcetri, your affectionate daughter.

NARRATOR: In contrast to his daughter's life, Galileo's was becoming more comfortable and secure enough to take a risk, even in the doctrinaire atmosphere of Florence. Galileo adopted the view that Copernicus was right. The Sun, not the Earth, was the center of our planetary system. Months passed as he struggled for a way to prove it.

ERNAN MCMULLIN (University of Notre Dame): For him, demonstration was the mark of science. For something to count as a scientific claim, it had to be demonstrated. It had to be conclusively shown to be the case. Anything short of that was called conjecture or opinion.

NARRATOR: While he searched for a demonstration, a letter arrived from one of his followers, Benedetto Castelli, suggesting that the planet Venus could hold the key.

BENEDETTO CASTELLI: My dear Galileo, if Copernicus is correct and Venus revolves around the Sun rather than the Earth, it is clear that she would be seen, not unlike the phases of the moon, sometimes as a crescent and sometimes not. Pray tell me if, with your wonderful telescopes, you have noticed such an appearance.

NARRATOR: To the naked eye, Venus was just a point of light, but through his telescope Galileo saw the planet as a disk. Over a period of months Venus changed from a small disk to a larger crescent. Galileo immediately grasped that in a sun-centered system this crescent would appear as Venus circled in an orbit between the sun and the earth. Venus must be revolving around the Sun rather than the Earth.

GALILEO: With absolute necessity, I had to accept the theory of Copernicus that Venus revolves around the Sun, as do all the planets, including the Earth. No longer did we have to endure any argument, however feeble, from persons whose philosophy had been badly upset by this new arrangement of the universe.

NARRATOR: But the argument was just beginning, and Galileo utterly misjudged the opposition. Opportunistic priests in Florence announced from their pulpits that Galileo was spouting dangerous new ideas. A chorus of jealous academics, bruised by Galileo's arrogance joined the clamor. Galileo counted on his Medici patrons to protect him. But that protection started to erode when the Grand Duke Cosimo's mother began to have doubts.

OWEN GINGERICH: One of Galileo's young protégés, uh, was teaching mathematics and astronomy, Benedetto Castelli, and he got invited to one of the intellectual brunches that Cosimo's mother the Grand Duchess Christina, uh, was wont to put on. And so the conversation got around to these satellites of Jupiter...

NARRATOR: Galileo had named the moons of Jupiter for the Medici family, but the Grand Duchess questioned their authenticity.

OWEN GINGERICH: "Are they real?" "Oh, yes," said Castelli, "even the Jesuits down in Rome have confirmed this." And then she switched the subject. She said, "What about Copernicus, and what about Joshua at the Battle of Gibeon when he commanded the Sun and not the Earth to stand still."

NARRATOR: In the Book of Joshua, the Lord halts the movement of the Sun allowing the Israelites a bit more daylight to defeat their enemies. This, and a half dozen other biblical passages, seemed to suggest that it was the Sun which moved, not the Earth. The Grand Duchess Christina worried that her new court philosopher was contradicting the Bible.

Galileo answered Madama Christina with a letter that went far beyond astronomy.

GALILEO: Yeah, I agreed to...with Madama Christina, that the Holy Scripture never lies. The decrees contained therein are absolutely true and inviolable. Now, I should have added that, though the scripture never errs, its interpreters and expounders are liable to err in many things, when they base themselves, always, on the literal meaning of the words.

DAVA SOBEL: Galileo was honest when he said that if the Bible seemed to say something different from what science said, then you had just misinterpreted the Bible.

GALILEO: I believe that the Holy Writ exists in order to persuade men of the truths necessary for salvation. But it's, it's not necessary that the same God that gave us our speech and our senses, our intellects, would have us put aside those things, particularly in the case of, of, of, of science, where it's...there's not the smallest mention in the Holy Bible. I mean, if the Sacred Scribes meant to teach men astronomy, then why did they leave it out?

NARRATOR: Galileo's outspoken letter to Madama Christina, intended to resolve the discrepancies between science and the Bible, came to be seen as an assault on the Bible itself.

ALBERT VAN HELDEN: And that letter gets circulated, and local priests read it and they're outraged. And they're sending copies to Rome, and they're saying to people at the Inquisition, "You should investigate Galileo. You should do something about this. This guy's a heretic."

NARRATOR: Galileo surely knew what could happen to heretics when the cardinals of the Inquisition organized to purify society by combating heresy. Much of their work was the banning of books, but the Inquisition also had the powers of both torture and execution. Rome's dungeons had seen the end of many heretics, including the infamous Giordano Bruno, fallen priest and occult dabbler in science.

To the Inquisition, extreme measures were justified. Whatever pain was inflicted to save the soul of a heretic was nothing compared to the pain of eternal damnation.

INGRID ROWLAND: One of the things that the papacy wants to show to a united Europe, Catholics above all, is that there's no tolerance for dissent, that dissent will be routed out and punished. A Scottish heretic is burned at the stake with a pitch shirt so that he'll burn all the more brightly. And Bruno, who's burned alive—which is quite unusual, most people are burned when corpses—is one of a whole series of people who are put to death as a way of showing that Orthodoxy will be enforced.

NARRATOR: Giordano Bruno was a priest and a new age charlatan who denied the divinity of Christ, but like Galileo he had described a vision of the universe which had the Earth spinning around the Sun.

ERNAN MCMULLIN: There's been a lot of different views as to how much the Bruno parallel weighed on Galileo. Undoubtedly it must have had some influence—he realized of course what had happened to Bruno. I think...I doubt if he thought himself to be in danger of that. But at the same time there was that looming thing in the background that if he defied the inquisition here, he could suffer very severe penalties.

NARRATOR: Behind Bruno's execution was Rome's greatest Inquisitor, the "Hammer of Heretics," Roberto Cardinal Bellarmine. Now, years later, this same Cardinal Bellarmine was receiving reports about Galileo.

