What is heat?

[Tom Booth]

Tom Booth, on 22 August 2011 - 11:41 PM, said:

What is the topic of this thread?

 

~~ WHAT IS HEAT ~~

 

Defining HEAT is the stated theme of this thread is it not? I think everyone here in one way or another has put forward their definition of the term. What reason would you have for objecting to my doing the same ?

 

 

There is this branch of science called physics and within in there is a subject called thermodynamics. The term "heat" has a well-established meaning within thermodynamics and that definition is the answer to your question.

 

 

If you choose to ignore that definition, which you may certainly do, then what you are discussing is something other than physics.

 

I think the question was "What is heat ?" Not what is the specialized meaning of the term but literally, What is it in layman's terms.

 

Of course, I do not know that but that is my assumption.

 

But there is no point in usurping a widely recognized term, like heat, and applying it to something else. That is poor communication, and just plain silly. Call it Oscar, and don't confuse the discussion of Oscar with a discussion of physics.

 

I don't think I'm doing that. I haven't argued for applying the term to "something else". I've argued for dropping the term altogether if anything. If the term were not ambiguous to begin with why would anyone ask the question in the first place ? Why any debate about it whatsoever ? and please don't try to tell me I'm the ONLY ONE having some issue with it. I did not start the thread.

 

You really do need to read a book on thermodynamics.

 

I've read several.

 

"Thermal Radiation", "Heat Radiation" and "Black Body Radiation" are quite often used interchangeably in thermodynamic literature. As if this were not confusing enough, Heat is said to be "Kinetic Energy" in one breath and some kind of apparently abstract non-material "Thermal Radiation" or "Heat Radiation" or "Black Body Radiation" in the next and this is associated with a "Spectrum" which apparently is the EM or Light Spectrum but is often called "Thermal Spectrum", "Heat Spectrum" or "Black Body Spectrum", In some older text "Heat" is associated with "Infrared" and as has been pointed out this is a common misconception so I think it no wonder that someone trying to understand thermodynamics would ask the question: "What is Heat" Anyway ?

 

I'm probably at least as familiar with the literature as the average person wandering in here and I would also like some clarification.

 

I've proposed some solutions that seem to make things clearer in my own mind. I don't see why I should be censured for pointing out the obvious.

 

It would be nice to have some clarification or "cleaning up" of obsolete terminology IMO.

Edited August 23, 2011 by Tom Booth

[finiter]

This seems to me to be a fundamental change in how reality is viewed not just a change in terminology. It was thought that heat itself could radiate. This was discovered to be false, apparently. Something else fundamentally different from heat radiates. This something else is converted to or from Heat at either end but is not itself heat but light. There is no such thing as "Heat Radiation" so why continue to use the outmoded terminology or "consider" something to be something that it isn't ?

Your argument is logical, but whether definitions have been changed accordingly is the question. I don't know whether there is any mechanism, other than an unwritten consensus among the scientists, to redefine the terms.

[DrRocket]

I just got confused with the existing theory and my personal theory (I do not agree with the concept that energy transfer takes place just because a force acts).

Sorry, I saw your reply (post no. 124) just now. My objection is particularly to what you have pointed out "It is application of force over a distance, work, that transfers energy."

 

Bold added.

 

Do you disagree that application of force over distance imparts energy ? This is basic Newtonian mechanics.

[finiter]

Do you disagree that application of force over distance imparts energy ? This is basic Newtonian mechanics.

I do disagree. However, I cannot discuss it in this forum just because the forum rules does not allow that. I will post a reply in the speculation forum.

[pantheory]

I do disagree. However, I cannot discuss it in this forum just because the forum rules does not allow that. I will post a reply in the speculation forum.

You can disagree with theory but never definitions. The word energy has several dictionary definitions. Even in physics energy has more than one meaning. You could say that I prefer another definition of the word energy to explain reality because of XYZ reasons or you could invent another word for what you mean. But not simply to say the definition of the word energy is wrong when it is the primary definition and meaning of the word in physics. It is simply a matter of your knowledge of all the definitions, and your choice of the proper vocabulary to explain your opinion.

