Kepler vs Galileo

[Hop_David]

Kepler's heliocentric model is so much better at making accurate predictions. And his insights so much deeper. So I had always assumed Kepler came after Galileo.

I was recently surprised to learn that Kepler was a contemporary of Galileo.
Johannes Kepler 1571 to 1630
Galileo Galilei 1564 to 1642

Given Kepler's 3rd law and Huygens' expression for centrifugal acceleration, it's trivial to demonstrate inverse square gravity for circular orbits:


However does inverse square gravity imply the elliptical orbits that Kepler had discovered? This is a much more difficult question.

This is state of affairs when Christopher Wren asked Robert Hooke and Edmund Halley "would an inverse squared law of attraction lead to Kepler's laws of planetary motion?" None of them could answer this question.

Which led to the famous Newton-Halley encounter as described by Thony Christie:

What Halley actually asked was, assuming an inverse squared law of attraction what would be the shape of aa planetary orbit? This goes back to a question posed earlier by Christopher Wren in a discussion with Halley and Robert Hooke, “would an inverse squared law of attraction lead to Kepler’s laws of planetary motion?” Halley could not solve the problem so took the opportunity to ask Newton, at that time an acquaintance rather than a friend, who supposedly answered Halley’s question spontaneously with, “an ellipse.” Halley then asked how he knew it and Newton supposedly answered, “I have calculated it.” Newton being unable to find his claimed calculation sent Halley away and after some time supplied him with the nine-page manuscript De motu corporum in gyrum, which in massively expanded form would become Newton’s Principia.

Newton didn't come up with his laws of motion and his law of gravity. These concepts had been floating around from some time. Descartes had worked on the concept of inertia. Inverse square gravity was suggested by Ismael Boulliau in 1645 in his publication Astronomia philolaica. Newton was three years old at the time.

Newton's crowning achievement was mathematically demonstrating these notions implied Kepler's three laws which were already well substantiated by empirical evidence.

It is Kepler that paved the way for Newton's Principia.

So why does Galileo get the press?

Because Kepler did not get placed under house arrest for flipping off an oligarch. Dissing an oligarch is a good way to get publicity but not always good for your health. Just ask anyone who has ridiculed the Kim family oligarchs in the atheist state of North Korea:

 

[The Hammer]

What's N. Korea's Atheism have to do with anything?

 

[Jayhawker Soule]

What's N. Korea's Atheism have to do with anything?

It possibly reflects one of two things ...

A.) a series of reasonable inferences, e.g.,

Korea is a Stalinist dictatorship

Stalinist dictatorships purport to be communist

Classical communist political theory flows from the works of Karl Mark

Marx and Marxism give rise to the label "dialectical materialism"

Dialectical materialism is one of many atheist world views

Therefore: all pizza is better with anchovies.
​

B.) it's a childish slight, e.g.,

Pizza with anchovies is preferred by dirty stinkin' commies.​

 

[The Hammer]

It possibly reflects one of two things ...

A.) a series of reasonable inferences, e.g.,

Korea is a Stalinist dictatorship

Stalinist dictatorships purport to be communist

Classical communist political theory flows from the works of Karl Mark

Marx and Marxism give rise to the label "dialectical materialism"

Dialectical materialism is one of many atheist world views

Therefore: all pizza is better with anchovies.
​

B.) it's a childish slight, e.g.,

Pizza with anchovies is preferred by dirty stinkin' commies.​

I'm aiming that it was B.

It's usually B.

But either way. Just because the "state's" religion is "Atheist", doesn't mean the populace is.

For instance. Shamanism still plays a part in both N. and S. Korea.

 

[Hop_David]

What's N. Korea's Atheism have to do with anything?

TL;DR version for those with short attention spans.

The Galileo affair is often portrayed as The Church vs Science.

However Kepler's heliocentric model was a much greater contribution to science. And he didn't ping on the The Church's radar.

Galileo's dramatic story had more to do a man defying an oligarchy than Religion vs Science.

And Oligarchies come in all flavors. Oligarchs can be Christian, Muslim, or even atheist. As the atheist state of North Korea demonstrates.