ALBERT VAN HELDEN: Church theologians have been alert to the possible implications of what Galileo is doing, and there is slowly somewhat of a Galileo file building in Rome, in, in, in the Inquisition. And as these noises coming from the lower tier of the clergy in Florence become louder and louder and louder in Rome, Galileo goes to Rome to try to argue his case.

GALILEO: I decided to stand openly, alone, on the theater of the world, to bear witness to the sober truth. I believe that good philosophers, like eagles, fly alone, not in flocks like starlings. I wanted people to understand that Nature not only gave them eyes to see her works, but brains to make them capable of understanding them.

NARRATOR: Galileo journeyed to Rome in the winter of 1616. As a member of the Medici Court, he became a guest of the Tuscan Ambassador at the palatial Villa Medici. Perched on a hill overlooking the city, from his balcony Galileo could see the Domes of the Vatican as he eagerly awaited his meeting with the Inquisitor, Cardinal Bellarmine.

OWEN GINGERICH: Galileo tended to overestimate his own powers of persuasion. He thought that if he could go down to Rome and talk to some of the hierarchy, he could easily persuade them to remain open on the question of, "was the Earth moving or was the Earth fixed."

NARRATOR: Theologians listened as Galileo confidently made the case for Copernicus.

ALBERT VAN HELDEN: Galileo is fully committed to the Copernican theory—and we mustn't see the church there as a monolith—and he goes to see bishops and cardinals and theologians, and he argues his case, of course, very passionately. However, the Medici ambassador to the Vatican is writing home, "Listen, Galileo needs to be calm, to shut up, and not go around arguing his case so much."

NARRATOR: In his letter the ambassador worried that the Medici family might be drawn into an ugly controversy.

MEDICI AMBASSADOR TO THE VATICAN: Galileo is passionately involved in this fight of his, and he may well get himself in serious trouble, along with anyone who supports his views. This business is not a joke, and the man is staying here under our protection.

ERNAN MCMULLIN: He thought he could convince the more open-minded theologians in Rome of the merits of the Copernican doctrine. He thought, also, that he could convince them that the matter of astronomy was not a matter for theologians in the first place. And so, even though he must have acutely known the powers and the dangers of opposing the Inquisition, he evidently thought his own powers of persuasion were such that he could bring them around to his view.

OWEN GINGERICH: But as he began talking up the Copernican system, uh, he also raised alarm signals, and the conservatives in the Catholic Church decided that something had to be done.

NARRATOR: Galileo actually welcomed the chance to make his case to Cardinal Bellarmine. He had heard that Bellarmine had an interest in astronomy and was fascinated by the telescope.

INGRID ROWLAND: Bellarmine himself, who began interested in science, as he progressed in science, realized that there were a number of aspects to scientific discovery that threatened Orthodoxy as he saw it, and realized that science might interfere with his theology, and decided at that point to shut down his scientific investigations. And he made a personal choice to opt for piety rather than scientific curiosity, which never, I think, is a completely satisfactory solution. And it may explain some of his virulence in going after what he perceives as scientific heresy.

NARRATOR: The pious Cardinal Bellarmine had countenanced burning men alive, but he was ethereal and unworldly. Even the ruling families of Italy considered the Cardinal a bit too saintly. For Galileo, counting on the influence of his Medici patrons, the Cardinal's incorruptible piety was not good news. But Galileo never even had a chance to persuade Bellarmine. Three days before his planned meeting with the Cardinal, the Holy Office of the Inquisition met at the Collegio Romano to vote on the theories of Copernicus.

ALBERT VAN HELDEN: The theologians get involved and they're giving their professional opinion about this matter. And that professional opinion is that the proposition that the Sun is the center of the world, and that the Earth is going around the Sun are propositions that are, in view of the Scriptures, heretical.

NARRATOR: The vote was 11 to nothing. The hypothesis that the Earth moved was foolish and absurd. The belief that the sun was the center of the world was a matter of formal heresy. Cardinal Bellarmine would use his meeting with Galileo to deliver the edict.

ALBERT VAN HELDEN: Galileo will be told formally not to hold and defend the Copernican position, and what's more, in the decision it is stated that, should Galileo refuse this order, he will be silenced.

NARRATOR: Galileo is forced to turn his back on Copernicus, whose work is added to the Index of Prohibited Books.

GALILEO: When the theologians were merely thinking of prohibiting Copernicus' book, I held it to be true. Then those learned gentlemen actually did prohibit the work, declaring its opinions to be false and contrary to scripture. Knowing, as I do, that it always behooves us to accept the decisions of the authorities, guided as they are by a higher insight than my humble brain could ever attain to, I declared my former defense to be merely a poetical conceit, a dream, a fancy of my own, a mere chimera.

NARRATOR: Galileo had been certain that he could turn the Church to his new astronomy, but instead matters had become much worse. With the stroke of a quill, the Church had banned Copernicus and, for now, muzzled Italy's greatest scientist. If there were to be a struggle between religion and science, religion had won the first round.

Only months after Galileo's collision with the church his oldest daughter embraced one of its most ancient rituals. Renouncing her worldly possessions, she surrendered her given name, Virginia, and chose for herself the name Sister Maria Celeste—by tradition, a name whispered to her by God.

PRIEST: IN LATIN.

MARIA CELESTE: IN LATIN.

DAVA SOBEL: I think she chose her name for him—Maria Celeste—because he was so interested in the stars. Of course, it's not an out of the realm name for a nun, it could be chosen completely in a religious context and would still make sense, but she was so clever that I feel certain that that was her intent.

NUN: IN LATIN.

MARIA CELESTE: SUOR MARIA CELESTE

PRIEST: IN LATIN.