//

Edited August 23, 2011 by pantheory

[finiter]

You can disagree with theory but not definitions. You could say that I prefer another definition of the word energy to explain reality because of XYZ reasons. But not simply say the definition of the word energy is wrong, period. It is simply a matter of language and logic.//

The disagreement is in the concept of a particular relation between force and energy. ( Regarding this , I have just posted my view in the speculation forum.)

[DrRocket]

I do disagree. However, I cannot discuss it in this forum just because the forum rules does not allow that. I will post a reply in the speculation forum.

 

If you accept Newton's laws of motion then it is a logical consequnce that the application of a force [math]F[/math] over a distance [math]d[/math] to a body of mass[math] m[/math] results in

 

[math]\frac{1}{2} mv^2 = Fd [/math]

 

and [math]\frac{1}{2} mv^2 [/math] is defined to be the kinetic energy of the body.

 

So to reject force over distance as imparting energy you must logically either reject Newton's mechanics or you must impose a decidedly non-standard definition of energy. Going to special relativity does not materially change this picture. In any case to reject this implies that you are no longer talking about physics. There is no room for speculation when it comes to definitions.

[spin-1/2-nuclei]

The disagreement is in the concept of a particular relation between force and energy. ( Regarding this , I have just posted my view in the speculation forum.)

 

Hello Finter,

 

I think it's great to always question the world around you, and to be especially questioning of concepts that - for whatever reason - don't easily sit well with you.. BUT, in order to avoid confusion - especially when discussing well accepted topics like the basic laws of physics - it is necessary to define what your preconceptions are prior to entering the conversation.

 

That way the people attempting to come to your aid will at least realize that you already understand how these basic concepts are stated to work and you merely disagree with those descriptions. Otherwise, those trying to help you get the false impression that you are confused when you are in reality dissenting from the norm (which is okay). I value freewill above pretty much everything else in the universe. It is - I think - the most precious attribute of mankind.

 

All that being said though,

If you disagree with work resulting in an increase in kinetic energy then nobody here could have given you any satisfactory definition of heat from your perspective. If you'd stated that from the word go I'd still have been more than happy to discuss the definition of heat from your perspective to see if common ground could be reached, and if not, exchanging different ideas without coming to agreement is not a catastrophe. I will look at what you've written in the speculation thread and restrict any future comments to that thread.

 

best of luck with your studies.

Cheers

[finiter]

If you accept Newton's laws of motion then it is a logical consequnce that the application of a force [math]F[/math] over a distance [math]d[/math] to a body of mass[math] m[/math] results in

 

[math]\frac{1}{2} mv^2 = Fd [/math]

 

and [math]\frac{1}{2} mv^2 [/math] is defined to be the kinetic energy of the body.

 

So to reject force over distance as imparting energy you must logically either reject Newton's mechanics or you must impose a decidedly non-standard definition of energy.

The mathematical relation between force and energy is correct and one cannot deny that. If I disagree with that, that will surely imply that I am not talking about physics. But, remember, the relation does not explicitly state from where the energy comes. I argue that the increase in speed is at the cost of internal energy of the body. No energy transfer from outside takes place. That is, if the body is perfectly insulated from all sources of energy, the initial acceleration is not maintainable and you cannot increase the speed further.

[spin-1/2-nuclei]

Your argument is logical, but whether definitions have been changed accordingly is the question. I don't know whether there is any mechanism, other than an unwritten consensus among the scientists, to redefine the terms.

 

Hello Finter,

 

The definitions being used here, might be confusing, but the concepts themselves have been widely tested and hold true. Thus the question of what should we call X or Y should be removed from the description of what X or Y does.

 

This is why mathematics is the easiest way to define scientific concepts, in my opinion. It is very difficult to confuse concepts when looking at their mathematical representation. Dr. Rocket, is a maths expert, and I'm sure if you could relay which concepts you're trying to discuss in different terms to him - a mathematical representation rather than a semantic one would follow - and then we would in fact all be on the same page...

 

Please do not take this the wrong way - as I do not mean this an as insult, but rather just an observation that I readily admit might be wrong. However, from perspective, it seems that in Tom's case, he knows what he is doing mathematically and is arguing the use of terms and conclusions drawn in some cases. This is what I would consider a true difference of opinion, whereas, in you case, after reading your post in the speculation thread, I'm not yet sure if you understand the mathematical representation of these concepts and are truly confused as opposed to simply dissenting.

