Talk:Galileo Galilei/Archive 9

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Citations

Some of the books in the "References" section don't appear to be cited. Should those be moved to a "Further reading" section?—RJH (talk) 17:56, 9 June 2008 (UTC) rjh —Preceding unsigned comment added by 76.122.27.92 (talk) 14:56, 9 March 2009 (UTC)

Domingo de Soto and the times-squared law

The article currently says that the times-squared law was "already discovered by Domingo de Soto in the 16th century". I have been unable to find a source to confirm this. In Domingo de Soto and the Early Galileo (pp.І 120, ІІ 384) William Wallace merely says that de Soto gave the law of free fall (i.e. that the speed of falling bodies increases "uniformly difformly"—or, in modern terminology, that they are uniformly accelerated) and went on to explain that, as a consequence, they obeyed the mean speed rule. He gives no indication that de Soto ever stated the times-squared law. In Galileo: Decisive Innovator (p.198) Michael Sharratt writes "Domingo de Soto, who did recognise that free fall was a case of uniformly accelerated motion, showed indeed, though only incidentally, a clear grasp of the consequences of medieval analyses, but he was content to leave it at that". Since Sharrat then goes on to discuss Galileo's exposition of the times-squared law, there is a strong implication that if de Soto had actually stated this law, Sharratt at least was unaware of it.

It could be argued that the times-squared law is a trivial consequence of the mean speed rule, but that is only true with the tools of modern mathematics, and with those tools the mean speed rule itself is a trivial consequence of the definition of uniform acceleration. With the geometric methods used by medieval and renaissance physicists to prove these results, the proof of the times-squared law from the mean speed rule is of about the same length and difficulty as that of the mean speed rule itself.

I have therefore requested a citation for the claim that de Soto discovered the times-squared law. —David Wilson (talk · cont) 08:02, 15 June 2008 (UTC)

I can't speak specifically to de Soto but in the Fourteenth century Nicole Oresme had demonstrated that a body acquiring a quality (such as motion) in a uniformly difform fashion (uniformly accelerated motion in modern terms) would obey what we call the times-squared law. He discussed it in his Questions on the Geometry of Euclid, q. 14. (ed. M. Clagett, Nicole Oresme and the Medieval Geometries of Qualities and Motions, 1968, p. 561). "every quality uniformly difform at no degree whose subject is imagined to be divided into some number of equal parts ought to be designated by the square number of which the number of parts would be the root."

Since De Soto considered falling bodies as examples of uniformly difform motion, it would not have been too big a step for him (or one of his contemporaries) to apply Oresme's conclusion to the specific case of falling bodies. --SteveMcCluskey (talk) 22:47, 15 June 2008 (UTC)

Logicus writes: This claim was made by Duhem, at least in Section XVI of his potted 'History of Physics' article in the 1911 Catholic Encyclopedia, available online at http://www.newadvent.org/cathen/12047a.htm . Also see the third paragraph of its Section XVII on Galileo.

Duhem claims:

"This law which Vinci was not able to determine was published in 1545 by a Spanish Dominican Domingo Soto (1494-1560), an alumnus of the University of Paris..."

where the immediate context of the preceding paragraph implies 'this law Vinci was unable to determine' refers to the time-squared law s @ tt, rather than to the intermediary mean speed theorem s = vt/2 required to deduce it from the speed-time law v @ t. However, Duhem notably does not then state Soto's expression of the time-squared law, but only of the speed-time law and the mean speed theorem. If you wish to confirm that Soto actually published the time-squared law in 1545, then you may have to actually do some original research and check out this publication, the reference of which you may find in the third volume of Duhem's Leonardo Studies or in his Systeme. In case of difficulty Duhem experts such as Roger Ariew or Stanley Jaki may be able to assist you further. Or it may be that somebody has published a rebuttal of Duhem's claim somewhere. I take it William Wallaces's 1968 Isis 59 article on de Soto does not actually refute Duhem’s claim? But given the frequent unreliability of historians of science, it may be that de Soto went no further than just asserting the MST held for gravitational free-fall. If original research on de Soto’s publication confirms he did not assert the time-squared law,but at most only the MST, please do appropriately qualify the claim. Meanwhile I have posted in the Duhem reference for the claim. —Preceding unsigned comment added by Logicus (talk • contribs) 17:47, 17 June 2008 (UTC)

I have now had a chance to go carefully through two of William Wallace's articles, The Enigma of Domingo de Soto: Uniformiter difformis and Falling bodies in Late Medieval Physics, and Domingo de Soto's "Laws" of Motion: Text and Context, collected together in Domingo de Soto and the Early Galileo, published by Ashgate Publishing Limited, Aldershot, 2004. The first of these is a reprint of Wallace's Isis, 59 paper, referred to by Logicus above. The second contains Wallace's translation of the relevant parts of Soto's commentary and questions on Aristotle's physics, in which Soto suggested that falling bodies were uniformly accelerated. I could find nowhere in the texts of Soto's translated by Walllace where he displays any knowledge of the times-squared law. Nor could I find any statement of Wallace's that credited him with such knowledge in either of these two papers.

On the contrary, remarks of Wallace's in both papers seem to indicate that he was unaware of any such knowledge on Soto's part, for he says in the first (p.II 384) that Soto "indicates that the distance of fall can be calculated from the elapsed time by means of the so-called Mertonian mean-speed theorem", and in the second (p.III 272) that Soto had explained how the distance of fall could be calculated "through the application of the mean-speed theorem". Now, once one has derived the times-squared law, the mean-speed theorem becomes completely superfluous in deriving the distance travelled from time elapsed. So if Wallace had been aware that Soto knew the time-squared law, surely one would expect him to have given that as Soto's suggested method for calculating distances, rather than the more indirect application of the mean-speed theorem.

In any case, since the time-squared law was already known to Nicole Oresme I don't think we should be saying that it was "discovered" by Soto anyway. I have amended the text of the article accordingly.
—David Wilson (talk · cont) 17:52, 24 August 2008 (UTC)

Rethinking de Soto ?

The article currently claims:

"Galileo proposed that a freely falling body would fall with a uniform acceleration,,,He was not, however, the first to advance [this proposition]...Domingo de Soto had suggested that falling bodies were uniformly accelerated in the 16th [century]."

But I now note that according to Edward Grant, de Soto only held that gravitational fall in a homogeneous medium, which is of course not free-fall, would be uniformly accelerated. Grant says

"Sometime around 1545, Domingo de Soto declared, in his Questions on the Physics of Aristotle, that a body that falls through a homogeneous medium from some height increases its motion "uniformly difformly", that is, falls with a uniform acceleration. [p103 The Foundations of Modern Science in the Middle Ages CUP 1996]

But of course this claim of uniform acceleration in a fluid medium is grossly false in Newtonian and classical mechanics, which predict the rate of acceleration in a fluid medium would continually decline exponentially(-:? with speed as it increases until a terminal constant speed is attained.

If Grant is right, and unless we know what sort of motion, if any, De Soto predicted for gravitational free-fall, that is, gravitational fall in a vacuum without the resistance of any medium, then either it should be made clear in the article that his 'mistaken' prediction of uniformly accelerated fall in a medium was not for the same dynamical kind of motion, namely free-fall, for which Galileo (mistakenly) predicted uniform acceleration, OR else maybe the whole bit on de Soto should be deleted as thereby irrelevant ?

Immediately I propose to flag the de Soto claim for a source that he claimed gravitational free-fall would be uniformly accelerated. What do you think, David ?--Logicus (talk) 18:18, 16 October 2008 (UTC)

Thank you for identifying this ambiguity. I have now amended the text so it is hopefully now less susceptible to misinterpretation. Unless someone indicates that it is still unclear I will remove the {{Clarifyme}} template in a few days.

In my opinion, Soto's suggestion that falling bodies would be accelerated uniformly is at least as siginficant an anticipation of Galileo's theories as Lucretius's and Stevins's suggestions that all bodies would fall with the same speed in a vacuum; so if theirs are to get a mention in the article then it seems to me that so should his. Judging by the relative amounts of space devoted to each of these suggestions in Sharratt's book, he would appear to have a similar opinion of their relative importance.

—David Wilson (talk · cont) 15:32, 19 October 2008 (UTC)

Since there has been no further objection after the text was modified, I have now removed the {{Clarifyme}} template

—David Wilson (talk · cont) 13:10, 22 November 2008 (UTC)

Did Sizzi’s sunspot path variations refute geocentrism ?

On a very quick reading of Drake’s 1970 analysis of this issue, it seems they only refuted purely geostatic geocentric models without a daily rotating Earth, unlike such as Longomontanus’s model. But this reading was in great haste and I could be wrong.

But if right, the claim made in the article that they “provided a powerful argument against both the Ptolemaic system and the geoheliocentric system of Tycho Brahe.[10]” is rather misleading, and should be replaced by something like

‘refuted all geostatic geocentric systems such as the Ptolemaic and Tycho Brahe’s, but not geocentric models with a daily rotating Earth such as that of Longomantanus’

but better expressed.

Interesting issue here is whether Sizzi’s sunpots historically promoted preference for what Christine Schofield calls the ‘semi-Tychonic’ model of Longomontanus.

The point is potentially important but difficult and needs better explanation. --Logicus (talk) 18:16, 17 June 2008 (UTC)

Vatican proposes statue of Galileo

In March of 2008, it was announced that the Vatican will erect a statue of Galileo.

