Talk:Heat/Archive 12

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Archive 10

It is energy that moves with temperature difference,

It is energy that moves with temperature difference, 'heat' is not a Conserved quantity.--Damorbel (talk) 14:16, 23 November 2012 (UTC)

Indeed, heat is not a conserved quantity. That's true by definition - heat exists only during transient processes, so it obviously cannot be conserved. Your point? Waleswatcher (talk) 14:25, 23 November 2012 (UTC)

"heat exists only during transient processes" What is it that 'flows' then, in "Heat flow from high to low temperature"? (Heat article, 1^st line, 2^nd para? --Damorbel (talk) 16:16, 23 November 2012 (UTC)

Energy. How many times have you asked that same question? And why is the answer so hard for you to grasp? Yes, the semantics are a little confusing, because heat is used differently in common parlance than in physics. And yes, "heat flow" and "heat transfer" are a bit redundant, since "heat" already implies a flow. But after months and months of being told the same thing, I would have thought you'd understand it by now. Waleswatcher (talk) 20:48, 23 November 2012 (UTC)

Waleswatcher:Your [my] point? You say "heat exists only during transient processes" and the article says "Heat flow from high to low temperature occurs spontaneously"

Now my point is that it is energy that goes from a high temperature to a low - as in a "heat" engine and it is energy that comes out - in the form of work along the crank shaft. The energy going in equals the energy coming out - conservation of energy OK?

So my question is, in your (heat ) book, what is this transient heat that flows from hot to cold? Does it only exist when going in? In that case, what do you call the energy that comes out along the crank shaft, and what do you call the energy that comes out with the cooling water? --Damorbel (talk) 21:04, 23 November 2012 (UTC)

Now my point is that it is energy that goes from a high temperature to a low...and it is energy that comes out - in the form of work along the crank shaft. And it is money that goes into your bank account, and money that comes out. But we still have terms for "salary" and "bill payment". As I said, I haven't a clue why you find this so hard to understand, so I'm afraid I give up trying to explain it to you. Waleswatcher (talk) 21:18, 23 November 2012 (UTC)

"And it is money....." and "....I give up trying to explain..." I responded to this here: http://en.wikipedia.org/w/index.php?title=User_talk:Waleswatcher&oldid=524554339#Your_talk_page but it has since been removed. --Damorbel (talk) 07:48, 24 November 2012 (UTC)

Heat Transfer

One of the main problems with this discussion, that seems to be going in circles, is that we are mixing two different things. One is "heat", a concept in "thermodynamics" and another is the dynamics of "heat transfer". This is similar to confussing "work" as a concept of thermdynamics with dynamics (mechanics). When one annalyses a thermodynamic "system", it's changes between _equilibrium_ states and the ammount of heat and work that might exist through different paths one does not delve in, either, a mechanistic annalysis of how work is perfomed, nor of how heat is transfered nor of the internal dynamics of the system.

Of course statistical mechanics does a lot into explaining phenomena that mechanistically explain some concepts as temperature, entropy, internal energy.

Of course mechanics explains how forces do work.

Of course heat transfer explains how heat is transfered from one place to another.

But these are not _required_ from a classical thermodynamics stand point: wether heat is transfered via conduction, convection or radiation is not that relevant, in the thermodynamic annalysis of the system.

If one, i.e., defines the system as a volume of control, all energy that crosses the borders of the volume of control _is_ heat: whether it includes mass transfer of not. That means that an influx of mass _implies_ an influx of energy: it implies "heat".

If one does a balance of mass all the mass that enters the system minus all the mass that exits the system is accumulated in the system (in the volume of control).

If one does a balance of energy one has that all the energy that enters the system minus all the energy that exits the system is accumulated in the system. (in the volume of control).

Energy accumulation would be the enthalpy of incomming mass flux, minus the enthalpy of the exiting mass flux, plus the work done on the system, plus the heat absorbed by the system minus the heat released by the system. In this case it is clear that these last two "heaat" quantities imply _conduction_ and _radiation_, since _convective_ components are already considered with the enthalpy of the mass flux.

Regarding entropy: the entropy accumulation within the system is the ammount of entropy carried by the flux of mass, pluss the entropy that is transfered between the sorroundings and the system generated by heat transfer, plus the entropy production within the system.

If a system is closed this is simplified.

Darmobel is finding it difficulty to understand the basic concepts of thermodynamics. Energy is exchanged between a system and it's sorroundigs through two different path dependent functions: heat and work. When heat is exchanged or work is performed it is _energy_ that is being transfer from one system to another. The work done by a force through a distance _is_energy_, the heat transfered from a body to another body _is_energy_. Energy conservation implies that, when two systems exchange energy through work or heat, energy is conserved. _But_ the ammount of energy that is actually avaiable to do work _diminishes_ with each process: in every process there is an ammount of energy that is realeased without performing work. Free energy is actually the energy avaiable for _doing_ work (either A=U-TS or G=H-TS). In a more general case where concentration of materials are studied and required (i.e. difussion) the uidNi must be taken into account (ui being the chemical potential of component i and dNi it's number of molecules or mols).

At constant temperature and pressure dGtp=SUM(uiDNi).

Advection misdirection

I also responded to SBHarris:

Actually when there is passive difussion there is an increase in entropy, see: http://www.rsc.org/learn-chemistry/content/filerepository/CMP/00/001/061/Why%20passive%20transport%20happens%20entropy.pdf?v=1352425760476 For a TS diagram of a heat pump figure 2 in http://en.wikipedia.org/wiki/Heat_pump_and_refrigeration_cycle is quite a good example. For a TS diagram of Carnot cycle see:http://en.wikipedia.org/wiki/Carnot_cycle Figure 2. Specially http://en.wikipedia.org/wiki/File:Carnot_Cycle2.png is of interest. The Carnot cycle is _the_most_eficient_ thermodynamic process between to different temperatures, where work is done isentropically and heat is released isothermally. Actually the example of you moving a cylinder of has is flawed: it is _quite_ inefficient ;-) and it is not reversible (you need to expend a lot of work in doing so: it is not reversible, it does not happen spontaneously). Advection and convection are not reversible, quite the contrary: they tend to be quite irreversible process: when a mass of fluid is heated up by a hot surface it rises. But it will not lower itself heating the surface back without external work. I forced convection one is _introducing_ an external force into the system in order to perform work in order to do process that _are_ irreversible. A reversible process is that which occurs spontaneously.

You have taken much trouble to explain things here that I already understand. But let me return the favor by correcting your misconception about advection. You CAN do work advecting a hot object, but you need not, in theory. When I toss a hot thermos of coffee from one side of the ISS space station to the other side, Newton's first law is a big help. The only work is adding a wee bit of kinetic energy to the thermos, and it's entirely reversible (as can be seen if it hits something elastic and comes right back, at the same speed). Ideally, advection itself takes vanishingly small energy, and what it does take is reversible and does not of course increase entropy. Hence, advection is not heat transfer, but only energy transfer. Advection can transfer HUGE amounts of energy without ever transferring heat. S B H arris 22:19, 25 November 2012 (UTC)

But I was not logged in: sorry!

The main thing there being that in a thermodynamic cycle Carnot's cycle is the optimum cycle between 2 temperatures. At:

http://en.wikipedia.org/wiki/Carnot_cycle

One can check a TS and VP diagram for Carnot's cycle and see the ammount of heat exchanged at both isothermic ends and the ammount of work actually done.

Sorry that I have not had the time to summarize my contributions here but I should be working!

Wow: I am really amazed at how much of my physics, physical chemsitry, thermodynamics, transport phenomena and heat and mass transfer classes I do remember with a litte of work... I haven't really thought about these subjects in about 15 years!!!

--Crio de la Paz (talk) 21:34, 23 November 2012 (UTC)

Crio de la paz, please excuse me for reducing the space between your thoughts, it makes them a lot easier to follow.

What you write suggests you are not following the discussion very well.

There are two arguments here, one maintains that heat is some mysterious substance that appears when temperature differences exist.

The other is that heat is the vibrational/kinetic energy of particles due to their temperature when above zero K.

There that should help a little! --Damorbel (talk) 21:52, 23 November 2012 (UTC)

As for your just above response to SBHarris. I hope I did the right thing. I didn't know if it was written by you or by someone else. In any case, I think I moved it to its natural home, to here? I hope so.Chjoaygame (talk) 22:02, 23 November 2012 (UTC)

In physics, the difference between modes of internal energy transfer doesn't matter too much for some parts of classical thermodynamics, that is to say, for some parts of equilibrium thermodynamics. But for non-equilibrium thermodynamics, the distinction between conduction, radiation, and convection does matter.Chjoaygame (talk) 22:14, 23 November 2012 (UTC)

The difference between transfers of internal energy as heat and work is not uniquely defined for open systems; so it is an arbitrary wording to say that the transfer with matter is heat; more systematic just to say that it is transfer of internal energy; some writers invent their own arbitrary distinctions and say they are specifically talking about "heat".Chjoaygame (talk) 22:14, 23 November 2012 (UTC)

No, Darmobel, you are not quite understanding the basic aspects of thermodynamics: I told you the same thing that is in any thermodynamics book but you do not seem to grasp it. ΔU(T)=Q+W. What you are dubbing "heat" is "internal energy", not "heat". For any process in the universe where there is a change in energy in a system, the same ammount of energy is transfered to the sourroundings of the system by _two_mechanisms_: "heat" and "work". Total energy is _always_ conserved for an isolated system. If you divide an isolated system (i.e. "the universe") in two systems, the system you are annalyzing, and the "sorroundings" the ammount of change in the energy of the system is equal but of opposing sign the ammount of chage of the energy of the sorroundings. In _any_ physical process there is an exchange of heat, and in some work is done either on the system or by the system. The total ammount of change of energy in the universe must always be zero. But part of that energy is not avaiable to do work. The ammount of entropy by the temperature (TdS) gives the minimal ammount of energy "dispersed" as heat when transforming energy. "Heat" in physics is the ammount of energy transfered that did not do "work" in a given process. Darmobel: you are confusing the concepts of classical thermodynamics of "heat" and "thermal energy" or "internal "energy" or "enthalpy" depending on the situation.