 

So I take back some of what I said in my previous post. If you could clarify that part for me I would better know how to communicate with you from this point on.

Cheers

[J.C.MacSwell]

 

 

I know all about thermodynamics. I spent most of the afternoon stacking firewood.

 

The pile of firewood went "spontaneously" from a completely disordered pile to a very orderly neat stack. Of course, "I" was involved in the process somehow I think but "I" don't count.

 

Life evolved "spontaneously" on earth. I'm a part of that apparent "negative entropy". You can't hold to the theory of "entropy" (i.e. the second law) without ignoring the obvious fact that you violate it by your existence.

 

 

There is absolutely nothing that you did that is in violation of the second law. If you understood the second law, you would realize that is just another example of the second law at work.

 

Nothing wrong with trying to break it, or speculate how it could be possible (in Speculations) but unless you can stack firewood without use of fuel of any kind then you are only confirming the law once again.

 

The Tom/firewood/fuel system will only increase in entropy over time... quickly if you burn the wood, slowly if you stack it, slower still if you have a nap beside it, but you can't beat it. You cannot manipulate an isolated system to reduce it's entropy.

[finiter]

... in you case, after reading your post in the speculation thread, I'm not yet sure if you understand the mathematical representation of these concepts and are truly confused as opposed to simply dissenting.

I am not questioning the mathematical representation of force and energy. Force may not be having a non-mathematical definition. However, these are strictly mathematical. I am questioning the physical part of it. From where does this energy come physically? The energy for the increase/decrease in the speed can be adjusted due to the thermodynamic change involving the internal energy and speed of the body.

 

 

For example, in the case of the two containers, I would propose that the larger container has a higher energy. When you compress it, it reaches a hot potential state, its energy remaining the same (the work done on it does not alter its energy in any way, but just changes its state). You remove this hotness by cooling it, ie, removing some energy. So the smaller container is at the same temperature as the larger one and has a lower energy. Here, the energy removed is already present in the larger container ( we have not measured the actual energy of the gas, we know the intensity of its potential state or temperature, which I think is not a measure of its energy). The compression (the work done) did not impart any energy to the container.

 

 

I think my view does not go against the mathematical equations.

 

 

[swansont]

"Thermal Radiation", "Heat Radiation" and "Black Body Radiation" are quite often used interchangeably in thermodynamic literature. As if this were not confusing enough, Heat is said to be "Kinetic Energy" in one breath and some kind of apparently abstract non-material "Thermal Radiation" or "Heat Radiation" or "Black Body Radiation" in the next and this is associated with a "Spectrum" which apparently is the EM or Light Spectrum but is often called "Thermal Spectrum", "Heat Spectrum" or "Black Body Spectrum", In some older text "Heat" is associated with "Infrared" and as has been pointed out this is a common misconception so I think it no wonder that someone trying to understand thermodynamics would ask the question: "What is Heat" Anyway ?

 

Heat includes the processes of radiation, convection and conduction. So while all radiation from a thermal source is heat, not all heat is radiation and not all radiation is heat.

 

I'm probably at least as familiar with the literature as the average person wandering in here and I would also like some clarification.

But you have disagreed with everyone who has given a definition of heat that disagrees with your own lay definition. So it would seem you do not want clarification, you want validation. And your view disagrees with that of the physics community (who actually make the definitions). The answer to the question has been given by people familiar with physics.

 

I am not questioning the mathematical representation of force and energy. Force may not be having a non-mathematical definition. However, these are strictly mathematical. I am questioning the physical part of it. From where does this energy come physically? The energy for the increase/decrease in the speed can be adjusted due to the thermodynamic change involving the internal energy and speed of the body.

 

 

For example, in the case of the two containers, I would propose that the larger container has a higher energy. When you compress it, it reaches a hot potential state, its energy remaining the same (the work done on it does not alter its energy in any way, but just changes its state). You remove this hotness by cooling it, ie, removing some energy. So the smaller container is at the same temperature as the larger one and has a lower energy. Here, the energy removed is already present in the larger container ( we have not measured the actual energy of the gas, we know the intensity of its potential state or temperature, which I think is not a measure of its energy). The compression (the work done) did not impart any energy to the container.