Nicola Cabibbo, head of the Pontifical Academy of Sciences and a nuclear physicist, said: “The Church wants to close the Galileo affair and reach a definitive understanding not only of his great legacy but also of the relationship between science and faith.”

The planned statue is to stand in the Vatican gardens near the apartment in which Galileo was incarcerated while awaiting trial in 1633 for advocating heliocentrism, the Copernican doctrine that the Earth revolves around the Sun. —Preceding unsigned comment added by 63.227.96.214 (talk) 21:00, 17 June 2008 (UTC)

Logicus comments: My understanding of this issue is that Galileo was not charged and tried for advocating heliocentrism, but rather for advocating it as empirically proven fact in his 1632 Dialogo when it was not and having agreed not to. And since it was not so proven at that time, the Church was right and Galileo wrong in this respect. Added to that is Galileo's outrageous misrepresentation of the scientific position at the time as a debate between just two world systems, the Ptolemaic geocentric and heliocentric when in fact the prevailing models at the time were superior geoheliocentric ones, but which he never discussed and compared with the heliocentric model.

It should also be pointed out that on one account it was Scheiner who persuaded the Pope to charge Galileo by persuading him Galileo had portrayed him as Simplicius, the fool, in the Dialogo. What had incensed Scheiner was Galileo's pilloring of him in the Dialogo for his estimate that it would take a canonball some 6 days to fall to earth from the altitude of the Moon, whereas Galileo predicted it would take less than 4 hours on the basis of his grossly mistaken universal law of gravitational fall as being uniformly accelerated. In fact as even Galileo hagiographer Stillman Drake sheepishly admitted, according to modern estimates Scheiner was roughly right (i.e. it would take some 5 days) and Galileo radically wrong ! [See p219-225 of Dialogo tr Drake University of California Press 1967. This was where Galileo first published his grossly mistaken law of free-fall.]

But I could be wrong about the charge against him. It would be helpful if the article could clarify and source exactly what Galileo was charged with and also what he was convicted of. --Logicus (talk) 17:08, 23 June 2008 (UTC)

Sizzi and others

I am somewhat puzzled by the reinsertion of a {{fact}} template on a statement for which I had already provided a good reference two days ago. The cited reference (p.209 of Stillman Drake's Galileo at Work) unequivocally supports everything said in the clause immediately preceding its citation, including the fact that others as well as Sizzi had made the observations of the sunspots which he reported. I am therefore at a loss as to what else there is that needs to be supported by another citation. I have therefore commented out the {{fact}} template until the reason for it has been further clarified.

The edit summary given for the insertion of the {{fact}} template asked for Sizzi's companions to be identified. Unfortunately, their identities do not appear to be known. At any rate, Drake doesn't identify them in the cited reference. One of them might have been the mathematician Jacques Aleaume, whom Drake identifies as one of the mathematicians whom Sizzi had met and discussed Galileo's work with. But it is not sufficiently clear from Drake's text that Aleaume was amongst those who observed the sunspots that it could be used to justify his identification as one of them in the article. —David Wilson (talk · cont) 15:09, 19 June 2008 (UTC)

Logicus explains: Thanks David! First, there was no reinsertion of the fact template as you claim, but rather a new insertion at a different place for clarification of a different issue this time, about who the “others” were. Thanks for the clarification and sources you supplied for the previous fact template. To explain background here, the reason for the request was that I recall from reading Drake’s 1970 when first published when I was a referee/reviewer for an academic journal, I discounted its Ch 9 as saying the sunspot variations proved heliocentrism. But the article appears to be saying they refuted all geocentrism, or is at least easily construed as such. So I wanted to know your sources. And if my analysis in my second 17 June Talk contribution is right, the gloss on Drake’s 1970 analysis is indeed misleading, and some kind of edit as I have proposed is required and maybe most of footnote 35 could be deleted. But maybe you think I am wrong ?

Re the ‘others’ issue, I think the important issue of there being identified is that of just how widely the variation observations and the issue were publicly aired and the apparent refutation of all geostatic geocentrism appreciated, apart from Sizzi’s private letter to Galileo. Its importance is it might explain the empirical rationale of the semi-Tychonic/semi-Copernican geoheliocentric model of Longomontanus with a daily rotating Earth. Note he did not publish his Astronomica Danica until 1622, almost a decade after the Sizzi sunspot observations. And more generally it might explain the apparent relative popularity of his geoheliocntric model/tables well into the 17th century.

Anyway, thanks for your helpful efforts on this. Maybe what you have said on this here could now form a clarificatory addition to footnote 34 ? --Logicus (talk) 17:51, 19 June 2008 (UTC)

Historic significance of the sunspot observations ?: I should perhaps point out the possible bigger significance of the sunspot variation issue. Was Foucault's pendulum the first empirical proof of the Earth's daily rotation, or was it already proven earlier as the Wikipedia article on it claims? ("In 1851 it was well known that Earth rotated: observational evidence included Earth's measured polar flattening and equatorial bulge.")

If it was the first proof, then science is empirically irrationalised by the fact of its conversion to georotationalism much earlier without empirical proof, contrary to Wikipedia claims that at least since the 17th century science has used an empirical scientific method of proof and theory change.

So were there any earlier proofs ? One possible candidate for an earlier proof is the 1730s discovery by Maupertuis that the Earth is oblate if its equatorial bulge could be deduced as caused by its rotation. But the key problem here, in addition to the fact that Newton's Principia predictions of its size were all refuted, (these were variously 17, 32 and 17 miles high in its three different editions, but it is 13 miles high) is that it seems the conversion was earlier. The 1613 discovery of the seasonal variation in sunspot trajectories is apparently another candidate, and seems to just pre-date the georotational conversion that seems to have occurred in the 17th century in its geoheliocentric models such as that of Longomontanus published in 1622, with Galileo's Dialogo argument from sunspots published a decade later.--Logicus (talk) 14:25, 20 June 2008 (UTC)

Passages

Passages in which Einstein criticised Galileo are omitted in one version of Einstein's Preface to Stillman Drake's translation of the Dialogue. —Preceding unsigned comment added by 86.139.211.191 (talk) 15:37, 25 June 2008 (UTC)

In popular culture...

The album Eppur_Si_Muove by Haggard (band) is based on the life of Galileo Galilei. 217.99.123.90 (talk) 20:29, 28 June 2008 (UTC)

And. Ceoil ^sláinte 20:36, 28 June 2008 (UTC)

That is not a reliable source. —Preceding unsigned comment added by 87.194.4.21 (talk) 09:18, 1 July 2008 (UTC)

Music in general is not an original or reliable source. —Preceding unsigned comment added by 87.194.4.21 (talk) 09:40, 1 July 2008 (UTC)

The phrase 'geoheliocentric geocentric models' makes no sense, and the section it is in seems far from Galiean history

The sentence "...the 17th century majority conversion of the scientific community to geoheliocentric geocentric models such as the Tychonic and Capellan models" doesn't seem to make sense. What is the (undefined) 'geoheliocentric' model? (There is in general a good deal in the relevant section that is far from Galileo's beliefs or discoveries.) Cshirky (talk) 02:42, 30 June 2008 (UTC) The word "or" could be put between the two words.

Possibly, Logicus meant to put an oblique between "geoheliocentric" and the next word. —Preceding unsigned comment added by 87.194.4.21 (talk) 09:42, 1 July 2008 (UTC)

Logicus explains: If I might explain, the locution 'geoheliocentric geocentric models' was intended as a qualifying contrast with non-geoheliocentric or pure geocentric models, such as that of Ptolemy, in contrast with those geoheliocentric models of Tycho or of Capellus, or whoever. As distinct from pure geocentric models that posited the Earth to be the one centre of all celestial orbits, geoheliocentric geocentric models have at least two centres of celestial orbits rather than one, namely both the Sun and the Earth. with some bodies orbiting the Earth in epicycles of the Sun's orbit around the Earth. They seem to have started with Heracleides' planetary model in which it seems at least Venus and Mercury orbited the Sun, which in turn orbited the Earth.

I specifically coined the phrase 'geoheliocentric geocentric models' as the most linguistically economical/efficient brief way of summarising the contrast. But if it constitutes a stumbling block to the attempts of the contemporary average American or others to understand the English language and 17th century astronomy, I am happy to consider proposals for a better alternative phraseology for Americans and possibly other non-English speakers of English in the English language Wikipedia.

But the relevant and main point here remains that it was apparently Galileo's telescopic confirmation of the full set of phases of Venus that precipitated the scientific conversion from pure geocentric models to geoheliocentric models in the 17th century.

--Logicus (talk) 14:37, 20 July 2008 (UTC)

Equal speed of free-fall for unequal weights not confirmed on inclined plane ?

The article currently claims

"However, Galileo did perform experiments which proved the same thing [unequal weights fall with equal speed in a void] by rolling balls down inclined planes:[73]..."

But do the cited sources really make this idiosyncratic claim ? In the First Day of his 1638 Discorsi Galileo has Salviati claim to have demonstrated unequal weights would fall with the same speed in a void by comparing pendulum motions with bobs of lead and of cork, not by motion on an inclined plane, which he rejects as unreliable. The only thing it is claimed was demonstrated on the inclined plane was the gross falsehood that naturally accelerated motion is uniformly accelerated, but not any equality of that uniform acceleration for different weights.