Of course that when "heat" is transfered from the system onto the sorroundings there is always a "mechanism", either conduction (which in statistical mechanics would be mostly energy of the particles that compose the system), or radiation (where electomagnetic waves/photons are exchanged until temperature is equilibrated) or, depending of your stand point even by convection (the concerted movement of a mass or a group of particles if you will within a fluid) or, maybe, gravitational waves (see http://www.omirp.it/www/Gravity+Gravitational_Waves/GW+Matter/GW_and_Matter.pdf). When work is transfered there is also a mechanism (a force that moves a body in a field or that changes it's inertial propierties. The field could be electrical, magnetic or modeled as an electromagnetic phenomena in relativity, could be gravitational or related to the weak or strong nuclear force. The inertial propierties might be equivalent or not to gravitational phenomena...). But in order to do thermodynamical analyisis one does not _need_ to delve into the intrincancies of the mechanics of such matters. Of course that when work is done and whe heat is transfered it is _energy_ that is being exchanged, not "a mysterious substance that appears when there is a temperature difference": but energy can be transfered in _two_forms_ (heat or work) from a system to it's sorroundings. Even more, for every physical process there is a minimal ammount of heat "realeased" that will not be avaiable to do work, save in ideal, reversible processess (TdS=Qrev) for the system and (TdS=Qrev) for the sorroundings, so the entropy of the "universe" (isolated system) remains the same on these procecess, but if you want to do work through a reversible process dE=W+Qrev => dE=W+TdS. That means that the energy avaiable to do work would be dE-TdS

It is true what Chjoaygame says, in respect to, that, when there is a mass transfer it is a measure of it's internal energy (usually enthalpy that includes the presure volume component of the enery being transfered into the volume of control, if I remember correctly).

I think Darmobel is missing a huge point in classical thermodynamics and it's fundamental laws of the conservation of energy, the necessity of some heat released when doing work, and the specification of the minimal ammout of heat required to do a process between two states. These laws are compatible with and even explained mechanistically by statistical mechanics, that is _true_ there he has a point. But the same is true for Von Newmann's generalization of entropy with regard to quantum mechanics, Shannon's entropy in information theory, black hole thermodynamics, etc. There are many mechanisms (of which statistical thermodynamics is a really important one) that are mechanistical models that are compatible with classical thermodynamics, but the general formulations of classical thermodynamics do not delve into them (wether it is "caloric" moving from one place to the other, electromagnetic waves, gravitational waves, energy residing in the vibration of molecules, it does not matter), it just starts from the concept that energy is conserved but that when there is a physical process some energy is transfered but does not do work, _ALWAYS_ for every single physical process, no matter what. Actually the measurement of the entropy of a black hole comes from this annalysis: "The only way to satisfy the second law of thermodynamics is to admit that black holes have entropy. If black holes carried no entropy, it would be possible to violate the second law by throwing mass into the black hole. The increase of the entropy of the black hole more than compensates for the decrease of the entropy carried by the object that was swallowed." http://en.wikipedia.org/wiki/Black_hole_thermodynamics.

As the quote by the famous scientist Sir Arthur Stanley Eddington states:

"The law that entropy always increases holds, I think, the supreme position among the laws of Nature. If someone points out to you that your pet theory of the universe is in disagreement with Maxwell's equations — then so much the worse for Maxwell's equations. If it is found to be contradicted by observation — well, these experimentalists do bungle things sometimes. But if your theory is found to be against the second law of thermodynamics I can give you no hope; there is nothing for it but to collapse in deepest humiliation."

So I would avoid trying to find thought experiments or comparissions with courrency where people try to describes process where the entropy of the universe is not increased or, at most, remains the same, and where, when using energy to do "work", some of the energy, at least δQrev=TdS, is not usefull for work.

--Crio de la Paz (talk) 23:44, 23 November 2012 (UTC)

Or: The second law of thermodynamics is, without a doubt, one of the most perfect laws in physics. Any reproducible violation of it, however small, would bring the discoverer great riches as well as a trip to Stockholm. The world’s energy problems would be solved at one stroke. It is not possible to find any other law (except, perhaps, for super selection rules such as charge conservation) for which a proposed violation would bring more skepticism than this one. Not even Maxwell’s laws of electricity or Newton’s law of gravitation are so sacrosanct, for each has measurable corrections coming from quantum effects or general relativity. The law has caught the attention of poets and philosophers and has been called the greatest scientific achievement of the nineteenth century. Engels disliked it, for it supported opposition to Dialectical Materialism, while Pope Pius XII regarded it as proving the existence of a higher being. Ivan P. Bazarov, "Thermodynamics" (1964)--Crio de la Paz (talk) 23:56, 23 November 2012 (UTC) A theory is the more impressive the greater the simplicity of its premises, the more different kinds of things it relates, and the more extended its area of applicability. Therefore the deep impression that classical thermodynamics made upon me. It is the only physical theory of universal content which I am convinced will never be overthrown, within the framework of applicability of its basic concepts. Albert Einstein (author), Paul Arthur, Schilpp (editor). Autobiographical Notes. A Centennial Edition. Open Court Publishing Company. 1979. p. 31 [As quoted by Don Howard, John Stachel. Einstein: The Formative Years, 1879-1909 (Einstein Studies, vol. 8). Birkhäuser Boston. 2000. p. 1]

Can somebody please clean this mess up? It is completely impenetrable, close to disruptive editing.

For example:

No, Darmobel, you are not quite understanding the basic aspects of thermodynamics: I told you the same thing that is in any thermodynamics book but you do not seem to grasp it. ΔU(T)=Q+W. What you are dubbing "heat" is "internal energy", not "heat"

How can I possibly respond to an item that, without a reference, begins No, Darmobel....? --Damorbel (talk) 08:05, 24 November 2012 (UTC)

Conservation of ' 'Heat ' ' ?

Heat is not a conserved quantity so, in thermodynamic terms, it cannot be transferred. What is transferred is energy. The article should make clear that common usage does not explain subtle differences in language. The Heat article currently doesn't explain these subtle differences either; this is a serious deficiency because it contains statements such as :-

Heat flow from high to low temperature occurs spontaneously (Opening statement, 2^ndpara 1^stline)

which is thermodynamic nonsense because it does not respect the conservation of energy according to the 1^st Law of thermodynamics. --Damorbel (talk) 08:47, 24 November 2012 (UTC)

Nope: 'work' and 'heat' are forms of _transfer_ of energy. Neither is conserved. What is conserved is _energy_ not 'work' and not 'heat'. Nobody is saying (only Darmobel) that "heat is conserved". Energy is conserved and for any thermodynamic process 'heat' must be released when doing 'work'. ΔE=Q+W. What flows spontaneously from high to low temperature is 'heat' which is _a_form_ of energy transfer. In that (when only heat is tranfered) case W=0 and ΔE=Q: the change in energy is exactly the ammount of heat released. But when work is also being done then ΔE=Q+W. Energy is used to do work _but_ some energy is transfered as heat _always_. What this means is that not all energy is avaiable to do work. The minimal ammount of heat released during a process is δQrev=TdS: in general ΔS>=Q/T. Notice that is not "ΔQ": there is not a "heat change" there is an "energy change" where energy is tranfered via 'heat' with no 'work'. There are two main phenomena for energy transfer: 'heat' and 'work', which are distinct and are not conserved in themselves: that which is conserved is energy (for an isolated system) ΔETOT=0. This is why the first law of thermodynamics is stated as ΔE=Q+W or as ΔU(T)=Q+W when only the internal energy of the system is used. This internal energy might have been at a time considered only as 'thermal energy' but nowdays we know there is also "chemical energy" and "nuclear energy", etc., involved. Darmobel is missing the basic point of the laws of thermodynamics entirely, especialy the second law. He wants "heat" to be "thermal energy", which it is not. The main point of the laws of thermodynamics is that, when you use energy to do work some of the energy is _always_ transfered but not used as work. These concepts arose from a generalization of real world observations of physical processes: it is by no means self evident, but it seems to be the truth in the universe we live in, similarly to the arrow of time or that the velocity of light in a vacuum is a constant. The laws of thermodynamics (as happened with Newton's laws of motion) _might_ be disproven for some generalized case, but that has not been the case (as per the quotes if somebody finds a case where the laws of thermodynamics do not hold he or she probably would win a Nobel Prize of physics and hailed as greater than Einstein, Newton Et.al. all together. Even when studying black holes the concepts of conservation and of the increase in entropy of the universe and conservation of information arise). What Darmobel is missing is not easy matter to understand: the need for 'heat' that arises when realising that, when using 'energy' for doing 'work', not all 'energy' that is transfered is used as 'work' but some is transfered and not transformed into 'work'. This is the quantity that in thermodynamics is called 'heat'. This means that perpetuum mobile of the second kind _does_not_exist_ Whenever you use 'energy' to do 'work' some 'energy' is transfered but not used to do 'work'. These concepts began as an analysis of thermal engines and thermal procecess but later ere generalized as laws for "the universe". The interesting thing is that these "laws" have never being disproved but actually seem to hold in one form or another for all physical processes. It seemed to be a bold move to generalize the laws of thermodynamics to _every_physical_process_in_the_universe_ but, up until this day and age, there is not a single process where the laws of thermodynamics are not obeyed. Darmobel: the concept of 'heat' in physics arises when it is realized that an energy change cannot be used only to generate work. The rest of the energy that is tranfered is then called 'heat' and it seems to be related to a gradient in the quantity called temperature. Even in the study of "heat transfer' the differences in temperature are an important part of the velocity at which heat transfer occurs. Depending of the mechanism the dependence is different. In conduction the quantity of heat flow is a function of the gradient of temperature (dQ=kAdT/dx in one dimmenssion), in convection it is a function of a generalized gradient of temperature(dQ=hAdT), in radiation a function of the fourth power of temperature (dQ=σεdAT^4). Actually here we have a distinction between convection and conduction, even more established by Nusselt's number Nu=(h/k)L, where L is a characteristic distance. Here we have a ratio of convective heat transfer over conductive heat transfer. In http://en.wikipedia.org/wiki/Nusselt_number One can find a derivation of Nusselt's number from Fourier's equation. When one delves into the details of dimenssional annalysis and convection one starts to realize that the mechanics of heat transfer through convenction are, indeed, distinct from conduction and radiation... --186.32.17.47 (talk) 15:47, 24 November 2012 (UTC)

Nameless 186.32.17.47 - You write:- " Nobody is saying (only Darmobel) that "heat is conserved"" I doubt if I ever wrote Heat was conserved I opened this section and it has the title Conservation of ' 'Heat ' ' ?, the question mark is important. If you did not realise that I have been arguing the importance of the consevation of energy, not heat, for some time, then you may be struggling with the whole matter.

Nameless 186.32.17.47, you write What flows spontaneously from high to low temperature is 'heat' which is _a_form_ of energy transfer. Well written" Why don't you open a section enttled Conservation of ' 'Heat ' ' ?

