The Trial of Galileo

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"It is impossible to obtain wages from a republic, however splendid and generous it may be, without having duties attached."

- Galileo Galilei

Certainly Galileo Galilei did not expect the Spanish Inquisition. But then Galileo wasn't in Spain.

Now the Roman Inquisition, that was something else again. But Galileo probably didn't expect them either.

After all, why should he? In the early 1600's the heliocentric theory of Copernicus was not - that's NOT! NOT! NOT! - prohibited by Church doctrine. That is, it was OK to believe the planets orbited around the Sun. And as Perchik told the Rabbi, if it's not forbidden, it must be all right.

So in 1610 when Galileo published his bestseller, The Starry Messenger, there was no problem. Although the book was primarily about his astronomical discoveries using the telescope, Galileo also felt that buried within his findings was plenty to support the Copernican System.

But most people still bought in to the - quote - "traditional" theory - unquote - of Ptolemy, the Greek astronomer who had lived in Egypt about 1500 years before. Ptolemy, who accepted science as taught by Aristotle, had decided that the other planets and the Sun orbited the Earth which was the center of the solar system. Because the Earth seemed to be pretty solid and didn't move, this geocentric model made the most sense.

So why did the theory of Copernicus gain ground?

Well, you may read that the Copernican system was not only more accurate but it was simpler. For the Ptolemaic system to make the predictions properly, it had to employ a complex system of orbits linked to other orbits called epicycles. Also to get the best accuracy, the planets were not placed at the center of their main orbit (called the deferent). Instead they were offset a bit at an equant and the planet actually orbited around the other (and empty) equant. The speed of the planet was uniform only when observed from the empty equant, not the center of the orbit or from the Earth.

The net result was that with the Ptolemaic solar system all the talk of the perfection of uniform circular motion was absolute nonsense. The paths of the planets were actually extremely complex and sometimes the planets moved forwards and sometimes backwards and sometimes they sped up and slowed down. True, this quirky system of epicycles, deferents, and equants did permit quantitative predictions about where the planets appeared in the sky. But it's obvious artificiality caused some people to see it as good mathematics but rotten physics.

So in stepped Nicholas Copernicus in 1543. He decided that if you put the Sun in the center of the solar system, a lot of things made a lot more sense. For instance every astronomer knew that the planets Mercury and Venus were always close to the Sun when seen in the sky. Other planets, though, like Mars, Jupiter, and Saturn would sometimes appear to be close to the Sun and sometimes they'd move further away and be "in opposition" to the Sun.

Copernicus figured these observations meant that the planets circled the Sun, not the Earth. Mercury and Venus looked like they were close to the Sun because they literally were closer to the Sun. And the other planets were sometimes in opposition to the Sun because they really were further from the Sun than the Earth was. This all worked out best if the planets circled the Sun.

And the Earth?

Well, it too was orbiting the Sun. A moving Earth not only fit in well with the observations of where the planets were in relation to the Sun but it also explained why some planets, particularly Mars, looked like they sometimes moved backwards. In a Sun centered solar system this "retrograde" motion of the planets was not real. Instead it was simply an optical illusion due to the inner planets catching up and passing the outer planets.

Admittedly the scholarly publications and lectures about Copernicus can be confusing. Some sources state that for quantitative accuracy Copernicus still had to use deferents and epicycles, and equants. But they say, he had fewer epicycles (something like 135 instead of 140).

Actually Nicholas did discard the equants and to compensate he replaced them by more epicycles. The advantage was that he could return to using uniform circular motion at least regarding the deferents and epicycles. So at the least the heliocentric solar system was "more pleasing to the mind" than Ptolemy's. But regarding the calculations, we read that the Copernican system was no more accurate than Ptolemy's nor was it simpler.

Well, this is true and false.

Yes, the Copernican and Ptolemein systems used similar calculations. Copernicus still had epicycles which have to have their own rotational speeds and orbital velocity along the deferent.

On the other hand, the predicted physical motion of the planets was far simpler in Copernicus's solar system than Ptolemy's. If you look at animations of the Copernican system it's simply the planets orbiting the Sun. But Ptolemy's planets move in oddball loops and twirls. It's so weird that you wonder why people ever thought the Ptolemic system could have any basis in reality.

Galileo wasn't interested in a system that was just a collection of mathematical tricks and early on had become a firm Copernican. And he believed his telescope found yet another proof for Copernicus.