Thus I flag what I believe to be a mistaken claim, with a view to its eventual replacement by an account of what Salviati claims or else preferably by an account of what Galileo himself actually did or not. Immediately I request actual quotation of what Drake and Sharatti actually say about this. --Logicus (talk) 14:45, 19 July 2008 (UTC)

I am surprised to find that it was I who added the citations for this statement, since I don't believe it's possible to prove "the same thing" by rolling balls down inclined planes. Though I did modify the statement when I added the citations, I was not its originator, and I suspect I misread it—but I'm damned if I can now see what else I could have mistaken it to be claiming. In any case, you're correct that the cited references don't suppport it and I apologise for my carelessness.

It's possible that Galileo did show experimentally that (spherical) balls of different weights descend down inclined planes at the same speed, but neither Drake nor Sharrat make that claim, and it wouldn't "prove" that the same rule must hold for free fall anyway.

—David Wilson (talk · cont) 20:30, 19 July 2008 (UTC)

Logicus to David Wilson:Thanks very much for this clarification, and your candour. We all make booboos ! I am pleased to learn that of Drake's many unscholarly sins, claiming that Galileo attempted to prove unequal weights fall with the same speed in a void on the inclined plane was not one of them.

However, unfortunately I fear that after your corrective edit, this paragraph now even more evidently makes no logical sense. I offer an extended critical discussion on this important issue.

Its first sentence tells us that although Galileo argued the speed of free-fall is independent of weight, presumably referring to his prediction in The First Day of his 1638 Discorsi that all unequal weights would all fall with the same speed in a void, nevertheless he was not the first to do so. But rather than then being given a list of others who had previously also argued this, instead we are given a list of 10 people who it is alleged only argued bodies of the same substance (and hence same specific weight) but of different mass would fall with the same speed in a void, which is blatantly not the same more radical proposition Galileo argued. But on the other hand, nobody is listed who held that all unequal weights, whether of the same substance and hence same specific weight or not, would nevertheless all fall with the same speed in a void, as 'Galileo' did in his Discorsi. Thus the (unsourced) claim that he was not the first to do so is not proven by any example being provided of any predecessor who also held this.

For whatever it may be worth, I believe it is true that at least 3 of the 10 listed - Philoponus, Stevin and Benedetti - held that the speed of free-fall would be proportional to specific weight, and thus at least the same for the same materials, but different for bodies of different specific weight, just as Galileo had also held in his 1590 Pisan dynamics of De Motu. Thus contrary to the later Galileo of his Paduan Discorsi, they denied all unequal weights would fall with the same speed - some bodies would but others would not, depending upon their specific weight. The reason for this is that they had no concept of inherent inertial resistance to motion that is proportional to weight, an innovation due to Averroes and Aquinas.

As for the other 7, I simply do not know what their positions on this issue were. For all I know they may well have been the same. But I also believe that the reason why those three held speed in a void would be proportional to specific weight was because like Aristotle did, they also held that the speed of fall in a fluid medium is directly proportional to the excess specific weight of the body over that of the medium. Thus when there is no medium the speed is directly proportional to the body's specific weight. But where they differed here from Aristotle's prediction that all bodies of whatever weights would fall with the same speed in a void, namely with infinite speed, by instead predicting it would take different finite amounts of time according to specific weight, was in denying their speed of fall would also be inversely proportional to the density or specific weight of the medium as a resistance. But if Stoke's law of the terminal velocity of fall in a fluid medium is taken to be the truth about it, then as the WW1 British army ballistics expert Major Hardcastle and also Stephen Toulmin have effectively argued, Aristotle was essentially empirically right in his law of fall in a fluid medium insamuch as it is essentially determined by the ratio of buoyancy to fluid resistance - he was just wrong in measuring that inverse fluid resistance by density as opposed to viscosity as in Stoke's law.

It should perhaps be pointed out that nobody, including Galileo, has ever documented in Aristotle's texts the ludicrous claim of Galileo-Salviati and positivist history of science that Aristotle held that speed of fall is proportional to absolute weight.

However, on the issue of whether Galileo had any predecessors in his prediction that unequal weights would have the same finite speed in gravitational free-fall, my own research into the secondary literature to date suggests this cannot have been theoretically predicted before Aquinas's 'discovery' of inertial resistant mass m, such as portrayed by Duhem and Sorabji, whereby Aristotle's law of motion for the void v @ W/0 = infinite becomes v @ W/m = k instead because of the constant proportionality of weight and mass. In other words the prediction of unequal weights falling with the same speed in a void is an immediate logical consequence of Aquinas's important innovation of inertial Aristotelian dynamics. But who first drew it and also asserted its truth ?

On this important issue in his Systeme Duhem cites Paul of Venice in the early 15th century as at least actually drawing this conclusion from Thomist inertial dynamics as at least not absurd as Aristotle held, but yet apparently not asserting it himself. So the question of who, if anybody, drew this conclusion and also predicted it would be true before Galileo did, remains to be discovered from the literature. As also does whether or not Galileo was the first to maintain it could be experimentally demonstrated by pendulum motion considered as dynamically exemplifying gravitational free-fall. Some predecessor of Galileo at Padua University following Paul of Venice seems the most likely possibility, given Venice took over Padua in the early 15th century.

[However, it is perhaps worth noting that in a draft Preface to the Principia Ed2 Newton claimed the ancients knew "that all bodies in a vacuum fall to the earth with equal velocity and thus are heavy in proportion to the quantity of matter in each of them." See p53 Cohen's 1999 Guide.]

So I propose (i) to immediately flag the claim Galileo was not the first to claim unequal weights fall with the same speed in a void for some source, which might attract somebody to find such a claim and predecessor

(ii) to consider replacing the whole paragraph by some text of the following ilk pro tem:

'In his 1638 Discorsi Galileo's character Salviati, widely regarded as largely Galileo's spokesman, held that unequal weights would fall with the same speed in a vacuum. Whether or not he was the first to predict this is uncertain. He also held it could be experimentally demonstrated by the comparison of pendulum motions in air with otherwise similar but different weight bobs of lead and of cork.'

(iii) The considerable research that has apparently been done in providing the list of 10 who held speed of free-fall is proportional to specific weight could be salvaged by tagging on to the above text 'In his 1590 Pisa University lecture notes On Motion , Galileo had previously held that a body's natural speed of free-fall would be proportional to its specific weight or density. Others who had also held this previously include.....[then give the list of 10, if reliable.]

(iv) I suggest this episode needs much more dynamical and historical explanation, and which I shall maybe attempt if time, but meanwhile propose this unsatisfactory stop gap.

(v) In particular, I suggest the bigger important issue here is not just what is predicted for the speed of free-fall, but rather what is the 'correct' law of the speed of gravitational fall in a fluid medium (e.g. Stoke's law ?) and what Galileo/Salviati explicitly or implicitly said it was in such as pp105-142 of the Discorsi, and whether this represented any historical scientific progress. Thus what is really required is a logical algebraic summary of the mathematical law Galileo proposes in these pages, which somebody may have already done.

--Logicus (talk) 17:49, 21 July 2008 (UTC)

In popular culture

Is this section really necessary? For a start, lists are discouraged, especially for FA status which we are aiming for. What's more only the first of these facts are actually cited! I propose the section be removed but welcome other suggestions. Jdrewitt (talk) 18:14, 20 July 2008 (UTC)

I removed the list, its contents are below. It doesn't make sense to have a long list of uncited claims in an article that is aiming for FA status. It might be useful to incorporate some of these facts into the Legacy section but NOT without citations and the content should also be converted to prose. Jdrewitt (talk) 10:37, 23 July 2008 (UTC)

• Singer-songwriter Ellis Paul wrote and recorded a song Did Galileo Pray. See also commentary on the song published in the June/July 2006 issue of the physics journal Symmetry.
• There is a play called Life of Galileo by the German dramatist Bertolt Brecht. It was filmed in 1975 as Galileo, with Topol in the title role, and an all-star cast.
• A play about Galileo's struggle with the Church, Lamp at Midnight, was first televised in 1966 on the Hallmark Hall of Fame, with Melvyn Douglas as Galileo and Kim Hunter as his daughter. The production also featured an appearance by Roy Scheider in an early role.
• Galileo is mentioned in Queen's song, Bohemian Rhapsody.
• The American duo Indigo Girls released a song in 1992 about the "king of night vision" whose head was "on the block." Entitled "Galileo," the song hit the #10 spot on the Billboard's Modern Rock Tracks chart, the biggest hit to date for the musical duo.
• Galileo is also the title of a song by Amy Grant.
• The Philadelphia Atmospheric Sludge Metal band named their 2005 full length "The Galilean Satellites", wherein most songs are about Jupiter and its 4 Galilean moons, specifically Europa.
• The Symphonic Metal band Haggard made an album based on the life of Galileo and the legend that he muttered the phrase Eppur si muove meaning "And yet it does move", after being forced to recant, in front of the Inquisition.
• The shuttlecraft used in the Star Trek first season episode The Galileo Seven is named after the famed astronomer. When that shuttle is destroyed at the end of the episode, another shuttlecraft is named the Galileo II.

