[HN Gopher] Weighing Up Galileo's Evidence
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Weighing Up Galileo's Evidence
Author : Hooke
Score : 39 points
Date : 2024-06-24 03:35 UTC (19 hours ago)
(HTM) web link (www.historytoday.com)
(TXT) w3m dump (www.historytoday.com)
| bonzini wrote:
| It is easy to treat Galileo as fighting the obscurantist church
| of the 15th century, but as the article explains briefly:
|
| > provocatively voiced the pope's own arguments through an obtuse
| Aristotelian called Simplicio
|
| ... Galileo's ordeal with the inquisition was mostly due to him
| making fun of the pope (probably not a good idea). The truth is
| that until Kepler introduced elliptical orbits and variable
| orbital speeds, the Copernican heliocentric model still needed
| epicycles and was not much better than the ptolemaic model.
|
| And the church didn't even care _that_ much. Copernicus himself
| was a priest and, while he himself was wary of publishing it and
| framed it as a way to do astronomical calculations without any
| kind of philosophical implication, in the end it circulated
| without much fuss.
|
| This of course should not diminish his contributions to the
| scientific method and his other contribution to astronomical
| observations (mostly the satellites of Jupiter and the rings of
| Saturn, though his instrument wasn't good enough to recognize
| them as rings).
| gwd wrote:
| > Galileo's ordeal with the inquisition was mostly due to him
| making fun of the pope (probably not a good idea).
|
| And at least one history I read on the subject questions
| whether Galileo was even intending to make fun of the Pope. My
| memory of the basic story that book told:
|
| - The Pope encouraged Galileo to publish a book with his new
| theories, but just told him to add a theological "escape hatch"
| (provided by the Pope himself) to make sure he wasn't viewed as
| heretical
|
| - The book is a dialogue between three people, one of whom,
| "Simplicio", is kind of stupid and backwards the whole book,
| but in the last chapter says effectively, "Actually I've just
| been pretending this whole time to be foolish; but actually I"m
| wise, and let me tell you why." He then gives the Pope's
| argument and the book ends -- giving the Pope the last word, as
| it were.
|
| - At the time no books can be printed unless they're officially
| approved by the Church as being non-heretical. The book was
| reviewed, and approved, by two different Papal censors in two
| different cities. It was only sometime later that the Pope
| became offended by his words being placed in Simplicio's mouth;
| in what the author I read thought was almost certainly a
| misunderstanding.
|
| As the author said, Galileo was encouraged to write the book;
| was told some theology to put into it; he did so. The book was
| submitted for review and approved twice. What more could
| Galileo have done?
|
| If I could read Renaissance Italian I'd go back and read it and
| judge for myself. Anyone here read it that can weigh in on the
| theory that Galileo never meant to offend the Pope?
| michaelmrose wrote:
| Galileo could have not had the Pope's words come out of the
| mouth of a moron. If I was the Pope I would have correctly
| inferred the insult.
| darkerside wrote:
| Painted as not only stupid but disingenuous.
| gjm11 wrote:
| This http://law2.umkc.edu/faculty/projects/ftrials/galileo/di
| alog... appears to be an English translation of the fourth
| and final "day" in the Dialogue. Here's the last thing
| Simplicio says:
|
| [begins]
|
| You need not make any excuses; they are superfluous, and
| especially so to me, who, being accustomed to public debates,
| have heard disputants countless times not merely grow angry
| and get excited at each other, but even break out into
| insulting speech and sometimes come very close to blows.
|
| As to the discourses we have held, and especially this last
| one concerning the reasons for the ebbing and flowing of the
| ocean, I am really not entirely convinced; but from such
| feeble ideas of the matter as I have formed, I admit that
| your thoughts seem to me more ingenious than many others I
| have heard. I do not therefore consider them true and
| conclusive; indeed, keeping always before my mind's eye a
| most solid doctrine that I once heard from a most eminent and
| learned person, and before which one must fall silent, I know
| that if asked whether God in His infinite power and wisdom
| could have conferred upon the watery element its observed
| reciprocating motion using some other means than moving its
| containing vessels, both of you would reply that He could
| have, and that He would have known how to do this in many
| ways which are unthinkable to our minds. From this I
| forthwith conclude that, this being so, it would be excessive
| boldness for anyone to limit and restrict the Divine power
| and wisdom to some particular fancy of his own.
|
| [ends]
|
| That doesn't seem like it's quite the same as what you're
| saying you read. Simplicio ends up professing a sort of pious
| agnosticism about what Galileo is talking about. I don't get
| any particular sense from this that we're meant to think "oh,
| hey, Simplicio is much smarter than we were giving him credit
| for being".
|
| (I do not know enough about any pope's astronomical opinions
| to have a useful opinion on how closely Simplicio's professed
| positions match those of the pope, or how likely it is that
| Galileo was and/or seemed to be making fun of the pope. My
| highly inexpert impression was that Simplicio wasn't modelled
| on the pope specifically but on other people with whom
| Galileo had more of a grudge.)
| gwd wrote:
| Thanks for that; this part in particular:
|
| > I do not therefore consider them true and conclusive;
| indeed, keeping always before my mind's eye a _most solid
| doctrine that I once heard from a most eminent and learned
| person_ , and before which one must fall silent,
|
| Assuming that the following really is the "theological
| angle" suggested by the Pope, it's literally saying that
| the Pope is a most eminent and learned person, and that the
| argument he's made is "solid doctrine" and an unassailable
| argument. And Simplicio isn't coming up with the argument
| himself; he's saying he's heard it from this other eminent
| and learned person. All that's perfectly consistent with a
| good-faith attempt to flatter the Pope's wisdom and
| influence, and accommodate his request regarding the
| theological "escape hatch".