If the planets circled the Sun, he said, then the planets inside the Earth's orbit should exhibit phases like the Moon. And sure enough, in The Starry Messenger he reported that's exactly what he had seen when observing the planet Venus. This proved, he said if further proof was needed, that the planets circled the Sun, not the Earth.

Anyone with brains and eyes, Galileo felt, would immediately see that the Sun was the center of the solar system. The simpler motion of the planets (if not the calculations), the proximity of Mercury and Venus to the Sun, the opposition of the outer planets, and that Venus exhibited phases like the Moon all argued for the reality of the heliocentric solar system.

Unfortunately, there were still people who said none of Galileo's arguments were proof. That's because there was yet another Earth centered solar system that worked as well as Copernicus's.

The "other system" (if we may so call it) was devised by the famous Danish astronomer Tycho Brahe (pronounced TEE-koh brah-HAY) not too long before. Around 1580, Tycho - who didn't have a nose by the way - had come up with a system that was able to explain the proximity of Venus and Mercury, the opposition of the other planets, and the phases of Venus, and it kept the Earth at the center of the solar system.

On the other hand Tycho's system was really a heliocentric system but used the most ad-hoc of ad-hoc additions to put the Earth in the center. The Earth was at the center, yes, and the Sun circled the Earth.

But - and pardon us if we shout - TYCHO HAD THE OTHER PLANETS CIRCLING THE SUN!!!!! So even though Tycho's solar system was every bit as accurate as Copernicus and the oddball properties of the planets were natural phenomenon from their orbits, it really strained to keep the Earth in the center.

But it is true that except for one characteristic - which we'll touch on later - the two systems of Copernicus and Tycho are mathematically equivalent. It's simply boils down to what you put at the center.

Given all the tricks and ad-hoc devices the astronomers were using - whether Ptolemeic, Copernican, or Brahean - you can see why the Church hadn't really been too concerned about which system anyone used. In the early 1600's the church leaders considered astronomy was simply mathematics and number crunching. They couldn't care less about whether any of the theories was the - quote - "real system" - unquote. In fact they considered it a meaningless question.

But with Galileo touting Copernicus, things began to change. After the publication of The Starry Messenger in 1610, he had become the most famous - and highest paid - scientist in the world. And with his new found fame, he began a self-proclaimed and very public mission to convert the world to Copernicanism.

In fact with his constant in-your-face proselytizing Galileo was making a complete rompicoglioni of himself. He didn't engage in gentlemanly debate either. He maintained that he and he alone was destined to convince the world that Copernicus was right. As far as he was concerned if anyone disagreed with him they were narrow minded dunderheads not to mention - and he used these words - imbeciles, mental pygmies, dumb idiots, people hardly deserving to be called human beings, people too stupid to recognize their own limitations, and eunuchs.

Soon people of considerable influence began murmuring that Galileo was not being just a pain in the [neck]. But by touting Copernicanism he was actually promoting doctrines that were contrary to Christianity. After all, 1 Chronicles 16:30, Psalm 93:1, Psalm 96:10, Psalm 104:5, and Ecclesiastes 1:5 all talked about a stationary Earth and a moving Sun. To speak otherwise was defying Scripture.

Things started getting serious when in 1613 a Dominican friar, Fra Niccolo Lorini, filed a written complaint to the Holy Office. Niccolo specifically mentioned Galileo by name and that he was violating Church doctrine. Then another Dominican went so far as to give verbal testimony claiming Galileo was actually guilty of heresy. The Holy Office, by the way, was the official name of what later generations would call the Inquisition.

Galileo pooh-poohed the objections. Anyone who complained that Copernicanism was heretical was just misinterpreting the Bible. The verses about the Sun rising and setting were clearly just using language to describe an apparent motion and not physical reality. The verses didn't mean the Sun was literally moving up and down. Just that it looked like it was moving up and down.

Galileo still didn't convince many people. In fact, opposition to him increased. Soon trashing Galileo became something of a cottage industry.

Suddenly Galileo had a great idea. If he went to Rome and personally explained the Copernican system to the cardinals and the Pope, then everyone would immediately see his logic. The Church would then gleefully agree that Copernicus had been right all along.

Unfortunately that's not what happened. After hearing Galileo's arguments, the Pope, Paul V, took a modern approach: he appointed a committee. The committee, headed by Cardinal Robert Bellarmine, met and weighed the pros and cons of Copernicus and Ptolemy.

On February 24, 1616, they released their findings. The Copernican theory, they said - that is, the Earth moving around the Sun - was both foolish and absurd. Ridiculous and asinine.