For the most part I agree with removing these entries. The one exception might be to suggest having a paragraph about media portraying the life of Galileo. Hence the second and third bullets above, plus any comparable media instances (such as Galileo's Daughter and NOVA's Galileo's Battle for the Heavens).—RJH (talk) 22:20, 24 July 2008 (UTC)

Logicus's opinion: For whatever its worth, I disagree about the removal of this section, which surely made the article more interesting. I don't see why it should impede achieving the grail of FA status ? I say 'Put it back please !' --Logicus (talk) 21:59, 26 July 2008 (UTC)

As described above the section is almost entirely uncited and cannot therefore be retained. I did mention that maybe 'some' of the information could be incorporated into the Legacy section but i am not willing to put any uncited claims back into this article. The section is nothing more than a poorly researched and frivalous trivia section. Jdrewitt (talk) 08:29, 27 July 2008 (UTC)

"1919"

1919 in the main article seems to be a mistake for 1619. Guiducci is said to have published in 1619 elsewhere. —Preceding unsigned comment added by 81.149.117.81 (talk) 15:35, 21 July 2008 (UTC)

Typo fixed. Jdrewitt (talk) 15:52, 21 July 2008 (UTC)

Who held unequal weights free-fall with the same speed before Galileo ?

To revise the above discussion (i.e. 'Equal speed of free-fall for unequal weight...plane?') of this question currently posed by the article, further research suggests all the citations of the 10 people said to have held specific weights fall with the same speed in a vacuum must be queried for actual quotations that show this, or else show that they preceded Galileo in claiming all unequal weights fall with the same speed in a vacuum, rather than only some. For the quotation from the atomist Lucretius provided by Lane Cooper's 1935

"...all things must needs be borne on through the calm void, moving at equal rate with unequal weights."

suggests he held all things would fall with the same speed in a vacuum, thus vindicating Newton's claim that it was known in antiquity that all unequal weights fall with the same speed in a vacuum, if not for the same reason. Lucretius's reason appears to be the same as Aristotle's for the same conclusion, namely that differences of speed are due to differential powers to cut through the resisting medium because of differences in weight but this power is the same for all weights in a void because there is no medium to be cut that would differentiate speeds. But it seems that unlike Aristotle, Lucretius did not reject this logical conclusion as absurd, but rather accepted it. Thus it seems he did not draw this conclusion because of positing any constant ratio for all bodies between their motive weight and inertial resistant mass, as Newton said the ancients did. I suspect Newton was erroneously speculatively projecting this much later Thomist inertial dynamics reasoning onto antiquity.

As for Stevin, in the quotation from a 1605 publication given by Lane Cooper 1935 p79-80, having claimed two balls of lead with a weight ratio of 10:1 reach the ground in the same time for a 30 foot fall, he says

"And the same thing happens with bodies of equal magnitude but differing in weight as ten to one."

Presumably he held this would also be the case in a vacuum.

However, he then immediately gives a contrary example of a body of greater specific weight falling more slowly than one of less specific weight. But I suspect the immediately following text which is not given then explains this anomaly as not in conflict with the principle.

Stevin published his position in 1605, but we do not know when Galileo changed from his 1590 view that bodies would free-fall with speeds in proportion to their specific weight, hence that SOME but not ALL unequal weights would free-fall with the same speed, to his 1630s view that ALL unequal weights would do so. This could possibly have been before 1605. However, the relevant issue here is surely date of publication, in which Stevin certainly preceded Galileo.

Thus I propose at least 2 of the 10 people listed publicly held that all unequal weights would fall with equal speed in a vacuum before Galileo did, namely Lucretius and Stevin.

And of the remaining 8 listed, so far as I am aware Philoponus and Benedetti certainly did not, both holding that speed of gravitational fall in a vacuum would be proportional to specific weight.

Philoponus said:

"But if bodies in themselves have more or less downward tendency, they will obviously have such a difference among themselves even if they move in a void and the same distance in a void will be traversed in less time by the heavier and in more by the lighter, not because of being more or less obstructed, but because of having a greater or lesser downward tendency in proportion to the difference in their NATURAL weight." [David Furley's translation of Philoponus's Physics 678,29-679.23 in Sorabji's 2004 The Philosophy of the Commentators 200-600 AD Volume 2 Physics. My caps for emphasis. It is thought natural weight meant specific weight rather than absolute weight.]

So the remaining question is whether any of Albert of Saxony, Bradwardine, de Soto, Monte, Varchi or Moletti held all unequal weights would free-fall with the same speed.

This whole list and its references were provided by user Cwkmail, who may be kind enough to provide the relevant quotations for each from these references.

Meanwhile I shall flag all the citations as needing quotations to be provided —Preceding unsigned comment added by Logicus (talk • contribs) 15:22, 25 July 2008 (UTC)

As a result of this it may now be said

'In his 1638 Discorsi Galileo's character Salviati, widely regarded as largely Galileo's spokesman, held that all unequal weights would fall with the same speed in a vacuum. But this had previously been proposed by Lucretius and Simon Stevin. Salviati also held it could be experimentally demonstrated by the comparison of pendulum motions in air with otherwise similar but different weight bobs of lead and of cork.' --Logicus (talk) 15:52, 25 July 2008 (UTC)

Logicus on Moletti: On the question of whether Moletti held that all unequal weights would fall with the same finite speed in a vacuum, as the later 1638 Galileo did, investigation of Laird's 2000 English translation of Moletti's Dialogue on Mechanics online at Google Books [[1]]

suggests this cannot be so. For whilst it seems he held unequal weights fall with the same speed in fluid media, his explanation for this is that the resistance of the medium is always proportional to the weight as motive power because its resistance is in proportion to its density and the medium beneath the falling body is compressed in proportion to the body's weight. But of course in a vacuum there is no such proportional resistance, whereby it seems Moletti must have held like Aristotle that the speed of fall in a vacuum would be infinite and thus the same for all weights, or else maybe like Philoponus and the younger Galileo that it would be proportional to specific weight. According to Laird it seems Moletti had some notion of inertial resistant mass internal to bodies, but if so why did he not draw the conclusion from such Thomist inertial dynamics as Paul of Venice did that this entailed equal speeds of fall for all unequal weights in a vacuum, because of the constant proportionality of motive weight to inertial resistant mass ?

Laird tells us:

"The Prince then offer's Girolamo Cardano's explanation why two unequal weights would fall simultaneously but again he is less than satisfied with it. The power of descending is proportional to the weight, that a falling body compresses the medium beneath it in proportion to this weight, and that the resistance offered by the compressed medium is in proportion to its density Thus a ball three times the diameter of another of the same material and thus weighing twenty seven times as much has twenty seven times the power of descending. But it also compresses the medium to twenty seven times the density, and thus encounters twenty seven times the resistance. Its greater power of descending, then, is exactly balanced by the greater resistance it encounters, so it descends at the same speed as the smaller ball....Had Moletti applied his notion of internal resistance to falling bodies, so that the heavier body would have exactly that much more internal resistance to motion as it has more power of descending, he would have come very close to the concept of inertial free fall. But while internal resistance works well when applied to violent motions, where the moving power is extrinsic to the things moved, if applied to natural motions it produces a paradox. For how can one and the same weight be both the cause of a body's motion and at the same time offer the resistance ? [p34-5 The Unfinished Mechanics of Giuseppe Moletti Walter Roy Laird 2000] "

It should be noted there is no paradox for "inertial free-fall" of the weight being both motor and resistance, such as Laird claims, for in Thomist inertial dynamics the weight is the motive form but the resistance is the inertial mass of the prime matter of the body that is moved by its form. And it is the constant proportionality of the form to the mass that entails all unequal weights fall with the same speed.

From Laird's report here it also seems that nor could Cardano have held all unequal weights fall with the same finite speed in a vacuum where there is no resistant medium.

So on this basis it seems Moletti should be eliminated from the list of those who held all unequal weights free-fall with the same finite speed before Galileo did, which leaves Albert of Saxony, Bradwardine, de Soto, Monte, Varchi still to be investigated. But at this stage I now propose the current paragraph be replaced by the following text, with other names to be added if further research reveals it is justified. However, maybe a footnote on the peculiar positions of Moletti and Cardano on equal speeds in fluid media, the contrary of Galileo's thesis of unequal speeds in fluid media, should be considered ?

"In his 1638 Discorsi Galileo's character Salviati, widely regarded as largely Galileo's spokesman, held that all unequal weights would fall with the same finite speed in a vacuum. But this had previously been proposed by Lucretius[ref> ref </ref> and Simon Stevin.[ref> ref </ref>Salviati also held it could be experimentally demonstrated by the comparison of pendulum motions in air with otherwise similar but different weight bobs of lead and of cork."

--Logicus (talk) 14:16, 27 July 2008 (UTC)

Albert & Bradwardine: Consultation of page 209 of Grant's A History of Natural Philosophy: From the Ancient World to the Nineteenth Century(Cambridge, England: Cambridge University Press, 2007) reveals neither Albert of Saxony nor Bradwardine held that all unequal weights would fall with the same finite speed in a vacuum, but rather as originally claimed here they only held like the younger Galileo of his 1590 De Motu that unequal weights of the same material or specific weight would do so, but that bodies of different materials or specific weights would fall with different speeds in proportion to their specific weights.

This just leaves the opinions of de Soto, Monte and Varchi still to be determined.