 

[exchemist]

Kepler's heliocentric model is so much better at making accurate predictions. And his insights so much deeper. So I had always assumed Kepler came after Galileo.

I was recently surprised to learn that Kepler was a contemporary of Galileo.
Johannes Kepler 1571 to 1630
Galileo Galilei 1564 to 1642

Given Kepler's 3rd law and Huygens' expression for centrifugal acceleration, it's trivial to demonstrate inverse square gravity for circular orbits:

View attachment 65183
However does inverse square gravity imply the elliptical orbits that Kepler had discovered? This is a much more difficult question.

This is state of affairs when Christopher Wren asked Robert Hooke and Edmund Halley "would an inverse squared law of attraction lead to Kepler's laws of planetary motion?" None of them could answer this question.

Which led to the famous Newton-Halley encounter as described by Thony Christie:



Newton didn't come up with his laws of motion and his law of gravity. These concepts had been floating around from some time. Descartes had worked on the concept of inertia. Inverse square gravity was suggested by Ismael Boulliau in 1645 in his publication Astronomia philolaica. Newton was three years old at the time.

Newton's crowning achievement was mathematically demonstrating these notions implied Kepler's three laws which were already well substantiated by empirical evidence.

It is Kepler that paved the way for Newton's Principia.

So why does Galileo get the press?

Because Kepler did not get placed under house arrest for flipping off an oligarch. Dissing an oligarch is a good way to get publicity but not always good for your health. Just ask anyone who has ridiculed the Kim family oligarchs in the atheist state of North Korea:
View attachment 65184

I always thought it was Copernicus who "got the press" over heliocentrism. But it's true Kepler refined it a lot and got rid of the epicycles etc.

 

[danieldemol]

TL;DR version for those with short attention spans.

The Galileo affair is often portrayed as The Church vs Science.

However Kepler's heliocentric model was a much greater contribution to science. And he didn't ping on the The Church's radar.

Galileo's dramatic story had more to do a man defying an oligarchy than Religion vs Science.

And Oligarchies come in all flavors. Oligarchs can be Christian, Muslim, or even atheist. As the atheist state of North Korea demonstrates.

Are you just making whataboutery for theocracy here?

It's not a binary choice between Catholic theocracy and North Korea, there are plenty of liberal democratic countries we can and should prefer.

In my opinion.

 

[Hop_David]

I always thought it was Copernicus who "got the press" over heliocentrism. But it's true Kepler refined it a lot and got rid of the epicycles etc.

It seems to me Galileo and Copernicus got the most attention. As well as Giordano Bruno.

And Copernicus deserves a good deal of credit. He's the first major shift from geocentrism. And it's noteworthy that Copernicus shared his ideas with the Pope, some cardinals, bishops and archbishops. And he never got in trouble with his contemporaries.

Kepler also stayed out of trouble for the most part.

Galileo and Kepler were contemporaries. Galileo's models were flawed and didn't predict well. Whereas Kepler's models predict planetary orbits very well. But Kepler didn't pick fights with oligarchs. So guess who gets the spotlight?

 

[gnostic]

Kepler's heliocentric model is so much better at making accurate predictions. And his insights so much deeper. So I had always assumed Kepler came after Galileo.

I was recently surprised to learn that Kepler was a contemporary of Galileo.
Johannes Kepler 1571 to 1630
Galileo Galilei 1564 to 1642

Given Kepler's 3rd law and Huygens' expression for centrifugal acceleration, it's trivial to demonstrate inverse square gravity for circular orbits:

View attachment 65183
However does inverse square gravity imply the elliptical orbits that Kepler had discovered? This is a much more difficult question.

This is state of affairs when Christopher Wren asked Robert Hooke and Edmund Halley "would an inverse squared law of attraction lead to Kepler's laws of planetary motion?" None of them could answer this question.

Which led to the famous Newton-Halley encounter as described by Thony Christie:



Newton didn't come up with his laws of motion and his law of gravity. These concepts had been floating around from some time. Descartes had worked on the concept of inertia. Inverse square gravity was suggested by Ismael Boulliau in 1645 in his publication Astronomia philolaica. Newton was three years old at the time.

