Talk:Celestial spheres/Archive 2

Restoration of section on impetus dynamics of spheres in ‘Middle Ages’
Logicus proposes:I shall now restore the section on impetus dynamics previously deleted by user Deor without any good reason, but for which deletion Deor has provided no valid justification, but rather to the contrary a justification that entails it definitely must be included.(See above) Deor claimed "The article should deal with exactly what its title implies—the spheres, their natures, and their history in human thought — not the theories of impetus or inertia." But to explain again for Deor and the hard of understanding, the theory of impetus deals exactly with the natures of the spheres, namely whether they are animistic or mechanistic, driven by inner animate souls or by angels or by inanimate forces in their natures.

For a 'scholarly' precedent in the inclusion of discussion of the issue of impetus dynamical explanations of the motions of the celestial spheres in discussions of the medieval physics of the spheres, Deor may wish to consult that American author much favoured by McCluskey, Edward Grant, in his 1996 The Foundations of Modern Science in the Middle Ages. Discussion of Buridan’s impetus mechanics of the spheres is included in its section on the physics of the celestial region ‘The Celestial Region: The causes of celestial motion.’ on page 112.--Logicus (talk) 16:14, 27 June 2008 (UTC)

Logicus restores Deor deletion: Deor has unjustifiably deleted this restoration on the patently invalid ground it is unsourced, and with the bogus objection of no consensus on the Talk page. If such expressed consensus were required, there would be virtually no articles.--158.143.135.0 (talk) 18:02, 28 June 2008 (UTC)

Logicus's restoration is as follows:

Parisian impetus dynamics and the spheres

In the 14th century the logician and natural philosopher Jean Buridan, Rector of Paris University, subscribed to the Avicennan variant of Aristotelian impetus dynamics according to which impetus is conserved forever in the absence of any resistance to motion, rather than being evanescent and self-decaying as in the Hipparchan variant. In order to dispense with the need for positing continually moving intelligences or souls in the celestial spheres, which he pointed out are not posited by the Bible, Buridan applied the Avicennan self-conserving impetus theory to their endless rotation by extension of a terrestrial example of its application to rotary motion in the form of a rotating millwheel that continues rotating for a long time after the originally propelling hand is withdrawn, driven by the impetus impressed within it.[ref>See p112 of Edward Grant's 1996 The Foundations of Modern Science in the Middle Ages for his account of Buridan's application of impetus dynamics to celestial motion.[/ref>[ref>According to Buridan's theory impetus acts in the same direction or manner in which it was created, and thus a circularly or rotationally created impetus acts circularly thereafter. Earlier Franciscus de Marchia had given a partial impetus dynamics account of celestial motion in the form of the sphere’s angel continually impressing impetus in its sphere whereby it was moved directly by impetus and only indirectly by its moving angel.[ref>See p112 The Foundations of Modern Science in the Middle Ages Edward Grant 1996 This hybrid mechanico-animistic explanation was necessitated by the fact that de Marchia only subscribed to the Hipparchan-Philoponan impetus theory in which impetus is self-dissipating rather than self-conserving, and thus would not last forever but need constant renewal even in the absence of any resistance to motion.

Buridan wrote on the impetus of the celestial spheres as follows:


 * "God, when He created the world, moved each of the celestial orbs as He pleased, and in moving them he impressed in them impetuses which moved them without his having to move them any more...And those impetuses which he impressed in the celestial bodies were not decreased or corrupted afterwards, because there was no inclination of the celestial bodies for other movements. Nor was there resistance which would be corruptive or repressive of that impetus."[ref>Questions on the Eight Books of the Physics of Aristotle: Book VIII Question 12 English translation in Clagett's 1959 Science of Mechanics in the Middle Ages p536

However, having discounted the possibility of any resistance due to a contrary inclination to move in any opposite direction and due to any external resistance, Buridan obviously also discounted any inherent resistance to motion in the form of an inclination to rest within the spheres themselves, such as the inertia posited by Averroes and Aquinas. And in fact contrary to that inertial variant of Aristotelian dynamics, according to Buridan "prime matter does not resist motion". But this then raises the question within Aristotelian dynamics of why the motive force of impetus does not therefore move them with infinite speed. The impetus dynamics answer seemed to be that it was a secondary kind of motive force that produced uniform motion rather than infinite speed, just as it seemed Aristotle had supposed the planets' moving souls do, or rather than uniformly accelerated motion like the primary force of gravity did by producing increasing amounts of impetus. --158.143.135.0 (talk) 18:04, 28 June 2008 (UTC)


 * You've sourced the material in part, but the question of relevance to this article still remains, as does, more importantly, the fact that the speculative conclusions ("obviously discounted"; "the impetus dynamics answer seemed to be") drawn in the final paragraph violate WP:OR. I suggest that you read that policy—in particular, the section WP:SYN—before attempting to readd the material. Deor (talk) 10:56, 29 June 2008 (UTC)


 * Logicus improvement: Deor yet again fails to explain why material on the causes of motion of the celestial spheres is not of absolutely central relevance to an article on the spheres. His claims that the last paragraph of the above text violates Wiki OR rules are also mistaken. But this may be made clearer by the following proposed improved version of the last paragraph of the above text on impetus dynamics and the spheres:


 * 'However, having discounted the possibility of any resistance due to a contrary inclination to move in any opposite direction or due to any external resistance, in concluding their impetus was therefore not corrupted by any resistance Buridan also discounted any inherent resistance to motion in the form of an inclination to rest within the spheres themselves, such as the inertia posited by Averroes and Aquinas. For otherwise that resistance would destroy their impetus, as the anti-Duhemian historian of science Annaliese Maier maintained the Parisian impetus dynamicists were forced to conclude because of their belief in an inherent inclinatio ad quietem or inertia in all bodies. But in fact contrary to that inertial variant of Aristotelian dynamics, according to Buridan prime matter does not resist motion.[ref>See e.g. Moody's statement "What I have found in Buridan's writings...is the repeated assertion that "prime matter" does not resist motion..." in footnote 7 p32 of his essay Galileo and his precursors in Galileo Reappraised Golino (ed) University of California Press 1966 But this then raised the question within Aristotelian dynamics of why the motive force of impetus does not therefore move the spheres with infinite speed. One impetus dynamics answer seemed to be that it was a secondary kind of motive force that produced uniform motion rather than infinite speed,[ref>The distinction between primary motive forces and secondary motive forces such as impetus was expressed by Oresme, for example, in his De Caelo Bk2 Qu13, which said of impetus, "it is a certain quality of the second species...; it is generated by the motor by means of motion,.." [See p552 Clagett 1959]. And in 1494 Thomas Bricot of Paris also spoke of impetus as a second quality, and as an instrument which begins motion under the influence of a principal particular agent but which continues it alone. [See p639 Clagett 1959]. just as it seemed Aristotle had supposed the spheres' moving souls do, or rather than uniformly accelerated motion like the primary force of gravity did by producing constantly increasing amounts of impetus. However in his Treatise on the heavens and the world in which the heavens are moved by inanimate inherent mechanical forces, Buridan's pupil Oresme offered an alternative 'Thomist' response to this problem in that he did posit a resistance to motion inherent in the heavens (i.e. in the spheres), but which is only a resistance to acceleration beyond their natural speed, rather than to motion itself, and was thus a tendency to preserve their natural speed.[ref>"For the resistance that is in the heavens does not tend to some other motion or to rest, but only to not being moved any faster." Bk2 Ch 3 Treatise on the heavens and he world This analysis of the dynamics of the motions of the spheres seems to have been a first anticipation of Newton's conception of inertia as only resisting accelerated motion but not resisting uniform motion.'  —Preceding unsigned comment added by 80.6.94.131 (talk) 18:05, 2 July 2008 (UTC)


 * Police Constable Deor ? Logicus says No !


 * Imperious User Deor has elected to set himself up as Police Constable Wikipedian who polices Wikipedia and reports breaches of what he imagines to be its rules and breaches of its rules to its administrators. Here we present Deor's latest arrogant imperious mistaken comments posted to Logicus's User Talk page for everybody to read


 * "[edit] Celestial spheres redux
 * I'm going to revert your additions and deletions once again. Repeatedly adding material that is not relevant to the article's topic and, in essence, constitutes an original synthesis of material in primary sources is disruptive and impermissible in Wikipedia. Any further disruption at this article will be brought up at Wikipedia:Administrators' noticeboard/Incidents, as you have repeatedly attempted to insert your original research and personal interpretations of historical sources into multiple articles. This is an encyclopedia that relies on information gleaned from secondary sources, not a forum for posting what appears to individuals to be "logically" inferrable from the historical record. Deor (talk) 18:31, 3 July 2008 (UTC)


 * Retrieved from "http://en.wikipedia.org/wiki/User_talk:Logicus" "


 * But on the cardinal issue here of relevance, it should be self-evident to one and all that any material on the causes of the motions of the celestial spheres, such as the theories of Buridan, is of absolutely central relevance to any article on the celestial spheres and their motions. And yet Wiki User Deor repeatedly seeks to deny this, and under repeated challenge to provide any rational justification for this unjustifiable POV, repeatedly fails to do so. Why is this ? Should User Deor be banned from meddling with Wikpeida articles because of his anti-educational tendency. [Watch this space !]  Logicus


 * The Restoration: Logicus has courteously given Deor over three weeks to substantiate his unsubstantiated allegations that (i) the medieval impetus dynamics of the celestial spheres is not relevant to this article and (ii) Logicus's account of it constitutes Wiki Original Research. But he has done neither, in spite of Logicus having posted the text of his account on User talk:Deor with the following invitation:


 * "Logicus now invites Deor to either demonstrate his claim that the following text is 'in essence an original synthesis of material in primary sources' within 48 hours, or else desist from any further unagreed deletions of Logicus's contributions to the article on this topic."