--Logicus (talk) 20:31, 28 July 2008 (UTC)

On Lindberg on Philoponus: In Talk:Science in the Middle Ages the knowledgeable and analytical User Thony C has suggested that in his 2007 Beginnings of Western Science David Lindberg claims Philoponus claimed all unequal weights would fall with the same finite speed in a void long before Galileo did. However consulting that work reveals this is not so, for as Lindberg says on p310 "Philoponus did not state that the rapidity of motion in the void would be directly proportional to the weight, but presumably he expected this to be presumed." Thus Lindberg's opinion is in line with Logicus's on Philoponus if "weight" here refers to specific weight.

--Logicus (talk) 21:53, 30 July 2008 (UTC)

Proposed deletion of the current 'Classical mechanics' box diagram

This diagram in the 'Physics' section is simply wrong. Galileo never stated the general law that a constant force produces a uniform acceleration, although he mistakenly held gravity causes a uniform acceleration. And I do not know of anybody who ever said he did assert F = ma or similar. So I doubt any citation for this claim will be found, and so this ahistorical misleading diagram should be deleted from this article. --Logicus (talk) 16:18, 25 July 2008 (UTC)

Wot theoretical basis ?

The article currently ungrammatically claims

"Galileo's writings contrasted with his contemporaries by formulating [a?] theoretical basis [bases ?] to experimental observations."

But what does this mean ? What experimental observations and what theoretical basis ? Does it mean his contemporaries' writings just reported experimental observations with no theoretical basis or bases ? This is surely just nonsense if one considers the works of such as Benedetti, Kepler, Descartes, Moletti etc. And on the other hand it was Galileo who the Cartesians famously accused of publishing such as his supposedly experimental law of free-fall without any theoretical basis. And of course even his great supporter and French translator Mersenne thought Galileo never did any experiments, and the Cartesians regarded the law as not verified by experiment.

I have flagged the claim to request some justifying source in case somebody, such as an academic historian of science, has been silly enough to make it, but reckon is must just be deleted as false.

--Logicus (talk) 21:48, 26 July 2008 (UTC)

The statement probably shouldn't be as all inclusive as it suggests. The main reason for this statement is that Galileo's theories are ultimately based on observation and the develpment of mathematical models based around these observations as opposed to simply taking the Ptolemaic model of the Universe and using Aristotle's physics just because these happen to be popular. I didn't mean to suggest he was the first to make judgements from observations so yes, this should be removed as it is misleading. Jdrewitt (talk) 09:29, 27 July 2008 (UTC)

Thanks ! --Logicus (talk) 14:17, 27 July 2008 (UTC)

Wot pioneer ?

The article currently claims

"He was a pioneer, at least in the European tradition, in performing rigorous experiments and insisting on a mathematical description of the laws of nature."

But this is surely blatant nonsense. On the matter of mathematical description of the laws of nature, surely the European pioneers were the Pythagoreans (or earlier ancients), Plato ('Let no one enter here without geometry' and perhaps most of all Aristotle in his systematic application of the new Eudoxan theory of proportions (later axiomatised in the 5th book of Euclid) across the board from mathematical physics to mathematical ethics in his Nicomachean proportionalist theory of justice. As for Galileo pioneering performing rigorous experiments, surely the views of Mersenne and Einstein that this was all baloney should now be accepted following the risible debacle of the collapse of the 1638 Discorsi claim to have confirmed the grossly mistaken law that naturally accelerated motion is uniformly accelerated to within one-tenth of a pulse beat by means of a water tank, ridiculed by Einstein in his Preface to Drake's English translation of the 1632 'Dialogo', into the utterly desparate farcical thesis eventually proposed by Drake that Galileo measured time intervals on the inclined plane by beating out time to a popular song, no doubt the Rock Around the Clock of his day. This is before we even consider the utter absurdity of claiming to demonstrate a cosmologically universal law of fall governing planetary motion by a purely terrestrial fall down a mere 18ft inclined gutter, an experiment as rigorous as boiled rhubarb. Nor to mention Galileo's measurement of g in the Dialogo was less than half its standard value. Surely this twin claim should be deleted ? —Preceding unsigned comment added by Logicus (talk • contribs) 14:50, 27 July 2008 (UTC)

Logicus writes:

"As for Galileo pioneering performing rigorous experiments, surely the views of Mersenne and Einstein that this was all baloney should now be accepted following the risible debacle of the collapse of the 1638 Discorsi claim to have confirmed the grossly mistaken law that naturally accelerated motion is uniformly accelerated to within one-tenth of a pulse beat by means of a water tank, ridiculed by Einstein in his Preface to Drake's English translation of the 1632 'Dialogo', ... "

Not being able to recall any such ridicule by Einstein in the indicated "preface" (it was actually titled "Foreword", not "Preface"), I decided I needed to re-read it. On doing so I couldn't find anywhere in it where Einstein even mentions tbe supposed claim, let alone ridicules it. All Einstein has to say about Galileo's theory of free fall is the following:

"Galileo also recognized that the effect of gravity on freely falling bodies manifests itself in a vertical acceleration of constant value; likewise that an unaccelerated horizontal motion can be superposed on this vertical accelerated motion.

"These discoveries contain essentially — at least qualitatively — the basis of the theory later formulated by Newton. But first of all the general formulation of the principle of inertia is lacking, although this would have been easy to obtain from Galileo's law of falling bodies by a limiting process. (Transition to vanishing vertical acceleration.) Lacking also is the idea that the same matter which causes a vertical acceleration at the surface of a heavenly body can also accelerate another heavenly body and that such accelerations together with inertia can produce revolving motions."

This hardly constitutes "ridicule". Further on, Einstein does assess the quality of experimental techniques available to Galileo as being very poor:

"Moreover, the experimental methods at Galileo's disposal were so imperfect that only the boldest speculation could possibly bridge the gaps between the empirical data. (For example, there existed no means to measure times shorter than a second.)"

but again, this hardly constitutes "ridicule", and in any case this assessment of Einstein's has simply not withstood the test of time. It was probably derived from the armchair speculations commonly favoured by prominent science historians of that period (especially Alexandre Koyré) that Galileo couldn't possibly have achieved the level of accuracy he claimed with an apparatus of the kind he described. However, all those armchair speculations were thoroughly discredited by Thomas Settle in 1961. Settle re-performed Galileo's experiment with a crude water clock satisfying Galileo's description, and found he was able to achieve the level of accuracy claimed by Galileo with very little trouble at all.

Nevertheless, I agree that the text Logicus has objected to does smack too much of hagiography to be allowed to stand without the support of a good reference.

—David Wilson (talk · cont) 17:46, 29 July 2008 (UTC)

Logicus: Thanks ! I never knew anybody took Settle seriously. But I'll deal properly with the experimentation issue and your interesting comments later. Meanwhile, so in your view if Settle succeeded, then why did Drake so ludicrously end up with Galileo singing a song to keep time as the ball clickety-clacked over the increasingly spaced sleepers on the inclined gutter, having given up on the water-tank timer devised in antiquity ? (But I should confess I am recalling all this from many many moons ago.)

However, I made two points about the two claims made in the disputed sentence, the other being that Galileo was by no means the first in "insisting on a mathematical description of the laws of nature." Can I take it you do not deny this claim is grossly mistaken ? (The founder of mathematical dynamics in particular was of course Aristotle.) So I doubt you will find a good reference to support that claim. --Logicus (talk) 13:16, 30 July 2008 (UTC)

Logicus to David: Since you do not object to my point that this second claim is obviously grossly mistaken (e.g. Archimedes, Galileo's alleged mentor), I shall now delete it. OK ? --Logicus (talk) 14:21, 2 August 2008 (UTC)

As I thought I had already indicated, since the claim in question has not been attributed to a reliable source after a challenge to provide one has been issued, I have no objections to its being removed. Though it's not really relevant, I note for the record that this does not mean that I support the contrary claim that the deleted opinion was "obviously grossly mistaken".

In raising Thomas Settle's work during my previous comment I would appear to have strayed well off-topic (where topic is how to improve the article on Galileo). Rather than clutter up this talk page with further off-topic discussion on this issue, I have decided to respond to Logicus's reply on my talk page.
—David Wilson (talk · cont) 15:51, 3 August 2008 (UTC)

Thomas Settle and Stillman Drake (Inserted here 17 Aug by Logicus from David Wilson's User Talk page)

On the Galileo Galilei talk page Logicus wrote:

"I never knew anybody took Settle seriously."

Well, according to Michael Segre, in The Cambridge Companion to Galileo (p.405), Settle's "nice short article is among the most quoted in Galilean studies." Of course this doesn't mean that everyone who has quoted his article can be assumed to have "taken him seriously", but I have yet to find a single counterexample. Examples of scholars who did most definitely take him seriously include Segre himself, Stillman Drake (Galileo at Work, p.xviii; Galileo Studies, p.238; Galileo: Pioneer Scientist, pp.11–12; Isis, 64 (1973), p.291, cited by Segre as an article in which Drake refers to Settle's work as a "refutation" of Koyré's claims on the matter), Michael Sharratt (Galileo: Decisive Innovator, p.200), Jürgen Renn (Galileo in Context, p.19), and Stephen Mason (History of Science, 40 (2002), p.378).

" ... if Settle succeeded, then why did Drake so ludicrously end up with Galileo singing a song to keep time as the ball clickety-clacked over the increasingly spaced sleepers on the inclined gutter, having given up on the water-tank timer devised in antiquity ?"