DAVA SOBEL: Although their lives were difficult, many of the intelligent young women actually chose the convent because they knew that would be the place they could think and write. And they had more status in society than they might have had even as married women with children.

Galileo was a good Catholic so he had no interest in fighting the Church. What he was about, from the very beginning of his public support of Copernicus, was to bring the Church to an understanding of the theory and of the theory's complete lack of threat to the Church. If the Church struck a defensive posture about something that looked like it had a very good chance of being true in fact, the church would face embarrassment.

NARRATOR: Galileo vented his frustration in outspoken letters to close friends and supporters.

GALILEO: To ban Copernicus, when his doctrine is daily reinforced with many new observations, seems, in my judgment, to be a contravention of truth, hiding and suppressing her when she is most clearly and plainly revealed, despite the advances of Copernicus, even when his theories are couched in mysteries so sublime and concepts so profound, that hundreds upon hundreds of the most acute minds have still not pierced them.

NARRATOR: Cardinal Bellarmine may have slammed the door on Copernicus, but his philosophy left one small opening for Galileo to seize upon.

ALBERT VAN HELDEN: Cardinal Bellarmine had argued that the Church can change its opinion, but only if there is real proof that the Earth goes around the Sun.

NARRATOR: The church did not accept Galileo's claim that the phases of Venus proved a Sun-centered universe. So he set out to find physical proof that the earth was moving.

From his younger days in Venice, where the water level could rise or fall many feet in a day, Galileo had developed an interest in the tides. Just as water sloshes back and forth in a swinging container, Galileo reasoned that the earth, as a giant vessel spinning on its axis, might cause the seas to rise and fall twice a day. He believed that the tidal motions of a body of water like the Mediterranean might offer proof that the earth moved.

GALILEO: To make the water contained in the basin of the Mediterranean behave as it does, surpasses my imagination, and perhaps that of anyone else who enters more than superficially into these reflections. Some say Aristotle, after observing the tides for a long time from some cliffs, plunged into the sea in a fit of despair and willfully destroyed himself for the mystery of them.

ALBERT VAN HELDEN: Up to this point he's been very bold. In 1616 he had, in fact, circulated...given to some Cardinals, a tract on the tides in which he argued that this is actual, physical proof that the Earth moves.

ERNAN MCMULLIN: He does think, enthusiastically think, passionately think that he has the key here to prove, to demonstrate the Earth's motions by turning to the motions of the tides. Now we know that that is, in fact, incorrect, but he thought he had it.

NARRATOR: For once, Galileo's intuition failed him. Although a link between the tides and the phases of the moon had been observed for centuries, Galileo rejected the idea. For him, the suggestion that the moon could influence events on Earth smacked of astrology or the occult. The search for physical proof of the Earth's rotation would take another 200 years.

GALILEO: "I don't know"—what a beautiful expression that is—so candid in its honesty. It's better than the occult explanations offered by certain philosophers. The number of people that can reason well is much smaller than those that can reason badly. If reasoning were like hauling rocks, then several reasoners might be better than one. But reasoning isn't like hauling rocks, it's like, it's like racing, where a single, galloping Barbary steed easily outruns a hundred wagon-pulling horses.

NARRATOR: If, like a galloping steed, the earth is hurtling through space, why can't we feel the movement? Galileo seized on the paradox that the Earth could spin on its axis fast enough to cause day and night without people sensing the motion.

JULIAN BARBOUR: What is really exciting about Galileo and you see it exactly the same in Einstein, too, was the way he, he, he picked up what seemed to be an absolute impossibility. He said, "we have this incredibly strong evidence that the Earth is not moving. Everything that our senses tell us, is that the Earth is not moving, and yet Copernicus has got these rather strong arguments from astronomy to suggest that the Earth is moving." So then, Galileo says, "Well, this actually should tell us something very deep about how nature works."

NARRATOR: So he devised an intriguing thought experiment. He used a horse to represent the motion of the earth. If a rider dropped a ball while standing still, the ball would, of course, fall straight down, landing beside the horse. But what would happen if the same rider dropped the ball with the horse at full gallop?

In Galileo's experiment, the forward motion of the horse would be communicated to the ball through the rider's hand. As the ball dropped, it would continue to move forward, and would still land beside the horse, just as it had done when the horse stood still.

To Galileo, when the horse and the ball shared the same motion, it was as if the motion did not exist. If the Earth were moving, could we be carried along with it and not be conscious of its motion?

JULIAN BARBOUR: There is a sort of a principle of relativity where, if you're sort of moving with the Earth, everything shares the same motion. Not only is the Earth moving, but I'm sharing that motion as well. And, therefore, it is all hidden.

It was probably the first really great thought experiment in, in physics. He, he, in fact, he was so confident of the result, he never even bothered to do the experiment to show it was right.

NARRATOR: Despite his troubles with the church, Galileo was still well supported by the Medicis. He moved closer to his daughter, to a hillside villa outside of Florence.

FRANCO PACINI (Osservatorio Astronomico, Arcetri): Florence is surrounded by these hills, and Arcetri, like the others, was a place where the wealthy families of Florence would have their villas. There were also normal farmhouses. There were convents. It was relatively difficult to get into town. And when the daughter of Galileo was in a convent nearby, down there, when she also found, for the father, a location next to the convent, where he had fields, he had olive oil. The daughter was also telling him that it was producing wine, but that he should not drink too much wine.

DAVA SOBEL: Maria Celeste is extraordinary in every way. She, she lives in this cloister, she is cut off from the world and yet she has her hands in everything. The real estate market, the foods, the small favors, the laundry—she never did lose her sense of being a dutiful Italian daughter.

NARRATOR: The aging Galileo constantly complained of terrible ailments.

