The Day the Universe Changed - James Burke [69]
that they were, in fact, Jovian satellites.
Galileo’s handwritten description of his observations on the satellites of Jupiter. The planet is drawn as a smart cartwheel and the satellites as asterisks. The changing positions of the tiny objects on either side of Jupiter convinced Galileo that they were orbiting the planet.
If Jupiter could have satellites while itself orbiting the sun, why could the earth not do the same? Galileo propounded these theories in a brief paper called The Starry Messenger, published in the spring of 1610. Everybody who read it looked through a telescope and saw what Galileo had seen. Then, in 1613, Galileo published again. This time it was to explain the sunspots reported by various people. He said that these were imperfections on the sun, because the mathematics of optics showed that they were on its surface. He also noted that the sun rotated. These were two more blows at Aristotelian doctrine. The Jesuits did nothing, continuing to accept his views, as they had accepted those of Copernicus, as a convenient mathematical fiction.
Then Galileo wrote a letter to the Tuscan Grand Duchess Christina, in which he referred to criticisms of his work and argued that he was not imputing scientific error to the Bible because the Bible was not a scientific text. He gave a detailed defence of the independence of scientific investigation and of his preference for the evidence of the senses. This was a dangerous move, since it took Galileo into the arena with the theologians who had recently burned a heretic called Giordano Bruno for his view that the universe was infinite and contained countless planets like the earth. Bruno was a mystic, and his interpretation of the conversion of the Protestant French king Henry IV as an event which heralded revolution in Rome made him a political embarrassment. In 1600, after eight years of trial, he was sent to the stake as a ‘magician’.
With this and other disturbances in mind, the attitude of the Church began to stiffen. Fifty years before they had been prepared to accept a convenient fiction to make the calendar work because it did not appear to threaten God’s design, only man’s perception of it. But now the tune changed. The new heliocentric theory might be interpreted by the credulous as invalidating everything the Church decreed.
In 1624 Galileo went to Rome to argue for more freedom. If he could prove the action of the tides to be due to the earth’s moving and not because of some magic effect of the moon, would that, for instance, be acceptable? He was told to take care that his hypothetical arguments should be explained slowly and carefully over a period of time so as not to cause Catholics to lose their faith in the Scriptures for the wrong reasons. Galileo insisted on total freedom.
In 1632 he published The Dialogue on the Two Chief Systems of the World. It caused a sensation. The book showed the opponents of the Copernican system to be simpletons, which was seen to be a full-blooded attack on the Church. In 1633 Galileo was condemned to house arrest, where he remained, in Arcetri, near Florence, until he died in 1642. His book was placed in the Index of Prohibited Books until 1835.
Galileo’s trial virtually ended scientific work in Italy and changed the nature of scientific investigation permitted by the Church. After his efforts the Church insisted that hypotheses should relate to reality and not to convenient fictions. They must be compatible with the principles of physics, but at the same time they could not contradict the Scriptures in any way. Two conditions were imposed on any hypothesis: it must not be falsa in philosophia, or erronea in fide. Galileo’s Dialogue had broken both rules by presenting physical evidence which validated Copernicus’ theory in support of a heretical view. No more such hypotheses were to be permitted in Italy or anywhere else under Rome’s authority.
It was in the north, where the Roman writ ran less effectively, that the work continued, thanks to one of Galileo’s German contemporaries who had avoided trouble