Talk:Laws of thermodynamics

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[edit] Are the 'laws' of thermodynamics a subset of the principles of energetics?

I made the assertion that the 'laws' of thermodynamics can be considered a subset of the principles of energetics. Karol edited this on the account that most people do not see this to be the case.

1. Do most people believe that the 'laws' of thermodynamics are not subset of the principles of energetics? 2. Does it matter how many people believe in something for it to be true or useful? 3. What is a 'law' or 'principle'? 4. Is the fourth principle which is based on electronics, a fourth law of thermodynamics?

In the text it says. They are often associated with concepts far beyond what is directly stated in the wording. I think that this might be a good point to provide an example so I have added the following, For example, some scientists believe they can be considered a subset of the Principles of energetics, however currently this is not a widely held opinion. I hope that this is approprite. Sholto Maud 21:38, 29 November 2005 (UTC)

I think extensions and less widely held opinions may need a separate section, but if its not a widely held opinion, I don't think we should put it in the introduction. I moved it to a separate section, along with Heat death. PAR 03:09, 30 November 2005 (UTC)
Nice one PAR :). I'd still like it confirmed whether the Fourth principle is included in the "laws" of thermodynamics Sholto Maud 03:20, 30 November 2005 (UTC)
I dont know about that - but I do know that the Onsager reciprocal relations are sometimes called the fourth law of thermodynamics. I'm not to familiar with them, though. PAR 04:12, 30 November 2005 (UTC)

Sholto, I'm sorry for my rapid edit, I meant to comment on it. I don't have the time right now, but I'll get back to it soon. Karol 08:41, 30 November 2005 (UTC)

One of the most crippling aspects of the laws of science, is how researchers and theorists take them for granted as inviolable prescriptions of how nature must work. It is important to remember that they are merely descriptions of how nature universally and invariably appears to work, and may be disproved if new facts or evidence arise to contradict them. Many speculative theories in other Wikipedia articles link to this article with the suggestion that the theory is impossible because it would violate one of these laws, when in fact the theory may be an exception to these laws. —Preceding unsigned comment added by Gcsnelgar (talk • contribs) 05:37, 29 December 2007 (UTC)

[edit] Some background, history?

Since now there is a separate article about these laws, it would be nice to put in some background info, a little bit of history, maybe some anegdote? Karol 20:50, 28 October 2005 (UTC)

I noticed the history section makes unclear commentary about the transition from using the term principle to using the term law to name the laws of thermodynamics. This isn't really a strong or relible point to make. It's nomenclature only. It doesn't mean much beyond that.--68.122.193.47 (talk) 03:19, 24 December 2007 (UTC)

[edit] Maxwell's demon

Maxwell's demon might exist, but it must use energy to detect the particles it is selecting, and the resultant increase in entropy offsets the amount lost by the actions of the demon. PAR 03:18, 14 November 2005 (UTC)

[edit] Combined law of thermodynamics

We don't have an article on the combined law of thermodynamics. Should it go here? -- Kjkolb 12:45, 1 December 2005 (UTC)

This is presently part of the Thermodynamic potentials article under "fundamental equations", but yes, it is in a way the most fundamental of the fundamental equations and should be mentioned here. PAR 04:02, 2 December 2005 (UTC)
Added to page per request (I've seen this version used as well).--Sadi Carnot 02:21, 5 April 2006 (UTC)

[edit] Other Laws

In my General Chem Lecture the other day, the professor mentioned a -1st law which defines the number of variables needed to completely define the state of a system given the number of components in the system. Is there a reason why that is not included here? Gershwinrb 08:48, 13 January 2006 (UTC)

What you speak of is not the 1st Law, but rather the state postulate developed by Willard Gibbs, i.e. the number of properties required to fix the state of a system is given by the state postulate, which dictates that the state of a simple compressible system is completely specified by two independent, intensive properties. See: thermodynamic state.--Sadi Carnot 00:33, 5 April 2006 (UTC)

[edit] Energy...work law of t/ds

What ever happened to "energy can be created nor destroyed, only converted to a different form, or used to do work", and I know this isn't possibly a valid source but my chemistry teacher (yes I am fully aware it is physics but they cross over a lot in the AS Mod: CHM2) states this as the first law, and he's an Oxford graduate, discuss if you don't mind. Have you missed it, or put it in overcomplicated terminology so that Ive missed it.