In fact, it was worse than foolish, absurd, ridiculous, and asinine.

Yes. The theory of Copernicus was indeed contrary to Scripture. The Bible says the Earth is fixed and immoveable. And Copernicus - and Galileo - said it moved. The conclusion, Robert and his friends said, was a no-brainer. Copernicus and Galileo were wrong.

Well, with everything settled, the Pope told Robert to tell Galileo that he couldn't believe in Copernicus anymore - that is, he couldn't "hold or defend" that the Earth orbited the Sun. The two men met on February 26, and Galileo said, well, OK, if that's the decision, then that's the decision.

Oh, yes, he added. Could Robert give him a letter saying that he had simply been notified of the committee's decision and that he personally had not been found at fault? After all, there were curmudgeons - petty, small minded men envious of Galileo's fame - who were spreading rumors that he had actually been found guilty of heresy and forced to "abjure" and "repent" before the Inquisition.

Robert said no problem. So when Galileo headed back to Florence, he had the letter in hand. The wording was friendly and Galileo was left with the option to discuss and write about Copernicanism as long as he taught it as a "hypothesis".

Despite his public acceptance of the ruling, Galileo was considerably miffed. Certainly things hadn't turned out as he had hoped. He had gone to Rome expecting everyone to be amazed by his sagacity and agree the Sun was the center of the solar system.

Instead his whole plan had completely backfired. Not only had he completely failed to persuaded the cardinals and the Pope that Copernicanism was the truth, but now believing in Copernicus was heresy, a capital crime.

In fact, Galileo's efforts had even gotten Copernicus's book, De Revolutionibus Orbium Coelestium banned. Or rather the book was "indexed", that is, "banned until corrected." True, the corrections weren't very many and involved editing only nine sentences and adding the words "The Hypothesis of" to the chapter titled "The Triple Motion of the Earth". But this wasn't something Galileo had been counting on.

There was that one crumb of comfort, though. At least Galileo could keep talking and writing about the (hypothetical) Copernican theory. And that's what he did.

And sure enough, after a while people again began to gripe. They felt Galileo was doing more than just discussing a hypothetical computational method. Instead he was once more "holding and defending" Copernicanism. Not only did he believe Copernicus was factually correct, but he had kept going around trashing anyone who believed Ptolemy.

Today it's easy to see the "Galileo Affair" as a face off between a far seeing and intelligent scientist (Galileo) and a bunch of narrow minded reactionary superstitious bumpkins. But in fact Galileo had his supporters in the Church. Mainstream theologians were very well aware that not all the Bible was to be taken literally. The Jesuit order had always been very science friendly, and Paolo Antonio Foscarini, a Carmelite priest who was also professor at the University of Messina, went so far as to say the Copernican theory was NOT contrary to Scripture.

Even Robert Bellarmine, the chairman of the Pope's committee, had told Galileo that if he could come up with a convincing proof that the Earth was circling the Sun, then the theologians would have to re-interpret the verses that said the Earth was fixed and immoveable. So the door to the Church actually recognizing Copernicanism as a physical reality wasn't completely shut.

The question, though, is what would the Church accept as proof?

What sent Galileo into spittle flinging diatribes was, dang it!, he had provided the proof. Everything's right there in The Starry Messenger! Why don't people use their heads, for crying out loud!

You see, beginning in 1610 Galileo had been living in Florence as the court philosopher of the Grand Duke of Tuscany, Cosimo de Medici. He had left his professorship at the University of Padua to take what was admittedly about the cushiest job around. All Galileo had to do in Florence was work on his research and he didn't have to bother with teaching those pesky students. Every now and then he'd cast the odd horoscope and naturally he discussed the Copernican theory with people in the palace and that included Cosimo's mom, Christiana.

At one point Christina had been at a dinner and had sat next to a professor of philosophy from the University of Pisa, Cosimo Boscaglia. Christina, who was a quite religious and thoughtful person, had asked Cosimo if the Copernican theory could be squared with the Bible.

Professor Boscaglia was adamant. No, he snorted, it could not. The Copernican theory - and Galileo's support of it - was against the Scriptures. He pointed out that the Bible was clear that the Earth is "firmly established; it cannot be moved" (1 Chronicles 16:30 and Psalms 96:10), "the world is established, firm and secure" (Psalms 93:1), and that the Earth "can never be moved" Psalm 104:5. So according to the Bible, he said, the Earth could not be circling the Sun.