GALILEO: I find this very thin, cold air in Florence, uhh, to be most cruel to my head and to all the rest of my body. Constipation, discharge of blood, colds, over the last three months, I've been in such a state of despair, that I'm practically confined to my room, no, to my bed, without the benefit of either sleep or rest.

NARRATOR: Somehow, Galileo's every passing need, his ailments, his interests were known to his daughter behind her convent walls.

MARIA CELESTE: Most illustrious lord, Father, please do not forget the grave condition you are in, and have a little more love for yourself than for the garden. In this season of Lent, make this one sacrifice, if only for me: deprive yourself, for a time, of the pleasure of the garden.

NARRATOR: Sacrifice and exhaustion were conditions Sister Maria Celeste knew first hand.

DAVA SOBEL: The convent where Virginia became Maria Celeste was a particularly poor convent. Being a convent of the Poor Clares it was, of course, committed to poverty. That was their way of life, their chosen way of life. So they expected to have little to eat and to be cold in the winter and to experience harshness in, in every day's every moment.

MARIA CELESTE: Sire, I assure you that I am never vexed by boredom, but sooner by the hunger, caused I believe by the coldness of my stomach which does not get the full complement of sleep it requires. I only tell you this to excuse myself for the haphazard appearance of my letter, as I was compelled to put down and then take up my pen again more than once, before I could complete it.

DAVA SOBEL: Maria Celeste is a bright personality. She's in a dark place—there's at least one nun who tries to kill herself in this convent—and yet, Maria Celeste always has a way of seeing the higher purpose, the higher good, that never fails her.

NARRATOR: Such graceful submission to the ways of the faith was not a path Galileo would follow. He could never emulate his daughter's obedience to the Church, even under the watchful eyes of the Inquisition.

The church taught that all heavenly bodies were unchanging and pristine, but Galileo's telescope continued to reveal a cosmos quite unlike the officially accepted truth. Even on the bright surface of the sun itself, Galileo observed dark blemishes, which he named "sunspots." He could not have known that the spots were actually magnetic storms, but his descriptions of them were remarkably accurate.

GALILEO: Sunspots are generated and decay in longer and shorter periods. Some condense and others greatly expand from day to day. They change their shapes, and some are most irregular. They must be enormous in bulk, being either on the Sun or very close to it.

ALBERT VAN HELDEN: Galileo gets into an argument with a German Jesuit mathematician named Cristoff Scheiner about the nature of sunspots. The German argues that the spots are, in fact, little satellites that go around the Sun. Whereas Galileo argues that these spots are really either on the surface of the Sun or very close to it and that they're sort of like, perhaps, clouds.

NARRATOR: If the Jesuit were right and the spots were independent satellites, then the surface of the sun would remain pristine as doctrine demanded.

ALBERT VAN HELDEN: Sunspots have a very irregular appearance, and if you can bring that out visually then the argument that these are satellites of the Sun becomes absurd.

And so Galileo very carefully planned the publication of his letters of sunspots. They're all oriented properly, so that you can see them from one day to the next being sort of born on the Sun and dying there. All of a sudden, in the middle of the Sun, there is...appears on one day a little spot. And the next day it grows, and then it grows some more. And then it slowly goes off the edge.

Clearly there were spots on the Sun that are so irregularly shaped that they can't possibly be satellites.

There is a visual essay in which you have uninterrupted views of sunspots.

NARRATOR: Galileo produced a series of intricate engravings, recording the daily changes of his sunspots. The continuous movements of the blemishes suggested that the sun might actually rotate on its axis.

ALBERT VAN HELDEN: The visual evidence is accepted by both Copernicans and people who still believe that, that the Earth is the center of the universe.

But it is the interpretation of that, of that evidence...and more and more and more you see these conservative astronomers, then, stretching, because if you can say that these are satellites of the Sun, you can still say that the Sun is perfect.

NARRATOR: Galileo knew that his adversaries were wrong. It didn't matter if the Jesuit mathematician wished the sun to be unblemished. Galileo had demonstrated real spots on the surface of the real sun.

Seven years after the inquisition banned Copernicus, news reached Galileo that a new pope had ascended the throne of St. Peter. The College of Cardinals had chosen a member of a prominent Tuscan family, a man Galileo actually considered a friend. Maffeo Barberini would become Pope Urban VIII.

GUY CONSOLMAGNO: Urban VIII is an interesting choice for a pope at that point. He's a member of the Barberini family, and the old joke was, "What the barbarians didn't loot from Rome, the Barberini's did."

INGRID ROWLAND: His coat of arms, when he was a young prelate, had three horseflies. And horseflies became increasingly undignified for someone who's rising that far in the Church. And so the horseflies, at a certain point, change into busy bees. And Maffeo Barberini therefore becomes the personification of a hard working, productive individual.

GUY CONSOLMAGNO: Everything that you see that is a sign of the beautiful Renaissance Rome was either started, continued or inspired by what Urban VIII had done.

INGRID ROWLAND: At the bottom of the Via Veneto you have a fountain with three Barberini bees, reminding you which pope gave you this water fountain and also reminding you that you shouldn't be just lounging around at the fountain. You should be making like the bee and producing honey.

ALBERT VAN HELDEN: The new pope is a great fan of Galileo. He had written poems to Galileo. And all of a sudden, then, the situation appeared very different from the way it did in 1616.

NARRATOR: When news of Urban VIII's elevation reached her convent, Maria Celeste hoped that her father's silencing at the hands of the church would be over. Galileo secretly shared a letter he received from his old friend, the Pope.

MARIA CELESTE: Father, the happiness I derived from the letter written to you by the Supreme Pontiff was indescribable. His note so clearly expresses the affection this great man has for you. I have read and reread it, savoring it in private, and here I return it to you, as you insist, without having shown it to anyone.

NARRATOR: Galileo made the difficult two-week journey to Rome especially to meet with Pope Urban VIII. The two old friends had a series of conversations as they strolled the paths of the Vatican.

