B00B7H7M2E EBOK (16 page)

The story gets increasingly murky. Perhaps Barberini was doing his best to be both a cautious Church ruler and a friend to this brilliant, volatile man. Perhaps he still hoped to let matters evolve more gradually. Would a more politically sensitive and diplomatic person than Galileo have recognized that writing an impartial book was as good as it was going to get, very good indeed in view of the 1616 decision? Such a book might have achieved a significant victory for Copernicanism, without requiring him to become a martyr in the process.

Galileo was almost surely not thinking of martyrdom as a possible outcome. What
was
he thinking? He might quite understandably have decided, in view of the Church’s earlier policy of tolerance, that the 1616 judgement had been only a temporary conservative aberration. Significantly, he now thought he had discovered the proof that he had been warned to find when that judgement was delivered – his new theory of the tides. It’s possible he took Barberini’s statement that as Pope he could no longer chat off the record to mean that he couldn’t tell Galileo outright to author a pro-Copernican book but would like to see it happen. If Galileo
had
produced a less pointedly pro-Copernican book, would his fate or the future of Copernican theory
vis-à-vis
the Catholic Church have been different? Arguably not, for Galileo’s trial as it turned out was a trumped-up charade in which science, religion and even Church authority were paid little more than lip service. What was really at the heart of the problem? That is still a mystery.

In any case, Galileo’s book, though it was to seal the triumph of Copernican astronomy in the long run, in the short run played directly into the hands of his enemies.
Dialogue Concerning the Two Chief World Systems
, more often called by its shortened Italian name,
Dialogo
, makes a powerful case for Copernicus. Unlike
De revolutionibus
, it is not a technical,
mathematical
book. It is an entertaining masterpiece of popularization, written in Italian rather than in scholarly Latin, designed to appeal to a great many readers – as no book on Ptolemaic astronomy, indeed no book on astronomy, ever had before. It takes the form of a lively four-day discussion among three friends. The first day is used to demolish the ideas of Aristotle. The second and third days are devoted to proving that the Earth turns on its axis and orbits the Sun. The fourth is spent on Galileo’s theory of the tides, a theory which is in error but which he thought was his clinching argument. (Galileo in fact called Kepler childish for supposing that the Moon affects the tides.)

Galileo left no doubt whatsoever that the character ‘Salviati’, who is a far more intelligent man than either of the other characters and who argues eloquently for Copernican theory, represents Galileo himself. Salviati has the floor much of the time. The character who argues the Aristotelian/Ptolemaic side of the case – Simplicio – gets the last word, but he is little better than a buffoon, confused and slow. One is tempted to say that he provides the comic interest. Lest any of Galileo’s readers miss the point, a third character, Sagredo, a skilful discussion leader who asks thoughtful questions to move the conversation along, scolds Simplicio for his stupidity and inability to see reason and congratulates him condescendingly whenever he does see the light just a little. Galileo was a master of ridicule, and he used that weapon mercilessly in
Dialogo
. Doubtless it seemed to him that anyone who would continue to defend Aristotle and Ptolemy in the face of compelling arguments for Copernican astronomy
could
only be a half-wit. Galileo surely could not possibly have thought his book was impartial or that anyone else would think it was.

How amazing then to learn that there was initially no adverse reaction! The book made its way through Church bureaucracy with only a few annoying delays which only with hindsight look ominous. After minor changes, it actually won approval from
the
Church censors, who made one inadvertent improvement by requiring Galileo to change the title from
Dialogue Concerning the Tides
to
Dialogue Concerning the Two Chief World Systems
. The censors had no way of knowing that the section of the book about the tides was its one embarrassing weakness.

It might begin to seem at this point that Galileo had judged the situation entirely correctly.
Dialogo
appeared in February 1632 with a great flurry of publicity, and the reception was overwhelmingly enthusiastic. There was, to be sure, some criticism, notably from one Christoph Scheiner, a Jesuit who had earlier clashed with Galileo about which of them had first discovered and correctly interpreted Sun-spots. Galileo had pretty well trounced Scheiner in that encounter and was not gracious about the victory. It comes as no great surprise that Scheiner was more than a little sour about Galileo’s latest triumph.