The gist of the conversation got back to Galileo, and he wrote a letter defending the Copernican system to his friend, Benedetto Castelli, who was also a professor at Pisa. He figured Benedetto would spread the word but for good measure he also wrote a letter directly to Christina. Just like Oscar Wilde, Galileo never wrote except for publication and the letter was printed up as a book.

Among the things that Galileo's wrote (with some editing of his garrulousness) were:

"In my studies I hold the Sun, without moving, remains in the center of the planet's orbits, and that the Earth moves around it, as I prove by refuting Ptolemy and Aristotle."

Now in light of what Galileo said later it's important to note that if we go by his own words it is clear 1) Galileo believed that the Earth orbited the Sun. So he did "hold" to Copernicanism. And 2) he believed he had proven it.

And just what was that proof?

Well, there were the phases of Venus. That showed Venus circled the Sun. He also thought that since Jupiter had its own moons, it was clear that not all celestial objects circled the Earth.

But above all he had a clincher.

The proof that Galileo thought was most convincing was that the Earth had tides. The tides, he said, came about because the Earth's movements sloshed the water around like tea swirling in a cup. The motion of tides, he felt, was a definitive and clear proof. The Earth did move.

Needless to say none of Galileo's proofs convinced the die-hard Ptolemeists. Certainly the theory of the tides didn't, manly because it's dead wrong.

There was, though, one proof that would convince the Church. That was stellar parallax. That is, if the Earth orbited the Sun, then the stars that were nearest to the Earth would appear to shift back and forth.

Unfortunately, stellar parallax is small. Alpha Centauri, a star system closest to the Earth, has a parallax of only 0.0002 of a degree. This is far too small to be measured by the instruments of Galileo's time which were good to about 0.01 degrees. In fact, it was because Tycho saw no stellar movement that he said the Earth had to be at the center of the solar system.

So things remained until a couple of Popes later. Then in 1623 Cardinal Maffeo Vincenzo Barberini was elected as Pope Urban VIII. Pope Urban, it turned out, was a personal friend and admirer of Galileo and his science.

Hot dog! Galileo was now convinced he could get Copernicanism away from that "hypothetical" schtick and convince everyone it was true. So in 1624 he once more hied off to Rome hoping to convince his friend that it was time to toss Ptolemy out on his epicyclical rear end.

But to Galileo's disappointment Urban was no more willing to substitute Copernicus for Ptolemy than the previous popes. Taking a stare decis approach, Urban stuck with the Church's ruling of 1616. The Earth was still fixed and immoveable.

So Galileo asked Urban if he could at least write a book explaining the Copernican theory? Well, that would be OK, Urban said. But he waved an admonitory papal finger. It was OK as long as Galileo did not "hold or defend" the theory. Copernicus must still be taught "hypothetically". And Galileo also had to give equal time to Ptolemy.

So Galileo went back to Florence and wrote his book, the Dialogue of Galileo Galilei Where in Meetings of Four Days Are Discussed the Two Chief Systems of the World, Ptolemaic and Copernican, Indeterminately Proposing the Philosophical and Natural Arguments, as Well on One Side as on the Other. Today the title is usually and mercifully reduced to Dialogue Concerning the Two Chief World Systems or even better just Galileo's Dialogue.

The book was about three guys talking about the pros and cons of the Copernican system versus that of Ptolemy. One of the speakers was a Copernican, the other an interested but sharp minded layman, and the third was an "Aristotelian", that is a supporter of traditional science and so he believed in the Ptolemy's theory.

Of course, Galileo had to submit the book to the Church so they could verify Copernicanism was just being presented hypothetically. He did so, and the ecclesiastical bigwigs looked at it and said it was OK. The book was approved and duly printed. It was issued in Florence in 1632 and became a best seller.

No, Galileo was not expecting the Inquisition. And so he wasn't expecting their letter summoning him to Rome.

Galileo knew the usual procedure. He'd be hauled before a panel of Inquisitors, they'd ask him some questions, and if they didn't like his answers he'd be tortured until he gave them answers they did like.

He was really in a quandary. In Florence he was under the protection of Cosimo de Medici. But that would end if he went to Rome.

So he wrote back to the Inquisitors. Uh, couldn't the business be handled in Florence rather than in Rome? The trip would not be just a hardship. He was elderly and had been ill. Traveling the more than 50 leagues from Florence to Rome in the dead of winter would take over three weeks and would be dangerous to his health. Surely the church officers in Florence could ask questions just as well as those in Rome.