ALBERT VAN HELDEN: The Pope and Galileo walked around in the Vatican gardens talking about various things, and of course one of the things they talked about was whether or not Galileo could publish on the Copernican theory. And the Pope told him that, as long as he limited himself to speaking about it hypothetically, there would be no problem.

NARRATOR: So as long as the Copernican view that the Earth moved around the Sun was presented only as a hypothesis, one theory among many, Urban VIII would allow it to be debated.

ALBERT VAN HELDEN: Galileo came away from these meetings feeling that this was the time to write his big book on cosmology which he'd been promising since 1610.

NARRATOR: Now 60 years old, he threw himself into his new book. The Pope had given Galileo license to embark on what he hoped would be his most important work. Writing in Italian not Latin, laying out his most persuasive evidence in a witty, popular style, Galileo set out to entertain and win over everyone who read it to the Copernican worldview.

Maria Celeste's letters suggest that her father permitted her to read his unfinished manuscript.

DAVA SOBEL: There seems to be a genuine interest on her part in his work. Of course she's self-denigrating. She always says, "I'd love to see what you're writing, if you think I could understand it. And of course I promise not to talk about it to anyone else."

So they have an intimacy on the work level. And possibly the most interesting thing that comes out of the letters is this strong indication that, when he's working on the Dialogue, their back and forth starts to include something called "cuttings," which are obviously pieces of a manuscript. And it seems that she is the one who's actually preparing the manuscript.

NARRATOR: Months of writing stretched on as sickness interrupted his work. Finally, after five years, the end was in sight.

GALILEO: By the grace of God, I've got on the right path. The book will be quite large and full of novelties which, by writing it in the manner of a dialogue, I can introduce without affectation or drudgery. If I can just survive this winter, I shall bring it to an end and publish it immediately.

NARRATOR: Galileo finished his great book on Christmas Eve, 1629. It was called Dialogue on the Two Chief Systems of the World.

ALBERT VAN HELDEN: It is a rhetorical masterpiece. Galileo explains the new view of the world. It is a debate about the world systems. Is the Sun the center of the universe or is the Earth the center of the universe? He brings forward all his wonderful discoveries with the telescope and, you...you're just pulled along by this narrative.

NARRATOR: Galileo creates three spirited characters, noblemen of Venice. The first character, the host, prompts a debate between his two talkative guests. One of the visitors clearly speaks up for Copernicus and Galileo. But the other guest, Simplicio, the simpleton, is a comic foil, mouthing the church's doctrines on science and philosophy.

Galileo got permission from a friendly censor to publish his book in Florence. He knew the censors in Rome would be much more difficult to persuade. He dispatched a handful of copies to the Vatican, but, before he could hear the result, Florence was hit with a terrible catastrophe.

In 1630, the bubonic plague struck all of Tuscany. In a matter of weeks, 6,000 Florentines were dead, and Galileo lost touch with Rome. Every night, as the city cowered behind barred doors, carts would collect the bodies. Physicians wandered the streets in masks stuffed with straw to protect them from contagion.

INGRID ROWLAND: An outbreak of bubonic plague strikes all of Italy, strikes badly in Tuscany. And because of the development of science, there's some idea that there is contagion involved. And so there are attempts by the Grand Duchy of Tuscany—which is a pretty centralized governmental system—to establish quarantines, often in terms that we'd find inhuman, sealing up people's houses.

NARRATOR: The rulers of Tuscany couldn't decide whether to rely on quarantine or on the power of prayer. Just to be certain, they tried both.

INGRID ROWLAND: Parading the Madonna of Impruneta around the city is a way of invoking her divine aid, and, of course, having a religious procession somewhat militates against the effect of quarantine. You hope that faith will override what looks like the law of nature.

NARRATOR: The Magistry of Public Health enlisted the help of Maria Celeste's convent.

DAVA SOBEL: Praying for the rest of the world really had importance, and the nuns knew that. And in fact, during the plague, they were specifically commissioned to pray two at a time for 40 days 'round the clock. And that was considered one of the most active interventions that could be made against the plague.

NARRATOR: Maria Celeste worried about her aging father. As the convent's apothecary, she prepared a medication for him, hoping to shield him from infection.

MARIA CELESTE: Put your faith in this remedy, Sire. It is held together with honey. Take it once every morning in a dose about the size of a walnut, followed by a taste of Greek wine. The Magistry of Health claims it provides a marvelous defense. Please use every possible precaution to protect yourself from the danger.

NARRATOR: Washing linens in boiling vinegar was seen to provide a measure of defense, although no one knew the reason why. The sisters' cloistered isolation became a benefit, and the infection passed them by. The next spring the epidemic had subsided enough to permit limited communication with the rest of Italy.

For months Galileo heard nothing from the Roman censors. Had his manuscript been lost in quarantine? Had his work been stolen? The Florentine censor had endorsed the book, but Galileo needed the approval of Rome.

GALILEO: The Father told me, more than once, that tears came into his eyes when he was reading, and he acknowledged that I should be begged to publish such a book. Meanwhile it sits in the corner and my life wastes away. All I want to know, while I'm still alive, what is the outcome of all my hard work?

NARRATOR: While Galileo waited, the copies of his Dialogue were quietly passed among powerful Roman churchmen. But, curiously, Galileo's great admirer, the Pope, may not have actually read it. Instead, Urban VIII heard rumors, rumors that Galileo had put his words into the mouth of a fool, rumors that Galileo had not written a scientific discourse, but a literary satire.

INGRID ROWLAND: What Galileo's doing is writing a work of great literature. He wrote it as a dialogue so that it would be both a scientific and a literary work, and is expecting that this most cultured, cosmopolitan and progressive of popes will appreciate it, forgetting probably, temporarily, that in the end of this beautiful, rhetorical production there's a rather grievous insult.

