# #716 ゼロから分かるガリレオ・ガリレイ！宇宙の常識を覆し、教会と対立した科学者 - Show: 歴史を紐解く！聞き流し偉人伝 - Published: 2026-10-16 - Canonical: https://podc.club/en/episode/1623824742_e48543b9bdc2.html - Audio: https://api.robotstart.jp/api/for-media/v1/articles/37ec04a1/permanent/with-advertise/podcast/1bbe30acc5fb88a7b57f2d6d95aa463d9a92eb2dc003bbd5fbfcb3c16df9389a.mp3 - Source: Edited from a machine transcript of the first 30 minutes of the episode. Not an official summary. The opening episode of a new series traces the life of Galileo Galilei, the father of modern science, from his Pisan childhood to his death in 1642. The hosts examine why the famous quote "And yet it moves" has no verified record of ever being said, how Galileo upgraded the telescope to gather observational proof for heliocentrism, and how he continued his research under house arrest even after publicly recanting before the Inquisition. ## What this episode answers ### Did Galileo really say "And yet it moves"? Almost certainly not — no verified record exists of the statement. The hosts point out that Galileo was not the type to make emotional outbursts; even in politically charged situations he read the room calmly and retreated strategically when necessary, making such a dramatic declaration entirely out of character. ### What was Galileo's upbringing, and how did he come to pursue science? Born in 1564 in Pisa to a music theorist father, Galileo enrolled at the University of Pisa to study medicine but switched to mathematics and physics. In his twenties he discovered the isochronism of the pendulum and demonstrated that objects of different weights fall at the same speed, showing exceptional experimental talent from an early age. ### What did Galileo discover with his telescope, and why did those observations serve as evidence for heliocentrism? After improving the telescope on his own from its standard 3–4× magnification to 20–30×, Galileo observed craters on the Moon, moons orbiting Jupiter (now called the Galilean moons), and the phases of Venus. The phases of Venus cannot be explained by the geocentric model in which all bodies orbit a stationary Earth, making them compelling evidence for heliocentrism. ### Why did the Catholic Church view Galileo as a threat, and what punishment did it impose? The Church deemed heliocentrism dangerous because it contradicted Scripture and threatened the foundations of religious authority. It issued Galileo a formal warning in 1616, and after he published Dialogue Concerning the Two Chief World Systems in 1632, put him on trial in 1633, forced him to publicly renounce heliocentrism, and placed him under house arrest near Florence. ### How did Galileo continue his work after being forced to recant at the Inquisition? While publicly recanting, Galileo continued his research under house arrest, secretly completed a major work, and arranged for it to be published abroad. That book, known as Two New Sciences, profoundly influenced Newton and the next generation of scientists and became a cornerstone of modern physics. ## Article ## "And Yet It Moves" — Did He Ever Say It? The phrase most associated with Galileo Galilei — "And yet it moves" — has no verified written record to confirm he ever uttered it. The hosts describe the "he didn't say it" theory as highly probable, and argue that the quote runs entirely counter to who Galileo actually was. He was not the kind of person to blurt out his convictions in an emotional moment. Even in politically fraught situations he read the room carefully, judging when to retreat strategically rather than risk losing everything by an outburst, then pressing his advantage quietly afterward. Keeping that portrait in mind makes every episode that follows far more vivid. ## Early Life and the Awakening of a Scientist Galileo was born in 1564 in Pisa, Italy. His father was a music theorist — a scholar who sought to explain tuning and harmonic relationships through mathematics — and Galileo grew up in a cultivated, prosperous household. He enrolled at the University of Pisa intending to study medicine, but his fascination with mathematics and physics proved stronger, and he switched fields. Among the best-known anecdotes from Galileo's twenties is his discovery of the isochronism of the pendulum: a pendulum's period remains nearly constant regardless of the amplitude of its swing. He also overturned the accepted wisdom that heavier objects fall faster than lighter ones, demonstrating that objects of very different weights fall at the same speed. The famous story of him dropping two balls from the Leaning Tower of Pisa to prove this is touched on in the episode — but explicitly labeled "complete legend." ## The Telescope and the Evidence for Heliocentrism Around 1609, Galileo heard that a telescope had been invented in the Netherlands and set about improving it himself. Where a standard instrument of the day offered magnifications of only 3 to 4 times, Galileo first pushed that to 8×, then to 20–30×, while also significantly improving its resolution. What he observed through this upgraded instrument was revolutionary. He confirmed craters on the surface of the Moon. He discovered moons orbiting Jupiter — bodies now known as the Galilean moons. And most critically, he observed the phases of Venus. Like the Moon, Venus passes through a complete cycle of phases — a phenomenon that simply cannot be accounted for under the geocentric model, in which every body revolves around a stationary Earth. In other words, Galileo had obtained decisive observational evidence in favor of heliocentrism. ## Conflict with the Church and the Inquisition For the Catholic Church of the era, heliocentrism was a dangerous idea. Scripture presupposed a cosmos centered on Earth, and if heliocentrism gained broad acceptance, the foundations of religious authority could be shaken. In 1616 the Church issued Galileo a formal warning prohibiting him from teaching or defending the heliocentric theory. Galileo's intellectual curiosity could not be stilled. In 1632 he published Dialogue Concerning the Two Chief World Systems, structured as a conversation comparing heliocentrism and geocentrism. The format was ostensibly neutral, but the content clearly favored heliocentrism — Galileo judged that a direct essay-style argument would be suppressed immediately. The Church, however, saw through the strategy. In 1633, at the age of 69, Galileo was brought before the Inquisition in Rome and forced to publicly renounce heliocentrism. He spent the remainder of his life under house arrest near Florence. ## The Final Years: Research Behind a Recantation Despite his public recantation, Galileo never stopped working. Under house arrest he completed what would be the crowning achievement of his research, then arranged for it to be smuggled out and published abroad. Rather than shouting "And yet it moves" in a theatrical act of defiance, he adapted to circumstances, changing his outward form while never abandoning his convictions — entirely in line with the "clever maneuvering" described at the outset. He continued working even as his eyesight failed, producing Two New Sciences (Discorsi e dimostrazioni matematiche intorno a due nuove scienze). That work exerted enormous influence on Isaac Newton and the next generation of scientists and became a foundation of modern physics. Galileo died in 1642 at the age of 77. In a twist the hosts call "fateful," Newton was born in that same year — a symbolic passing of the torch in the history of science. ## Takeaways - "And yet it moves" almost certainly was never said — it contradicts both the historical record and Galileo's known character as a strategic, calculating thinker rather than an emotional one. - By improving the telescope from 3–4× to 20–30× magnification on his own, Galileo observed the phases of Venus — a phenomenon the geocentric model cannot explain — and secured concrete observational evidence for heliocentrism. - Even after publicly recanting heliocentrism before the Inquisition, Galileo continued his research under house arrest, and his work published abroad became a cornerstone of modern physics that shaped Newton and the generations that followed.