Nameless 186.32.17.47, you write Darmobel: the concept of 'heat' in physics arises when it is realized that an energy change cannot be used only to generate.... Which of course raises the question: do you have special evening for teaching your grandmother to suck eggs? --Damorbel (talk) 22:00, 24 November 2012 (UTC)

In the immediately foregoing, written I guess by Crio de la paz, good points are made, I think.Chjoaygame (talk) 17:46, 24 November 2012 (UTC)

I agree - heat and work are process functions, not state functions. They are not something associated with a state. Asking how much heat a system contains is like asking how much work it contains. It's nonsense. You must ask how much work has a system done, how much heating has it done, etc. A system may lose internal energy by doing work or by heating another system, or may gain internal energy by having work done on it or by cooling another system. This idea is at odds with the non-scientific use of the word heat, the idea that a hot body contains a lot of heat, a cool body not so much. If we are going to speak scientifically, then we must use the scientific definition of heat and not confuse it with the unscientific common-usage "definition". PAR (talk) 18:13, 24 November 2012 (UTC)

PAR, you write:- "heat and work are process functions, not state functions." Do you recognise any connection between heat and temperature? Or between temperature and energy? Or between temperature and state functions? --Damorbel (talk) 22:00, 24 November 2012 (UTC)

I do not understand what the whole "teaching your grandmother to suck eggs" reference is about. PAR and Chjoaygame are right but Darmobel seems only to be trying to pick a fight. If he already undertsand these subjects then: What is he arguing about? Where has _anybody_ argued that "heat is conserved" or that "some mysterious substance that appears when temperature differences exist" besides him? If he already understands all we are saying and he does not require any explanation on thermodynamics: What is he arguing about? For all I've read in these discussions he is arguing only with himself. --Crio (talk) 00:44, 25 November 2012 (UTC)

This is a confusion of the everyday usage of the word heat and the thermodynamic definition. In the thermodynamic definition, heat and work are mathematically similar. The problem is in the English. If "work" and "heat" were to be made as similar verbally as they are mathematically, we could write:

A system transfers energy to another system by doing work on it.
A system transfers energy to another system by doing heat on it.

A system transfers energy to another system by working it.
A system transfers energy to another system by heating it.

Work is something that is done, it does not "exist".
Heat is something that is done, it does not "exist".

PdV represents the amount of energy transferred by work.
TdS represents the amount of energy transferred by heat.

Some of these sentences sound odd - they conflict with everyday English usage. Damorbel has failed to realize that the problem with these sentences is not with the physics, it is with the English. The word "heat" was perhaps a bad choice for TdS, but we seem to be stuck with it, and we have to deal with it and not declare that the English language guides the physics. You don't "do heat" the way you "do work", but rather, you "heat". You don't say "heat is done, it does not exist", you say "heating is done, it does not exist". You don't say "TdS is the energy transferred by heat", you say "TdS is the energy transferred by heating". That's an unfortunate verbal mess, but it has nothing to do with the physics.

As regards "thermal energy", I don't know the rigorous definition. If I have a box with a piece of ice in it at the temperature of the triple point, and I then heat the system until all the ice turns to water, it is still at the triple point temperature. The temperature has not changed, but the internal energy has increased because entropy has increased. Has the "thermal energy" increased? I don't know. PAR (talk) 16:20, 25 November 2012 (UTC)

PAR referring to your , it is still at the triple point temperature...". In practical terms this wouldn't happen because the water would not turn to ice at the same instant. The triple point cell does not normally allow much heating or cooling, it is supposed to be an equilibrium cell, where energy exchanges occur only between the ice, the water and the vapour, the total cell energy should remain constant.

I am interested in this post, I hope to return later, you identify misunderstanding via language as a problem - I agree with you!--Damorbel (talk) 16:54, 25 November 2012 (UTC)

This is not correct. You can heat a fixed-volume system containing ice, water, and vapor at the triple point. Let it equilibrate. As long as you have not added enough energy to melt all of the ice, the temperature will still be at the triple point. There will just be more water and less ice. That's why a triple point cell is so useful - heat it, cool it, work it, make it work, thereby adding or subtracting from its internal energy. When it comes to equilibrium, it will still be at the triple point as long as the three phases still coexist. The internal energy will have changed because the entropy has changed, but the temperature will not have changed. PAR (talk) 19:10, 25 November 2012 (UTC)

What you said is "....until all the ice turns to water That means that the buffering effect of the ice is no longer working..... But I understand what you mean!

A system transfers energy to another system by doing work on it.

The effect you get depends on how the work is done - if the system is a shell (in the barrel of a gun) work done is the propellant pushing the shell out of the barrel and the work gives the shell velocity. If you are forging a billet of steel the work is changing the shape of the billet and it gets hotter

A system transfers energy to another system by doing heat on it.

The gun's propellant burns in the breech, producing hot gas that heats the barrel.

A system transfers energy to another system by working it.

1/When forging a billet of steel the work is changing the shape of the billet and it gets hotter

2/When bending a nail stuck in a plank of wood the nail gets hot fron the internal friction resisting the force bending the nail,

A system transfers energy to another system by heating it.

The gun's propellant burns in the breech, producing hot gas that heats the barrel.

Work is something that is done, it does not "exist".

The work done by the propellant gas accelerates the (depleted uranium anti-tank) shell to 1500m/s, giving it a lot of kinetic energy. The (depleted uranium anti-tank) shell hits the enemy tank, deforming the tank and, by means of friction, the tank brings the shell's 1500m/s velocity to zero. This friction changes the kinetic energy of the shell into heat, and induces chemical change by cooking the people in the tank.

Heat is something that is done, it does not "exist".

There is chemical (thus potential) energy in the propellant, waiting for someone to trigger its release. When burning, the propellant decomposes to gas which is very hot (flames and suchlike) and so at a high pressure, this hot gas forces the (depleted uranium anti-tank) shell out of the barrel. The potential energy in the propellant does a number of things 1/it raises the temperature and pressure of the combustion gases 2/ it heats the gun's barrel and 3/pushes the shell out of the gun at high speed; cooking the enemy in their tank. From this you will realise that the chemical energy, when triggered, is spread all over the place but it is not destroyed it just gets spread around to lower and lower concentrations, always lower than the orignal (chemical) energy in the propellant.

PdV represents the amount of energy transferred by work.

Only if it is a gas that is worked on and only if the action is adiabatic.

TdS represents the amount of energy transferred by heat.

Depends on what dS means. Is the system at maximum entropy. I assume there is only one source of energy, but it the energy doesn't have to be evenly distributed, perhaps there is (= there always is) a gravitational field.--Damorbel (talk) 21:49, 25 November 2012 (UTC)

I wrote above:-

the chemical energy, when triggered, is spread all over the place but it is not destroyed it just gets spread around to lower and lower concentrations, always lower than the orignal (chemical) energy in the propellant.

What I should have mentioned is that the total energy released by burning the propellant remains traceable i.e. it is conserved but it is continually changing its form: from chemical energy to heat: to kinetic energy of the gas and the shell: to low temperature energ in the gun barrel: back to heat energy, possibly hotter than the combustion products when the shell strikes the tank. Other energy products from triggering the propellant are sound and perhaps gravitational potential energy - I invite contributions! But also it should be noted that none of the combustion energy is transformed into another conserved quantity such as momentum. --Damorbel (talk) 07:04, 26 November 2012 (UTC)

The simple answer to your question is that "thermal energy" is undefined and is a bad term to use because it seems to have meaning when it does not. Likewise thermal internal energy which suggests we can identify what part of U came from heat and what didn't. If you have a sample of hot gas, did it get hot from compression PdV or heating TdS? No way to know. Either is possible or some combo. To pretend you know, perhaps by crystal ball, is fooling yourself and others. Thus there is no heat content. There is no latent heat content. Potential energy goes up in a phase change, and that's the way internal energy is stored, but you don't know how it got there or how that energy will come out, so you're kidding yourself if you think it's tagged by Mother Nature as "thermal" energy. It's just potential energy. It follows that heat cannot be advected. Heat is not, and cannot be, stored. Heat is not a noun! As declares a famous pedagogical paper. This all goes back to Mark Zemanski's opus of 1970, called "The Use and Misuse of the Word "Heat" In Physics". Still widely cited after 42 years (but still not online, alas). But also widely ignored by college text writing boobs, which makes well-nigh impossible to cover these topics on Wikipedia. Much as happened with "weight" and "matter". There are ten careless writers for every rigorous one. And WP editors would rather win an argument than think. S B H arris 17:15, 25 November 2012 (UTC)

SBHarris writes words of wisdom: "There are ten careless writers for every rigorous one." His next sentence I think needs a slight amendment, the addition of the word some: "And some WP editors would rather win an argument than think."Chjoaygame (talk) 18:51, 25 November 2012 (UTC)

definition of heat in this article

The present article starts by defining heat in a way not precisely that of any particular reliable source. The sources cited are Reif and Kittel & Kroemer, two student texts of statistical or thermal physics. They both come from a particular pedagogical viewpoint, that one should teach thermodynamics along with statistical mechanics. In his introduction, Reif makes the point that he thinks he is particularly clever to do this. Another well represented pedagogical viewpoint is that thermodynamics should be taught separately from and prior to statistical mechanics. The reason for the latter viewpoint is that it is good for the physicist to have a good grasp of what can be done with thermodynamics alone, without calling on the special notions of statistical mechanics.

The present article's precise wording is nearer to Reif's than to Kittel & Kroemer's definition. The article's definition omits the word "purely" from Reif's definition. Reif, like most sources, defines heat in a carefully constructed context, and does not intend his definition to make sense without that context. The present article's definition omits that context. It follows that the present article's definition of heat is original research.

Reif defines heat in a context of classical thermodynamics. There are two bodies which can interact by exchanging energy. There are, according to Reif here, two types of interaction available for them. Reif has already defined a system or body in specific terms; the terms point to the working body of a classical thermodynamic system, defined statically by external parameters. Regrettably, as a result of his pedagogical stance, Reif's definition is partly clouded by its inclusion of loosely worded ideas that refer vaguely to the quantum mechanical Hamiltonian, with the result that the context of his sentence that introduces the word heat on page 67 is complicated or even, one might say, cluttered.

Kittel & Kroemer are likewise practitioners of the mixed-teaching pedagogical persuasion. They do not use the same definition as Reif, though the difference does not amount to a significant conflict. They specify on page 227 that "Heat is the transfer of energy to a system by thermal contact with a reservoir." Their reservoir is assumed to possess a well-defined temperature.