 

 

I think my view does not go against the mathematical equations.

 

In the example of the two containers the temperatures were equal and so were the number of particles — they have the same energy. By definition. In fact, that was a given condition in the problem.

[spin-1/2-nuclei]

I am not questioning the mathematical representation of force and energy. Force may not be having a non-mathematical definition. However, these are strictly mathematical. I am questioning the physical part of it. From where does this energy come physically? The energy for the increase/decrease in the speed can be adjusted due to the thermodynamic change involving the internal energy and speed of the body.

 

Okay, my apologies, then I stand corrected about your position regarding the maths.

 

For example, in the case of the two containers, I would propose that the larger container has a higher energy.

 

Okay, well we can test this theory with a thought experiment.

Absent of any external heating and cooling sources the larger container will be colder than the smaller container - meaning that their kinetic energies are not the same. (adiabatic conditions)

 

In isothermal conditions, when we are holding temperature and mass constant.. then their kinetic energies are the same, because their temperatures are the same...

 

Now, as for their internal energies, well that would depend on their specific heat. So, the question now is, if we are using isothermal conditions, and we want to check to see of the internal energies are the same, then we simply must take the two containers of let's say 1g of an identical gas in each..

 

but, remembering that both containers are under a different pressure, and raise or lower their temperature by 1 degree K.

 

So the question is, which container will experience an increase in temperature faster, or will the increase in temperature be the same?

Another question will be covered below..

 

Here, the energy removed is already present in the larger container ( we have not measured the actual energy of the gas, we know the intensity of its potential state or temperature, which I think is not a measure of its energy). The compression (the work done) did not impart any energy to the container.

 

The potential energy is not the same as the kinetic energy. When talking about molecules the potential energy is best described by the structural arrangement of the atoms in the molecules and with supramolecular structures as the arrangement of the molecules in the supramolecular structure. So now we must talk about the molecules and the chemical potential.

 

A molecule has a higher chemical potential in areas of higher concentration and a lower chemical potential in areas of lower concentration.

 

In thermo (when holding entropy and volume fixed) - the chemical potential is described as the amount the system's energy would increase if one additional particle was added to the system. At equilibrium chemical potentials are equal, and no energy is being released - i.e. - no energy is being converted to kinetic energy and increasing the temperature of the system.

 

Mathematically speaking:

 

a.) temperature, is the derivative of entropy with respect to energy.

 

b.) chemical potential: In order to get equilibrium from two reactive systems we need the derivative of entropy with respect to the number of molecules. The ratio of the chemical potential over the temperature.

 

c.) Pressure: In order to get equilibrium from two systems with differing volumes we use the derivative of entropy with respect to volume. Which can be viewed as the ratio of pressure over temperature.

 

I will give you a hint to help with the thought experiment.

Increasing the pressure on chemical reactions involving gasses increases the rate of the reaction, but increasing the pressure on reactions of solids and liquids does not.

Q. In the case of your two containers the temperatures are the same, but the pressures are not. Thus if the conditions in the two containers are kept as described in your question and a reactive substrate is added to the gasses, the reaction of one container will go faster, but the question is, why and can this increase in rate be attributed to a higher internal energy - with respect to chemical potential - in one container over the other?

 

*note remember what I said above about chemical potential and concentration.

 

I think this is a good place to stop and check our bearings to see that they match up..

Cheers..

 

Another hint:

 

"Internal energy has two major components, kinetic energy and potential energy. The kinetic energy is due to the motion of the system's particles (translations, rotations, vibrations), and the potential energy is associated with the static constituents of matter, static electric energy of atoms within molecules or crystals, and the static energy of chemical bonds. The internal energy of a system can be changed by heating the system or by doing work on it;[1] the first law of thermodynamics states that the increase in internal energy is equal to the total heat added and work done. If the system is isolated, its internal energy cannot change." - http://en.wikipedia.org/wiki/Internal_energy

Edited August 23, 2011 by spin-1/2-nuclei

[swansont]

No, I admittedly do not understand the second law of thermodynamics.

 

For one thing I would object to anything in scientific circles being referred to as a "LAW". In my mind this is unscientific and stifles the imagination and the possibility of progress.