ALBERT VAN HELDEN: At the very end, he puts the words of the Pope in the mouth of the simpleton. That if God wanted to make the universe some other way, any other way, but make it appear to us the way it does now, he could have. And, therefore, none of these arguments about whether the Sun is the center or whether the Earth is the center can be definitive.

NARRATOR: Years earlier, when he had strolled through the Vatican gardens with Galileo, the Pope had made the very same argument, saying that the works of God can be beyond human understanding.

OWEN GINGERICH: Urban's advisors persuaded him that he had been the model for Simplicio and that he was being made a fool.

DAVA SOBEL: Urban took a very angry view of the book and the two never spoke again.

ALBERT VAN HELDEN: The Pope convened a special commission to look at the Galileo case, to look at the manuscript. And that commission, uh, recommended that...a process by the Inquisition.

NARRATOR: The Inquisition served a paper on Galileo ordering him to appear in Rome the coming October. The old man tried to delay his trip by claiming ill health. By Christmas, Galileo was again ordered to appear. He could come voluntarily, or he could come in chains.

As he arranged to leave Florence, Galileo's daughter sought to prepare him for his ordeal.

MARIA CELESTE: Father, I beseech you not to grasp the knife of these current troubles by its sharp edge. But rather, seizing it by the blunt side, use it to cut out all the imperfections you may recognize in yourself, and arrive at an awareness of the vanity and fallacy of all earthly things.

NARRATOR: In Rome, Galileo again could see the Vatican from the windows of the Tuscan Embassy, but for months his summons to the Inquisition did not appear. His trial order finally arrived in April. Like most such proceedings, Galileo's was conducted with strict formality and perfect civility.

INQUISITOR: Galileo, son of the late Vincenzio Galilei, Florentine, 70 years of age, sworn to testify the truth: Galileo Galilei, by what means and how long ago did you come to Rome?

GALILEO: What? I came to Rome on the first Sunday in Lent, in a litter.

INQUISITOR: State whether you know or can guess at the reason that you were ordered to come.

GALILEO: I'd imagine that I was ordered to present myself before the Holy Office to give an account of my recently printed book.

INQUISITOR: State whether, if you were shown the said book, you would recognize it as yours.

GALILEO: I, huh, h-hope so. Yes, I, I, if I, if, if I was shown it, I would, I hope I would recognize it.

INQUISITOR: There was shown to him a book printed at Florence in the year 1632 with the title Dialogue by Galileo Galilei, et cetera. And when he had looked at it and inspected it, he said, "I know this book very well, and I acknowledge it as mine. And I acknowledge all it contains as having been written by me."

NARRATOR: The Inquisition limited the trial to two simple questions of fact: Did the late Cardinal Bellarmine forbid Galileo to advocate Copernicus when the two faced each other 16 years earlier? And had Galileo violated the Cardinal's injunction by writing his Dialogue?

INQUISITOR: Let Galileo state what the most eminent Cardinal Bellarmine told him about the decision of the Holy Congregation of the Index on a certain day in the year sixteen hundred and sixteen.

GALILEO: The Lord Cardinal Bellarmine informed me that the opinion of the stability of the Sun and the motion of the Earth was deemed to be repugnant to Holy Scripture. I believe the Cardinal notified me that it was possible to hold the opinion hypothetically, as Copernicus did.

INQUISITOR: Can Galileo explain what is in his book which he imagines was the reason for the order that he appear before us?

GALILEO: Well, eh, when I was writing the Dialogue, I did not do so because I held that the doctrine of Copernicus was true. Instead I set forth the astronomical reasons that could be advanced on either side of the debate and tried to show that neither side of the argument has conclusive force to favor one opinion over the other. I do not now hold and, since the determination of Cardinal Bellarmine, I have not held the condemned opinion.

NARRATOR: All who read the Dialogue could see that the defense of Copernicus was, by far, the stronger argument in the book. The character Simplicio, mouthing the words of Urban VIII, was really more satire than science. Galileo was forced into a position of false humility and humility was never his style.

GALILEO: With respect to the Court, I've recently reread my Dialogues after three years, and I freely concede that in several places a reader ignorant of my real purposes could suppose several arguments might suggest real conviction on my part. My error, I confess, was one of ambition, the natural inclination of most men with regard to their subtleties to show themselves more skillful than other men in devising arguments in favor of propositions, even false propositions.

NARRATOR: Galileo was remanded to a small room in the Palace of the Inquisition. It seemed certain that his Dialogue would be banned. The question now became what punishment would befall Galileo himself.

GUY CONSOLMAGNO: It very quickly boiled down to a technicality. In 1616, Galileo had agreed not to teach or defend the Copernican theory; the accusation was he had violated this agreement. And Galileo said, "No, I didn't violate the agreement, uh, if you see, by the time you read the end of the book, I come out in favor of the Church's position, and I just bring up these other arguments as an arguing tool." Well, anybody who read the book knew better.

NARRATOR: News of Galileo's confinement reached Maria Celeste, and she nervously sent off a letter of cautious advice, not knowing if it would ever get to her father.

MARIA CELESTE: Detained in the Chambers of the Holy Office. I have given no hint of these difficulties to anyone else, wanting to keep the unpleasant news to myself. Father, now it is the time to avail yourself of that prudence which the Lord God has granted you.

NARRATOR: The path Galileo followed to the chambers where he would hear his sentence led through the Cloisters of Santa Maria Sopra Minerva. The walls and ceiling warned heretics what fate might await them.

INGRID ROWLAND: The people who were conducting the Inquisition hope that anybody who's coming into the Inquisition sees these scenes of people who've died in the correct faith, realize that they should use the courage of the martyrs to confront their own case, face their heresy squarely, and go off to their punishment with a clean conscience because it's been brought back to Orthodoxy.

