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posted by chromas on Tuesday February 12 2019, @03:41PM   Printer-friendly

Submitted via IRC for Bytram

The truth about Galileo and his conflict with the Catholic Church

Today virtually every child grows up learning that the earth orbits the sun.

But four centuries ago, the idea of a heliocentric solar system was so controversial that the Catholic Church classified it as a heresy, and warned the Italian astronomer Galileo Galilei to abandon it.

Many people believe that Galileo was hounded by the church for almost two decades, that he openly maintained a belief in heliocentrism, and that he was only spared torture and death because his powerful friends intervened on his behalf. But an examination of the fine details of Galileo’s conflict with church leaders doesn’t bear that out, according to English department distinguished research professor Henry Kelly.

In an article published this month in the journal “Church History,” Kelly clarifies some popularly held notions around Galileo’s travails with the church.

“We can only guess at what he really believed,” said Kelly, who for his research undertook a thorough examination of the judicial procedure used by the church in its investigation of Galileo. “Galileo was clearly stretching the truth when he maintained at his trial in 1633 that after 1616 he had never considered heliocentrism to be possible. Admitting otherwise would have increased the penance he was given, but would not have endangered his life, since he agreed to renounce the heresy — and in fact it would have spared him even the threat of torture.”

This year marks the 400th anniversary of the beginning of the Catholic Church’s investigation into Galileo.

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  • (Score: 2) by AthanasiusKircher on Wednesday February 13 2019, @04:33AM

    by AthanasiusKircher (5291) on Wednesday February 13 2019, @04:33AM (#800491) Journal

    It was a theory that was at least 1800 years old at that stage

    Emphasis on the word "theory." That's not empirical evidence, which is what I pointed out in my prior post. Heliocentrism prior to the 1600s was usually treated as a sort of abstract computational model, if at all. Most people subscribed to the standard physics and accepted science of the time, as well as common observation: do you feel like you're whizzing through space and rotating at thousands of miles per hour? I don't. But when I say that, I mean I don't feel motion in the way most people assumed they would feel motion if they were undergoing such crazy speeds. Remember that it was basically Galileo who first really put forward a detailed theory of inertia. Without that understanding, it's tough to imagine the earth is actually in motion.

    For empirical evidence, there were astrolabes dating back over 600 years that were based on the principle that, and therefore would only be accurate if, earth and the other heavenly objects went round the sun. I thereby deny your claims.

    First, I'm not sure you understand the workings of astrolabes. They are fundamentally premised on observation from earth, which is necessarily geocentric. The differences in the Ptolemaic vs. heliocentric models in astrolabe measurements were rarely spotted, because the Ptolemaic theory worked reasonably well (mostly through the various computed tables that tended to be passed around -- very few people were working with the abstract mathematical models themselves). It's true that some Arab astronomers proposed heliocentric models and incorporated elements of that model into measuring devices -- but on the whole the vast majority of scientists continued to work with a geocentric model (and assumed it when using their astrolabes) until the 1600s.

    To make an analogy for how heliocentrism was widely perceived before the 1600s: if there were mathematical advantages to it, it was still perceived as a theory without necessarily having empirical support. Kind of like the way we teach freshman physics assuming frictionless diagrams and point masses and such. Those aren't descriptions of the real world, but they simplify the math. And it should be noted that Copernican heliocentrism didn't actually simplify the math: Copernicus's circular model contained epicycles and was basically as complex as the Ptolemaic model. It wasn't until Kepler figured out elliptical orbits, worked out the math for them, and then other scientists and eventually Newton put it all together into a coherent theory that the advantages of heliocentrism were really apparent.

    Also, the main obstacle to belief in heliocentrism, as I mentioned, is the obstacle to proving that the earth is in motion. And that's surprisingly difficult to do. It wasn't until James Bradley's measurements of stellar aberration in the 1720s that we actually had that empirical evidence. Stellar parallax, which had been predicted for centuries, wasn't observed until the mid-1800s. The fact that it hadn't been observed was seen as a huge strike against the idea that the earth was in motion.

    Beyond that, I've given you plenty of information in the links in my previous post that detail why heliocentrism was so hard to accept by many scientific authorities of Galileo's day.

    > Galileo's real sin (as noted in other posts) was challenging the hierarchy in an impolite and very public way.

    You mean in the way that had been traditional in the Mediterranean for nearly two millennia?

    Nah, I think this is pretty different. You have the local political and religious leader inviting a renowned scientist to publish a pluralistic treatise that examines different viewpoints. Instead, this scientist effectively publishes a rant promoting a hypothetical theory as if it were truth -- something said scientist had been warned about before -- and lampooning his critics as morons. Meanwhile, the ONLY empirical evidence said scientist could muster to argue for the earth's motion was tides -- which he thought were caused by the sun (except that would only have one high tide per day at noon, which obviously wasn't true... but Galileo handwaved that all away). You want more details -- again, look in the links. And again, I'm NOT defending the church's actions, but I condemn their censorship, not their scientific views which were pretty mainstream for the time.

    As a postscript, I personally think it's fun to note that heliocentrism did gradually become accepted in the mid and late 1600s, despite the lack of empirical evidence. With Newton's elegant theory bringing it all together, heliocentrism became dominant by the early 1700s. I think it's an interesting lesson for those who criticize theories like dark matter in modern cosmology: the earth's motion wasn't proven until the 1720s (and Newton's theory depended on weird invisible forces acting at a distance), but the theoretical model worked so well that the scientific establishment migrated toward that model. Just because we haven't yet observed dark matter doesn't mean there isn't something there to explain it...

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