 

In science a law is a condition that can be expressed in fairly simple mathematical terms. It does not mean it is dogma or something that cannot be challenged.

 

Properly I think it should read the second theory if it is science rather than dogma.

 

Similarly, theory has a particular definition. Theory does not mean guess, or take the place of a law.

 

 

I know all about thermodynamics. I spent most of the afternoon stacking firewood.

 

The pile of firewood went "spontaneously" from a completely disordered pile to a very orderly neat stack. Of course, "I" was involved in the process somehow I think but "I" don't count.

 

You would be wrong about that latter part, making you wrong about the former. You did work on the firewood. The logs did not stack themselves spontaneously. This shows a basic misunderstanding of thermodynamics.

[Tom Booth]

...You did work on the firewood. The logs did not stack themselves spontaneously. This shows a basic misunderstanding of thermodynamics.

 

Well,

 

There are a few things posted earlier I might respond to at some other time but I have a thought on this at the moment so I'll post it before going off to work. (to stack more firewood).

 

My point in my earlier posts made last night was that Life seems to violate entropy. (i.e. 2nd Law.)

 

True, the firewood did not stack itself. A life form stacked the firewood.

 

Your statement above it seems to me, reflects an unconscious assumption that this "Life Form" is excluded from the "system" under consideration. This goes all the way back to the earliest formulations of the "Laws" of thermodynamics.

 

If as suggested earlier I took a nap on the ground, taking the "Tom, Yard, Firewood" system as a whole and viewing it strictly in terms of a collection of inanimate atoms. (i.e. making no pre-judgement in regard to the definition of "animate" or "inanimate") There was an apparent "spontaneous" ordering performed by the collection of atoms that compose the Tom-Firewood-Yard "System".

 

This "Spontaneous ordering" or apparent "negative entropy" took place on a Maco scale over a period of several hours, not nano-seconds.

 

So why is a few seconds of "negative entropy" of a few beads floating in water so Newsworthy ?

 

What is the basis for making a distinction between "animate" and "inanimate" and excluding the latter ?

 

What I am saying is that in order for the "Law" to hold it is necessary to arbitrarily discount "Life forms" as being part of the "System" or to make an arbitrary distinction between "animate" and "inanimate". according to the original formulation of "The Law".

 

This is reflected in the wording of the text or "Laws".

 

i.e. No "inanimate" machine can... such and such and so and so.

 

So what energy was applied to the system that caused the apparent "spontaneous" ordering ?

 

There was a pile of matter on the ground composed mostly of "inanimate" firewood that happened to include a relatively small sleeping life form.

 

Viewed as a simple pile of "inanimate" material, what energy invaded the "system" which suddenly caused a portion of this inert matter to "wake up" and begin putting things in order (stacking the firewood) ?

 

I'm not asking for an answer to that question. I'm just pointing out that "Life" as a factor in the "System" or in thermodynamic calculations has apparently and I think admittedly been excluded as an element.

 

I think this is arbitrary.

 

But this is an entirely different issue than the "Heat" question and probably off-topic for this thread. Just something to think about.

 

-----------------

"II., no inanimate material agency could produce more mechanical effect from a given quantity of heat, with a given available range of temperatures, than an engine satisfying the criterion stated in the enunciation of the proposition."

 

(Source: "The Second Law of Thermodynamics" by William Francis Magie pg 127)

 

"The demonstration of the second proposition is founded on the following axiom:

 

"It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects."

 

(pg 116)

 

-----------------------

[J.C.MacSwell]

Well,

 

There are a few things posted earlier I might respond to at some other time but I have a thought on this at the moment so I'll post it before going off to work. (to stack more firewood).

 

My point in my earlier posts made last night was that Life seems to violate entropy. (i.e. 2nd Law.)

 

True, the firewood did not stack itself. A life form stacked the firewood.

 

Your statement above it seems to me, reflects an unconscious assumption that this "Life Form" is excluded from the "system" under consideration. This goes all the way back to the earliest formulations of the "Laws" of thermodynamics.

 

If as suggested earlier I took a nap on the ground, taking the "Tom, Yard, Firewood" system as a whole and viewing it strictly in terms of a collection of inanimate atoms. (i.e. making no pre-judgement in regard to the definition of "animate" or "inanimate") There was an apparent "spontaneous" ordering performed by the collection of atoms that compose the Tom-Firewood-Yard "System".