[edit] Infinity

I'm a high school student. The way I understood the article it said that everything is going to end eventually simply because it began. Am I right or wrong. Please correct me. But if I am right doesn't that imply that is something doesn't stop never began and therefore goes on into infinity?ch 17:25, 24 March 2006 (UTC)

Close; but, essentially, from what we currently know of the universe, there are 12 fundamental particles and 4 fundamental forces, and this collection of particles interact via exchanges such that localized associations of these particles will tend to evolve onto equilibrium configurations or "attractors" for set durations of time, which we can loosely ascribe to as being the twice the half-life of the configuration; the 4 Laws of thermodynamics simply set limits to the types of interactions possible.
Once an observable interaction begins it will spontaneously continue to react, interact, or evolve towards a more stable energy configuration and through this process some energy will be lost to dissipation (2nd Law). Next, the energy-mass content of the initial "state" of each interaction process must be equal to that of the "final" state (1st Law). Each such observable system can be assigned an arbitrary temperature, i.e. the ability of the system to give up energy; if two adjoined systems have the same temperature they are said to be in thermal equilibrium (0th Law). To "force" any such system to 0 degrees Kelvin would require an infinite amount of energy; hence, absolute zero is unattainable (3rd Law). Regarding whether or not these interactive processes will continue on into infinity, that question currently remains open. This is what the article should essentially say.--Sadi Carnot 00:59, 5 April 2006 (UTC)

[edit] "Chaos"

The term "chaos" is used in the following sentences: "the Second Law states that energy systems have a tendency to increase their entropy (chaos) rather than decrease it" and "if one imagines atoms flying around in a box, hitting each other randomly, all the time, one can imagine a lot of chaos. Then, imagine what would happen if the temperature begins to decrease. The atoms slow down, hit each other less frequently, begin to settle as gravity has more effect on them; the chaos decreases" in the second and third law sections, respectively.

Does anyone else agree that using the term "chaos" to describe entropy is a misleading, if not outright incorrect, description of entropy? For one thing, "chaos", in this context, isn't really given a firm definition, and I assume we're left to picture a box full of gas particles flying about at high speeds and in random directions and colliding with each other all the time, or some such scenario. This picture, though it might describe what's going on in the box, doesn't seem to me to provide an accurate conceptual picture of what entropy is.

I would suggest that the meaning to be conveyed by using the word "chaos" is presented more clearly, and that the word "chaos" be removed completely, so that people do not make erroneous connections between entropy and what they think chaos means (or even Chaos Theory, I suppose).

-Unregistered User, 07/31/06

This seems like a reasonable idea (although many do argue that entropy is a measure of chaos); I'll make the change to "transformation content"; see: Mechanical Theory of Heat – by Rudolf Clausius [1850-1865]; Thanks:--Sadi Carnot 02:57, 1 August 2006 (UTC)

The 19th century notion of describing entropy as "chaos 'or "randomness" is silly and circular. The statement above about a system with "increasing chaos" attempts to quantify a chaos, which is quite ill-defined in a quantitative sense. No ! Please read a book on modeern statistical physics. Entropy is directly proportional to the logarithm of the number of available states in a system; that is a quantitative and theoretically measurable definition. See Kittel, "Solid State Physics", J.Wiley circa 1970 for a good development.

And at any rate, if you're going to use that probably inaccurate qualitative explanation, you should say "disorder" rather than "chaos," as chaos has a very specific mathematical meaning nowadays which is far removed from what would it mean in this context.--129.2.109.84 17:43, 27 August 2007 (UTC)

[edit] "Biology"

I've changed

The majority of these tentative fourth law statements are attempts to reconcile the thermodynamics with evolution, predominantly.

to

The majority of these tentative fourth law statements are attempts to apply thermodynamics to biological evolution.

since the former seemed to suggest a contradiction between thermodynamics and the theory of evolution (as well as some observed phenomena). Even if that were the case, however, adding an additional law cannot possible rectify a contradiction. From the material I have read (albeit, on Wikipedia) it seems that the latter statement more correctly summarizes the state of theory.