NARRATOR: On the morning of his sentencing, Galileo was once more brought before the Inquisition, this time wearing the white robes of a penitent.

INQUISITOR: We pronounce sentence. We declare that you, Galileo Galilei, by reason of the matters detailed in this trial, have rendered yourself, in the Judgement of this Holy Office, vehemently suspected of heresy; namely, having held and believed a doctrine which is false and contrary to Scripture, that the Sun is the center of the world and does not move, that the Earth is not the center of the World and does move. We condemn you to formal imprisonment, in this Holy Office, at our pleasure.

NARRATOR: A settlement was likely worked out. Galileo was given a chance to renounce his errors. Rather than spending the rest of his life in a dungeon, the old man knelt as ordered.

GALILEO: I, Galileo, son of Vincenzo Galilei, of Florentine, 70 years of age, kneeling before you, swear that I have always believed, I believe now and, with God's help, I will always believe all that has been taught, held and preached by the Holy Catholic Church. I abjure with unfeigned faith and sincere heart. I curse and detest any errors and heresies, so help me, God. Amen.

NARRATOR: The trial of Galileo was over. Waiting in the Tuscan embassy he would not know for months when he would be allowed to return home. Dialogue on the Two Chief Systems of the World was added to the Index of Prohibited Books. It would remain banned for the next 200 years. Galileo had believed that Pope Urban VIII would protect him from censure but the Pope had not.

DAVA SOBEL: Being the pope is different from being the cardinal. The Pope had many battles to fight, the most important being the Protestant Reformation. And there he was the head of the Catholic Counter-Reformation. And Urban was actually accused of not doing the right things to further the Catholic cause.

INGRID ROWLAND: The Pope maintained interest in what Galileo was doing, but the Pope, in many ways, had other concerns besides science. Urban VIII is facing the Thirty Years War—the entire reign is under the shadow of a terrible, vicious civil war that's tearing apart the Christian world.

DAVA SOBEL: So when Galileo came to trial the Pope could not risk defending his friend when he, personally, was under such scrutiny. And Galileo became expendable.

INGRID ROWLAND: He feels he can afford to turn his back on Galileo. And I think Galileo didn't know what was coming. Tuscany, at that point, has nothing but culture.

Galileo is their vanguard of scientific thought. Galileo gets silenced by the Pope, so it's a Tuscan turning back and smacking his Tuscan friend, who he feels smacked him at the end of this Dialogue, so that it's a wonderful Florentine vendetta.

NARRATOR: Six months after his trial, news arrived in Florence that Galileo would finally be allowed to return home. It had taken the pleas of the Tuscan Ambassador, the intervention of the Medici family, and the quiet influence of his own daughter.

MARIA CELESTE: We are awaiting your arrival with great longing, and we cheer ourselves to see how the weather has cleared for your journey. Sire, my sudden joy is as great as it is unexpected.

NARRATOR: Galileo was home but confined to his own house, unable to teach, travel or even visit his daughter without permission. He signed his letters, "From my prison in Arcetri."

FRANCO PACINI: He was under house arrest. He could not move without authorization, and also what he could do, what he could not do was dictated by the Church.

GALILEO: Not so many years have passed since I was often received by cardinals and princes of the city who wanted to see only for a moment some of the things I have observed. Latin orations were occasionally recited in honor of me, the Duke's mathematician, the discoverer of new planets, eyewitness of wonders unknown to the ancient philosophers. But now I spend fruitless days, made long by inactivity and yet brief compared to the years that have passed, my only comfort, the memory of former friendships, of which so few remain.

NARRATOR: Galileo was ordered to recite prayers of penitence each week. Although ailing, Maria Celeste undertook to relieve him of this burden.

MARIA CELESTE: I obtained permission to view your sentence, Sire. By taking upon myself the obligation you have to recite each week the seven Psalms, I have already begun to fulfill this requirement. Had I been able to substitute myself in your punishment, I would accept a prison even stricter than this one in which I dwell, if, by doing so, I could set you again at liberty.

NARRATOR: Although her letters had not dwelled on it, Maria Celeste's physical condition had deteriorated in her father's yearlong absence.

DAVA SOBEL: I think that during Galileo's trial and detention after the trial, he was too broken and too needy to realize the state she'd been reduced to.

MARIA CELESTE: I am not very well, but by now I am so accustomed to poor health that I hardly think about it, as it pleases the Lord to keep testing me with some little pain or other. I thank him, and I pray that he grant you, Sire, the greatest possible well being.

NARRATOR: At the end of March, news came that Maria Celeste was gravely ill with fever. For the next 10 days, Galileo made the short walk to the convent trying to hold onto her. But late one night she succumbed to dysentery, leaving the world at the age of 33. When Maria Celeste died, it was as if a light had gone out in Galileo's life.

DAVA SOBEL: It was only when he got home, as he reports later in letters to colleagues, that he, he found her so weakened that she actually succumbed to a, a fairly common illness that need not have been fatal, but in her state proved to be fatal.

GALILEO: I'm full of melancholy and sadness. I'm hateful to myself, and I continually hear my beloved daughter calling out to me. Maria Celeste suffered ill health during my absence and, and she didn't look after herself. Go on, goodbye. She was a woman of exquisite mind, singular goodness—and most tender in her feelings towards me.

NARRATOR: Dozens of Galileo's personal letters have survived, but not one of the letters he wrote to his daughter has ever been found. Today, we have only her side of their communication.

GUY CONSOLMAGNO: It's a shame. It's really a shame we don't have his letters to her. It's clear from her letters that she loves this man, and she cares about him, and she knows what it is to love another person. And we can only hope that this love was inspired by a similar affection on his side. We'll never know.