Newton's crowning achievement was mathematically demonstrating these notions implied Kepler's three laws which were already well substantiated by empirical evidence.

It is Kepler that paved the way for Newton's Principia.

So why does Galileo get the press?

Because Kepler did not get placed under house arrest for flipping off an oligarch. Dissing an oligarch is a good way to get publicity but not always good for your health. Just ask anyone who has ridiculed the Kim family oligarchs in the atheist state of North Korea:
View attachment 65184

Science allow for progress, allowing for any one’s theory to expand, to be corrected, refined, modified, updated.

So...Personally, I think they all should get credits for their contributions to the heliocentric model: Copernicus, Galileo, Kepler & Newton.

Forgotten was Aristarchus of Samos, a 3rd century BCE Hellenistic astronomer, who started the heliocentric model in the first place. He challenged the astronomy of the Babylonian, Egyptian and Greek, that favored the geocentric model.

I think Aristarchus also deserve the credit.

 

[Augustus]

Are you just making whataboutery for theocracy here?

It's not a binary choice between Catholic theocracy and North Korea, there are plenty of liberal democratic countries we can and should prefer.

In my opinion.

He's making the point that Galileo wasn't sanctioned simply for proposing a theory of heliocentrism. For example, Copernicus' De revolutionibus was published by a bishop and dedicated to the Pope.

In short (lacks a bit of nuance):

He had been told under injunction he could teach heliocentrism as a hypothesis, but not as a fact (and at that point it still was a hypothesis that had several shortcomings and was not accepted even by most astronomers). Heliocentrism wasn't the insurmountable theological problem often assumed, a Cardinal had even acknowledged to Galileo that if it were proven, then they might have to reconsider the traditional interpretation of scripture. The problem was that it was not yet proven.

GG was pretty conceited, and basically misjudged how much clout he had among the powerful to shield him and defied the injunction while mocking the Pope.

The NK analogy is that if you mocked Lil' Kim Jong-un thinking his sister would protect you as you once entertained her, it is a pretty stupid thing to do. Of course it would be nice if NK had free speech, but it doesn't.

17th C Europe, in both secular and religious domains, was similar, especially given the post-Reformation conflicts. And GG had strayed a bit much into the domain of telling the Pope how to interpret scripture.

With a bit more tact and foresight, Galileo could have continued to promote heliocentrism while trying to find solutions for the holes in his hypothesis.

But by basically asserting the church should revise its understanding of scripture based on an unproven hypothesis that wasn't even supported by a majority of astronomers, he overplayed his hand.

The elites didn't really appreciate being lectured by "uppity commoners" back then though.

 

[Hop_David]

Are you just making whataboutery for theocracy here?

It's not a binary choice between Catholic theocracy and North Korea, there are plenty of liberal democratic countries we can and should prefer.

Agreed. Oligarchies should be avoided. Whether they be atheist or theocracies.

What Pope Urban VIII and Kim Jong-Un teach us is not that religion is bad. But that oligarchies are bad.

Kepler lived in Galileo's time and did not suffer persecution. And his contributions were more substantial than Galileo's. Religion did not impede Kepler's explorations. By and large he managed to avoid conflict with powerful people.

 

[danieldemol]

The elites didn't really appreciate being lectured by "uppity commoners" back then though.

Ok, but surely the right for "uppity commoners" to lecture elites is a positive one, and for being an uppity commoner who challenged the elites when it was risky to do so Galileo deserves special recognition.

In my opinion.

 

[danieldemol]

Agreed. Oligarchies should be avoided. Whether they be atheist or theocracies.

What Pope Urban VIII and Kim Jong-Un teach us is not that religion is bad. But that oligarchies are bad.

Kepler lived in Galileo's time and did not suffer persecution. And his contributions were more substantial than Galileo's. Religion did not impede Kepler's explorations. By and large he managed to avoid conflict with powerful people.

Ok, but I for one see challenging powerful people when it is risky to do so as being a positive thing.

Without such people we would arguably be stuck with theocracy, and in North Korea a lack of sufficient people being prepared to risk conflict with the powerful is arguably why they are stuck with a dictatorship.