The term "thermal contact" is worth examining. It comes from a tradition of rigorous classical thermodynamic thinking started by Bryan, and continued by Carathéodory, and blessed by the authority of Born. The tradition examines very simple assemblies of bodies of respectively homogeneous chemical constitution, in communication with each other through defined partitions. The partitions are considered to be permeable to or capable of transferring energy or matter in specific ways. Amongst the ways is the thermal way, in Carathéodory's translated words, "as heat". This refers to the case when matter cannot permeate the partition, and where the partition does not move so as to produce volume-related work, and where external long-range forces are invariant. Carathéodory is burning to obey Born's advice to follow up on Bryan's observation that if one relies on the principle of conservation of energy as a prior supposition, or if one imagines that one can perform reversible work, then one can simply define heat transfer as transfer of energy that is not as work. This thinking is often regarded with awe as brilliant physical insight. Carathéodory admits the existence of partitions permeable only to "heat", but he carefully words his definition of them so that the words heat and temperature are not explicit in them. Indeed, he continues his article without actually offering a definition of heat according to his scheme of development of the basic ideas of classical thermodynamics for closed systems. Nevertheless, his scheme has built into it, for its definition of the equilibrium states of parts of his systems (the only states defined in his development), a "non-deformation" variable, that other more traditional developments would regard as a potential measure of empirical temparature, Carathéodory's development carefully avoids explicit mention of empirical temperature. Thus for Carathéodory, the father of this very rigorous way of thinking, heat is transferred by conduction or by radiation, though, for the sake of the brillianct cleverness of the development, the wording is carefully constructed to hide this fact, a fact which appears clearly in other more traditional developments that do not consider themselves quite as brilliantly clever as Carathéodory.

Many texts, such as Reif and Kittel & Kroemer, in developing the notion of transfer of energy as heat, do not proceed to discuss the first law of thermodynamics for open systems, but restrict their systematic development to closed systems.Chjoaygame (talk) 17:40, 24 November 2012 (UTC)

Response by Crio

Quite an interesting exposition Chjoaygame! --Crio (talk) 00:50, 25 November 2012 (UTC)

Response by Damorbel

Looking at your sources (BTW, please don't cite sources without refencing some relevant passage(s)):- Kittel & Kroemer on the 1^st law of themodynamics p49:- First law. Heat is a form of energy. This law is no more than a statement of the principle of the conservation of energy, Ch.8 discusses what form of energy heat is. Ch.8Has the heading :-

Energy and entropy transfer

Definition of Heat and Work

They open:- Heat and work are two different forms of energy transfer but heat is not a conserved quantity. Later they go on about entropy transferbut entropy is not a conserved quantity.

Thus form the beginning Kittel & Kroemer are mixing conserved and none conserved items and not drawing attention to the fact that only conserved items can be transferred, non-conserved items can appear or disappear, sometimes without trace, e.g. chemical energy and kinetic energy. Thus Kittel & Kroemer cannot be considered as a reliable source on the first law of thermodynamics, so the the rest of their arguments are necessarily quite doubtful.--Damorbel (talk) 10:43, 25 November 2012 (UTC)

Dear Darmorbel, contrary to your comment, they are not my sources; they are, as I wrote, the sources cited in the article, which gives the relevant page numbers, only p. 227 in the case of K & K, not the p. 49 to which you further refer. I am not proposing that these sources are, or are not, reliable. I am pointing that they are the ones cited in the article for its definition, though that definition does not follow them precisely, and is therefore original research.

By the way, you are utterly mistaken to say that only conserved quantities can be transferred. In systems which can gain or lose bulk potential energy by long-range forces with the surroundings, internal energy is not conserved, but can be transferred. It is customary in the field theory of non-equilibrium thermodynamics to say that entropy can be transferred, though at least one writer, B.C. Eu, uses a specially invented word, "calortropy", to deal with the concern that "entropy" can be created as well as transferred, which should make you happy.

Above, you say that you are "arguing that Kinetic theory ... is ... at the base [italics by Chjoaygame] of thermodynamics and statistical mechanics". You are missing a main point there. No one is denying that kinetic theory or statistical mechanics can be considered to be "at the base [italics by Chjoaygame] of thermodynamics"; I think it clearer to say that they explain thermodynamics, though many people, including you, like to say that the explanation is "basic", relegating thermodynamics proper to a derivative or secondary status. What is being said, and is the consensus here, is that for the definition of quantity of energy transferred as heat, thermodynamics provides the primary definition, which is then exported to statistical thermodynamics, there to provide the target propositions that it aims to derive and thus explain in terms of the microscopic picture. How many times do we need to repeat this to you, before you hoist it in? One problem here is that much of the time you are arguing against straw men of your own making, misrepresenting what we try to tell you.Chjoaygame (talk) 11:47, 25 November 2012 (UTC)

Chjoaygame, you write they are not my sources; Who cares whether they are your sources? The article is not "your article". Kittel & Kroemer are in the article, they are being used to support unsupportable 1^st Law assertions (heat flow.)

Further you write:- B.C. Eu, uses a specially invented word, "calortropy" Possibly related to caloric? Chjoaygame without explaning its relevance to the Heat article. This comment is utterly irrelevant and is time wasting. Usng this kind of logic you must not be surprised when your contributions get reversed. Please stop this kind of disruptive editing.

As regards reliable references WRT kinetic theory and thermodynamics you will find that the Royal Society and Sir Humphry Davy denied that heat was a property of molecules and deliberately obstructed publications on the matter (see here) so the aricle in distinguished company with Kittel & Kroemer as references!

Further you write:- By the way, you are utterly mistaken to say that only conserved quantities can be transferred. Really?

You go on toexplain with:- In systems which can gain or lose bulk potential energy by long-range forces with the surroundings, internal energy is not conserved Who is saying internal energy should be conserved? Please explain, this idea cannot possibly be supported in Wikipedia. --Damorbel (talk) 13:06, 25 November 2012 (UTC)

Damorbel, you write tetchily: "Chjoaygame, you write they are not my sources; Who cares whether they are your sources?" Damorbel, you care, as is shown by your gratuitously attributing them to me, a straw man of your own creation. In fact I had written: "... contrary to your comment, they are not my sources." Dear Damorbel, you now misrepresent my response to a previous misrepresentation by you of what I wrote previously. Previously you inaccurately wrote that they were my sources; I was just observing that I had written that they are the article's sources; I was just corrrecting your inaccurate statement about what I wrote. Now you try to make out that this means that I am engaging in disruptive editing. And next you write further erratic and irrational remarks. Your misrepresentations are too much. I don't have time for your antics. Why do we reply to you at all? We know from painful experience that trying to discuss physics with you is futile because of the way you behave. You have a current invitation by other editors, to put into the section on the statistical mechanical explanation what you want to about the Boltzmann constant, your heart's desire, but instead of doing so, you turn aside to behave so as to make another editor write just above here: "... Damorbel seems only to be trying to pick a fight." Chjoaygame (talk) 14:08, 25 November 2012 (UTC)

Comment by Chjoaygame

No one has responded to my statement at the beginning of this section, that the present article's definition of heat is original research. A reasonable response would be that the lead is a summary and cannot be required to be limited to exactly sourced material; it should accurately summarize the properly sourced material of the body of the article.Chjoaygame (talk) 22:04, 25 November 2012 (UTC)

I don't have it here to check, but the definition in the first line of the article is nearly verbatim K&K's definition of heat, isn't it? If so, how in the world can you construe that as "original research"? Are you familiar with the meaning of the phrase? Waleswatcher (talk)

No, it isn't "nearly verbatim K&K's definition of heat". When you wrote the above, you were not in a position to ask any rhetorical questions, let alone insulting ones. Please come back to us when you have done your homework.Chjoaygame (talk) 02:34, 26 November 2012 (UTC)

"Homework" - you have a very bizarre idea of what this talk page is for, don't you? Anyway, I checked. According to K&K, "heat is the transfer of energy to a system by thermal contact with a reservoir". Doesn't quite coincide with our first sentence, but "original research"? As I suspected, you clearly have no idea what that phrase means. Now why don't you go do your "homework" and get us Reif's definition, Chjoaygame. Waleswatcher (talk) 04:15, 26 November 2012 (UTC)

Good of you to do at least half of your homework; thank you. As I remarked above, Reif's definition includes essential context, which takes nearly a page, but is not supplied in the lead definition in the article. It cannot be copied safely here without copyright problems, I think.Chjoaygame (talk) 04:52, 26 November 2012 (UTC)

Waleswatcher, there is no way Kittel & Kroemer can be considered a reliable source on thermal physics. They are both highly qualified and have published an interesting book but neither have a background in teching the matter, Kittel is a solid state physicist and Kroemer a solid state engineer. In no way does it rule out their book but it does mean that, when citing it, it is necessary to examine what they have written. I regard reliable sources papers by people like Fourier, Einstein and Clausius. Such people have defended their theories and we may attack them (if we dare!). The problem with Kittel & Kroemer is over the first law of thermodynamics; on p49 they have:-

Heat is a form of energy [true, but then] This law is no more than the principle of conservation of energy.

It isn't, it is the energy that is conserved, but it need not be as heat, it may well be (and frequently is) chemical energy.

The arguments put forward by Kittel & Kroemer for their "Thermal Physics" fall down badly on the fundamentals, they treat thermal energy as a conserved quantity, it isn't. What is conserved is the energy of the heat but the whole of modern physics revolves around the fact that energy has many different forms, Heat, potential energy, chemical energy, sound energy, electrical energy etc.etc. None of these forms are conserved, that is why Heat flow (in the article) is not a scientific concept. I am not saying that Heat flow should not appear in the article, it should, but it must be put in the category of practical but unscientifc ideas about heat. --Damorbel (talk) 09:58, 26 November 2012 (UTC)

The immediately above comment by Damorbel is mostly drivel. I would say that Waleswatcher has no need to respond to such drivel.Chjoaygame (talk) 11:01, 26 November 2012 (UTC)

Good morning Chjoaygame. I would like to know why you think my contribution is drivel. Also I think you owe it to the other users of Wiipedia to show them you can manage better than simple abuse. --Damorbel (talk) 11:55, 26 November 2012 (UTC)

Damorbel, K&K is plainly a reliable source for this article. If you don't believe me, please go and read wiki's guidelines for reliable sources. You might note that K&K is one of the standard texts for undergraduate and Ph.D. level courses in thermal physics and statistical mechanics. Regarding the physics in your comment, I've decided to stop engaging you (and to a lesser extent, everyone else here) on physics unless it is directly related to a specific edit of the page. Waleswatcher (talk) 13:26, 26 November 2012 (UTC)

So if Kittel & Kroemer say that heat is a conserved quantity that is right is it? And if Richard Tolman - Principles of Statistical Mechanics. p 528 section 118. 1^st para p529 section 119 says it isn't then he is somehow just - wrong?