Then, out of the blue, disaster struck. Barberini, Pope Urban VIII, Galileo’s old friend, suddenly turned bitterly against him. To this day Barberini’s belated change of heart remains unexplained. Had he only just got around to reading the book? The argument that the Pope was under political and military pressures that caused him to change his mind about Galileo is unconvincing. These problems were so far removed from Galileo and the Copernican question that it is difficult to imagine they had an impact except to contribute to a state of tension. It also makes little sense to say that the Church could not be seen to waver on any decision. On what decision was it wavering? The 1616 dictum? Copernicanism had not been officially declared heresy then, and lest anyone had missed that technicality, much more recently Church censors had approved Galileo’s book. Why waver from
that
decision? Barberini seems to have unleashed the fury of the Church against Galileo
in spite
of the fact that he must have known the result would be to make the Church and himself look vacillating and foolish. Many devout liberal Catholics were
shocked
when the Church finally condemned and prohibited the teaching of Copernicanism, because it committed the Church to a theory that now looked untenable. Barberini would have anticipated this reaction.

One popular explanation is that advisers around the Pope convinced him that Galileo had meant Simplicio to be a caricature of Barberini himself. Galileo had made the mistake of putting in Simplicio’s mouth an argument that Barberini had once expressed in their discussions. Even so, the reaction seems extreme. The interpretation that makes this episode into a major confrontation between science and religion is that the Pope saw Galileo and Copernicanism as a threat to belief in the validity of scripture and to the Church’s right to be the final arbiter of truth. In fact, such motivation might have pushed a good politician, which Barberini was, to side with the theory that looked likely to win the day. Approving Galileo’s book was a strong move for the Church. A more likely reason for Barberini’s ire is more subtle – that Galileo had finally managed to make it appear to the public that the Church had thrown its weight solidly behind Copernican astronomy. The decision to do that should have come, if it came at all, from Church officials, not from Galileo. This issue had little to do with the Church’s right to declare what was true. It had to do with its right to choose its own political moment. In this respect, Galileo had indeed outmanoeuvred the cautious Church hierarchy and usurped Barberini’s power.

When the printer of
Dialogo
received the surprising order to send all unsold copies of the book to Rome, he couldn’t comply. They were sold out. But the news soon got about that
Dialogo
was to be re-examined to determine whether it was heretical. The Holy Office sent for Galileo. He went to Rome and resided at the home of the Tuscan ambassador for some weeks while the Holy Office scrambled to put together a coherent case – no easy matter, since Church censors had found no fault with Galileo’s book and the opinion that Copernican
theory
was heresy had never been the official opinion of the Church. Church legal experts nevertheless did their best (or worst), and Galileo stood trial for ‘a vehement suspicion of heresy’. Galileo’s letter from Cardinal Bellarmine that said Galileo had not been forbidden by the 1616 decree to teach Copernicanism carried little weight, though it did cause chagrin. Even less effective was Galileo’s pitiful defence strategy. He told the court that his accusers had misinterpreted
Dialogo
. The book actually favoured Ptolemy, not Copernicus, and he could add some pages at the end to make that clear. Even the least astute among the inquisitors could not be expected to believe this, for Galileo had, in
Dialogo
, called defenders of Ptolemy ‘dumb idiots’.

Galileo was not tortured nor was he sentenced to death. It seemed to be his complete humiliation that the Pope wanted. He was forced to renounce Copernicanism in a long, demeaning statement before a resplendent crowd of dignitaries, nearly all of whom must have known the old man didn’t mean a word of it. The story goes that he made his exit muttering ‘
eppur si muove
’ (‘and yet it does move’). Whether or not he really said the words out loud, he must surely have been thinking them.

Galileo was sentenced to spend the rest of his life in isolation, under house arrest at his own villa at Arcetri. Some scholars argue that the only thing that saved him from a harsher punishment was that Barberini, for all his inexplicable blind rage,
was
smart enough to recognize that this was going to be a Pyrrhic victory, that history and many of his contemporaries within Church officialdom would ridicule him for upholding Earth-centred astronomy. As it turns out, history remembers him as a cruel, irrational bigot. His Church and Catholic scholarship and science suffered irreparable damage and loss of credibility. After the trial, Italy lapsed into what was almost a scientific dark age with the prohibition of Copernican theory. The centre of scientific endeavour and achievement shifted to northern Europe and England, never to return.

