Talk:Maxwell's thermodynamic surface

Further guidance

• Maxwell's thermodynamic surface

--Libb Thims (talk) 16:15, 25 July 2010 (UTC)

• Sadly, that doesn't constitute a reliable source. -- Radagast3 (talk) 08:06, 2 August 2010 (UTC)
  • You're missing the rather obvious. It cites 15 reliable sources. Uncle G (talk) 03:01, 3 August 2010 (UTC)
    • But most of those sources are about the thermodynamic concept; this article is about a specific object. Nor are they all reliable, in Wikipedia's sense. -- Radagast3 (talk) 09:14, 3 August 2010 (UTC)
      • You're now missing the fact that people have found several of those self-same sources, to cite here, the hard way. ☺ Note also, a second letter by Maxwell, to be found cited there. Uncle G (talk) 09:38, 3 August 2010 (UTC)
        • This article currently cites two letters. If you know of a third relevant letter, feel free to add a citation to the article. -- Radagast3 (talk) 10:17, 3 August 2010 (UTC)

Image?

The article is essentially useless without a picture of the model: either a photograph taken at Yale or Cambridge, and uploaded to commons, or a 3D-rendered reconstruction. I've added a sketch of the lines he drew on the surface, which is not quite so good as a picture of the model. I've also fixed some factual errors, and added references. -- Radagast3 (talk) 06:34, 31 July 2010 (UTC)

We do have a nice photograph now, thanks to Libb Thims, although I think some things, such as the date of the photograph, may require some clarification. -- Radagast3 (talk) 08:06, 2 August 2010 (UTC)

And we still need a photograph of one of the objects as they appear today, if anyone is visiting the places where they are on display... -- Radagast3 (talk) 23:48, 3 August 2010 (UTC)

This composite photo I made today is pretty good:

• Maxwell’s surface (adjacent photos) – 3D sketch shown adjacent to dark-scale photo. —Preceding unsigned comment added by Libb Thims (talk • contribs) 10:53, 4 August 2010 (UTC)

--Libb Thims (talk) 10:53, 4 August 2010 (UTC)

Very nice, but what are the licensing conditions on the photo? -- Radagast3 (talk) 11:11, 4 August 2010 (UTC)

Discussion moved from a user talk page

Now that this article has been de-stubbed, you might want to go back and fix some of the errors in EoHT, e.g. the fact that the surface is not of water, the sculpture was done in 1874, etc. -- Radagast3 (talk) 01:42, 4 August 2010 (UTC)

Thanks for the contributions and for digging around in the Maxwell’s letters. I changed the date to November 1874, based on the letter to Andrews. Being that enough sources state 1875, and that it is said that he worked on it over the “entire winter”, it may be that he finished it in early 1875, e.g. added on the isothermal, isobaric lines, etc.

As far as the surface not being water, as you are arguing (based on excerpts from Maxwell’s correspondence letters), this may require further investigation (a through reading of Gibbs and Maxwell’s various papers connected to this subject) to find the detailed definition of what Maxwell defined his sculpture as. Gibbs’ biographers Muriel Rukeyser (1942) calls it a “statue of water” and Lynde Wheeler calls it a “thermodynamic surface for water”. If anyone would know best, it would be Wheeler as he entered Yale in 1891 completing his BS in 1894 and PhD in 1902 both at the Yale Sheffield Scientific School (home to the statue), and remained at Yale as a professor of physics until 1926. Also, as the recent work of American engineer Ronald Kriz has shown, Maxwell’s sculpture is clearly constructed based on Gibbs figures 2 and 3; and figure 3, in particular, is discussed by Gibbs in the context of the freezing and boiling points of water. In any event, it seems to be the case that both Maxwell and Gibbs’ papers were discussing theoretical ‘heterogeneous substances’, on the logic that all physical bodies can be transformed into any one of the three states of existence, but that the water model worked best as a conceptual device.

Down the road, when I go back through Gibbs 1873 papers (and Maxwell’s 1975 book) in more detail, I might have a better answer. In any event, I wouldn’t jump to conclusions as to what the exactly the substance is. I would call it, in the mean time, a theoretical heterogeneous substance modeled on the properties of water. I amend the article a bit to reflect this. --Libb Thims (talk) 10:39, 4 August 2010 (UTC)

Maxwell's own words, as quoted in the footnote of the article, are unambiguous though: "a fictitious substance" (though noting several water-like properties). I suggest we use those words, given that this article is about Maxwell's work. The term "heterogeneous substance" is probably WP:SYNTH.