Waleswatcher, there are some things in life that you have to be able to work out for yourself; I invite you to read Kittel & Kroemer and Tolman and explain which is the better argument. --Damorbel (talk) 14:00, 26 November 2012 (UTC)

Further comment

This section is relevant because Waleswatcher wants to put convection in the lead on the same status as conduction and radiation as modes of transfer of energy as heat. The definition that he adverts to just above, "heat is the transfer of energy to a system by contact with a reservoir", is taken from the student text by K&K in which the exact word "convection" does not appear at all, and in which the nearest to it is the term "convective isentropic equilibrium of the atmosphere"; the rest of the book concentrates on conduction and radiation. The other cited source, Reif, mentions convection only in order to exclude it, while the rest of Reif's book concentrates on conduction and radiation. Waleswatcher here is minimizing the departure of the article definition from its cited sources, that is to say, minimizing its aspect of original research. Apparently this minimizing of the aspect of original research is in order to bolster his effort to put convection in the lead on same status as conduction and radiation. I would describe this as spinning by Waleswatcher.Chjoaygame (talk) 08:19, 26 November 2012 (UTC)

As is his nature, Waleswatcher has now made a trivial edit that he thinks further minimizes the problem with the lead. He has replaced the word body with the word system, which is vague as to the important point that it is a closed system that is being considered. He is referring to the definition of Reif. He continues to omit the important word "purely" used by Reif; it is hard to be sure, but it seems perhaps that his cover note intends to excuse this omission by appeal to something about Wiki style? He writes an unusually long cover note because it is beneath his dignity to reply here on the talk page. But not long enough to actually deal clearly with the problem. And as for context in K & K, Waleswatcher omits their "contact with a reservoir", which for them has a temperature. Thus Waleswatcher continues to omit the important contexts indicated by K & K and by Reif. He also avoids mention of the important absence of convection from either K & K or Reif. He is a master of spin, but not of physics.Chjoaygame (talk) 16:35, 26 November 2012 (UTC)Chjoaygame (talk) 16:46, 26 November 2012 (UTC)

Your problem, Chjoaygame, is that you are an atrocious writer. You are incapable of writing coherently even here on talk pages, let alone in articles. You persist in embellishing, qualifying, decorating, and otherwise festooning your prose with so many unnecessary and overly elaborate semantic details that even an expert in the topic can barely follow them, let alone some innocent layperson that simply wants to know what "heat" is. When I read articles you've edited, I can see right away what part you wrote and what anyone else wrote. If you get nothing else from this discussion, at least understand that you need to learn how to write. Learning how not to insult and antagonize anyone that disagrees with you or prunes your bloviations would help, too.

The first sentence of the lead of a wiki article is supposed to succinctly introduce the subject. It should have the title of the article in bold, preferably as the first word or phrase of the sentence. It is not the place to insert caveats, details, or if at all possible terms with a meaning that won't be clear to the average reader. That's what the rest of the article is for, to explain the details.

As for your patently absurd assertion that the first line is "original research", there's no point in even commenting on it further. From this point on, I will no longer respond to you on the talk page, as it is a clear waste of my time. The only exception will be if you have a specific objection or suggestion to a specific passage in the article. If you think "purely" is important, why haven't you edited it in rather than wasting everyone's time? Waleswatcher (talk) 21:10, 26 November 2012 (UTC)

Comment by Count Iblis

Thermodynamics is part of physics, and in physics we tend to put things in a broader context. Physics is, after all, about describing Nature and there are no imaginary boundaries between subjects such as electromagnetism, relativity, thermodynamics etc. etc. in Nature. When you do an experiment, you are dealing with all of Nature, not some aspect of it that only exists in some limit. This is why I support he way Reif treats this subjects. He approaches the topic from the point of view of physics, he motivates what he is doing, justifies approximations etc. etc. Count Iblis (talk) 23:30, 25 November 2012 (UTC)

The reason that I said there is a departure from sources, that warrants the technical term own research, is that the definition in the article departs from that of Reif, its closest source, by omitting the careful setting of context that Reif offers, and by omitting the word "purely" that he puts in front of "thermal". I further pointed out that Reif's book does not have the word convection in its index; I may now add that a computer search through Amazon reveals just one use of the word in its text, as follows. On page 492, in problem 12.15, Reif considers an experiment. He writes: "In the absence of any convection in the gas, make a rough estimate ..." I also pointed out that Kittel & Kroemer do not write the exact word 'convection' at all; they pose one problem in which they write of "convective isentropic equilibrium of the atmosphere".Chjoaygame (talk) 02:28, 26 November 2012 (UTC)

Reif does consider some specific examples, but the main definition is based on the definition of macroscopic work. The First Law is then taken to be the definition of heat, I think Reif makes that very clear. So, the question is then how Reif defines macroscopic work. This is done in terms of external parameters which define some macroscopic properties (constraints) of a system, such as the volume. A change in these external parameters will lead to a change in the internal energy. The work done by a system is the decrease in the internal energy due to the change in the external parameters. And here you always have to consider an ensemble of systems and take mean values to make this well defined. Count Iblis (talk) 03:42, 26 November 2012 (UTC)

It seems you and I agree here, in the major point that Reif states his definition carefully, referring explicitly to a context of closed systems, allowed only to exchange heat, through a diathermic partition, when the adiabatic partition is removed. Reif also follows the Bryan-Carathéodory-Born tradition of considering heat as strictly defined as a residual from work transfer, with respect to a strict requirement for conservation of energy and a well-defined internal energy, work being defined, as you note, by changes in external parameters under an adiabatic constraint.

Reif does indeed consider an ensemble of systems, because his context is that of quantum statistical mechanics. The present article takes instead the point of view of thermodynamics in its plain sense. I think you would like the article to change its point of view to that of quantum statistical mechanics.Chjoaygame (talk) 05:22, 26 November 2012 (UTC)

Thermodynamic and mechanistic explanations

Statements above like: " A proper explanation of heat has to be based on the energy contained in the motion of particles, not on the transfer of that energy between particles" by Damorbel ilustrate the problem with some of these approaches. Even though the laws of thermodynamics predate statistical mechanics and do not require it in order to be formulated (but are explained, in some cases, by it) when texts rely on statistical mechanics in order to explain thermodynamics they create confussion. The basic laws and concepts of thermodynamics were well under way before being "explained" by statistical mechanics and are compatible also with, i.e., Von Neuman entropy, Shannon entropy, Balck hole entropy, the entropy of gravitational fields, etc. That the mechanistic approach of statistical mechanics is compatible with classical thermodynamics is true, as are Newton's laws of motion, regarding work, in a non relativistic framework. But classical thermodynamics does not "need" statistical mechanics to be formulated, anymore that it need's Fourier's law of conduction, or Newton's laws of motion, or general relatitivy, or information physics theory. --Crio (talk) 01:18, 25 November 2012 (UTC)

Response by Damorbel

Crio I have previously explained to Chjoaygame what I am arguing as the nature of heat:

From what you write above (...your idea that heat is the energy of vibrating particles...) I understand your argument to be that heat is not the energy of vibrating particles, OK?

In that case would you care to explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles?

This is not a trivial question because it is some of this kinetic energy that is transferred between material at different temperatures. It is entirely necessary that this energy is preserved, in one form or another, during and after the transfer; were this not so the 1st law of thermodynamics would not be valid ( 28 September 2012 (UTC))

I am arguing that Kinetic theory, as extended to solids by phonons, is the only sucessful theory at the base of thermodynamics and statistical mechanics. Am I wrong? If you think I'm wrong, would you care to say where? --Damorbel (talk) 07:45, 25 November 2012 (UTC)

Comment by Crio

'Heat', in a classical thermodynamic explanation of it, does not require a mechanistic explanation of either the system nor 'heat transfer'. Classical thermodynamics do not require, in principle, mechanistic explanations for it's formulation. Statistical mechanics provide _a_ framework that_explains_ (mechanistically) what does happen with _some_ of the internal energy of a 'body' and what does happen where conduction occurs. Radiation is exlained (mechanistically) in the terms of electromagnetic radiation. These two are forms of 'heat transfer', one explained by 'statistical mechanics' (conduction) the other by electromagnetic radiation (radiation). When one deals with turbulence in a fluid there are other complications: gases _do_ have a conductive heat transfer coefficient and, for specific transfer phenomena, different convective heat transfer coefficients, which are related through Nusselt's number. Nusselt's number is a function of Reynolds number and Prandtl number. The main problem of turbulent flow, specially in compressible fluids, is the lack of a proper mathematical framework that is _usable_ (since the existence and smoothness of Navier Stokes has not even been proven). There are other issues that arise with the modelling of 'heat' and 'internal energy' of systems when gravitational phenomena and 'gravitational waves' are taken into account, when dealing with 'informational physics' 'black holes' 'quantum theory' other mechanistic relations regarding thermodynamics arise. One interesting thing is that (from what I understand) some of these mechanistical interpretations of entropy and other quantities are compatible (entropy in statistical mechanics, Von Neumann's entropy, Shannon's entropy). Other's might not be compatible as the general theory of relativity has not been 'unified' with quantum mechanics. Thus entropy in regard to gravitational waves or black holes might not be (as of yet) related to entropy ina quantum mechanics.

Still, one can see that the laws of thermodynamics are used without regard of the internal mechanics of the system, the mechanism of heat transfer or the mechanism for doing work. The concepual framework of thermodynamics is more abstract than that. --Crio de la Paz (talk) 15:19, 25 November 2012 (UTC)

But, I _do_ agree that, as far as mechanisms to explain classical thermodynamics go, for a mayority of cases (cases that do not deal with gravitational waves or black holes and those kind of things), statistical mechanics is fundamental and of great importance, since it derives macro thermodynamic formulations from the atomic structure of matter. This is _remarkable_. But there is also the concept of entropy in information theory and in informational physics which might be another example of a physical theory that is compatible with classical thermodynamics. Classsical thermodynamics theory seems to hold in regard to the atomic structure of matter (statistical mechanics), quantum theory (Von Neumann's entropy), information theory (Shannon's entropy), and, as far as I understand, the general theory of relativity (gravitational waves and the entropy of gravitational fields).

I agree with Darmobel in that the kinetic theory of gases, solids and liquids (including phonons)is a fundamental development that explains a lot of the phenomena studied in classical thermodynamics and heat transfer. But I do think he is wrong stating it is "the only theory" since, i.e. Shanon's model of informational entropy is compatible with thermodynamics too (and with statistical mechanics, in as much as I know). There are also theories of entropy related to the gravitational field (where this is the predominant form) and gravitational waves, as far as I know.

Now as per the question of what is the kinetic energy of the particles that constitute a system: it is 'thermal energy' or (part of) the 'internal energy' of the 'system' (not 'heat'). The internal energy of the system includes all forms of energy of the system that do not include energy related to moving the system as a whole (kinetic energy of the whole system) nor the potential energy of the system implied in it's position in a force field.