Galileo's polite letter got him a quick reply. He could come to Rome willingly or he would be hauled there in chains. Wearily Galileo made the trip and he arrived in Rome in February, 1633.

The famous Trial of Galileo stretched out for nearly six months but the actual proceedings only occupied about five days. Most of the time Galileo was cooling his heels. And his appearances before the Inquisition were brief, maybe an hour at a time.

First things first. The Inquisitors told Galileo flat out that they thought he believed Copernicus. Did he?

Well, he said, at first he wasn't sure and he thought Copernicus might be correct. But after the ruling of 1616 when the committee headed by Cardinal Bellarmine decreed Copernicus was wrong, the scales had fallen from his eyes. He immediately became a confirmed believer in Ptolemy and his solar system.

Besides, Galileo smiled, he had gone back and looked over the book. NOW he realized what the problem was. It was all a minor misunderstanding.

They had thought that his book was a defense of Copernicus, didn't they? Ho! Ho! Ha! Ha! How ridiculous! How absurd!

Actually, he had written the book to refute Copernicus. He had proven that Copernicus was illogical and couldn't be right.

But he had done such a good job of explaining Copernicus that it appeared he advocated it. Why, if they'd just let him go back to Florence, then he'd issue a new edition of the book and fix everything right up. Nothing could be simpler.

The Inquisition wasn't buying it. We think you do so believe in Copernicus, they insisted. Nope, Galileo repeated, he did not.

Well, the Inquisitors now nodded, we have ways to enhance the questioning. Will you now admit you believe in Copernicus? No, Galileo insisted, he did not.

Thinking that maybe Galileo wasn't getting the message, they flat out said he could be tortured (they actually used the word tortura). But Galileo still stuck to his guns. He did not "hold" with Copernicus. That was his final answer, he said, and he was in their hands.

Well, we know the outcome. Galileo was found guilty and on June 22, 1633, he was forced to "repent and abjure" his guilt that he was "vehemently suspect of heresy, that is, of having held and believed that the Sun is the center of the universe and immoveable, and that the Earth is not at the center of same, and that it does move."

And no, it's pretty well accepted that after the hearing was over, Galileo did not stand up firm and resolute and proclaim "Eppur si muove!" ("And yet it does move!"). Nor did he mutter it under his breath.

Well, whether the Earth moves or not, Galileo was sentenced to life imprisonment in the dungeons of the Inquisition. But this was commuted to life imprisonment under house arrest. The sentence was duly carried out. Galileo was allowed to return to Florence but couldn't leave his house. He died nine years later in 1642, ailing and blind.

A brief review of the facts may be in order here. Galileo was a firm believer in the Copernican heliocentric solar system. He had been told he could explain Copernicus as long as he also gave equal time to Ptolemy's Earth-centered system. To this end Galileo had been given permission to publish his book, the Dialogue Concerning the Two Chief World Systems, and it had been reviewed by the Church authorities and approved for publication. And Galileo ended up being sentenced to life imprisonment.

So what went wrong? Well, the answer is very simple. Somewhere along the line of all this brouhaha Galileo had ticked off the Pope.

You see, when Galileo was discussing writing the book with Pope Urban, Urban had told him he could not claim Copernicanism was fact. And even if Galileo thought he had proof, God, in His infinite power and wisdom, could have created the world in many ways, some which are unfathomable to the minds of men.

In other words, no matter what proof Galileo thought he had, Urban said, God could have done something different. To claim otherwise would be trying to limit God's power and wisdom. This disclaimer, Urban told Galileo, had to be put in the book.

Now the best thing to do would have been for Galileo to stick the disclaimer in a preface stating that the Copernican theory is being put forth hypothetically and that God in his infinite wisdom might have done things differently. That would have carried out Urban's wishes both in the spirit and the letter.

Instead, Galileo decided to slip in the disclaimer at the end of the book. Remember there were three guys. One was a Copernican who was obviously Galileo. The second was a sharp guy who is open to the Copernican system and tends to lean in its favor. Then there's the Aristotelian who argues that Ptolemy was right.

Since the text is nothing but the three guys talking, one of them would have to give the Pope's disclaimer. It couldn't be the two Copernicans, who were named Salviati and Sagredo. That didn't make any sense. So it had to be the Aristotelian.