 

This "Spontaneous ordering" or apparent "negative entropy" took place on a Maco scale over a period of several hours, not nano-seconds.

 

So why is a few seconds of "negative entropy" of a few beads floating in water so Newsworthy ?

 

What is the basis for making a distinction between "animate" and "inanimate" and excluding the latter ?

 

What I am saying is that in order for the "Law" to hold it is necessary to arbitrarily discount "Life forms" as being part of the "System" or to make an arbitrary distinction between "animate" and "inanimate". according to the original formulation of "The Law".

 

This is reflected in the wording of the text or "Laws".

 

i.e. No "inanimate" machine can... such and such and so and so.

 

So what energy was applied to the system that caused the apparent "spontaneous" ordering ?

 

There was a pile of matter on the ground composed mostly of "inanimate" firewood that happened to include a relatively small sleeping life form.

 

Viewed as a simple pile of "inanimate" material, what energy invaded the "system" which suddenly caused a portion of this inert matter to "wake up" and begin putting things in order (stacking the firewood) ?

 

I'm not asking for an answer to that question. I'm just pointing out that "Life" as a factor in the "System" or in thermodynamic calculations has apparently and I think admittedly been excluded as an element.

 

I think this is arbitrary.

 

But this is an entirely different issue than the "Heat" question and probably off-topic for this thread. Just something to think about.

 

-----------------

"II., no inanimate material agency could produce more mechanical effect from a given quantity of heat, with a given available range of temperatures, than an engine satisfying the criterion stated in the enunciation of the proposition."

 

(Source: "The Second Law of Thermodynamics" by William Francis Magie pg 127)

 

"The demonstration of the second proposition is founded on the following axiom:

 

"It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects."

 

(pg 116)

 

-----------------------

 

It is not arbitrary. Life is not excluded. If it was you would be quite correct, but you are not.

 

The only "seeming" violation is in your imagination.

 

No "seconds" of entropy decreasing took place at any time.

 

Assuming you did manage to stack the wood in such a way that the firewood itself was lower in entropy as a system than it had been previously, it was not an isolated system. Your entropy (and/or your lunch) increased even more.

 

At no time, not even temporarily, did you violate the second law.

[mississippichem]

A true violation would be some interval of time where the entropy of the entire universe increased and did not decrease accordingly. A perpetual motion machine would accomplish this. However, this will simply never happen.

 

Mis-type on my part. Should be:

 

A true violation would be some interval of time where the entropy of the entire universe increased decreased and did not decrease increase accordingly. A perpetual motion machine would accomplish this. However, this will simply never happen.

 

Thought that was worth correcting as it was totally backwards. Sorry

[J.C.MacSwell]

Mis-type on my part. Should be:

 

A true violation would be some interval of time where the entropy of the entire universe increased decreased and did not decrease increase accordingly. A perpetual motion machine would accomplish this. However, this will simply never happen.

 

Thought that was worth correcting as it was totally backwards. Sorry

 

You're setting the bar pretty high for any potential violator. I'd be happy just to get some "free" power.

[swansont]

Well,

 

There are a few things posted earlier I might respond to at some other time but I have a thought on this at the moment so I'll post it before going off to work. (to stack more firewood).

 

My point in my earlier posts made last night was that Life seems to violate entropy. (i.e. 2nd Law.)

 

It doesn't, and doesn't even seem to violate the 2nd law if you have a passing understanding of introductory thermodynamics.

 

True, the firewood did not stack itself. A life form stacked the firewood.

 

Your statement above it seems to me, reflects an unconscious assumption that this "Life Form" is excluded from the "system" under consideration. This goes all the way back to the earliest formulations of the "Laws" of thermodynamics.

 

If as suggested earlier I took a nap on the ground, taking the "Tom, Yard, Firewood" system as a whole and viewing it strictly in terms of a collection of inanimate atoms. (i.e. making no pre-judgement in regard to the definition of "animate" or "inanimate") There was an apparent "spontaneous" ordering performed by the collection of atoms that compose the Tom-Firewood-Yard "System".

 

This "Spontaneous ordering" or apparent "negative entropy" took place on a Maco scale over a period of several hours, not nano-seconds.