Darmobel seems to state that in a physical process, what is dubbed above, by me, as 'thermal energy' _has_ to be conserved. This is wrong: it is not an specific "form" of energy that is conserved, is energy as a whole. If there is a chemical reaction within the system that releases heat and rises the temperature of the system, thermal energy`is "created". So 'thermal energy' is not conserved: total energy for an isolated system is conserved.

To clearify: Darmobel states above: "

From what you write above (...your idea that heat is the energy of vibrating particles...) I understand your argument to be that heat is not the energy of vibrating particles, OK?

In that case would you care to explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles? This is not a trivial question because it is some of this kinetic energy that is transferred between material at different temperatures. It is entirely necessary that this energy is preserved, in one form or another, during and after the transfer; were this not so the 1st law of thermodynamics would not be valid "

Heat is _not_ the energy of vibrating particles. The energy of the vibrating particles of the system is 'thermal energy'. 'Thermal energy' is part of the 'internal energy' of a system. Total energy is conserved, not 'thermal energy'. 'Internal energy' includes all forms of energy contained in a system, but it does not contain the kinetic energy of the system as a whole nor it's potential energy as a whole system in the presence of a force field. It does contain 'thermal energy', but also 'chemical energy', 'nuclear energy', energy related to the formation of Van der Waals interactions, hydrogen bonds, etc. Even when the system is considered to expand one must make room for the pressure related work to make room for the substance and enthalpy comes into play. When (some) of the energy of a system is dispersed as heat and only heat it is true that energy is conserved and, thus, all energy exchanged is used as 'heat' and there is no work production. But when a system does _work_ there is always _some_ energy that is dispersed as heat, no matter if the energy is 'thermal energy' or 'electrical energy' or 'chemical energy'. The concepts of 'heat' and 'work' and the first and second laws of thermodynamics deal mostly to the ammount of energy that _must_ be rejected as heat in order to change a system from one state to the other.

ΔETOT=0 for an isolated system.

dE=δQ+δW. dS>=δQrev/T For a reversible (ideal) process dE=TdS+δW δW=dE-TdS So the ammount of work avaiable for an ideal process of maximum efficiency is dE-TdS because there is a minimal ammount of energy that _must_be dispersed as heat. Of course a molecular explanation of conductive heat transfer involves kinetic energy of the particles involved. In the case of radiation it is electromagnetic waves and photon exchange which explains how heat is tranfered (so, in this case, 'heat' is _not_ the kinetic energy of the particles involved at all...) The case for convection is more complex and solutions for problems are expresed via dimensional annalysis since modelling turbulent flow, specially for compressible fluids, is not something easily done (Navier Stokes smoothness and continuity have not even been proved yet, and they are not solvable in a lot of cases, with any practicallity). Energy and entropy related to gravitational waves must also be considered. I do believe that explaining conductive heat transfer with the kinetic theory is similar to explaining electrical work via the electrical field. It explains an specific form of 'heat transfer' but not all of them. And in a similar fashion the general theory of relativity is not compatible with non gravitational forces of nature in it's formulations, in as much as I undertand ,since no grand unified theory is amongst us. --Crio de la Paz (talk) 05:25, 26 November 2012 (UTC)

Crio you write above:-

Heat is _not_ the energy of vibrating particles. The energy of the vibrating particles of the system is 'thermal energy'.

This is not correct. Heat is energy with a temperature - the basis of the 2^nd law of thermodynamics. Thermal energy is all kinetic energy above zero K; the distinction is subtle but, because of the 2^nd law requirement, scientifically and practically very important indeed. --Damorbel (talk) 06:32, 26 November 2012 (UTC)

No: Darmobel is _completely_ wrong in this last statement. heat _is_not_ 'energy with temperature'. The second law of thermodynamics does not state this. The second law of thermodynamics states that, when using energy to do work, some energy is always transfered that does not do work. This ammount of energy transfered that does not do work is what is called 'heat'.

Alternatively a quantity called 'entropy' is introduced as a function of state such as dS=δQrev/T. For an isolated system ΔS>=0 for any given process. Alternatively permetual motion machines of the second kind: that is there is _not_ a machine _in_the_unvierse_ that transforms energy into work without releasing 'heat'. Nowhere in the source provided by Darmobel does it say this afirmation of his that 'heat is energy with temperature'. Darmobel insist in confussing thermal energy with heat.

He should take a basic course in thermodynamics.

--Crio de la Paz (talk) 23:21, 26 November 2012 (UTC)

first paragraph of the lead

See my edit comments. In addition to what I wrote there, heat transfer by radiation, conduction, and convection all involve mass transfer in the literal sense that the object being heated will end up being slightly more massive than it was. So "closed system" is misleading both to lay readers and as a matter of fact (not to mention that it does not appear in the definition of heat given in Reif, the source for that sentence). As for "purely", if we include that term we need to explain what is meant by it - namely, that heat is not work. Otherwise, it clashes with the next sentence. Waleswatcher (talk) 01:51, 27 November 2012 (UTC)

closed systems

Indeed the word 'closed' does not appear in the particular sentence of Reif to which you refer, nor indeed in the relevant section. But the context and full meaning of the sentence to which you refer are for closed systems. Reif writes: "Let us now consider two macroscopic systems $A$ and $A'$ which can interact with each other so that they can exchange energy. ... The first kind of interaction is that where the external parameters of the system remain unchanged. This represents the case of purely ″thermal interaction″." Reif is talking about closed systems. Wikipedia entry that cites him should reflect this because it is important here. You are right to use the term 'body' here, I think.Chjoaygame (talk) 02:16, 27 November 2012 (UTC)

Closed is correct, anyway. "Closed" means no matter transfer, not no mass-energy transfer. The last (no kind of transfer) is called an "isolated system." Closed systems go up (or down) in mass as they go up or down in energy (since mass is energy), but neither of these things happens as a result of a gain or loss in matter. Matter and mass are not the same thing, and this causes great confusion in relativity theory teaching. Matter (a poorly defined word, but usually means particles with rest mass) is not conserved. But mass is conserved. Mass and matter are equivalent to energy, but while all energy is mass (and has mass), not all energy is matter. Energy transmitted by heat is a good example-- mass goes with it, but matter does not. S B H arris 02:22, 27 November 2012 (UTC)

conduction of heat in metals

Conduction of heat in metals can occur through electrons, which are matter by any definition. In any case, such distinctions are far too subtle for the first sentence of a wiki article. "Exchange of energy between closed system" is a very confusing phrase, and gains nothing in terms of accuracy. Waleswatcher (talk) 02:30, 27 November 2012 (UTC)

Yes, but the total number of electrons in the metal that is your "system" stays the same, even if some go in and others go out. So nobody cares, as one electron is pretty much like another. The point is not so much that matter is allowed in or out, but whether NET matter is allowed in or out (number of each kind of atom or particles changes). The reason we specify a closed system is the first law of thermodynamics demands it if you state that law in terms of only two RHS terms (work and heat). If you use the first law form that says dU = dq + dw (pretend I put in the deltas) and if you allow net atoms or electrons in or out of your system that has an internal energy U, that changes dU without being either dq or dw, so this equation is wrong. So if you're going to use that equation to define heat, you have to specify "closed". Adding the terms for mass in or out gives you another set of terms, a different equation, and now you have the first law of thermo for open systems, which you've seen with the sigma and the particle numbers and chem potentials, etc. If you want to know how an electric current into and out of your system counts, most texts define this as a sort of "work" (it's potential*dC) where C is the charge that goes in and comes out with DC, or the charge that wiggles back and forth in AC.

By the way, "convection" doesn't necessessarily require an open system, since heat may be transfered into and out of your system to the surroundings by diffusion, even in convection. Mass moves (is advected) in the surroundings. If you want to analyze energy tranfer within the fluid plume, only then are you looking at an open sytem. As far as the system transfering heat to the fluid, that can remain closed in analysis. S B H arris 03:49, 27 November 2012 (UTC)

It improves communication and saves time to carefully specify the formalism one intends. Electric current carried by electrons can be considered as a whole discrete body macroscopic process, when one may think of it as doing work. Or it can be considered at a phase boundary, or in a continuous medium, or both at once, when it is connected with the Seebeck and Thomson and Peltier effects. Considerations like this apply also to convection.Chjoaygame (talk) 05:31, 27 November 2012 (UTC)

Okay, here's a problem that is fun. We stick one electrode in an object or even a person on an insulated stand, and ground the other. Now we connect them to a potential, letting their own self capacitance allow them to take a one-way current and build up a charge. Open system. How does their 1/2CV^2 energy compare with internal energy change just from gaining net electrons? And to what potential would you need to charge them before the two kinds of net internal E increase are comparable? Hint--it's comparable to e rest energy in eV. A reminder of how important closing the system is. S B H arris 07:14, 27 November 2012 (UTC)

Okay, here's another problem that is fun: guess what I'm thinking?Chjoaygame (talk) 08:39, 27 November 2012 (UTC)

matter

Just in case, the article on matter on the wiki says " Matter is generally considered to be a substance (often a particle) that has rest mass and (usually) also volume.".

It also states (correctly ) that "Albert Einstein showed[4] that ultimately all matter is capable of being converted to energy, by the formula:

E=mc^{2}\,\!

where

E

is the energy of a piece of matter of mass

m

, times

c 2

the speed of light squared"

Also "An example is positrons and electrons (matter) which may transform into photons (non-matter). However, although matter may be created or destroyed in such processes, neither the quantity of mass or energy change during the process".

But, also, it says "Scientifically, the term "mass" is well-defined, but the term "matter" is not. For this reason, none of the uses of the word "matter" in this article should be considered definitive.".

And then "Matter therefore is anything that contributes to the energy–momentum of a system, that is, anything that is not purely gravity.[17][18] This view is commonly held in fields that deal with general relativity such as cosmology".