And sure enough, when they were discussing the tides of the Earth, the Aristotelian says:

I once heard from a most eminent and learned person whether God in His infinite power and wisdom could have conferred upon the watery element its observed reciprocating motion using some other means than moving its containing vessels, both of you would reply that He could have, and that He would have known how to do this in many ways which are unthinkable to our minds. From this I forthwith conclude that, this being so, it would be excessive boldness for anyone to limit and restrict the Divine power and wisdom to some particular fancy of his own.

Now read by itself, the words don't seem objectionable. The Aristotelian is simply stating what the Pope said and even called him "a most eminent and learned person".

And what, we ask, was the Aristotelian's name?

It was - get this - Simplicio.

Galileo maintained the name was intended to honor the famous Aristotelian philosopher, Simplicius of Cilicia. But Galileo's Simplicio was - to quote one historian of science - an Aristotelian dunce. In the Dialogue he spent the four days spouting trite standard defenses of Ptolemy that were so banal that Salviati could shoot them down as easily as he could a wounded duck.

And it was Simplicio who had spoken the words of the Pope.

Urban had a cow. His words were not only stuck toward the end of the book where the reader could find it only with difficulty, but the words - his words - were put - direct quote - "in the mouth of a fool".

Now even the most charitable historian has acknowledged that Urban left a mixed legacy. He promoted the arts and his personal life was without scandal. But he also staffed the Vatican with friends and relatives and he drained the Church's coffers - even sympathetic authors used the word "squandered" - fighting pointless wars and building up the papal fortifications.

And not atypical of someone who becomes the most powerful person in the world, Urban had developed an autocratic side. If someone didn't do what he wanted, they could find themselves booted out and sent to some minor jobs around Rome or even exiled off to some post in the hinterlands. Urban was not a man to get ticked off at you. And Urban was ticked off at Galileo.

Urban wanted Galileo to be found guilty. So the Inquisition had to find some way to oblige. First they stated Galileo had not dealt with the Copernican and Ptolemeic theories equally. Worse, he did not treat the Copernican system as a hypothesis. He had put it forth as the truth and argued that Ptolemy's ideas were impossible. Therefore by publishing the book, Galileo had violated the earlier admonishment from 1616 never to "hold or defend" Copernicanism.

But Galileo denied he really believed in Copernicus. He maintained he weighted both the Copernican and Ptolemeic theories with equal credibility. So all he had done was teach the Copernican theory.

Well, then, the Inquisitors said, what about the instruction not to teach the Copernican theory in any way whatever, orally or in writing.

Ahi giustizia di Dio! (To quote Dante). Where did THAT order come from?

Remember Robert's letter? It said Galileo couldn't hold or defend Copernicus's theory. There was nothing saying that he could not "teach it in any way whatever, orally or in writing".

Weeehhheeeeelllllllll, there's a bit of a story here.

When Galileo appeared before the Inquisition, they had begun asking him the standard set of questions. They started off asking if he knew why he was summoned. He said he figured it had something to do with the book he wrote.

Moving on, they asked if he remembered the admonition from Robert back in 1616. Why, yes, Galileo said, and here's a copy of the letter. It said that he could not hold or defend the Copernican theory. And he had not. But he was allowed to discuss the theory as a hypothesis. He had even been given explicit permission from the Pope himself.

But what about this? the Inquisitors asked. They then pulled out another document they just happened to have handy.

The document was what is called a "precept" which is a basic religious instruction and it was written by a member of the 1616 committee, Cardinal Michelangelo Seghizzi. And it was this document that stated Galileo could not hold, defend or teach the Copernican theory in anyway whatsoever, either orally or in writing.

Hm, Galileo replied. He certainly did not remember any such admonition. Besides, it contradicted the letter Robert had sent him. He had never been told he couldn't teach Copernicanism, certainly not with the blanket "in anyway whatsoever" stipulation. And remember, even the Pope had given him the OK to go ahead to write the Dialogue.

Here's where things get tetchy.

Most conveniently for the Inquisition, both Robert Bellarmine and Michelangelo Seghizzi were long dead and couldn't explain the letter and the precept. And the discrepancies in the instructions raise a question that has been debated literally for hundreds of years.

Could the document now being waived in front of Galileo's face have been forged?

The documents of Galileo's trial are held in what is often called the Secret Vatican Archives although the archives are not secret - after all everyone knows about them - and they are usually open to qualified historians. The file on Galileo has long been available in copies, but no one in the last century or so has looked at the original file. So any forensic analysis for authenticity is limited to using photographic reproductions. One historian said flat out that his copy is worthless for a paleographic analysis.

