Part III on Dava Sobel's "Galileo's Daughter:"
Galileo’s contention that the earth revolved around the sun was controversial for several reasons:
1. It struck at the core of Aristotelean astronomy. It was not an edge modification to his theory: it demolished it. Aristotelean astronomy was built on an immovable earth at the center of the cosmos. A parallel today would be the firestorm that might erupt if an eminent scientist proposed a theory that destroyed the theory of evolution.
2. A moving earth appeared to challenge Scriptural truth, such as Psalm 103’s “O Lord my God ... thou fixed the earth upon its foundation, not to be moved forever.”
3. It challenged commonsense. Sobel points out that is was clear to people as they looked at the sky that the sun traveled across it, rising in the east and setting in the west. People also questioned why they didn’t get dizzy or why birds didn’t lose their way if the earth was moving around space at a high speed.
On the surface, reconciling the Bible to science was a fairly easy task. Contrary to what I was taught in school about Bible literalism in premodern times, people of the 15th and 16th centuries, even clerics, had a sophisticated understanding of metaphor. Remember, this was the period of Shakespeare and Donne, masters of metaphoric language. (Also remember that Donne was an Anglican priest.) While Europeans of this era took the Bible seriously, they understood that many passages in the scriptures were poetic or symbolic. One of their puzzles, as today, was determining which passages to take literally.
Helping Galileo was the fact that, contrary to what I learned in school, science and religion were not in an adversarial relationship during this period. There was not an overarching construct of “faith versus reason” or “science versus Christianity.” Instead, 17th century thinkers saw nature and scripture as the two main ways God revealed himself in the world. Nature and scripture were the two prongs (or manifestations) of a God-centered universe. People studied both nature and scripture for the same purpose: to get a better grasp of God’s attributes and his plan for the world. They looked to science--how God revealed himself in nature--to help them interpret the Bible, and they looked at scripture to help understand how God worked in nature. In fact, many scientists were also clergymen, including Copernicus.
Knowing people were going to challenge him on the basis of Scripture, Galileo prepared arguments to show that the Biblical passages that opposed a sun-centered solar system were metaphoric, and he marshalled other Bible verses that were clearly accepted as metaphor to bolster his claim. He asserted that the Bible used metaphor to help people grasp difficult truths and quoted Augustine that hypotheses not be condemned hastily, lest “that truth hereafter may reveal to be not contrary in any way to the sacred books of either the old or the new testaments.”
As with Copernicus, the biggest problem facing Galileo was not religion, but science. Neither man could offer any proof for the assertion that the earth moved around the sun. Copernicus used math and reason to support his theory: A sun-centered solar system was an elegant way to solve difficulties in what he observed about the movement of planets. Galileo, too, intuited from the movement of the planets and other celestial bodies that we live in a sun-centered solar system.
Galileo realized that what he “knew” to be true couldn’t be backed up scientifically. However, he needed empirical evidence to verify his claims. What he came up with were the tides. He attributed the tides’ movement to the earth revolving around the sun, sloshing the ocean’s water all around. He wrote a treatise on the subject, called “Treatise on the Tides.”
Of course, as we know now, Galileo was wrong about the tides, which are caused primarily by the moon’s gravitational pull. Galileo couldn’t know this because he lived in a gravity-free universe. Sir Isaac Newton, the discover of gravity, wasn't born until the year Galileo died. It’s stunning to think that the man who became famous from dropping objects from a tower and measuring how fast they fell never questioned why they fell.
Galileo might not have had proof for his theory, but he did have high-placed friends and admirers, including Cardinal Barberini, a fellow Tuscan who later became Pope Urban VIII.
If Galileo occupied a world in which the church was not wedded to Biblical literalism and which understood science as the revelation of God’s handiwork, and if high-ranking people in the church hierarchy were at least open to hypotheses about a sun-centered solar system, how did Galileo end up hauled in front of the Inquisition and forced to repudiate his claims?