The question presumes as fact a supposition (Drake's allegedly having "given up on the water-tank timer") which is flatly contradicted by overwhelming evidence to the contrary. Drake in fact remained a constant and unequivocal supporter of Settle's work from the earliest of the above cited works (Galileo at Work, 1978) to the latest (Galileo: Pioneer Scientist, 1990), published just 3 years before his death.

Drake's hypothesis on the use of musical rhythms to equalise time intervals was proposed to explain how Galileo might have carried out a different experiment from the one reproduced by Settle, so there is nothing at all inconsistent in his continuing both to support Settle's work and to promote his own hypothesis at the same time. The experiment described by Galileo in the Discorsi, and reproduced by Settle, was designed to measure the times taken for a ball to travel various fixed, prescribed distances down an inclined plane. Drake, on the other hand, was trying to explain data from Galileo's unpublished working notes which appear to have come from an experiment designed to measure the distances travelled by a ball down an inclined plane during fixed, prescribed time intervals.
—David Wilson (talk · cont) 15:45, 3 August 2008 (UTC)

To forestall any possible misunderstanding which my comments above and on the Galileo Galilei talk page might give rise to, I should note that Settle's experiment shows only that Galileo, using materials and techniques available to him, could have obtained the accuracy he claimed in the experiment he describes—and Settle didn't assert any more than that. Whether Galileo actually did perform the experiment and achieve the stated level of accuracy is a separate question. While most Galileo scholars now appear to accept that he did in fact perform such experiments, they still disagree over how successful they actually were, how accurate Galileo's published accounts of them were, and how much importance he attached to them.

—David Wilson (talk · cont) 14:56, 7 August 2008 (UTC)

Thanks very much indeed for all this interesting criticism and correction, on which I shall comment in detail asap. But immediately, especially in view of your 7 August comments, what now is the proposition about Galileo's experimental practice and its quality, if any, that you wish to state in the article, and with what justifying source ? Surely not just the current claim any longer ? --Logicus (talk) 14:48, 10 August 2008 (UTC)

I had given no consideration to what text might be used to replace that which you have proposed to delete, because I had thought that simply deleting it would have been reasonable. However, on reading the subsequent paragraph I now see that a considerable amount of work would have to be expended in appropriately modifying that if the preceding text were simply deleted. So it would probably be better to come up with a suitable replacement instead. I have found a sentence in Sharratt's book, Galileo: Decisive Innovator, which I believe can be adapted to provide a suitable NPOV replacement. I will propose it on the article's talk page. —David Wilson (talk · cont) 15:27, 13 August 2008 (UTC)

---

End of Insert from Wilson's User Talk page --Logicus (talk) 14:46, 17 August 2008 (UTC)

On reading the rest of the pararaph following the text proposed for deletion, I see that considerable work would have to be done to modify it if the preceding text were simply deleted.

On pages 204–05 of Galileo: Decisive Innovator, Michael Sharratt lists what he considers to be Galileo's main original contributions to scientific progress. On page 205 Sharratt writes "In physics the new science of motion, with its wedding of experiment and mathematics, has to count as his." I therefore propose that the text proposed for deletion be instead replaced with something like:

"Galileo made original contributions to the science of motion through an innovative fusion of experiment and mathematics.^[1]

References

1.^ Sharratt (1996, pp.204–05)."

Unless there are objections I shall make the change in a few days.

—David Wilson (talk · cont) 16:56, 13 August 2008 (UTC)

I object. I think we first need tio identify what his original contribs were.More later.--Logicus (talk) 16:26, 15 August 2008 (UTC)

Logicus to David Wilson: (1) Inserting the missing User Talk discussion since 3 August: I disagree with your view that discussion of Settle's work and the general issue of whether Galileo conducted rigorous experiments (to arrive at innovative theories in the science of motion) or not is irrelevant to improving the article, and therefore should not be on this page but in User Talk. It is surely of central relevance in improving it at least in respect of eliminating unjustified hagiography about Galileo and experimentation. In my view at present the article is too hagiographical in general so as to misrepresent the history and method of scientific development. Furthermore, your comments on what you see as a very mixed situation in the literature about whether Galileo did rigorous experiments or not seem to conflict with the text you now propose based on Sharratt's thereby surely one-sided view. So I now propose to insert the intervening User Talk discussion in which you make various interesting relevant points into its chronological place above.

(2) Your proposed text would maintain the paragraph's incoherence: As I read the current paragraph following the text whose deletion I propose, namely the claim that Galileo did rigorous experiments, rather than requiring considerable work re-editing it as you claim, surely it would require none since not claiming Galileo did rigorous experiments would accord with its present litany of experimental failure (e.g. free-fall,isochronous pendulum, speed of light, tides). At present we are first told Galileo did rigorous experiments, and then we are regaled with a list of his experimental failures. Thus the present paragraph is surely farcically incoherent. And if you replace the current claim with the even stronger claim of a fusion of experiment and maths, it will surely be rendered even more incoherent than it already is. More later... --Logicus (talk) 14:40, 17 August 2008 (UTC)

On looking at the article again, I see I have confused two different pieces of text. Removal of the text logicus proposes to delete will not affect the intelligibility of the subsequent paragraph (or any other) in any way, and I agree that it can be simply deleted without any other change being necessary. When I wrote my previous comment I had been looking at a different (but similar) piece of text that has also been tagged with a {{fact}} template. It was this latter piece of text which I meant to propose replacing with my suggested alternative. Apologies for the confusion.
—David Wilson (talk · cont) 16:58, 17 August 2008 (UTC)

Some time ago I deleted the piece of text which logicus challenged, and I have now amended the other one as I proposed above. I see no conflict whatever between this amended text and my own synthesized POV on what the scholarly literature has to say about the nature of Galileo's experiments. But even if there were such a conflict, Wikipedia's policies on neutral point of view and original research would prohibit me, or anyone else, from using it as a basis for excluding the text from the article. The text is well-supported by a reliable and authoritative source, so unless an equally authoritative and reliable source can be found to contradict it, I see no reasonable grounds for excluding it

—David Wilson (talk · cont) 14:27, 22 November 2008 (UTC)

First Biography found

http://www.smithsonianmag.com/science-nature/galileo-reconsidered.html?c=y&page=1 —Preceding unsigned comment added by 71.143.4.98 (talk) 18:53, 15 August 2008 (UTC)

Childish

As soon as semi-protection was removed, childish vandalism appeared. Note that Tiptoety is a sock-puppet of Dureo. —Preceding unsigned comment added by 217.43.46.202 (talk) 13:09, 18 August 2008 (UTC) The article has now been protected by Maxim, starting on the 24/8/2008. —Preceding unsigned comment added by 86.160.202.155 (talk) 12:06, 2 September 2008 (UTC)

Newton's law of gravitation?

I have placed {{fact}} templates on the following statement which currenly appears in the article:

" ... it [i.e. "gravitational free fall", apparently] is exponentially increasingly accelerated ... and inversely proportional to the distance between its gravitational centres."

and appears to be a garbled version of Newton's law of gravitation (although that's not entirely clear to me). In the first place, the gravitational force of attraction between two bodies (and hence also their accelerations towards each other) is inversely proportional to the square of the distance between their centres of gravity, not to the distance itself. This might well have been just a typographical slip. However, I'm not aware of any sense in which a body in gravitational free fall is "exponentially increasingly accelerated." So even if the statement as a whole is meant to refer to the law of gravitation, that part of it still certainly needs to be clarified and properly sourced.
—David Wilson (talk · cont) 23:23, 24 August 2008 (UTC)

Well spotted ! This is indeed a typo. I propose the following correction: 'gravitational free-fall [between two bodies]is exponentially increasingly accelerated, BEING inversely proportional to the SQUARE of the distance between its gravitational centres.'

The physico-mathematical question raised of whether gravitational free-fall is exponentially increasingly accelerated, according to the inverse-square law of gravitational attraction, the rate of acceleration of free-fall increases with proximity rather than being constantly uniform as maintained by Galileo and the scholastic impetus dynamics he converted to at Padua and thereafter. And moreover nor does it increase uniformly or linearly, but rather exponentially to the power of 2 i.e. the exponent is 2. But why does this particular point of elementary maths/physics need a source ? Does anybody seriously challenge the fact that the rate of acceleration of gravitational free-fall increases exponentially on the inverse-square law analysis ?

The overall main issue here is that Galileo's law of gravitational attraction/free-fall which was the core law of his universal celestial mechanics presented in his Dialogo and Discorsi was grossly mistaken and rejected. On the basis of the inverse-square law of gravitational attraction, in Newton's mechanics distance-time laws for gravitational free-fall are given in the Principia's Proposition 32 of Book 1. Chandrasekhar offers a modern interpretation of them in Chapter 8 'The rectilinear ascent and descent of bodies' of his 1995 Newton's Principia for the Common Reader. Perhaps this latter critical point should be added to the article.

--Logicus (talk) 17:20, 4 September 2008 (UTC)

Logicus wrote

" ... the rate of acceleration of free-fall increases with proximity rather than being constantly uniform as maintained by Galileo and the scholastic impetus dynamics he converted to at Padua and thereafter. And moreover nor does it increase uniformly or linearly, but rather exponentially to the power of 2 i.e. the exponent is 2. But why does this particular point of elementary maths/physics need a source ? Does anybody seriously challenge the fact that the rate of acceleration of gravitational free-fall increases exponentially."

