3 ms·

Precursors of Copernicus' heliocentric theory

54 points by chmaynard 2y ago

srean 2y ago
Fitting with epicycloids is a form of Fourier analysis/synthesis and such curves can approximate any smooth closed curve -- universal approximators. With deep NNs being used for Physics research to fit data it does make me wary if we are getting into epicycles again.
guyomes 2y ago
> Aristarchus had come up with a heliocentric theory way back around 250 BC. He notably did convincing calculations showing that the sun should be larger than Earth. However, this was not convincing enough for his opponents who argued notably that usually fire hardly remains in a fixed position. Also, if Earth was moving, it was hard to understand why there was no observed parallax on the stars at night. Actually, the first apparent proof that Earth was moving came after inventing instruments precise enough to observe parallax on far enough stars, in 1727, from James Bradley. It actually had different results from expectation, due to the finite speed of light [1]. Just after Aristarchus came also Seleucus of Seleucia [2]. He supposedly had a theoretical argument for heliocentrism, but it was lost. [0]: https://en.wikipedia.org/wiki/On_the_Sizes_and_Distances_(Aristarchus) https://en.wikipedia.org/wiki/On_the_Sizes_and_Distances_(Ar... [1]: https://en.wikipedia.org/wiki/James_Bradley https://en.wikipedia.org/wiki/James_Bradley [2]: https://en.wikipedia.org/wiki/Seleucus_of_Seleucia https://en.wikipedia.org/wiki/Seleucus_of_Seleucia
- mmooss 2y ago
  > Earth was moving They believed that the stars and Earth moved relative to each other, as far as I can tell. Why does it matter if they thought the Earth was moving or if they thought the stars were moving? Maybe the math is simpler if it's the Earth.
  - rcxdude 2y ago
    The night sky obviously rotates, but that the earth translates relative to the stars is not so obvious. This was especially a problem because it was generally thought the stars were much closer than they actually are, because stars do have an apparent diameter to the naked eye (and through a telescope) which we now know to be an optical illusion (Airy Disk), and if you extrapolate this like with the planets they are either not that much further away or ludicrously big, like many solar systems, and parallax measurements were precise enough to at least put a high bound on their distance if the earth moved with respect to the stars, and gigantic stars wasn't a popular option.
- sthu11182 2y ago
  I have recently been listening to the "The Complete History of Science" podcast [1]. I have not gotten to the Copernicus portion yet, but I really enjoyed the ancient Greek astronomy episodes (including the episode on Aristarchus). [1] - https://thecompletehistoryofscience.buzzsprout.com/1916377/episodes https://thecompletehistoryofscience.buzzsprout.com/1916377/e...
Dracophoenix 2y ago
There's a currently ongoing anime called Orb: Movements of The Earth m. It depicts a compelling albeit fictionalized account of the rocky and often dangerous road faced by proponents of heliocentrism in the 16th century. Despite its fictional nature, the show makes reference to real thinkers such as Aristarchus and Occam, among others.
- ryzvonusef 2y ago
  I understand that it isn't supposed to be accurate, given that it's based on a fictional country 'P' and based on a fictional church 'C', but the parallels are obvious to Polish/Catholic regime. As someone living in a country where blasphemy lynching are still a part of life, and professors are made to renounce scientific beliefs[1], it feels disturbingly familiar to me. [1]: https://www.dw.com/en/pakistani-clerics-cancel-theory-of-evolution-what-next/a-67213124 https://www.dw.com/en/pakistani-clerics-cancel-theory-of-evo...
  - selimthegrim 2y ago
    Is it true you still have to sign halafnama against Ahmedis to get your PhD?
    - ryzvonusef 2y ago
      To get your phd? That I don't know, but to get your passport, yes.
  - Dracophoenix 2y ago