|
| Unfortunately, it's also fairly open to being construed as
| being a sarcastic insult... or even an attempt at a sort of
| "dog whistle", where "devout" people take it as face value,
| but people "in the know" take it as being sarcastic.
|
| EDIT: And, seriously:
|
| > I know that if asked whether God in His infinite power
| and wisdom could have conferred upon the watery element its
| observed reciprocating motion using some other means than
| moving its containing vessels... From this I forthwith
| conclude that, this being so, it would be excessive
| boldness for anyone to limit and restrict the Divine power
| and wisdom to some particular fancy of his own.
|
| It's not saying "God could just magic things to make the
| water appear to move like this"; it's "There are lots of
| other possible reasons why the water might appear to move
| like that".
|
| It sounds to me like a description of necessary scientific
| humility. We have these observations, this one theory _is_
| consistent with them, but there lots of other
| possibilities, so we should keep an open mind and not be
| too insistent on one particular theory.
| baryphonic wrote:
| Galileo also couldn't explain the lack of an observed parallax
| effect between opposite seasons given the ideas about optics at
| the time.
|
| When Kepler's model arrived, it was so much better at
| predicting the positions of all planets except Mercury than any
| previous model that it was clearly superior. Galileo's was bad
| at predicting and just contradicted the accepted observations
| of the day.
|
| IMO Galileo should be better remembered for objects of
| different masses falling at the same rate and the original idea
| that all motion is relative (when observing from an internal
| frame).
| jcranmer wrote:
| > Galileo also couldn't explain the lack of an observed
| parallax effect between opposite seasons given the ideas
| about optics at the time.
|
| That's not entirely correct. The lack of parallax was
| explained by the stars being far away; the problem with
| _that_ explanation is that Brahe had measured the apparent
| stellar diameter of stars, which implied that for the stars
| to be as big as they appear to be to us, they would have to
| be far, far larger... which violates the underlying
| Copernican principle that the sun is but a normal star.
| graemep wrote:
| The Copernican model was heliocentric, surely? It placed
| the sun motionless at the centre of the universe. That
| makes the sun anything but a normal star.
| noslenwerdna wrote:
| The copernican principle is separate from the model.
| Basically it says that our position in the universe is
| random - we don't exist at the center of the universe.
|
| https://en.wikipedia.org/wiki/Copernican_principle
|
| "Hermann Bondi named the principle after Copernicus in
| the mid-20th century, although the principle itself dates
| back to the 16th-17th century paradigm shift away from
| the Ptolemaic system, which placed Earth at the center of
| the universe. Copernicus proposed that the motion of the
| planets could be explained by reference to an assumption
| that the Sun is centrally located and stationary in
| contrast to the geocentrism. "
| munchler wrote:
| > the evidence for Riccioli's system is weighing down the scale-
| pan, while Galileo's less substantiated suggestion rises upward
|
| What exactly is the difference between the two theories? It would
| be interesting to see them both in the context of the time.
| isidor3 wrote:
| I found this series to be a great read on some of the history of
| Galileo and the status of scientific understanding at the time I
| believe part of it has made the rounds on hn before:
| http://tofspot.blogspot.com/2013/10/the-great-ptolemaic-smac...
| throw0101b wrote:
| There were seven models floating around in the early 1600s:
|
| 1. Heraclidean. Geo-heliocentric. Mercury and Venus circle the
| Sun; everything else circles the Earth.
|
| 2. Ptolemaic. Geocentric, stationary Earth.
|
| 3. Copernican. Heliocentric, pure circles with lots of epicycles.
|
| 4. Gilbertian. Geocentric, rotating Earth. (proposed by William
| Gilbert in De magnete)
|
| 5. Tychonic. Geo-heliocentric. Sun and Moon circle the Earth;
| everything else circles the Sun.
|
| 6. Ursine. Tychonic, with rotating Earth.
|
| 7. Keplerian. Heliocentric, with elliptical orbits.
|
| See:
|
| * https://tofspot.blogspot.com/2013/08/the-great-ptolemaic-sma...
|
| * ToC: https://tofspot.blogspot.com/2013/10/the-great-ptolemaic-
| sma...
|
| * PDF: https://faculty.fiu.edu/~blissl/Flynngs.pdf
|
| By the mid-/late-1600s people leaned toward Kepler, mostly
| because the math was easiest.
|
| With regards to evidence for the Earth's motion, the first
| inkling was in 1728 with stellar aberration with in g-Draconis:
|
| * https://en.wikipedia.org/wiki/Aberration_(astronomy)#Discove...
|
| The first for the _rotation_ of the Earth (around an axis) was in
| 1791 by Guglielmini:
|
| * https://en.wikipedia.org/wiki/Giovanni_Battista_Guglielmini
|
| We finally got parallax in 1806 by Giuseppi Calandrelli in
| a-Lyrae.
|
| Stellar parallax was considered since at least Aristotle, as he
| mentions in his _On the Heavens_ (II.14), and since it is not
| observed then it is reasonable to conclude that there is no
| motion (it took several thousand years to develop instruments to
| actually measure it).
|
| Daniel Whitten's "Matters of Faith and Morals _Ex Suppositione_ "
| is an interesting read.
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