There is also the concept of "strange matter", "antimatter", "dark matter", and "dark energy", that complicate matters even more.--Crio de la Paz (talk) 16:21, 27 November 2012 (UTC)

Particle physicists tend to define "matter" as the fermions of the standard model, with the possible exception of neutrinos. So that includes electrons, muons, etc. and composites like the proton and neutron, but not for instance the W and Z bosons (even though they're massive) or the photon. Anyway, a system that allows electrons to flow in or out is obviously not "closed" by any sensible definition. If in some specific process the net flow of electrons is close to zero one can ignore the chemical potential terms, but calling such a system "closed" is very confusing, and I think we should avoid using the term in this article. Instead, we can simply explain that energy is conserved, and net matter flowing in or out contributes to the energy balance, which is hence simplest when the net flow is zero. Waleswatcher (talk) 16:52, 27 November 2012 (UTC)

Waleswatcher writes: "Anyway, a system that allows electrons to flow in or out is obviously not ″closed″ by any sensible definition", and "calling such a system ″closed″ is very confusing, and I think we should avoid using the term in this article. Instead, we can simply explain that energy is conserved, and net matter flowing in or out contributes to the energy balance, which is hence simplest when the net flow is zero." Thermodynamicists are not in general particle physicists, and this article is more about thermodynamics than about particle physics. Thermodynamicists may not use a "sensible definition", but for purposes like the present they often regard the flow of electricity as just that, without concern about whether particles carry it, and do not regard it as flow of matter. It it is true that K & K (1969/1980) and Callen (1960/1985) use the term 'closed' when more recent writers, including the Wikipedia and Reif, would use the term 'isolated'. It is clear from reading p. 227 that there K & K are referring to what more recent writers call 'closed systems'; they do not need to use the more recent terminology because they do not consider the thermodynamics of what more recent writers would call 'open systems' as distinct from 'closed systems'Chjoaygame (talk) 17:23, 27 November 2012 (UTC)Chjoaygame (talk) 02:27, 28 November 2012 (UTC)

Anyway, I agree with Waleswatcher that the word 'body' is convenient here. It did not strike me that SBHarris disagreed with that usage. I had the impression that he was just confirming that Reif and K & K are talking about closed systems, not that he was trying to insist on those very words 'closed system'?Chjoaygame (talk) 17:51, 27 November 2012 (UTC)

open systems

Actually for an _open_ system we have a balance of energy of the form:

dEk/dt+dEp/t+dU/dt=SUM(mi(Hi+vi^2/2+gzi))+q+w

Where: dEk/dt is the increase of kinematic energy of the system, Dep/Dt is the increase of the potential energy of the system and dU/dt is the increase of the internal energy of the system through time. This has to be equal to the sumatory of the enthalpies, kinetic energy and potential energy of the flows of matter into and out of the system, plus the net heat flow into the system plus the net work done on the system . mi is flow of matter "i", Hi it's enthalpy by unit of mass, vi it's velocity and zi it's position in a gravitational field (this can be even generalized more if it is allowed for potential energies that are not gravitational: in that case these potential energies must be taken into account). Of course q might be decomposed in different 'heat flows' either involving differents forms of heat transfer or and w in different forms of power done on the system or done by the system.

The important aspect for a conservation law is that the rate at which a given quantity varies for the system is equal to the net flows of the quantity plus net generation of the quantity within the system (this is useful for, i.e., a balance of mass of an specific susbstance in the mist of a chemical reaction.

As some oher users have pointed above entropy is another quantity that, for all processes that are not 'reversible' or 'ideal' actually might be 'generated' as far as I understand.--Crio de la Paz (talk) 22:51, 27 November 2012 (UTC)

For a simple introduction to an entropy balance see: https://ecourses.ou.edu/cgi-bin/ebook.cgi?doc=&topic=th&chap_sec=06.6&page=theory--Crio de la Paz (talk) 22:57, 27 November 2012 (UTC)

purely thermal interaction

Waleswatcher writes: "As for ″purely″, if we include that term we need to explain what is meant by it - namely, that heat is not work. Otherwise, it clashes with the next sentence." Indeed, otherwise, it clashes with the next sentence. "Purely" is repeated by Reif and is important for his presentation. It is also implicit in that of K & K.Chjoaygame (talk) 03:05, 27 November 2012 (UTC).

Definition of Heat

The problem is that the definition of heat in the article is inconsistent in that it does not distinguish between heat and the transfer of heat. To assist in clarifying this I asked a question - would you .... explain what you accept as the proper name for the kinetic energy in vibrating or colliding particles?. This would help to clear up contradictions in the article. --Damorbel (talk) 09:50, 29 September 2012 (UTC)

Indeed the definition of heat in the article does not distinguish between heat and the transfer of heat. Indeed, the article explicitly says ″In physics, "heat" is by definition a transfer of energy and is always associated with a process of some kind. "Heat" is used interchangeably with "heat flow" and "heat transfer".″ I think editors who watch this page know well enough that you do not like that definition and interchangeable usage, from your many times repeated comments to that effect.

I do not see a good reason why I should try to comply with your gratuitous request that I "explain what [I] accept as the proper name for the kinetic energy in vibrating or colliding particles", to use your words. I can say that your phrase does not give a good definition of heat in physics. In order to understand why this is so and to understand a sound physical definition of heat, one needs to have a fair understanding of thermodynamics, more than is likely to be expressed both adequately for your needs and briefly in this talk page. Your view that this article contains "contradictions" is due to your non-acceptance of the definition of heat that has been reached by consensus for this article.Chjoaygame (talk) 10:38, 29 September 2012 (UTC)

My question is simple, where in the article is the difference between heat (particle vibrations) and heat transfer? The matter is not difficult, particles at a high temperature vibrate with a geater energy than those at a lower temperature; when two (or more) samples matter with different temperature come into thermal contact (by whatever means) energy is transferred from the high temperature to the lower.

After a time the temperatures will equalise, which means that the vibrational energy of the particles is the same and heat transfer stops.

At present the article gives the impression that "heat has stopped" when the temperatures are equal; this can't be true because the particles are still vibrating with a common energy i.e. with a common temperature, even though the heating of the cooler body by the hotter has indeed come to a stop. --Damorbel (talk) 11:18, 29 September 2012 (UTC)

Dear Damorbel, you ask "where in the article is the difference between heat (particle vibrations) and heat transfer?" It seems to you that your question is simple, but in reality it is muddle-headedly posed, and so has no useful answer. Your muddle is of your own making. You find the article hard to understand because you insist on your own muddled approach to heat. By misdirecting your efforts to trying to force that muddled approach onto others, you distract yourself from getting a better understanding. You muddle yourself about a thermodynamic matter by prematurely dabbling in the kinetic theory that provides a microscopic explanation for it. Instead of that, if you spent some time trying to follow the approach of basic thermodynamics itself, you would find that things would become clearer to you.Chjoaygame (talk) 14:36, 29 September 2012 (UTC)

Chjoaygame, the article would be considerably improved if it contained a clear distinction between heat (energy - joules), heat transfer (power - watts or joules/second) and the role that temperature (joules/particle) plays in both. --Damorbel (talk) 06:03, 1 October 2012 (UTC)

Damorbel, you continue to express your view that "the article would be considerably improved if it contained a clear distinction between heat (energy - joules), heat transfer (power - watts or joules/second)..."

The article is based on a view different from yours, but found almost universally in reliable sources on thermodynamics, and accepted by the consensus on which the present article is based. It is that the idea of heat in thermodynamics refers to a quantity of energy transferred in a process. It is fundamental to thermodynamics that heat is a process quantity, not a state quantity. For a discrete process that carries an initial state of a closed system to a final state, with finitely separated initial and final states of thermodynamic equilibrium, the heat transferred is a quantity of energy. For a continuous-time process of a closed system, one can consider the rate of heat transfer as a power, energy transferred per unit time, provided a temperature exists throughout the process and provided some other conditions are satisfied. There is in thermodynamics no "state quantity of heat". The energy status of a closed system or body is described in thermodynamics by its internal energy. It is the message of the first law of thermodynamics that the internal energy is a state variable, and that it cannot in thermodynamics unconstrainedly be split into moieties which are also state variables. The notion of unconstrained splitting refers to the fact that different amounts of heat can be extracted from a body depending on the constraints under which the heat is to be extracted.

The reason for this is that energy of a body which might be available for extraction as heat, microscopically considered, is partly in the internal kinetic energy and partly in the mutual internal potential energy of the constituents of the body, and that the distinction between these two factors cannot be made without constraint for the process of extraction. This is another way of saying that the heat transferred in a process of a closed system is a function of the path of the process; the path of the process is specified in terms of constraints on it.

To judge from what you write, it seems clear that you do not accept the thermodynamic view that I have expressed just above, that is the basis of the present article.Chjoaygame (talk) 07:46, 1 October 2012 (UTC)

Chjoaygame, the concept of heat as the vibrational (kinetic) energy of fundamental particles is well established by kinetic theory, the heat article needs to recognise this, at present it doesn't, e.g. when it has "[Heat is not regarded as being stored within a system]"

Up until now nothing you have written explains what name or function the article should give to the energy stored in the motions of particles. I would be much more inclined to agree with you if you could sort this this out. --Damorbel (talk) 09:22, 1 October 2012 (UTC)

Damorbel, you are insisting on your own personal viewpoint that is fundamentally contrary to the viewpoint taken by the article as it stands, which is the result of consensus of editors based on reliable sources. Your personal viewpoint is a very personal and private reading of the sources. You insist on giving conceptual priority to your reading in terms of "kinetic theory", contrary to the general principle that the thermodynamics of heat is about macroscopic measurements made on closed systems. While you insist on this personal and private reading, you will not be able to understand the consensus viewpoint in terms of thermodynamics, which is that of this article as it stands. Your personal viewpoint is muddled and inconsistent, though you are blind to its defects. The thermodynamic concept that you need to understand is called 'internal energy'. Microscopically it is explained by the internal kinetic energy and the internal mutual potential energy of the constituents of the system. The great discovery of Clausius was that macroscopically for thermodynamics the internal energy is a state variable that cannot be "sorted out" (as you wish) into parts so as to produce part that would be an unconstrained quantity of heat that would be a further state variable. The internal energy discovered, but not named, by Clausius was not recognized by him at first as a quantity of energy; it took him 15 years to come to understand that it was such. Your notion of "the energy stored in the motions of particles" is not a well defined quantity; however much you might wish it to be recognized as a physical quantity, it is just wishful thinking without physical understanding. In chasing "the energy stored in the motions of particles" you are chasing a will-o'-the-wisp invented by you in your own internal word games, without physical understanding. It is possible that you are not to blame for your misunderstanding, but were led to it by would-be self-judged "clever" teachers who thought that they could teach kinetic theory without a prior basis of thermodynamics; this was a regrettable fashion in teaching at one stage.

In order to understand the thermodynamics of heat, you need to abandon your present personal and private viewpoint in this, because it blocks your understanding of the thermodynamical viewpoint. No progress will occur until you grasp this nettle.Chjoaygame (talk) 11:09, 1 October 2012 (UTC)

Chjoaygame, you write (above) "the energy stored in the motions of particles" is not a well defined quantity", I understand from this that you do not accept that this energy is a function of the temperature of the particles i.e E = 1/2m/v² = 1/2k_BT?

You seem to find Clausius slow "The internal energy discovered, ... by Clausius was not recognized .... as a quantity of energy; it took him 15 years to come to understand ...". Is his slowness important to your argument?

So when Clausius wrote an article “On the Nature of the Motion which we call Heat” (Über die Art der Bewegung die wir Wärme nennen - available in English from Google Books) was he wrong?