Yes, I do. Your terminology here is erroneous. To say that something is "exponentially increasing" means that, asymptotically at least, it is an increasing exponential function of some variable, r say—i.e. it has the functional form a^r for some constant a greater than 1. The mathematical function expressing the inverse-square law is not exponential. It is an instance of what are called "rational functions"—i.e. ratios of polynomials. More specifically, it is an inverse quadratic function. A correct statement would be that the gravitational acceleration of a body increases quadratically with the inverse of its distance from the centre of attraction, but I don't see what point is served by including that level of technical detail in the article.

The assertion that "Galileo's law of gravitational attraction/free-fall" was "the core law of his universal celestial mechanics presented in his Dialogo and Discorsi" or that he "claimed gravitational free-fall universally is uniformly accelerated as the fundamental law of motion of his cosmology and cosmogony", as the article currently does, does not tally with my understanding of Galileo's ideas. Those claims require citations to reliable sources.

—David Wilson (talk · cont) 14:47, 5 September 2008 (UTC)

Logicus to David Wilson: Thanks for the free but unsolicited A-level maths lecture ! But unfortunately it makes the literacy error of conflating the word 'exponentially' with the more specifically technical 'exponential function', meaning a function with a variable exponent of a constant. Rather the term 'exponentially' in the phrase 'exponentially increasingly' is used in the article in its general meaning of 'more and more rapidly increasing', as in the Popular Oxford Dictionary definition of 'exponential' as a mathematical term meaning 'of more and more rapid increase'. Thus 'exponentially increasing' means 'increasingly rapidly increasing', as opposed to 'uniformly rapidly increasing'. But if you know of a better no less succinct term to express this idea, please do suggest one for consideration. But as it is, the claim surely stands on standard English ?

But as for your claim that "A correct statement would be that the gravitational acceleration of a body increases quadratically with the inverse of its distance from the centre of attraction,..."

rather should it not say 'DECREASES quadratically with the inverse of the distance between the two centres of attraction' ? For as the distance increases, its inverse decreases and the rate of acceleration decreases with it. Maybe another typo (-: ?

At least one pedagogical purpose of explaining that the rate of acceleration of free-fall is not only increasing rather than constant as in scholastic and Galilean physics, but moreover is even exponentially increasing, is that this underlines just how grossly mistaken this scholastic law was, that is, gravitational acceleration is twofold removed from being a uniformly difform motion, being rather a difformly difform difform motion as it were. This helps correct the positivist hagiographical nonsense purveyed by some academic historians of science that Galileo was a good experimenter in mathematical physics. It also provides a corrective to the risibly mistaken deprecation of the Mertonian kinematicists by positivist academic historians of science for having failed to identify which form of motion was exemplified by gravitational free-fall in contrast with Galileo, who they imply identified the correct form. Rather the truth of the matter is that the Mertonians did not commit Galileo's blunder.

Re your claim that the article's current claims that "Galileo's law of gravitational attraction/free-fall" was "the core law of his universal celestial mechanics presented in his Dialogo and Discorsi" and that he "claimed gravitational free-fall universally is uniformly accelerated as the fundamental law of motion of his cosmology and cosmogony" do not tally with your understanding of Galileo's ideas, would you please be good enough to identify wherein exactly lies the conflict with your understanding, and thus exactly what point you think needs sourcing. For my part it is just evident from reading the Dialogo and Discorsi (in Drake's English translations). Do you claim his law of gravitational free-fall was not the fundamental law of motion of his cosmology and cosmogony, and if so, what law do you think was ?

--Logicus (talk) 14:40, 6 September 2008 (UTC)

Logicus wrote:

"Thanks for the free but unsolicited A-level maths lecture !"

You're welcome. Since you seemed to think it necessary to deliver one to me on "elementary math/physics", the least I could do was return the compliment.

Logicus: "But unfortunately it makes the literacy error of conflating the word 'exponentially' with the more specifically technical 'exponential function', ..."

Logicus is mistaken. I am perfectly well aware of the difference between the standard mathematical meaning of "exponential increase" and the informal, non-mathematical one, and I did not "conflate" them as he suggests. What I did do, apparently, is make an unwarranted assumption. Since I believe it is a Very Bad Idea to use the informal, non-mathematical meaning of "exponential increase" as a reference to the rate of increase of a quantity which has been expressed explicitly in terms of a mathematical formula^[1] (and especially so when one is attempting to instruct others on a "point of elementary math/physics"), it simply didn't occur to me that anyone would do such a thing. My mistake.

Logicus: "But if you know of a better no less succinct term to express this idea, please do suggest one for consideration. ...."

I don't believe any alternative is necessary or desirable. Readers with a sound mathematical education don't need to be told that an inverse square function is "increasingly increasing" as its argument decreases. One the other hand, I doubt if there's any succinct term that will convey that notion properly to anyone whose mathematics is weak.

Logicus: "But as it is, the claim surely stands on standard English ?"

Not in my opinion. But feel free to take it to an Rfc if you disagree. Otherwise, if you continue to dispute the point here I will take it to an Rfc.

Logicus: "... should it not say 'DECREASES quadratically with the inverse of the distance between the two centres of attraction' ? For as the distance increases, its inverse decreases and the rate of acceleration decreases with it. Maybe another typo (-: ?"

No. The statement is correct as given, and completely synonymous with your suggested alternative (which is therefore also correct). To see this, simply rephrase your second sentence as: "For as the distance decreases, its inverse increases and the rate of acceleration increases with it."

Logicus: "Do you claim his law of gravitational free-fall was not the fundamental law of motion of his cosmology and cosmogony, and if so, what law do you think was ?"

Why should I necessarily think that Galileo considered any principle or law to be the "fundamental law of motion of his cosmology and cosmogony"? I'm certainly not aware of one.

Logicus: "... would you please be good enough to identify wherein exactly lies the conflict with your understanding, and thus exactly what point you think needs sourcing."

I have already done so. They are the claims you have just quoted back to me.

Since my own POV is based on syntheses of primary and secondary sources it would be contrary to Wikipedia talk page guidelines for me to clutter up this page with arguments to justify it, and I do not intend to do so. It would also be contrary to Wikipedia's policy on no original research for me to attempt to have any part of that POV included in the article unless I could back it up with citations to reliable sources.

But you are also subject to the same guidelines and policies. It is not up to other editors to justify the exclusion of the claims from the article by producing evidence or arguments against them, it is up to you to justify their inclusion by providing citations to appropriate sources. In fact I would be delighted if you would do so, since I would then have learned something about which I was previously ignorant.

Logicus: "For my part it is just evident from reading the Dialogo and Discorsi (in Drake's English translations)."

In that case it should be easy for you to justify the claims by citing a quotation where Galileo specifically makes them in as many words—unless, of course, the claims rely on your own interpretation of those sources, in which case Wikipedia's policy on no original research requires citation to a reliable secondary source to justify the inclusion of your interpretation in the article.

1. In fact, on reflection, I would still be prepared to categorise such a use as erroneous.

—David Wilson (talk · cont) 12:49, 9 September 2008 (UTC)

Naming of Telescope

According to Dava Sobel's Galileo's Daughter chapter 4, "Greek mathematician Giovanni Demisiani, proposed the name 'telescope'...". This occurred April 14, 1611 at the banquet Cesi held for Galileo in Rome. As I am a new user that am not familiar with the protocol nor have the privileges, could someone please confirm and update the information? Thanks, Jeff eng (talk) 01:26, 7 September 2008 (UTC)

See http://homepages.tscnet.com/omard1/jportat3b.html —Preceding unsigned comment added by 86.160.202.155 (talk) 09:21, 8 September 2008 (UTC)

I have now updated the article as suggested by Jeff eng.

—David Wilson (talk · cont) 14:16, 12 September 2008 (UTC)

Practice/practise

In UK and Australian English the use of the spelling "practice" for the verb form of that word is considered incorrect. On the other hand, in the US, where "practice" appears to be the more common spelling, "practise" is nevertheless also considered acceptable (according to the on-line Merriam-Webster's dictionary, at least). I have therefore reverted the recent change of "practised" to "practiced" back to the form which is considered acceptable in a wider varietly of English dialects.
—David Wilson (talk · cont) 14:09, 11 September 2008 (UTC)

"(incorrectly)" under Physics Section

Why is there "(incorrectly)" in the first sentence of the fourth paragraph under the Physics Section ? —Preceding unsigned comment added by 193.188.46.254 (talk) 10:07, 12 September 2008 (UTC)

Because Galileo's scholastic law of free-fall was radically incorrect.It is not uniformly accelerated. --Logicus (talk) 16:27, 12 September 2008 (UTC)

Aristotle, Galileo and the Law of Inertia

Article claims:

"He also concluded that objects retain their velocity unless a force—often friction—acts upon them, refuting the generally accepted Aristotelian hypothesis that objects "naturally" slow down and stop unless a force acts upon them..."

But this ignores Aristotle had the law of inertia, as Dugas pointed out for instance:

Rene Dugas A History of Mechanics 1955/88 p22

"Aristotle believed in the impossibility of a vacuum (Physics, Book IV, Chapter 8) on the grounds that, in a vacuum, no natural motion, that is to say, no tendency towards a natural place, would be possible. Incidentally this idea led him to formulate a principle analogous to that of inertia, and to justify this in the same way as that used by the great physicists of the XVIIIth century.

