Galileo versus the Church
From experiments to inquisition, discover the Renaissance scientist’s iconic clash with the pope and how he proved that the Earth goes around the Sun
Inside the Renaissance scientist’s iconic clash with the pope
Galileo Galilei was never destined for a life as an astronomer and physicist. Ironically, he attended school at the local monastery and after this had been well on his way for a future as a doctor. His father, Vincenzio, had high hopes for his son and arranged for him to study medicine at the University of Pisa from 1581. In spite of this, Galileo never cared for biology, developing a far greater interest in philosophy and mathematics. Against the protestations of his father, he promptly switched subjects and never looked back.
Studying hard for four years, Galileo left university without a degree and turned his hand to private tutoring. During this time he wrote his short treatise, Cosmography, which he used to teach his students about the mysterious celestial bodies.
Cosmography adhered to the widely accepted, traditional geocentric philosophies of Aristotle and Ptolemy, which placed the Earth at the centre of the universe.
He soon moved on from his tutoring career and returned to the University of Pisa in 1589, where he spent the next three years as the professor of mathematics. It is likely that this is when he succeeded in disproving Aristotle’s theory that objects of different mass fall at different speeds, though whether Galileo actually tested this by dropping balls of the Leaning Tower of Pisa is disputed as the only record we have of it is a biography written by his pupil Vincenzo Viviani in 1717.
Unfortunately, his unconventional beliefs made Galileo unpopular so his contract at the university was not renewed. He moved once again in 1592 and travelled north to Padua, where he assumed a new, higher paid position as a professor of mathematics at the city’s university. Here, Galileo really began to hone his research. He conducted a number of experiments, many of which were in the field of mechanics.
Starting in 1602, he made some of the first scientific observations regarding pendulums. He also uncovered the principle of isochronism, where a pendulum would take the same time to complete a swing regardless of how big that swing was. Ultimately, this led to the invention of the accurate mechanical clock in 1656 – a device humanity came to rely on.
After a few years of dedicating his time to his experiments, everything changed. In 1609, Galileo heard rumours that a device that could make distant objects appear close had been invented in the Netherlands: the telescope. Once he learned that it had been simply made with just a tube and a lens on both ends, he immediately set out to re-create one for himself. His initial versions ranged in magnifying power, up to eight times, but by 1610, he had developed a telescope that could be magnified 20 times – far more powerful than the original, rudimentary invention.
Armed with his telescope, the possibilities open to Galileo were endless. Just between 1609 and 1610 alone, he discovered mountains on the Moon, the four satellites of Jupiter and numerous stars in the Milky Way. He observed the different phases of Venus and, mistakenly, believed that he had found two ‘ears’ that accompanied Saturn. Although he did not realise it, Galileo had actually observed Saturn’s iconic ring, which would first be confirmed in 1656.
“ARMED WITH HIS TELESCOPE, THE POSSIBILITIES OPEN TO GALILEO WERE ENDLESS”
Galileo’s celestial discoveries, coupled with his mathematical genius, placed him light years ahead of his contemporaries. His sudden fame came at a time when the Copernican Revolution was already well underway. Back in 1543, Nicolaus Copernicus published On the Revolution of Heavenly Spheres, which argued that the Sun, not the Earth, was at the centre of the universe. This theory became known as ‘heliocentrism’ (from the Greek ‘hēlios’ meaning ‘sun’), and contradicted the notion that the universe revolved around our planet, or geocentrism (from
‘gē’ meaning ‘Earth’). As Galileo was making his own celestial observations, German astronomer Johannes Kepler was also conducting significant research in the field.
Kepler’s Astronomia Nova was published in 1609 after his decade-long research into the motion of Mars. One of the most momentous works to ever grace the world of science, not only did Kepler conclude that orbital paths were elliptical and not circular, he also argued that his findings supported heliocentrism. With his telescope, Galileo’s revolutionary research was about to prove that Copernicanism was not just a hypothesis – it was reality.
Galileo decided to share his new discoveries, starting with his book Sidereus Nuncius in 1610. Also known by its English name, Starry Messenger, it drew a lot of interest and raised his celebrity profile to new heights. That same year, he was appointed to the prestigious position of court mathematician to Cosimo II de’ Medici, Grand Duke of Tuscany, one of his former pupils. However, Starry Messenger also attracted a lot of criticism. Galileo’s conclusion that it was the Sun at the centre of the universe was not accepted by the Catholic Church, the most powerful institution in Italy – it steadfastly supported the traditional geocentric views of Aristotle and Ptolemy.
But all was not yet lost for Galileo. He was not confronted with total opposition to his astronomical findings – for instance, Jesuit astronomers managed to repeat his observations themselves. Galileo even had a few admirers from the Church, most notably Cardinal Maffeo Barberini. Despite being faced
“Galileo refused to back down”
with all the evidence, the Church refused to reconcile with the Copernican model. Some astronomers within the Church, such as the Jesuits, advocated the Tychonic system, developed by astronomer Tycho Brahe, which mathematically supported Galileo’s research but also maintained the status quo. According to Brahe, the Sun and Moon revolved around the Earth but the other planets orbited the Sun – a mix of the two theories.
Infinitely frustrated that his evidence was being ignored, Galileo refused to back down. He campaigned incessantly in favour of Copernicus’ theories and clashed with theologians, who desperately clung to their geocentric views. Even though he provoked attention, his combative behaviour backfired and the Jesuits turned their back on him. Now the Catholic Church decided that they had let Galileo run wild long enough – it was time to put its foot down.
What followed was one of the most momentous events in history regarding the tentative relationship between religion and science: the ‘Galileo Affair’. In 1616, the Roman Catholic Inquisition investigated Galileo’s work, for which he was being accused of heresy. A group of theologians were asked to assess the theory of heliocentrism that Galileo had so defiantly defended and whether it held any merit.
Of course, the theologians’ primary task was the defence of the Catholic Church and the Bible and less than a week later, the judgement was passed. They announced that heliocentrism contradicted the Holy Scriptures and thus Copernicanism amounted to heresy. No sooner had the verdict been delivered than Galileo was ordered to stop his support for the theory and all works associated with it, including his, were banned pending suitable corrections. Instead of getting acceptance, Galileo had been left with disaster.
ABOVE This painting depicts Galileo teaching a student while working at the University of Padua
Galileo’s drawings of the phases and surface of the Moon from Sidereus Nuncius, 1610 BELOW
A replica based on Galileo’s design for a pendulum clock ABOVE