 * Thus Logicus has added the text to the article, and trusts Deor will desist from any further deletion of it.
 * --Logicus (talk) 15:33, 30 July 2008 (UTC)

Logicus restores pre 4 May paragraph 2
I have restored the pre 4 May paragraph 2 because subsequent edits have introduced error and confusion. See my critical comments on the subsequent version in square brackets as follows:

"The spheres were said to surround the earth [No, not the heliocentric spheres of Copernicus --Logicus (talk) 19:22, 10 July 2009 (UTC)], which was understood to be spherical, stationary, and at the center of the universe.[Not the heliocentric spheres--Logicus (talk) 19:22, 10 July 2009 (UTC)] The spheres were typically in this order up from the earth: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and fixed stars. Medieval Christians identified the sphere of stars with the Biblical firmament and sometimes posited an invisible layer of water above the firmament, to accord with Genesis. A tenth sphere [But there were dozens of spheres, not merely ten. --Logicus (talk) 19:22, 10 July 2009 (UTC)], inhabited by angels, appeared in some accounts. The order of the lower planets was not universally agreed. Because Venus and Mercury orbit closer to the sun than earth, their positions in the sky are always near the sun.[This is an unintelligible explanation of their bounded elongation--Logicus (talk) 19:22, 10 July 2009 (UTC)] The celestial sphere model doesn't explain this phenomenon [Wrong, it did explain their bounded elongation--Logicus (talk) 19:22, 10 July 2009 (UTC)], and scholars disagreed on the positions of Mercury and Venus. Plato and his followers ordered them Moon, Sun, Mercury, Venus, and then followed the standard model for the upper spheres. Ptolemy placed both of them beneath the Sun and with Venus beneath Mercury, but noted others placed them both above the Sun, and some even on either side of the Sun, as Alpetragius came to do. "

Proposed change from Celestial spheres to Celestial orbs
I've been looking at the literature on this topic lately, and I've found that there appears to be a tendency, especially among historians of science, to treat this topic under the title of Celestial orbs rather than Celestial spheres. It might be worthwhile to change the title of this article; this change would also have the advantage of avoiding confusion with the modern concept of the Celestial sphere.

Before undertaking such a change (which should involve careful editing to achieve consistent terminology within the article as well), I'd like to here comments on this idea. --SteveMcCluskey (talk) 20:33, 7 September 2009 (UTC)


 * This seems to me an unecessary upheaval. Why not just put in a redirect for 'celestial orbs' to 'celestial spheres'? I suspect the somewhat arch terminology of historians of science would not be that of Joanna Public (-: --Logicus (talk) 18:11, 8 September 2009 (UTC)

Restoring introductory text on order of spheres.
The replacement text introduced by McCluskey on 7/09/09is both wrong about the number of spheres and thus about their order, and also loses important informational detail in the original. And the sentence about medieval Christian spherist cosmology is a detail that really belongs to the section on the middle ages.

So I propose to restore an improved version of the original text, but incorporating the Eastwood reference supplied by McCluskey. I move the medieval Christian sentence to the medieval section.

For reference McCluskey's text was as follows:

"In geocentric models the spheres were said to surround the earth, which was understood to be spherical, stationary, and at the center of the universe.[2] The spheres were typically in this order up from the earth: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn, and fixed stars. Medieval Christians identified the sphere of stars with the Biblical firmament and sometimes posited an invisible layer of water above the firmament, to accord with Genesis.[2] A tenth sphere, inhabited by angels, appeared in some accounts.[2] The order of the lower planets was not universally agreed; Plato and his followers ordered them Moon, Sun, Mercury, Venus, and then followed the standard model for the upper spheres.[3]"

--Logicus (talk) 18:08, 9 September 2009 (UTC)

Physical spheres, not geometrical astronomy
The section on the Renaissance begins with a discussion of the Copernicus's understanding of the physical spheres and ends with their abandonment by Kepler, but the bulk of the section is concerned principally with the positional and geometrical astronomy of the planets. Indicative of this approach are two figures displaying the geoheliocentric models of Paul Wittich and Ursus, neither of which discuss three dimensional, physical planetary spheres. This material might fit better in the article on the Copernican revolution. --SteveMcCluskey (talk) 19:43, 7 October 2009 (UTC)

Newton & Lunar Orb
When Newton used the mathematical procedure described in the article to compute the force of the Moon from the center, he was not basing them on the Lunar orb. He imagined that a square circumscribes the circular path of the Moon, and on that basis computed the central force. (Westfall, Never at Rest, pp. 148-50) --SteveMcCluskey (talk) 20:08, 7 October 2009 (UTC)
 * The Galileo discussion is also dubious. Galileo wrote as early as 1615 to Monsignor Dini:
 * However, this is not to take away motions made by the stars in circles eccentric to earth or in epicycles, which are the genuine and simple assumptions of Ptolemy and the other great astronomers; it is rather to repudiate the solid, material, and distinct orbs, introduced by the builders of models to facilitate understanding by beginniers and computation by calculators; this is the only fictitious and unreal part, as God does not lack the means to make the stars move in the immense celestial space, within well-defined and definite paths, but without having them chained and forced. (Finocchiaro, The Galileo Affair, pp. 61-2)
 * Since Galileo speaks of epicycles, it is clear that he is using "stars" in the general sense, which includes planets. --SteveMcCluskey (talk) 20:24, 7 October 2009 (UTC)