It may be that US writers based what they wrote on what Gibbs understood, rather than on what Maxwell said. And as far as dates go, Gibbs presumably received his plaster cast in 1875. Making the plaster casts probably took a while. And drawing lines "with the aid of the sun" would have required waiting for sunny days.

Regarding Kriz, I'm not sure exactly what he's demonstrated. In any case, his web pages are probably not a WP:RS.

What would be interesting, though, is to actually render an accurate 3D volume-energy-entropy plot for water, and to see how close or different it is from what Maxwell sculpted. -- Radagast3 (talk) 11:05, 4 August 2010 (UTC)

The word “heterogeneous”, in a Gibbs-Maxwell thermodynamic sense, refers to a substance existing in multiple phases, as used proximately in Gibbs 1876 opus On the Equilibrium of Heterogeneous Substances, the capstone to his two 1873 graphical papers. The term “theoretical substance” is more academic than is Maxwell’s loose-speak, possibly one-time usage, letter communication term “fictitious substance”. To corroborate, when he finally wrote up the 13-page section “Representation of the Properties of a Substance by Means of a Surface”, Theory of Heat (pgs. 195-208), in late 1875, he does not use the word “fictitious”. He does, to note, curious use the term “fictitious” in about three other places in the book, in reference to fictitious isothermal and fictitious isentropic lines in regards to absolute zero, which is a issue in itself. In any event, the term “fictitious body” (or substance) doesn’t make any sense, and will likely make even less sense to a new reader.

Regarding the idea: "render an accurate 3D volume-energy-entropy plot for water" to compare to Maxwell's sculpture, I'll keep my eye open. --Libb Thims (talk) 17:34, 4 August 2010 (UTC)

Regarding the terms "fictitious" vs "heterogeneous", the issue is what can be authoritatively sourced (see the all-important policy WP:OR), and the most authoritative source for what he did that winter seems to be his letters. His book On Heat provides a theoretical rather than an autobiographical discussion (I can't read your link, but my edition says "If we wish to trace out on a model of the surface a series of lines of equal pressure, we have only to place it in the sunshine..." without even mentioning that he actually did that). As you point out, he does use the term "fictitious" as a technical term in that book (one which, to my mind, is more precise than "theoretical" in this context -- "fictitious" suggests "not based on real-world data", while "theoretical" suggests "according to theory"). However, in my edition of On Heat, he doesn't seem to use the word "heterogeneous" anywhere (and if he did, I would certainly interpret a "heterogeneous substance" as one composed of different substances rather than in the sense you use, which makes sense only at phase transition points). -- Radagast3 (talk) 23:21, 4 August 2010 (UTC)

Please refrain from doing straight reverts of sourced sentences, as your last edit did by deleting this sentence "Gibbs’ biographers Muriel Rukeyser (1942) calls the plaster surface a “statue of water” and Lynde Wheeler (1951) calls it a “thermodynamic surface for water”." To clarify this "fictitious substance" discussion, I'll add in a header section devoted to this issue in the article. --10:58, 5 August 2010 (UTC) —Preceding unsigned comment added by Libb Thims (talk • contribs)

In this particular case, books which do not take Maxwell's letters into account (in particular books about Gibbs) are not reliable sources. -- Radagast3 (talk) 11:06, 5 August 2010 (UTC)

You're "what you consider to be a reliable source" motto is getting tiring. In any event, I've been doing some historical digging around and it turns out there is a bit if a mystery as to what exactly Gibbs received. See the section Model substance: fictitious, imaginary, or water? I typed up today. In conclusion of this fiasco (more time than I wanted to spend on this subject), I will add in Maxwell's first definition of what he considered his substance to be (July 8th, 1875 letter to Irish engineer James Thomson). --Libb Thims (talk) 18:56, 5 August 2010 (UTC)

I've reworded slightly to avoid duplication. I think "imaginary" and "fictitious" are synonyms here. The Thomson letter suggests that Thomson may also have made a model, although that isn't quite clear, and raises a question about what exactly is in the Cavendish. -- Radagast3 (talk) 22:37, 5 August 2010 (UTC)

The model Thomson made seems to be this one. -- Radagast3 (talk) 13:08, 6 August 2010 (UTC)

links

The weblinks in footnode 16 are both corrupted. Does anyone know new ones? -- Room 608 (talk) 15:16, 17 June 2014 (UTC)

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