    By fictionalized, I mean to say that certain aspects of the anime are inconsistent with historical record. I don't just mean the thinly-veiled references to Poland or the Catholic Church. For instance, one glaring anachronism is the Pear of Anguish. While the inquisitor in the show refers to his as a "prototype", no such device in any form existed until some two to three centuries later. The Pear in the show is a literary device that gruesomely establishes the stakes faced by the characters. It also operates as a visual metaphor for the Church's desire to silence dissent. But in no way or shape was it an instrument of torture in the 16th century. Another point is that none of the characters in the show have existed in any capacity. They are not analogues of or stand-ins for the historical contributors to the heliocentric model. The characters' personalities and backgrounds, while consistent with the setting, are the inventions of the mangaka. Now with all that said, the show excellently conveys the difficulty and threats faced by thinkers across the ages in the course of the Scientific Revolution. The historical circumstances were no less dire than what was depicted in the anime. But as a show, it still has more in common with romanticized depictions of men looking up at the night sky, such as in the Sarah Williams poem, the Old Astronomer, than it does with a thoroughly scrutinized biography of the astronomers of the era. > As someone living in a country where blasphemy lynching are still a part of life, and professors are made to renounce scientific beliefs[1], it feels disturbingly familiar to me. It pains me to know the spirit of the Inquisition is still present in the 21st century.
nyc111 2y ago
"Sometime between 410 and 420 AD, Martianus Capella came out with a book saying Mercury and Venus orbit the Sun, while the other planets orbit the Earth!" Was there ever serious considerations of Capella's model? How do we know it is wrong? For instance, Tycho's model was found to be wrong because, if I remember correctly, some orbits crossed each other and that ruined the theory. Is there such a contradiction with Capella's model?
- margalabargala 2y ago
  > How do we know it is wrong? Well, for one thing, we have now sent assorted space probes to the other planets, something that requires precise knowledge of their current and future positions, something that cannot be done without an accurate model of their orbits. Are you seriously suggesting that Mars, Jupiter et al orbit the earth rather than the sun, or am I badly misreading your comment? > Was there ever serious considerations of Capella's model? TFA discusses at length how that model was quite popular in Europe for centuries.
awanderingmind 2y ago
For anyone interested in the topic of Copernicus' heliocentrism, I can recommend Arthur Koestler's 'The Sleepwalkers': https://en.wikipedia.org/wiki/The_Sleepwalkers:_A_History_of_Man%27s_Changing_Vision_of_the_Universe https://en.wikipedia.org/wiki/The_Sleepwalkers:_A_History_of.... While it does contain some speculation that is, in my opinion, poorly grounded, overall it is very informative and does a good job of dispelling some of the oversimplified narratives that are told about e.g. Galileo's persecution by the Church. (Of course since this is HN I can't wait to hear somebody tell me about some oversimplified narratives due to Koestler!) It's also just very written and full of amazing anecdotes - e.g. about how Kepler's mother was accused of witchcraft(!)
- awanderingmind 2y ago
  update: I consulted my copy of 'The Sleepwalkers' again, and I see that Martianus Capella is listed twice in the index. Koestler claims that Martianus Capella's system, wherein Venus and Mercury orbit around the Sun, while the rest of the planets orbit around the Earth, is originally due to Herakleides (https://en.wikipedia.org/wiki/Heraclides_Ponticus https://en.wikipedia.org/wiki/Heraclides_Ponticus, not to be confused with Heraclitus), a 4th century BC Greek philosopher. But I see that wikipedia links to an article [1] by Eastwood from 1992 that claims this to be a complete misattribution lacking any evidence. Link for the interested: https://adsabs.harvard.edu/pdf/1992JHA....23..233E https://adsabs.harvard.edu/pdf/1992JHA....23..233E. [1] Eastwood, B.S., 1992. Heraclides and heliocentrism: Texts, diagrams, and interpretations. Journal for the History of Astronomy, 23(4), pp.233-260.
jumping_frog 2y ago
I highly recommend this channel. The human story behind the discovery. Copernicus: The Man Who Made A God https://www.youtube.com/watch?v=OgVOhbk8H1c https://www.youtube.com/watch?v=OgVOhbk8H1c