There are some arguments for the document being a forgery independent of any technical analysis. For one thing the paragraphs about Galileo not teaching Copernicanism appeared on the same page as the previous day's record. This is most suspicious. If you entered information from another day, it was supposed to begin on a new page. So it is certainly possible - and looks suspiciously like - someone went back and squeezed the precept into a blank space on a page written sixteen years earlier.

Most of all, the discovery of the precept was just too convenient. Remember Pope Urban was REALLY ticked off at Galileo. He wanted a guilty verdict and no arguments.

But the actual case against Galileo was very iffy. Galileo had repeatedly denied he "held" or "defended" Copernicanism. He had inserted the Pope's disclaimer in his book. The book was submitted for review and it had been duly approved. Galileo even volunteered to clear up any misconceptions in a later edition. What the heck more was he supposed to do?

Above all how could Galileo have been ordered not to write or teach about Copernicus when the Pope himself said he could?

The Inquisition was in a bind. If they didn't find Galileo guilty, then the Pope would be mad at them. If they didn't want to end their up careers in the parishes of Giannutri, Basilicata, or Cookietown, Oklahoma, they really needed proof that Galileo had done something wrong.

And by golly, just when the Inquisition needed it the most, up pops a document dated 1616. Never mind that no one seems to have seen it before 1633. It said Galileo was not to teach Copernicus in any way whatsoever. And in publishing his book, Galileo had done just that.

Whew! The Inquisition was off the hook.

Recently historians have suggested that, despite the irregularities of how the precept was written and it's amazing appearance just in time, the document itself is not a forgery. Well, OK. But what if it is legitimate?

If the document is not a forgery, then Galileo was still probably telling the truth. That is, he personally had never been prohibited from teaching Copernicus. Instead, the precept was intended to be a fall-back position for the Church if Galileo decided to complain.

Remember that in 1616 the Pope was Paul V, not Urban. If the document is authentic, then what may have happened is that after the committee's ruling against Copernicus, Paul said Robert should contact Galileo personally. He should tell him that he could not hold or defend the Copernican theory. If Galileo said OK, then that would be that and he would have the option of teaching Copernicus as a hypothesis.

But if Galileo griped about the ruling - and he could be a bit fractious - then Robert should show him the precept and say, well, if you don't like our more lenient guidelines, we can enforce the stricter terms laid out here. But Galileo had decided to play ball from the first. So he never saw the precept and the prohibition against teaching never came into effect.

So even if the precept is authentic, Robert's letter still gave Galileo a good defense that he personally had never been instructed not to teach Copernicanism. But the Pope wanted a conviction and so the Inquisition then did an end run around the problem by convicting Galileo of something else.

Instead of being guilty of teaching Copernicanism, Galileo was found guilty of being "vehemently suspect of heresy". That is, he was guilty because the Inquisition suspected that he believed in the heliocentric theory. But even this is a weird verdict. Galileo was found guilty not of what he believed about the solar system, but of what members of the Inquisition thought he believed.

In recent years it's become a bit fashionable to shift the blame for the whole bloody mess onto Galileo's shoulders. He was too pushy, some say. He liked irritating people. He thought that he and he only was the person who could convince the world that Copernicus was right. If he had just taken a more laid back approach and not been such a wiseacre, he might have had far less trouble.

And we also read that it's incorrect to see Galileo's tiff with the Church as science vs. religion. Instead some say that the Church was fully justified in charging and convicting Galileo.

Ha? To quote Shakespeare. What the hey is this? Are people saying the Church was justified in trying and convicting a 67-year-old scientist under the threat of torture and death of being - and we quote - "of having held and believed that the Sun is the centre of the universe and immoveable, and that the Earth is not at the center of same, and that it does move"?

That was NOT science vs. religion?

You see, the historians say nodding sagely, you must look at the trial as a legal proceeding - that is it was about contravening the laws of the Church. By Galileo saying Copernicus was right, he was maintaining that the passages of the Bible of the immoveable Earth were not to be taken literally. In other words, he was "interpreting" Scripture.

But in 1565 the Church had convened the Council of Trent which among other things reiterated that interpreting Scripture was the job of the professionals, that is, Church officials specifically trained in canon law. Galileo had never taken holy orders and so he was a member of the laity, an amateur. And laypersons could NOT interpret scripture.

So Galileo was indeed violating the rules of the Church. The trial wasn't, the scholars say, about science verses religion. It was about Galileo breaking the law.

