Is God a Mathematician_ - Mario Livio [31]
Galileo’s father died in 1591, prompting the young man, who had now to support his family, to take an appointment in Padua, where his salary was tripled. The next eighteen years proved to be the happiest in Galileo’s life. In Padua he also began his long-term relationship with Marina Gamba, whom he never married, but who bore him three children—Virginia, Livia, and Vincenzio.
On August 4, 1597, Galileo wrote a personal letter to the great German astronomer Johannes Kepler in which he admitted that he had been a Copernican “for a long time,” adding that he found in the Copernican heliocentric model a way to explain a number of natural events that could not be explained by the geocentric doctrine. He lamented the fact, however, that Copernicus “appeared to be ridiculed and hissed off the stage.” This letter marked the widening of the momentous rift between Galileo and the Aristotelian cosmology. Modern astrophysics was starting to take shape.
The Celestial Messenger
On the evening of October 9, 1604, astronomers in Verona, Rome, and Padua were startled to discover a new star that rapidly became brighter than all the stars in the sky. The meteorologist Jan Brunowski, an imperial official in Prague, also saw it on October 10, and in acute agitation he immediately informed Kepler. Clouds prevented Kepler from observing the star until October 17, but once he started, he continued to record his observations for a period of about a year, and he eventually published a book about the “new star” in 1606. Today we know that the 1604 celestial spectacle did not mark the birth of a new star, but rather the explosive death of an old one. This event, now called Kepler’s supernova, caused quite a sensation in Padua. Galileo managed to see the new star with his own eyes late in October 1604, and the following December and January he gave three public lectures on the subject to large audiences. Appealing to knowledge over superstition, Galileo showed that the absence of any apparent shift (parallax) in the new star’s position (against the background of the fixed stars) demonstrated that the new star had to be located beyond the lunar region. The significance of this observation was enormous. In the Aristotelian world, all changes in the heavens were restricted to this side of the Moon, while the far more distant sphere of the fixed stars was assumed to be inviolable and immune to change.
The shattering of the immutable sphere had started already in 1572, when the Danish astronomer Tycho Brahe (1546–1601) observed another stellar explosion now known as Tycho’s supernova. The 1604 event put yet another nail in the coffin of Aristotle’s cosmology. But the true breakthrough in the understanding of the cosmos didn’t descend from either the realm of theoretical speculation or from naked-eye observations. It was rather the outcome of simple experimentation with convex (bulging outward) and concave (curving inward) glass lenses—hold the right two of those some thirteen inches apart and distant objects suddenly appear closer. By 1608, such spyglasses started to appear all over Europe, and one Dutch and two Flemish spectacle makers even applied for patents on them. Rumors of the miraculous instrument reached the Venetian theologian Paolo Sarpi, who informed Galileo around May of 1609. Anxious to confirm the information, Sarpi also wrote to a friend in Paris, Jacques Badovere, to inquire whether the rumors were true. According to his own testimony, Galileo was “seized with a desire for the beautiful thing.” He later described these events