DAVA SOBEL: Surely he answered her letters. There's no question about that because all through hers runs a thread of, "You asked me this," "You told me that." So one can almost reconstruct what he said, but you can't hear how it sounded. What's tantalizing here, is that it's also obvious that she saved all the letters because she says that repeatedly: "I keep them all. I reread them whenever I can because this brings me great joy" So where are they?

The most logical explanation is that when she died the Mother Abbess would have burned them, buried them, done something, because Galileo's trial was such a recent memory.

NARRATOR: Fighting advancing blindness and often confined to his bed, Galileo began to reexamine his own early work.

GALILEO: I find how much old age lessens the vividness and speed of my thinking. I now have to struggle quite hard to understand things which, when I was younger, I discovered and proved.

NARRATOR: Forced to avoid astronomy, Galileo looked back to a time before his telescope, to his brilliant but never published research on the physics of motion.

JULIAN BARBOUR: You get this extraordinary situation that he'd made these really great discoveries in the study of motion, right back in about 1604—something like that—and he'd written it up in a Latin text back then. But, it, it's, it's...so many other things, exciting things, happened to Galileo, he never seems to have gotten around to publishing it. So it was, in a way, a blessing that he was put in house arrest. It finally made him get around to writing these results up.

NARRATOR: Galileo had spent half a lifetime trying to prove the Earth moves. Now he would come to terms with something much more basic, the mathematics of motion itself. But motion is hard to measure.

JULIAN BARBOUR: It all happens just a bit too fast for you to see what is going on. Galileo hit on this wonderful idea of slowing down the motion. So instead of trying to watch a thing falling, he rolled balls down very gentle slopes, so that the speed built up very, very slowly.

NARRATOR: Galileo reasoned that as balls rolled down slopes they would accelerate just as they did in free fall, but more slowly.

As a young man, Galileo had designed a very accurate inclined plane, one of the most important pieces of experimental apparatus in the history of science. Galileo left behind no plans for his inclined plane, but based on his experimental notes, Professor Roberto Caffarelli is using what he believes to be Galileo's original design to discover how he was able to accurately measure acceleration.

PROFESSOR ROBERTO CAFFARELLI: [in Italian]: Galileo, estudia il plane inclineto...

(Through translator): Galileo studied the inclined plane, slowing the motion of falling bodies until he was able to observe the phenomena. He was able to measure exactly how fast a ball would roll, timed with the swing of a pendulum. Galileo was sure that the steady acceleration must be governed by a mathematical rule.

JULIAN BARBOUR: So he takes this very gentle inclined plane, and he lets the ball roll down, and he watches how that ball speeds up, and he measures how far it goes in a certain time. And then he makes his first empirical discovery: that if in the first unit of time it goes one unit of distance, in the next unit of time it travels three units of distance, and in the next, five, and in the next, seven. So it has this beautiful, numerical progression—one, three, five, seven. And he calls this "the odd numbers rule." And he really is entranced by this; he knows he's made a huge discovery.

NARRATOR: Galileo had found a mathematical rule for accurately predicting the motion of objects in the real world, a universal law which applied to any falling bodies.

JULIAN BARBOUR: Underneath this beautiful, empirical law that he found, he found a deeper law, clearly a deeper law, using mathematical logic and deductions. And this was actually the key to all the later, great successes—first of Newton and then of Einstein and all the other wonders of, of modern science.

NARRATOR: As a young man Galileo had revolutionized astronomy, but at the age of 74, his last great book revolutionized the physics of motion.

OWEN GINGERICH: From the point of view of physics his most important contribution is his Discourse on the Two New Sciences. Indeed, it's that book that provides the real foundation for Isaac Newton.

NARRATOR: Within a generation, Newton had built on Galileo's work to devise a set of laws so complete that they could describe the motion of the planets in their orbits and how apples fall from trees.

FRANCO PACINI: It's very difficult to judge which part of Galileo's work is most important, because, on one hand, he established some of the basic laws of physics. On the other hand, through his telescope he first discovered or proved that actually the Earth is only one of the bodies of the universe—that those things we see at night are not just little flames in the sky or in the atmosphere, but they are actual bodies similar to the Earth—that there are, everywhere in the universe, other bodies, which may be similar or different from our own, but they're our brothers and sisters in the universe.

NARRATOR: When Galileo was a young man, most people assumed that they lived at the unmoving center of the world. Armed with his telescope, he wrote persuasively that our earth was just one of many planets moving around the sun. The inquisition chose to ban Galileo's Dialogue, but it was powerless to ban Galileo's ideas.

OWEN GINGERICH: I always think that his Dialogue on the Two Great World Systems was the persuasive book that made it intellectually respectable to believe in a moving world, a Sun-centered universe. It was the book that won the war.

NARRATOR: The Catholic Church long ago accepted the science of Galileo, but it was not until 1992 that a papal commission reconsidered its handling of the Galileo affair.

ALBERT VAN HELDEN: John Paul II said that mistakes had been made in the Galileo case and used Galileo's language to talk about the relationship between faith and reason, between religion and science.

NARRATOR: Saying that faith should never conflict with reason, Pope John Paul II used the very words Galileo had once written in his own defense. The Pope, like Galileo, believed that the scriptures can never err, but theologians can err in their interpretation. The Pope expressed the church's regret that the Galileo affair had contributed to a "tragic mutual misunderstanding" between religion and science.

ALBERT VAN HELDEN: By the end of the twentieth century, Galileo is almost rehabilitated.

NARRATOR: Perhaps anticipating his own revival, the old heretic had scribbled a private warning to his adversaries in his copy of the Dialogue.

GALILEO: Take note, theologians, you run the risk of someday having to condemn as heretics those who would declare, as you do, that the Earth stands still.

NARRATOR: Galileo was right about the earth moving, but he was wrong about the tides. Learn more about what history has shown to have been his big mistake on NOVA's Web site at PBS.org or America Online, Keyword PBS.