• blog@thephotonmagazine

Galileo’s Crucifix — By Hari Krishan Choudhari

Taken from https://italoamericano.org/story/2016-12-6/galileo-florence

Galileo Galilei is a person who needs little introduction: if he sent in an application to any job today, his CV alone would be enough to guarantee him acceptance anywhere. He invented the pendulum clock, the geometric compass, the first rudimentary thermometer (the thermoscope), the first compound microscope (disputedly), and a telescope with magnification of 20x.[1]This last invention acted as the catalyst for the discovery of craters on the moon, sunspots, the phases of Venus, the rings of Saturn and, most famously, discovery of the four most massive moons of Jupiter, now known as the Galilean moons.[2]If that wasn’t enough, he also proved constant acceleration due to gravity on the side. What a guy.

Now, these discoveries and innovations were definitely extremely ground breaking in the fields of astronomy and physics, but no good deed goes unpunished: as Galileo tried to bend the arc of early Renaissance Europe towards progress, the Catholic Church worked as hard as it possibly could to bend that arc all the way back. But why would the Church have a problem with these seemingly harmless discoveries and observations? For the answer, we need to jump over to over a millennia before Galileo’s birth and understand the power and influence of the church at the time.

Aristotle (384–322 BCE) was a philosopher back in Ancient Greece. Another guy with an impressive resume, he wrote texts on almost every subject imaginable, from astronomy to physics to ethics. I remember him as the dude who was wrong about almost everything: I mean, he thought that some people were naturally born slavesand that it was both fitand justfor them to be slaves. But his more spectacular mistake was his model for the Geocentric universe. Aristotle proposed that the heavens were literally composed of concentric, crystalline spheres to which the celestial objects were attached and which rotated at different velocities (but the angular velocity was constant for a given sphere), with the Earth at the center. The sphere of the stars lay beyond the ones of the planets; finally, in the Aristotelian conception there was an outermost sphere that was the domain of the “Prime Mover”. The Prime Mover caused the outermost sphere to rotate at constant angular velocity, and this motion was imparted from sphere to sphere, thus causing the whole thing to rotate.[3]In the absence of sufficiently advanced telescopic equipment, this was a logically coherent model that sufficiently explained most observable astrological phenomena. By the Middle Ages, such ideas took on a new power as the Prime Mover of Aristotle’s universe became the God of Christian theology, the outermost sphere of the Prime Mover became identified with the Christian Heaven, and the position of the Earth at the center of it all was understood in terms of the concern that the Christian God had for the affairs of mankind.[4]

However, Galileo’s observations threw a spanner in the works. His observations of the phases of Venus proved that Venus revolved around the Sun, not the earth. In addition, Aristotle’s conception that the heavenly bodies were composed of a perfect material (aether) was disproven by the Galileo’s observation of craters on the moon. As Galileo propagated these discoveries and observations in support of Nicolaus Copernicus’ heliocentric theory (in which the planets, including earth, revolved around a stationary sun), the growing popularity of his ideas brought him the censure of the church, who launched an inquisition against him in 1616. It’s judgement was that the heliocentric proposition is “is foolish and absurd in philosophy, and formally heretical”, [5]and Galileo was ordered to cease from propagating it. Galileo, however, defied this order, and published “Dialogue Concerning the Two Chief World Systems”in which he mocked and ridiculed proponents of the Geocentric model. This snapped the patience of the Vatican, and Galileo once again faced inquisition in 1633 with a much harsher outcome: he spent the rest of his life under house arrest, and the Dialogue was banned from publication.

So, that was Galileo’s fate, his reward for all of the advances he made. From our modern standpoint, his treatment seems appalling, accustomed as we are to the open nature of scientific exploration today. However, I will leave the reader with this thought: can an argument be made that it was just? That to let Galileo flout authority and undermine the Church that held together Medieval Europe, for the sake of an impractical subject like Astronomy, would have brought more catastrophe and upheaval than it was worth? In the modern world of rapid scientific innovation, this is a question that needs to be considered.


[1]Bank, Eric. “List of Galileo’s Inventions.” Synonym. June 25, 2018. Accessed March 19, 2019. https://classroom.synonym.com/list-of-galileos-inventions-12079587.html.

[2]Redd, Nola Taylor. “Galileo Galilei: Biography, Inventions & Other Facts.” Space.com. November 14, 2017. Accessed March 19, 2019. https://www.space.com/15589-galileo-galilei.html.

[3]”The Universe of Aristotle and Ptolemy and the Role of Eratosthenes.” The Universe of Aristotle and Ptolemy, and the Role of Eratosthenes. Accessed March 19, 2019. http://www.pas.rochester.edu/~blackman/ast104/aristotle8.html.

[4]”The Universe of Aristotle and Ptolemy and the Role of Eratosthenes.” The Universe of Aristotle and Ptolemy, and the Role of Eratosthenes. Accessed March 19, 2019. http://www.pas.rochester.edu/~blackman/ast104/aristotle8.html.

[5]”The Galileo Affair: A Documentary History”. University of California Press. 1989. Archived from the original on September 30, 2007. Retrieved October 29, 2014.

  • Facebook Social Icon
  • Instagram