[edit] "Question"

RE: The first law of thermodynamics, that energy can niether be created or destroyed, if this were true how did energy come into being in the first place for if it cannot be created then how is it that it even exists? At some point didn't have to be created to exsist today? Makes you think doesn't it! Paul-11/28/06

[edit] Recent vandalism

On November 9, 2006 user 59.95.110.209 removed six main sections of this article in their entirety and completely blanked two related articles. Administrators: please revert to October 31, 2006 version by 68.186.185.49. --Neptunius 07:50, 4 December 2006 (UTC)

Edit from: 18:14, 11 November 2007 JzG (Talk | contribs) (14,319 bytes) (rm. blacklisted link) makes no sense; vandalised? —Preceding unsigned comment added by Snakeater (talk • contribs)

[edit] Third Law

I have included a very brief but correct statement of the core of the third law. The previous statement was very fuzzy, and included surprisingly irrelevant concepts that are much more complicated than the simple ingredients of the third law. I would welcome further editing to improve the appearance and expand upon the discussion and the historical references. For the mean time, however, it seemed important to have something correct and to the point. --Mbweissman 14:50, 23 December 2006 (CST)

Any idea what the statement at the end of this section means? "This law is in fact proven false by all evolutionists and creationists." Should we remove this or does it have some significance? --Acjohns 03:53, 15 April 2007 (UTC)

[edit] Second Law

I've heard from many sources that the law of conservation of matter and energy is only broken in the conversion of matter into energy as opposed to merely the release of energy. I am speaking of course of nuclear reactions. If we have consensus I'll edit the article. —The preceding unsigned comment was added by 63.229.221.138 (talk) 01:25, 4 January 2007 (UTC).

Could you please edit the double-quoted definition too. The double negative and unecessary reference to "cycles" makes the wording confusing and almost useless. This isn't the 19th century and we don't need the stilted language constructs.

[edit] Equations

Hey, the equations in Overview do not explain what each variable is, and they're definitely not self-explanatory to an outsider to physics. Would someone care to note which variable is which? Thanks. -Matt 15:37, 4 March 2007 (UTC)

[edit] what about in nuclear processes?

first law says that "In any process, the total energy of the universe remains constant."

what about in nuclear reactions where energy is actually created via conversion from matter? btw, is there proof of this occuring?

In fact all conversions of energy to/from some potential energy (such as nuclear potential energy) alter the mass of the particles... so two hydrogen atoms weigh more than one hydrogen molecule, because some energy was released in the reaction. This is discussed briefly in mass-energy equivalence Acjohns 03:46, 15 April 2007 (UTC)

[edit] Clausius Inequality - Typo?

I am afraid, there may be a mistake in the Clausius inequality formula on this page (in Overview / Second law of thermodynamics and also the page Second law of thermodynamics), as the integral must be less or equal to zero (not the other way as on the page): \oint{\frac{dQ}{T}} \le 0

I'd rather stick to the differential form dS \ge \frac{dQ}{T}

Let's run a cyclic process now and integrate \oint dS \ge \oint \frac{dQ}{T}

We get 0 \ge \oint \frac{dQ}{T}, which I stated above. (Zero on the left-hand-side is just as entropy is a state function)

You can see this result also on page Clausius theorem. Crocusino 17:43, 12 May 2007 (UTC)

There's no typo, that page has the math all backwards. I put a clean-up tag there. --Sadi Carnot 15:37, 30 September 2007 (UTC)

[edit] Creationist PoV pushing

User 80.195.246.104 keeps adding false statements claiming that the laws of thermodynamics contradict the Big Bang and Evolution. These are recognisable as common creationist arguments, and whilst I know I'm supposed to assume good faith it's hard to do so when such comments are stealthily added with the edit summary claiming that it's merely "(Small additions, corrections, hyperlink-insertions etc)". In keeping with wikipedia policy the bold claims this user keeps inserting require reputable scientific sources before they can be allowed to stay. Ifitmovesnukeit 23:24, 24 June 2007 (UTC)

I revered back some, and cleaned. It should be good now. --Sadi Carnot 15:26, 30 September 2007 (UTC)

[edit] The whole article is a mess

For a subject of such fundamental importance as thermodynamics this page is a complete mess. The "overview" is useless, the essential physical content of the theory being obfuscated by undefined symbols. The claim that the second law is not a law but a theorem is interesting, if true, but certainly shouldn't be made without citing the article where this is proven. —Preceding unsigned comment added by 65.19.15.68 (talk) 04:10, 7 April 2008 (UTC)


[edit] Five laws?

Moved from History section: "Presently, there are a total of five laws."
Seems to be contradicted by the rest of the article and doesn't have a cite. -- 201.37.229.117 (talk) 20:50, 5 May 2008 (UTC)