54 points by chmaynard 2y ago

Fitting with epicycloids is a form of Fourier analysis/synthesis and such curves can approximate any smooth closed curve -- universal approximators. With deep NNs being used for Physics research to fit data it does make me wary if we are getting into epicycles again.

guyomes 2y ago

> Aristarchus had come up with a heliocentric theory way back around 250 BC. He notably did convincing calculations showing that the sun should be larger than Earth. However, this was not convincing enough for his opponents who argued notably that usually fire hardly remains in a fixed position. Also, if Earth was moving, it was hard to understand why there was no observed parallax on the stars at night. Actually, the first apparent proof that Earth was moving came after inventing instruments precise enough to observe parallax on far enough stars, in 1727, from James Bradley. It actually had different results from expectation, due to the finite speed of light [1]. Just after Aristarchus came also Seleucus of Seleucia [2]. He supposedly had a theoretical argument for heliocentrism, but it was lost. [0]: https://en.wikipedia.org/wiki/On_the_Sizes_and_Distances_(Aristarchus) https://en.wikipedia.org/wiki/On_the_Sizes_and_Distances_(Ar... [1]: https://en.wikipedia.org/wiki/James_Bradley https://en.wikipedia.org/wiki/James_Bradley [2]: https://en.wikipedia.org/wiki/Seleucus_of_Seleucia https://en.wikipedia.org/wiki/Seleucus_of_Seleucia

mmooss 2y ago
> Earth was moving They believed that the stars and Earth moved relative to each other, as far as I can tell. Why does it matter if they thought the Earth was moving or if they thought the stars were moving? Maybe the math is simpler if it's the Earth.
- rcxdude 2y ago
  The night sky obviously rotates, but that the earth translates relative to the stars is not so obvious. This was especially a problem because it was generally thought the stars were much closer than they actually are, because stars do have an apparent diameter to the naked eye (and through a telescope) which we now know to be an optical illusion (Airy Disk), and if you extrapolate this like with the planets they are either not that much further away or ludicrously big, like many solar systems, and parallax measurements were precise enough to at least put a high bound on their distance if the earth moved with respect to the stars, and gigantic stars wasn't a popular option.
sthu11182 2y ago
I have recently been listening to the "The Complete History of Science" podcast [1]. I have not gotten to the Copernicus portion yet, but I really enjoyed the ancient Greek astronomy episodes (including the episode on Aristarchus). [1] - https://thecompletehistoryofscience.buzzsprout.com/1916377/episodes https://thecompletehistoryofscience.buzzsprout.com/1916377/e...

Dracophoenix 2y ago

There's a currently ongoing anime called Orb: Movements of The Earth m. It depicts a compelling albeit fictionalized account of the rocky and often dangerous road faced by proponents of heliocentrism in the 16th century. Despite its fictional nature, the show makes reference to real thinkers such as Aristarchus and Occam, among others.