Galileo lived for eight years after his trial. He was in his seventies, but still active. It was during these years that he got around to publishing much of the scientific work that he had carried out when he lived in Padua. He died in 1642, at the age of 78.

Did Galileo know that though he had suffered personal defeat he had won the war for Copernicanism? Probably. It’s less probable that he realized he would go down in history as a scientific martyr and a symbolic figure for all those who see religion as the enemy of science, and vice versa. He would not have liked that, surely. For he believed so firmly and argued so well, himself, that there was no contradiction between them.

As Kepler, Tycho Brahe, Galileo and other 16th- and 17th-century scholars made up their minds whether to become Copernicans, some less-than-familiar scientific values came into play. It certainly wasn’t always just a question of what fitted best with observation – not even for Galileo, who has been dubbed the father of modern science. Why else prefer one model to another?

Suppose that you and I, for reasons we won’t pause to examine, have chosen the Moon as the centre of the system. We know that the issue here is one of relative motion only, and that we can come up with a Moon-centred model that does indeed fit with all the data and that no one can prove is wrong. What then
would
make anyone prefer another model to ours? What has Copernicus got that we haven’t?

Imagine our planetary system represented as dots moving on a three-dimensional super-computer screen. Freeze first one dot and then another, each time allowing the computer to make sense of the movement of the other dots in terms of the unmoving dot. The picture may always be correct and accurate, but it will sometimes look far more complicated, and sometimes far simpler. The choice of one particular dot, the
Sun
, as ‘centre’ causes the picture to fall into place and appear remarkably simple and harmonious. We feel as though we have cracked the code. Why bother with the other ways, just because they don’t happen to be ‘wrong’? This reasoning causes scientists to prefer the Copernican model to Tycho Brahe’s.

Simplicity and harmony are strong pointers but not absolute clinchers of the sort Mr Elmendorf was hoping for. There are other criteria. Modern science obliges us to back up a choice of
how
the solar system moves with the answer to a second question:
Why?
It isn’t enough to claim that a model can predict where all the planets will be a month or a year or a century from now. What makes them go there? To use more scientific language, what are the ‘dynamics’ that cause them to move in this way rather than another? What makes them move at all rather than sit still? Ptolemaic astronomy explained the movement of the universe as originating in the sphere of the stars, with that movement transferred to the planetary spheres. There were those who thought that the Creator had given an initial push to each planet at the moment of creation, and that that movement would go on forever. There were others who suggested that angels move the spheres. Copernicus didn’t attempt to explain why the planets moved as he thought they did, although he recognized the importance of the question. Kepler believed that a whirling force emanating from the Sun drives the planets and that this could work only if the Sun was at the centre. But not until Isaac Newton and later Albert Einstein, with their explanations of gravity and the curvature of space time, was anyone able to suggest the reasons accepted today why the planets move as they do.

Is that how we know Copernicus was right? Not quite. Fred Hoyle has argued in his book about Copernicus that a subtler understanding of Einstein’s theories reveals that they may actually slightly favour an Earth-centred model. Had Galileo had Hoyle at his elbow, he might have produced the book that
would
have pleased the Pope and not have been tried for heresy!

Why, then, should poor Ptolemy lose out so badly? Paradoxically, the enormous success of Ptolemaic astronomy is not an argument in its favour. It can account for all apparent movement in the heavens. It could also account for a great deal that we never see happening. It allows for too much. Copernican astronomy, as it has evolved, allows for far less. It is easier to think of something that Copernican theory could not incorporate. The more scientific way of putting this is that Copernican theory is more easily ‘falsifiable’ than Ptolemy’s, easier to
dis
prove. Falsifiability is considered a strength. If a theory sets up a clear enough profile so that it provides numerous opportunities to shoot it down, and no one is able to shoot it down – if new discoveries don’t undermine it but fall neatly into place, as Galileo’s discoveries with his telescope did – if the picture gets more harmonious over time rather than more complicated, then a theory begins to look as though it is right on target.