We can't say this argument is completely convincing, particularly since based on canon law there are reasons for calling the entire trial into question. One historian (who is also a priest) has pointed out that the procedures of the Inquisition often violated the rights guaranteed to all Church members. And we're not just saying you shouldn't torture people who disagree with you.

For one thing no one is supposed to be forced to testify against themselves - yes, the Catholic Church has a Fifth Amendment. But in Galileo's case the Inquisition asked him to state what his personal views were regarding the reality of the Copernican System. So he was being asked to provide testimony against himself.

The question also violated another right. Members of the Church were not to be questioned on privately held beliefs. Instead only their confessor could do that, and like all matters discussed in confession, it was to be kept confidential.

Then there's one final point to bring up. Just what does it mean to say something is hypothetical?

Humpty Dumpty said that a word means what you want it to mean, nothing more or nothing less. And when you read about the conversations between Urban and Galileo, you get the impression they're using the same word but each has his own personal meaning.

When Galileo used the word "hypothetical", he seems to be using it the modern scientific sense. That is, it is a theory, tentative perhaps, but nevertheless something that very well may be true. A little more work and the hypothesis can become fact.

But Urban's meaning seems to have been that a hypothesis was what modern scientists call an "empirical method". That is, it's method of calculation independent of an actual theory. With Copernicus you might get the right answer, but the equations have nothing based in physical reality.

The sad truth is that in science the distinction between a hypothetical mathematical calculation and physical reality is pretty fuzzy. There's lots of reality that started out as hypothetical number crunching.

Max Planck proposed the photon in 1900 simply as a way to predict spectra and he wasn't sure if light quanta were real. As early as 1905 there were people who still questioned whether atoms were mere devices invented to fit with experiment (Einstein showed they were real).

Then when the neutrino was first proposed in 1930 it was simply a way to make the laws of the conservation of mass and energy work. But its existence was confirmed in 1956. More recently the presence of "dark matter" in the Universe - originally a mathematical device intended to explain why the expansion of the universe is accelerating - is now looking more and more like it's real.

As far as the die-hard Ptolemeins or Braheans go, Richard Feynman has pointed out that you can keep any theory as long as you're willing to add increasing complexity. But at some point you have to move to a new theory or you'll look ridiculous.

You can even have stellar parallax with an Earth centered solar system. Since in Tycho's theory, the Sun circled the Earth but the other planets circled the Sun, it was equivalent to the heliocentric system. The only thing it couldn't predict was the apparent wiggle of the stars - stellar parallax. But if you let the Sun circle the Earth and have the stars circle the Sun, you could have keep an Earth centered solar system with stellar parallax.

Ironically, Tycho himself stumbled on the answers why he hadn't seen parallax. He just thought the answers were wrong. If the stars were that far away, he said, they would have to be at least a whopping 700 times further from the Earth as the furthest planets! And some stars would have to be much larger than the Sun! Why, they would have to be a big as the orbits of the planets! What could be more ridiculous?

The resolution to all the problems of Copernicus's and Ptolemy's theories had been there all along. Ironically the solution came out of Tycho's research group. But you had to go to Germany to get the answer.

One of Tycho's chief assistants had been a fellow named Johannes Kepler. Like Galileo, whom Johannes knew and corresponded with, he thought the mathematical doodads needed by Ptolemy or Copernicus were a pain in the neck. A firm Copernican, Johannes began trying different types of geometrical figures for the orbits other than a circle.

And he hit pay dirt when he tried the ellipse. If you stuck the Sun, not at the center of the ellipse but at one of the focal points, then you could do away with deferents, epicycles, and equants. And the agreement with experiment was better than either Copernicus or Ptolemy. Best of all, the elliptical eccentricity of the planet's orbits is so small that if you draw them on paper they look like circles. So everyone should be happy.

Ultimately Johannes tossed out the deferents, epicycles, and equants and replaced them with three simple laws.

1. All planets move in elliptical orbits, not circles, with the Sun as a focus.

2. A planets sweeps out equal areas in equal times.

3. The square of the time for a planet to complete an orbit is proportional to the cube of the longest axis of the ellipse.

And things work out fine.

Will we ever read an essay about Johannes Kepler? After all has anyone ever starred in a TV show or a movie about Johannes?

Well, yes. In 1974 there was a film about the life of Kepler. It starred the German actor, Reimar Baur.

So it's certainly a hypothetical possibility.