Also you may not think that religion is overall bad, but can you agree that religion has negative aspects to it, such as the pope's opposition to abortion or the Jehovah's Witness refusal to acknowledge macro-evolution?

How do you see religion being able to lose the negative traits it has without undermining the concept of changeless religion?

In my opinion.

 

[gnostic]

Kepler lived in Galileo's time and did not suffer persecution. And his contributions were more substantial than Galileo's. Religion did not impede Kepler's explorations. By and large he managed to avoid conflict with powerful people.

Perhaps because Kepler lived in Germany, Austria and Bohemia, where he had powerful patrons.

I think you forget that his interests not only in astronomy but also in astrology. He was very superstitious.

 

[Augustus]

Ok, but surely the right for "uppity commoners" to lecture elites is a positive one, and for being an uppity commoner who challenged the elites when it was risky to do so Galileo deserves special recognition.

Of course it is, and no one is holding 17th C Europe up as a bastion of tolerance and open mindedness.

Galileo is not held up as a martyr for free speech though, but a martyr for science. As a martyr for free speech he wouldn't be a particularly impressive figure

He wasn't making a principled stand in favour of individual liberty, but being petty and trying to boost his career while miscalculating the degree of protection he had from other "oligarchs".

We tend not to look favourably on those who think they are above the law due to their powerful friends. So it's a mixed bag.

The 17th C wasn't a great time to pick fights with the powerful, be they religious or secular elites, due to it being a period of social instability. If you arrogant enough to think you are above this, and then find out you are not and desperately try to walk it all back, it's hard to have too much sympathy.

I guess that he kind of person who is most likely to hold up GG as a martyr for science, would also think that any early Christian martyrs were a bit stupid for not making a token sacrifice to the Emperor and instead getting thrown to the lions.

All he had to do was not publicly call the Pope a simpleton, and couch his language a bit when talking about heliocentrism until it could be proved more substantially.

 

[Hop_David]

He had been told under injunction he could teach heliocentrism as a hypothesis, but not as a fact (and at that point it still was a hypothesis that had several shortcomings and was not accepted even by most astronomers).

I've heard Galileo's model had shortcomings but I don't know much about this.

If he assumed circular orbits, I'd expect it'd do a poor job of predicting paths of the planets. Much like the Copernicus and Ptolemy models.

Kepler's heliocentric elliptical orbits on the other hand...

 

[Hop_David]

Ok, but surely the right for "uppity commoners" to lecture elites is a positive one, and for being an uppity commoner who challenged the elites when it was risky to do so Galileo deserves special recognition.

Does Galileo's model of the solar system deserve more recognition than Kepler's?

 

[Hop_David]

I think you forget that his interests not only in astronomy but also in astrology. He was very superstitious.

Well actually.... According to this source:

At that time astronomy and astrology were not yet distinctly separated from each other – and therefore one of Kepler’s duties as mathematician for land surveying was to create a calendar including predictions about weather, political events, etc. Being financially poor this was an important source of income for Kepler and furthermore he became a local celebrity because his predictions wondrously turned out to be true. However, he never took astrology seriously, but called it the silly little daughter of astronomy.

Astrology and religious holidays were major incentives for making painstaking records of how the heavenly bodies moved.

Kepler had some strange beliefs. But that did not stop him from making profound insights. Same could be said for Newton, Ramanujan, and Tesla

 

[danieldemol]

Does Galileo's model of the solar system deserve more recognition than Kepler's?

You are not answering my questions, but no, it doesn't deserve more recognition.

In my opinion.

 

[Hop_David]

You are not answering my questions,

IIRC You were asking me if religious people have done bad things

Given thousands of years and billions of people, of course bad things have been done in God's name.

However there have been a lot of good things as well.

I happen to believe the net effect of religion has been positive. But regard it as an open question.

but no, it doesn't deserve more recognition,

I'm happy to hear that.

In my opinion , Kepler's model is the game changing heliocentric model that came from that time.

But we never hear about Kepler's work in mainstream culture. Why does Galileo get more attention? Because the Galileo story supports a certain narrative.