Clausius writes (on p127, after equ.(9)) "No constant need be added, since, as before remarked, the heat in the gas is proportional to the vis viva [energy] of the translatory motion, and hence to the absolute temperature" --Damorbel (talk) 12:39, 1 October 2012 (UTC)

As I already mentioned several times, while you insist on your personal reading of the matter, you will not be able to understand the thermodynamics of heat. You are now trying to distract attention from thermodynamics by arguing in terms of Clausius' understanding in terms of kinetic theory. You may feel that this is a clever debating move, and indeed it looks good. But it doesn't cut it, because the argument that Clausius is using does not take into account the internal mutual potential energy of the constituents of the body. So, yes, I am saying that Clausius' argument here, on which you rely, is wrong if taken as a general argument for the thermodynamic nature of heat. As I mentioned, Clausius' discovery of internal energy was not at first fully recognized for what it was even by Clausius. The reason I mentioned it was to soften the blow for you when you are eventually struck by the weight of the concept of internal energy, which reduces to nonsense your wishful thinking about heat as a state variable. You are not the only person to have difficulty grasping the concept of internal energy. The article by Clausius that you cite was written in 1857, some years before 1865 when he accepted the understanding of his quantity

U

as internal energy. Your relying on Clausius' 1857 article for your case shows that you will go to any length to hold to your personal and private reading of heat, so as to avoid your gaining an understanding of heat in terms of changes in the internal energy of a closed system, as held by thermodynamics. There are none so blind as those who will not see.

It struck me that perhaps an analogy may help you. Perhaps not; perhaps you will just use it as another distractor to help you hold to your personal view and protect you from physical understanding which you are so strenuously avoiding. The analogy likens the internal energy of a body to the water in a pond. The pond is filled from a stream and emptied by a pump. It also receives water from the rain and from snow and dew. It also evaporates. The analogy likens the stream and the pump to "work" and it likens the rain, dew, snow, and evaporation to "heat". It is not possible by ordinary macroscopic measurements to split the water in the pond into "work" water and "heat" water. You would like to make such a split, but it won't happen.

Dear Damorbel, you are a master of distraction and irrelevant rhetoric, but you are no good at sound reasoning about the physics of heat. I have mentioned before that you are challenged in the logic department. In this case, it seems to me that you are perhaps making the logical error of taking ordinary language as if it had the compositional property that mathematical formulations mostly have. Compositionality means that the meaning of a clause can be determined simply by considering it as a composition of units each of which separately has its respective fixed and definite meaning. That is to say, you are thinking that because one speaks of extracting heat from a body, it follows that it makes sense to think of the body as storing heat. The ordinary language construction makes that look plausible, on the assumption of compositionality, but it is nevertheless wrong in logic, because ordinary speech does not have the compositional property.

You have indeed this time till now succeeded in luring me into trying to have a rational conversation with you, an error which I have previously recognized as an exercise in futility. You are afresh showing your ability to avoid real understanding by admittedly clever rhetoric. I have had a good try at helping you here, perhaps foolishly, given your present characteristics. While I congratulate on so far luring me into a futile exchange, I don't want to continue with it. You are showing every sign that you are unable to bring yourself to attend to reason in this matter, and are hardly likely to change in that respect in this conversation. You can lead a horse to water, but you can't make it drink.Chjoaygame (talk) 15:47, 1 October 2012 (UTC)

Perhaps it may be useful to Damorbel to read exactly why the Clausius 1857 paper does not support Damorbel's view of things as he supposes it does. Clausius had at that time, in 1857, not yet come to call his state function

U

the internal energy. In that paper he still spoke of the "generation and consumption of heat" and used the concept of "interior work". That 1857 use of the word heat by Clausius is not that of present day thermodynamics; in many cases Clausius spoke of "heat" when today we would speak of internal energy, but it was not not till 1865, some years after the 1857 paper to which Damorbel refers, that Clausius started using the term energy for his state function

U

which we now call internal energy. "Interior work" corresponds to what we might today call the internal mutual potential energy of the constituents of the material. For gases, this is usually not as great as the kinetic energy of the molecules, but for liquids and solids it is usually greater. Damorbel wants us to forget about the internal mutual potential energy of the constituents of the material, and so he thinks mostly, it seems, in terms of ideal gases, which behave somewhat differently from real gases and very differently from solids. For ideal gases one can indeed forget the internal mutual potential energy of the molecules. But the thermodynamic concept of quantity of heat tranferred is intended to deal not only with ideal gases but also with real gases, liquids, and solids. So it takes into account not only the kinetic energy that Damorbel thinks about, but also the potential energy that he doesn't think about. Damorbel makes the basic error of building his conception of heat from the kinetic theory of gases, instead of the simpler and more general theory of macroscopic thermodynamics, which is needed to get a full understanding of the nature of heat. Damorbel is not the only person to make this mistake, and often those who make it think they are very clever, and are being more "fundamental". The result is that Damorbel, and sometimes others, get a muddled view of the nature of heat.Chjoaygame (talk) 20:11, 2 October 2012 (UTC)

Chjoaygame, internal energy, U has two components kinetic energy (Q) which is 'heat' and potential energy which has many different forms, chemical bonds, van der Waals forces etc. Potential energy is completely separate from kinetic energy because it, by definition, is about static forces, i.e. it does not involve particle motion; for that reason potential energy is irrelevant to the definition of heat. --Damorbel (talk) 07:30, 3 October 2012 (UTC)

Damorbel, now you have put your cards on the table. Thermodynamics is largely interesting because its definition of quantity of heat transferred is sensitive to internal mutual potential energy, which you say here is irrelevant to your definition of heat. In direct conflict with your view, in thermodynamics, internal energy

U

cannot be unconstrainedly split into two components, one of which would be a state variable that might attract your private label

Q

. This puts you thoroughly in direct conflict with the thermodynamic analysis. You can cite the name of Clausius as a specious rhetorical move, but you have missed understanding the main point of his discovery of

U

. You will remain beyond help until you try to see your mistake here.Chjoaygame (talk) 08:38, 3 October 2012 (UTC)

Chjoaygame, you do not mention temperature. According to Clausius heat (vis viva; energy in modern terms) in a given substance, is proportional to absolute temperature. The energy in different substances at the same temperature is not the same because not all substances have the same specific heat because different substances have differing numbers of (kinetic) DOF (degrees of freedom). Non-kinetic e.g. potential energy, degrees of freedom, have a variable effect on internal energy e.g. zero for a perfect gas, (3 DOF) (there is no potential energy in a (theoretically) perfect gas). Real gases have intermolecular (van der Waals) forces that make them change state (liquify, solidify etc.) at various temperatures. --Damorbel (talk) 09:13, 3 October 2012 (UTC)

In thermodynamics, temperature is related to heat transfer between bodies or closed systems. When two bodies with different temperatures are in contact through a connection permeable only to heat (as noted by Carathéodory), then heat is spontanteously conducted from the one with the higher to the one with the lower temperature. In physical reality, there is no immediate and simple one-to-one relation between the temperature of a body and its internal energy. In examination of the microscopic mechanisms of energy, one finds various indirect and complicated relations between the temperature of a real body and its internal energy. Only in a merely idealized explanation, such as of an ideal gas, does one find more direct and simple relations between the temperature of a body and its internal energy. Yet you are demanding that such merely idealized cases expressed by idealized microscopic models should define your term "heat in a body", as if it were a state variable. The point of the thermodynamic analysis of heat is (without consideration of the microscopic models, which are in general beyond the feasible practical reach of precise calculation) to deal with the non-idealities which you wish to ignore when you engage in wishful thinking in terms of your idealized examples. Your approach ignores and effectively contradicts that of thermodynamics. And you are trying to force its acceptance as a new basis for this article, contrary to the (admittedly not quite unanimous) consensus of editors, and contrary to the weight of reliable current sources.Chjoaygame (talk) 11:53, 3 October 2012 (UTC)

"temperature is related to heat transfer" How? For transfer of energy? For energy to be transferred there needs to two temperatures, the heat source (T₁) and the heat sink (T₂). Which of the two do you have with a fever of 98.4^oF? --Damorbel (talk) 13:47, 3 October 2012 (UTC)

Chjoaygame, what does temperature measure? --Damorbel (talk) 13:50, 3 October 2012 (UTC)

With a temperature of 98.4°F, you don't have a fever.

Temperature measures the partial derivative of internal energy with respect to entropy at constant volume and chemical constitution.Chjoaygame (talk) 13:09, 4 October 2012 (UTC)Chjoaygame (talk) 23:02, 5 October 2012 (UTC)

Chjoaygame, temperature is the energy per particle, as with the Boltzmann constant. Temperature can only be defined at maximum entropy (Thermal equilibrium), or don't you agree. BTW(1), the thermal equilibrium article describes the equilibrium state as existing with >1 temperature thus with entropy <Smax, I intend to correct this. BTW(2) since temperature can only be defined at Smax (dS/dt = 0) how can it be the partial derivative of internal energy with respect to entropy? --Damorbel (talk) 10:10, 5 October 2012 (UTC)

In order to find the answer to your question about the partial derivative, you will need to study thermodynamics.Chjoaygame (talk) 13:59, 5 October 2012 (UTC)

response by WFPM

With regard to the internal motion of a system of particles, The contained energy of the system of particles is considered to be equal to the integral of the sum 1/2 of the squared value of the speed of the individual particles. This is really the heat energy but is usually called the heat. In order to be able to detect and quantitatively measure this value, devices have been created that will read out a variable "temperature" value derived from some observed physical condition (like expansion) of the physical measuring device. This measured "heat" value is then used to infer the heat energy content of the measured system. And then the rules of "thermodynamics" are used to determine how the heat energy content of the system is interchanged with other forms of kinetic energy of motion by the various devices that use heat energy exchange processes as a means of doing work or other physical or chemical accomplishments. But the word "heat" is not a name of anything other than a indication of a "temperature differential" unless it is associated with organization of a specific physical system which can be assessed as to its quantitative physical and/or chemical properties.WFPM (talk) 22:37, 6 December 2012 (UTC)

There are other microscopic forms of energy besides the kinetic energies of translation of the individual particles. These other forms are also important.Chjoaygame (talk) 00:52, 7 December 2012 (UTC)

Well, unless you want to talk about the conversion of mass into energy, I can't think of anything else that the mass can do other than to have kinetic energy of motion. If its volume is confined, then we have the pressure-volume factors. But for the individual particle, about the only thing it can do is to have internal energy of motion. Of course if it is located within a physical force field it has potential energy of motion, and then we have to analyze it as part of a work energy accumulating force field system. But as to its "heat energy" content, we're back to an energy value that's related to some kind of motion. The complication is due to an inability to correctly determine the mass and speed of motion of the moving constituents of the particle.WFPM (talk) 18:44, 8 December 2012 (UTC)