'It is impossible to say why a body that has been set in motion in a vacuum should ever come to rest; why indeed it should come to rest at one place rather than another. As a consequence, it will either necessarily stay at rest or, if in motion, will move indefinitely unless some obstacle comes into collision with it.' "

--Logicus (talk) 18:26, 22 September 2008 (UTC)

Vandalism

More vandalism has appeared, now that the article is not protected. —Preceding unsigned comment added by 217.41.51.240 (talk) 14:06, 7 October 2008 (UTC) More vandalism is appearing, from a school in America. —Preceding unsigned comment added by 87.194.4.21 (talk) 08:25, 8 October 2008 (UTC) Also, the vandalism is coming from other parties. —Preceding unsigned comment added by 87.194.4.21 (talk) 08:31, 8 October 2008 (UTC) The article is now protected again. —Preceding unsigned comment added by 87.194.4.21 (talk) 08:35, 10 October 2008 (UTC)

Jovian moons no problem for geocentrism

In its 'Astronomy: Contributions' section the article currently claims

"A planet with smaller planets orbiting it was problematic for the orderly, comprehensive picture of the geocentric model of the universe, in which everything was supposed to circle around the Earth. As a consequence, many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing.[31]"

But the first sentence is nonsense because the rule that the Earth is the centre of all celestial circular motions in geocentric astronomy had been broken since antiquity with the introduction of epicyclical geocentric astronomy, in which planets circulate around epicycles not centred on the Earth but on the circumference of a deferent sphere/ring centred on the Earth, as in Ptolemy's tambourine-jingle epicyclical planetary model, for example. Indeed some rejected epicyclical astronomy precisely because it broke this Platonic rule of complete geo-concentricity of all celestial rotations.

I thus initially flag this sentence for a source to be provided in the form of an actual quotation to determine whether this is possibly another(?) boo-boo of Drake and Sharratt cited or else just another example of typical Wikipedia Original Research via misinterpretation in which the interpretation of sources by article statements are in fact not justified by the source cited, but rather an editor's personal misinterpretation of them. Anything other than direct quotation is of course a personal interpretation, and it is the logical disjunctions between sources and their interpretation that renders a lot of Wikipedia articles' content Original Research, however unintented. But in mitigation it should be noted that academic historians of science are especialy notorious for such unreliable malpractice in some critical philosophy of science circles.

The claim of the second sentence of the paragraph in question, that

"many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing.[31]"

may possibly be true. But it can surely hardly be for the reason stated. Or else those astronomers and philosophers in question must have been adherents of the pre-Ptolemaic non-epicyclical planetary model of Aristotle or others consisting of nothing but geo-concentric spheres/bands without any epicyclical rotations.

And the claim sometimes made that the discovery of the moons of Jupiter supported heliocentrism against geocentrism by showing not all heavenly motions were Earth centred is belied by the fact that it was also cited by such as Riccioli as strong evidential support for geo-heliocentric geocentrism, with several planets orbiting the sun which in turn orbits the Earth, just like the moons of Jupiter orbit it whilst Jupiter in turn orbits the Earth (or else orbits the sun, depending upon the geo-heliocentric model in question).

The moons of Jupiter provided no specific evidential support for heliocentrism. (If anything, they only provided support for epicyclical astronomy of any form, geocentric or heliocentric). But Galileo may have regarded or presented them as such by virtue of his notorious invalid exclusion of the third world system of geo-heliocentrism from consideration in his comparative evaluations of evidential support for competing world systems that invalidly only considered the pure heliocentric and pure geocentric models, such as in his evidentially disastrous heliocentric polemic, his 1632 "Dialogue concerning the Two Chief World Systems - Ptolemaic and Copernican", that most flagrantly completely ignored the Catholic Church's favoured geo-heliocentric model, the orthodox Tychonic model, in its very title, implying there were only two competing world systems. But most ironically it was Galileo's discovery of the gibbous and full phases of Venus that empirically justified the 17th century conversion from pure geocentrism to geo-heliocentrism.

In conclusion, I propose it should either be determined for what reason some astronomers, if any, disbelieved Galileo's discovery of Jupiter's moons, or else this whole paragraph should be deleted.

--Logicus (talk) 14:13, 12 October 2008 (UTC)

According to Wikipedia guidelines, citation for a source should normally be placed "[i]mmediately after the text that requires" it. Editors should therefore normally presume that a citation placed after a sentence at the end of a paragraph is not necessarily intended to provide support for any other claims made earlier in that same paragraph. Since I was the editor who added the following sentence,

"As a consequence, many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing."

and its supporting citation, I can in fact affirm categorically that the citation was not intended to provide any support for the claims made in the preceding sentence (which was not inserted by me), and I can see no reasonable grounds for presuming that it was. Nor was the linking phrase, "As a consequence ...", intended to endorse the specific claims made in that preceding sentence, or imply that any of the philosophers and astronomers who opposed the existence of Jupiter's moons had argued that all celestial motions must be centred on the earth.^[1] However, since the sentence is apparently susceptible to possible misinterpretation as it stands, I am happy to reword it to eliminate that possiblity.

Concerning the first sentence in the disputed paragraph, I do believe that its wording could be improved considerably. As it now stands, some uncharitable readers might presume that it was intended to make the absurd claim that the moons of Jupiter provided evidence against heliocentric geocentric theories in general. While I believe such presumption would be unwarranted, I also believe it could be made much less likely by rewording the sentence appropriately. As it happens, when I first read the sentence, I recognised it as an overly generalised version of several similar statements I was reasonably sure I had read in reliable sources. ^[2] I was therefore confident that only a fairly minor rewording of the sentence would be necessary to come up with a version that would be both properly supported by reliable sources and acceptable to its original author. At the time, I did not regard this as particularly pressing, so I was content to leave it until either I could find the time to do the necessary literature search or (preferably) until someone else took it on.

Now that someone has proposed deleting the sentence as unsupported, I decided to get off my backside and consult a few references. Within about 5 minutes of browsing amongst the books on my bookshelf I managed to find the following:

"This discovery [i.e. of Jupiter's moons] further undermined Aristotelianism, as it implied the existence of another centre of rotation."

on page 205 of C.M. Linton's From Eudoxus to Einstein, and then this on page 98, concerning Alpetragius's model:

"By this process, eccentric circles and epicycles were removed from the theory, both of these mechanisms violating the Aristotelian principle of a single centre of rotation—the centre of the Earth."

After a little further browsing through books from a local library, I found the following:

"Galileo's first telescopic observations helped to support the Copernican system, largely because the circulation of the four stars around Jupiter showed that heavenly bodies could revolve around centers other than the earth."^[3]

on page 157 of Stillman Drake's Galileo at Work.

So all the sentence really needed to turn it into a supportable claim was to replace the phrase "the orderly, comprehensive picture of the geocentric model of the universe" with "Aristotelian cosmology". I have now rewritten the entire paragraph so that it is well supported with citations to impeccable sources.

Logicus writes:

"The claim of the second sentence of the paragraph in question, that

"many astronomers and philosophers initially refused to believe that Galileo could have discovered such a thing.[31]"

may possibly be true."

and

"In conclusion, I propose it should either be determined for what reason some astronomers, if any, disbelieved Galileo's discovery of Jupiter's moons, or else this whole paragraph should be deleted."

Well, I have given the numbers of specific pages in the cited references (and I give some more below) where the support for this statement can be found, so any editors who doubt my veracity or competence can easily check up on them by consulting the indicated locations. Ditto for editors who want to find out more details. In my opinion, the article already contains enough detail on the objections raised against the moons of Jupiter, but if other editors believe more detail is needed they should certainly feel free to consult the references and add it themselves. What the article certainly does need are a few words on the objections raised against the roughness of the Moon's surface, which were at least as significant as those raised against Jupiter's moons, if not more so, but the article currently says nothing at all about them.

I would strenuously object to the removal of this paragraph. The fact that many objections were raised against the discoveries Galileo reported in Sidereus Nuncius, including many against Jupiter's moons and also against the roughness of the Moon's surface, is well-known and very well-documented, and the controversy was a significant occurrence in his life. In fact, it is almost impossible to find an even moderately comprehensive biography of him which does not mention it, and most I have read devote at least one or two whole pages to it. Here are a few more references I was able to find in about 15 minutes or so browsing through the bookshelves of a local university library: Galileo's Daughter by Dava Sobel (pp. 39,40), Galileo in Rome by William Shea and Mario Artigas (pp.42-43), Galileo: Courtier by Mario Biagoli (pp.133-139), Galileo—a Dramatised Life by Gerald Smith (p.110).

Footnotes

1.^ For all I know some of them may well have done so, and I should be not at all surprised if that was the case. However, I'm not aware of any claim by a reliable source that that specific argument was used to dispute the possibility of Jupiter's having moons.

2.^ But whose precise details I had by then forgotten.

3.^{^}I note here most emphatically that the same thing had not at all been demonstrated already by the Apollonian and Ptolemaic epicyclic theories. The epicycles in these theories were purely theoretical constructs which could be dismissed as mere mathematical fictions, and were in fact so dismissed by many philosophers and astronomers. Galileo's discovery of the moons of Jupiter was indeed, the first observational evidence to show unequivocally that the earth was not the sole centre of rotation for heavenly bodies.

—David Wilson (talk · cont) 14:18, 17 October 2008 (UTC)