ryzvonusef 2y ago
I understand that it isn't supposed to be accurate, given that it's based on a fictional country 'P' and based on a fictional church 'C', but the parallels are obvious to Polish/Catholic regime. As someone living in a country where blasphemy lynching are still a part of life, and professors are made to renounce scientific beliefs[1], it feels disturbingly familiar to me. [1]: https://www.dw.com/en/pakistani-clerics-cancel-theory-of-evolution-what-next/a-67213124 https://www.dw.com/en/pakistani-clerics-cancel-theory-of-evo...
- selimthegrim 2y ago
  Is it true you still have to sign halafnama against Ahmedis to get your PhD?
  - ryzvonusef 2y ago
    To get your phd? That I don't know, but to get your passport, yes.
- Dracophoenix 2y ago
  By fictionalized, I mean to say that certain aspects of the anime are inconsistent with historical record. I don't just mean the thinly-veiled references to Poland or the Catholic Church. For instance, one glaring anachronism is the Pear of Anguish. While the inquisitor in the show refers to his as a "prototype", no such device in any form existed until some two to three centuries later. The Pear in the show is a literary device that gruesomely establishes the stakes faced by the characters. It also operates as a visual metaphor for the Church's desire to silence dissent. But in no way or shape was it an instrument of torture in the 16th century. Another point is that none of the characters in the show have existed in any capacity. They are not analogues of or stand-ins for the historical contributors to the heliocentric model. The characters' personalities and backgrounds, while consistent with the setting, are the inventions of the mangaka. Now with all that said, the show excellently conveys the difficulty and threats faced by thinkers across the ages in the course of the Scientific Revolution. The historical circumstances were no less dire than what was depicted in the anime. But as a show, it still has more in common with romanticized depictions of men looking up at the night sky, such as in the Sarah Williams poem, the Old Astronomer, than it does with a thoroughly scrutinized biography of the astronomers of the era. > As someone living in a country where blasphemy lynching are still a part of life, and professors are made to renounce scientific beliefs[1], it feels disturbingly familiar to me. It pains me to know the spirit of the Inquisition is still present in the 21st century.

nyc111 2y ago

"Sometime between 410 and 420 AD, Martianus Capella came out with a book saying Mercury and Venus orbit the Sun, while the other planets orbit the Earth!" Was there ever serious considerations of Capella's model? How do we know it is wrong? For instance, Tycho's model was found to be wrong because, if I remember correctly, some orbits crossed each other and that ruined the theory. Is there such a contradiction with Capella's model?

margalabargala 2y ago
> How do we know it is wrong? Well, for one thing, we have now sent assorted space probes to the other planets, something that requires precise knowledge of their current and future positions, something that cannot be done without an accurate model of their orbits. Are you seriously suggesting that Mars, Jupiter et al orbit the earth rather than the sun, or am I badly misreading your comment? > Was there ever serious considerations of Capella's model? TFA discusses at length how that model was quite popular in Europe for centuries.

awanderingmind 2y ago

For anyone interested in the topic of Copernicus' heliocentrism, I can recommend Arthur Koestler's 'The Sleepwalkers': https://en.wikipedia.org/wiki/The_Sleepwalkers:_A_History_of_Man%27s_Changing_Vision_of_the_Universe https://en.wikipedia.org/wiki/The_Sleepwalkers:_A_History_of.... While it does contain some speculation that is, in my opinion, poorly grounded, overall it is very informative and does a good job of dispelling some of the oversimplified narratives that are told about e.g. Galileo's persecution by the Church. (Of course since this is HN I can't wait to hear somebody tell me about some oversimplified narratives due to Koestler!) It's also just very written and full of amazing anecdotes - e.g. about how Kepler's mother was accused of witchcraft(!)

awanderingmind 2y ago
update: I consulted my copy of 'The Sleepwalkers' again, and I see that Martianus Capella is listed twice in the index. Koestler claims that Martianus Capella's system, wherein Venus and Mercury orbit around the Sun, while the rest of the planets orbit around the Earth, is originally due to Herakleides (https://en.wikipedia.org/wiki/Heraclides_Ponticus https://en.wikipedia.org/wiki/Heraclides_Ponticus, not to be confused with Heraclitus), a 4th century BC Greek philosopher. But I see that wikipedia links to an article [1] by Eastwood from 1992 that claims this to be a complete misattribution lacking any evidence. Link for the interested: https://adsabs.harvard.edu/pdf/1992JHA....23..233E https://adsabs.harvard.edu/pdf/1992JHA....23..233E. [1] Eastwood, B.S., 1992. Heraclides and heliocentrism: Texts, diagrams, and interpretations. Journal for the History of Astronomy, 23(4), pp.233-260.

jumping_frog 2y ago

I highly recommend this channel. The human story behind the discovery. Copernicus: The Man Who Made A God https://www.youtube.com/watch?v=OgVOhbk8H1c https://www.youtube.com/watch?v=OgVOhbk8H1c