Big Bang. Simon Singh

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      Figure 18 Copernicus (top left),Tycho (top right), Kepler (bottom left) and Galileo were responsible for driving the shift from an Earth-centred to a Suncentred model of the universe. Together their achievements illustrate a key feature of scientific progress, namely how theories and models are developed and refined over time by several scientists building on each other’s work. Copernicus was prepared to make the theoretical leap that relegated the Earth to a mere satellite and promoted the Sun to the central role. Tycho Brahe, despite his brass nose, provided the observational evidence that would later help Johannes Kepler to identify the outstanding flaw in Copernicus’s model, namely that the planetary orbits are slightly elliptical, not perfectly circular. Finally, Galileo used a telescope to discover the key evidence that should have convinced doubters. He showed that the Earth is not at the centre of everything, because Jupiter has its own satellites. Also, he showed that the phases of Venus are only compatible with a Sun-centred universe.

      Galileo and the new pope had known each other ever since they had attended the same university in Pisa, and soon after his election Urban VIII granted Galileo six lengthy audiences. During one audience, Galileo mentioned the idea of writing a book that compared the two rival views of the universe, and when he departed the Vatican he was left with the firm impression that he had received the Pope’s blessing. He returned to his study and made a start on what would turn out to be one of the most controversial books ever published in the history of science.

      In his Dialogue Concerning the Two Chief World Systems, Galileo used three characters to explore the merits of the Sun-centred and Earth-centred world-views. Salviati presented Galileo’s preferred Sun-centred view and was clearly an intelligent, well-read and eloquent man. Simplicio, the buffoon, attempted to defend the Earth-centred position. And Sagredo acted as a mediator, guiding the conversation between the other two characters, although his bias sometimes emerged when he scolded and mocked Simplicio along the way. This was a scholarly text, but the device of using characters to explain the arguments and counter-arguments made it accessible to a wider readership. Also, it was written in Italian, not Latin, so clearly Galileo’s objective was to win widespread popular backing for a Sun-centred universe.

      The Dialogue was eventually published in 1632, almost a decade after Galileo had apparently won the Pope’s approval. That huge delay between inception and publication turned out to have severe consequences, because the ongoing Thirty Years’ War had changed the political and religious landscape, and Pope Urban VIII was now ready to quash Galileo and his argument. The Thirty Years’ War had begun in 1618, when a group of Protestants marched into the Royal Palace in Prague and threw two of the town’s officials out of an upper window, an event known as the Defenestration of Prague. The local people had been angered because of the continual persecution of Protestants, and by taking this action they sparked a violent uprising by Protestant communities in Hungary, Transylvania, Bohemia and other parts of Europe.

      By the time the Dialogue was published, the war had been raging for fourteen years, and the Catholic Church felt increasingly alarmed by the growing Protestant threat. The Pope had to be seen to be a strong champion of the Catholic faith, and he decided that part of his new hard-hitting populist strategy would be to make a deft U-turn and condemn the blasphemous writings of any heretical scientists who dared question the traditional Earth-centred view of the universe.

      A more personal explanation for the Pope’s dramatic change of heart is that astronomers jealous of Galileo’s fame, together with the more conservative cardinals, had stirred up trouble by highlighting parallels between some of the Pope’s earlier and more naive pronouncements on astronomy and statements uttered by the Dialogue’s buffoon, Simplicio. For example, Urban had argued, much as Simplicio does, that an omnipotent God created a universe with no regard to the laws of physics, so the Pope must have been humiliated by Salviati’s sarcastic response to Simplicio in the Dialogue: ‘Surely, God could have caused birds to fly with their bones made of solid gold, with their veins full of quicksilver, with their flesh heavier than lead, and with their wings exceedingly small. He did not, and that ought to show something. It is only in order to shield your ignorance that you put the Lord at every turn.’

      Soon after the Dialogue’s publication, the Inquisition ordered Galileo to appear before them on a charge of ‘vehement suspicion of heresy’. When Galileo protested that he was too ill to travel, the Inquisition threatened to arrest him and drag him to Rome in chains, whereupon he acquiesced and prepared for the journey. While waiting for Galileo’s arrival, the Pope attempted to impound the Dialogue and ordered the printer to send all copies to Rome, but it was too late – every single copy had been sold.

      The trial began in April 1633. The accusation of heresy centred on the conflict between Galileo’s views and the Biblical statement that ‘God fixed the Earth upon its foundation, not to be moved for ever.’ Most members of the Inquisition took the view expressed by Cardinal Bellarmine: ‘To assert that the Earth revolves around the Sun is as erroneous as to claim that Jesus was not born of a virgin.’ However, among the ten cardinals presiding over the trial, there was a sympathetic rationalist faction led by Francesco Barberini, the nephew of Pope Urban VIII. For two weeks, the evidence mounted against Galileo and there were even threats of torture, but Barberini continually called for leniency and tolerance. To some extent he was successful. After being found guilty, Galileo was neither executed nor thrown into a dungeon, but sentenced instead to indefinite house arrest, and the Dialogue was added to the list of banned books, the Index librorum prohibitorum. СКАЧАТЬ