Chapter 1: Rebel with a Cause CHAPTER 1 Rebel with a Cause At a breakfast that took place at the Medici Palace in Pisa, Italy, in December 1613, Galileo''s former student Benedetto Castelli was asked to explain the significance of Galileo''s discoveries with the telescope. During the discussion that ensued, the Grand Duchess Christina of Lorraine badgered Castelli about what she perceived as contradictions between certain biblical passages and the Copernican view of an Earth orbiting a stationary Sun. She cited in particular the description from the book of Joshua, in which, at Joshua''s request, the Lord commanded the Sun (and not the Earth) to stand still over the ancient Canaanite city of Gibeon and the Moon to stop in its course over the Aijalon Valley. Castelli described the entire affair in a letter he sent to Galileo on December 14, 1613, claiming that he played the theologian "with such assurance and dignity" that it would have done Galileo good to hear him. Overall, Castelli summarized, he "carried things off like a paladin." Galileo was apparently less convinced of his student''s success in elucidating the issue, since in a long letter to Castelli that he sent on December 21, he explained in detail his own views on the impropriety of using Scripture to dispute science: "I believe that the authority of Holy Writ had only the aim of persuading men of those articles and propositions which, being necessary for our salvation and overriding all human reason, could not be made credible by any other science," he wrote. In a style characterizing much of his writing, he was quick to add sarcastically that he did not think "that the same God who has given us our senses, reason, and intelligence wished us to abandon their use." Simply put, Galileo argued that when an apparent conflict arises between Scripture and what experience and demonstration establish about nature, Scripture has to be reinterpreted in an alternative way.

"Especially," he noted, "in matters of which only a minimal part, and in partial conclusion, is to be read in Scripture, for such is astronomy, of which there is [in the Bible] so small a part that not even the planets are named." While the argument itself was not entirely new--theologian Saint Augustine had written already in the fifth century that the sacred writers did not intend to teach science, "since such knowledge was of no use to salvation"--Galileo''s bold statements were about to put him on a collision course with the Catholic Church. The Letter to Benedetto Castelli marked only the beginning of the risky road that would eventually lead to Galileo being pronounced "vehemently suspected of heresy" on June 22, 1633. Overall, if we examine the record of Galileo''s life in terms of his personal contentment, it traces something like an inverted-U shape, with a pronounced peak somewhere shortly after his numerous astronomical discoveries, followed by a fairly steep fall. Ironically, the parabolic paths of projectiles, which Galileo was the first to determine, form a similar curve. As history would have it, Galileo''s tragic end only helped to transform him into one of those larger-than-life heroes of our intellectual history. There aren''t many scientists, after all, about whose lives and achievements entire plays (such as Bertolt Brecht''s unforgettable Life of Galileo , first performed in 1943), and scores of poems have been written, or an opera has been composed. Suffice it also to note that a Google search on "Galileo Galilei" produced no fewer than 36 million results, again demonstrating an impact that many of today''s academics would love to have.

Albert Einstein once wrote about Galileo that "he is the father of modern physics--indeed, of modern science altogether." He was echoing here philosopher and mathematician Bertrand Russell, who also called Galileo "the greatest of the founders of modern science." Einstein added that Galileo''s "discovery and use of scientific reasoning" was "one of the most important achievements in the history of human thought." These two thinkers were not in the habit of offering profuse praise, but there was a solid base for these accolades. Through his pioneering, stubborn insistence that the book of nature was "written in the language of mathematics," and his successful fusion of experimentation, idealization, and quantification, Galileo literally reshaped natural history. He transformed it from being a mere collection of vague, verbal, nebulous accounts embellished by metaphors, to a magnificent opus encompassing (when the contemporary knowledge allowed it) rigorous mathematical theories. Within those theories, observations, experiments, and reasoning became the only acceptable methods for discovering facts about the world and for investigating new connections in nature. As Max Born, winner of the 1954 Nobel Prize in Physics, once put it: "The scientific attitude and methods of experimental and theoretical research have been the same through the centuries since Galileo and will remain so.

" His scientific prowess notwithstanding, we should not get the impression that Galileo was the easiest or kindest person, or, for that matter, even that he was an idealistic freethinker; an explorer who accidentally wandered into theological controversy. Whereas he could indeed be extremely empathic and supportive to members of his own family, he showed blistering intolerance and belligerence, wielding his sharp pen toward scientists who disagreed with him. A number of scholars labeled Galileo a zealot, although not always a zealot for the same cause. Some said it was for Copernicanism--the scheme in which the Earth and the other planets revolve around the Sun--others claimed he was a zealot for his own self-righteousness. Still others even believed he was fighting for the Catholic Church, anxious to stop it from making a mistake of historical proportions by condemning a scientific theory that he was convinced would be proven to represent a correct description of the cosmos. In defense of his zeal, though, one would probably expect nothing less from a man who set out not only to change a worldview that had existed for centuries but also to introduce entirely new approaches to what constitutes scientific knowledge. Undoubtedly, Galileo owes much of his scholarly fame to his spectacular discoveries with the telescope and his extremely effective dissemination of his findings. Turning this new device to the heavens instead of watching sailing ships or his neighbors, he was able to show wonders such as: there are mountains on the surface of the Moon; Jupiter has four satellites orbiting it; Venus displays a series of changing phases like the Moon; and the Milky Way is composed of a vast number of stars.

But even these proverbially out-of-this-world achievements are not sufficient to explain the enormous popularity that Galileo enjoys to this very day, and the fact that he, more than almost any other scientist (with the possible exceptions of Sir Isaac Newton and Einstein), has become the perennial symbol of scientific imagination and courage. In addition, the facts that Galileo was the first to firmly establish the laws of falling bodies and the founder of the crucial concept of dynamics in physics were clearly not enough to make him the hero of the scientific revolution. What at the end distinguished Galileo from most of his contemporaries was not so much what he believed in but rather why he believed it and how he reached that belief. Galileo based his convictions on experimental evidence (sometimes real, sometimes in the form of "thought experiments"--thinking through the consequences of a hypothesis) and theoretical contemplation, and not on authority. He was prepared to recognize and internalize that what had been trusted for centuries might be wrong. He also had the foresight to assert forcefully that the road to scientific truth is paved with patient experimentation leading to mathematical laws that weave all the observed facts into one harmonious tapestry. As such, he can definitely be regarded as one of the inventors of what we call today the scientific method: a sequence of steps that ideally (although rarely in reality) needs to be taken for the development of a new theory, or for acquiring more advanced knowledge. The Scottish empiricist philosopher David Hume gave in 1759 this personal comparison between Galileo and another famous empiricist, English philosopher and statesman Francis Bacon: "Bacon pointed out at a distance the road to true philosophy: Galileo both pointed it out to others, and made himself considerable advances in it.

The Englishman was ignorant of geometry; the Florentine revived that science, excelled in it, and was the first to apply it, together with experiment, to natural philosophy." All of Galileo''s impressive insights could not have happened in a vacuum. One could perhaps even argue that the age shapes individuals more than individuals shape the age. Art historian Heinrich Wolfflin wrote once: "Even the most original talent cannot proceed beyond certain limits which are fixed for it by the date of its birth." What, then, was the backdrop against which Galileo acted and produced his unique magic? Galileo was born in 1564, only a few days before the death of the great artist Michelangelo (and also the same year that brought the world the playwright William Shakespeare). He died in 1642, almost one year before the birth of Newton. One doesn''t have to believe in the transmigration at death of the soul of one human into a new body--nobody should--to realize that the torch.