 

So why is a few seconds of "negative entropy" of a few beads floating in water so Newsworthy ?

 

What is the basis for making a distinction between "animate" and "inanimate" and excluding the latter ?

 

There is no basis. Life does not violate the 2nd law. You are continually burning food to be able to do work, and do so at about 25% efficiency. Much of that energy is rejected as heat, meaning that you are a continual source of entropy. Further, the energy that fuels you ultimately comes from the sun, so you don't have a closed isolated system. Even when you are able to find local decreases in entropy (like the firewood) it is balanced by a larger increase elsewhere.

 

What I am saying is that in order for the "Law" to hold it is necessary to arbitrarily discount "Life forms" as being part of the "System" or to make an arbitrary distinction between "animate" and "inanimate". according to the original formulation of "The Law".

 

This is reflected in the wording of the text or "Laws".

 

i.e. No "inanimate" machine can... such and such and so and so.

 

So what energy was applied to the system that caused the apparent "spontaneous" ordering ?

 

There was a pile of matter on the ground composed mostly of "inanimate" firewood that happened to include a relatively small sleeping life form.

 

Viewed as a simple pile of "inanimate" material, what energy invaded the "system" which suddenly caused a portion of this inert matter to "wake up" and begin putting things in order (stacking the firewood) ?

 

I'm not asking for an answer to that question. I'm just pointing out that "Life" as a factor in the "System" or in thermodynamic calculations has apparently and I think admittedly been excluded as an element.

 

I think this is arbitrary.

 

But this is an entirely different issue than the "Heat" question and probably off-topic for this thread. Just something to think about.

 

-----------------

"II., no inanimate material agency could produce more mechanical effect from a given quantity of heat, with a given available range of temperatures, than an engine satisfying the criterion stated in the enunciation of the proposition."

 

(Source: "The Second Law of Thermodynamics" by William Francis Magie pg 127)

 

"The demonstration of the second proposition is founded on the following axiom:

 

"It is impossible, by means of inanimate material agency, to derive mechanical effect from any portion of matter by cooling it below the temperature of the coldest of the surrounding objects."

 

(pg 116)

 

-----------------------

That would be The second law of thermodynamics: memoirs by Carnot, Clausius, and Thomson translated by Magie and published 1899. Yeah, things have been polished a little since the time of the founding of the field. Inanimate does not appear in any modern formulation of the second law.

Edited August 24, 2011 by swansont
closed —> isolated

[J.C.MacSwell]

It doesn't, and doesn't even seem to violate the 2nd law if you have a passing understanding of introductory thermodynamics.

 

 

 

There is no basis. Life does not violate the 2nd law. You are continually burning food to be able to do work, and do so at about 25% efficiency. Much of that energy is rejected as heat, meaning that you are a continual source of entropy. Further, the energy that fuels you ultimately comes from the sun, so you don't have a closed system. Even when you are able to find local decreases in entropy (like the firewood) it is balanced by a larger increase elsewhere.

 

 

That would be The second law of thermodynamics: memoirs by Carnot, Clausius, and Thomson translated by Magie and published 1899. Yeah, things have been polished a little since the time of the founding of the field. Inanimate does not appear in any modern formulation of the second law.

 

Historically that's after Maxwell suggested his Demon, but well before Heisenberg introduced his uncertainty principle (which I think sets limits on the Demon's abilities)... so maybe they were deferring to Maxwell's thought experiment??

[swansont]

Historically that's after Maxwell suggested his Demon, but well before Heisenberg introduced his uncertainty principle (which I think sets limits on the Demon's abilities)... so maybe they were deferring to Maxwell's thought experiment??

 

I don't know. But the publication date is an upper limit to when the material was written. The statement was Thomson's and is quoted in Maxwell's The Theory of Heat published in 1872, so it predates that.

[Tom Booth]

It is not arbitrary. Life is not excluded. If it was you would be quite correct, but you are not.

 

OK,... if you say so.

 

Would you agree that at one time "animate" objects (life forms) were conceived to be excluded as obvious exceptions ?

 

If so, at what time or place was there an official change or pronouncement that "animate" life forms would be included in the formulation ? Or no longer excluded rather ?

 

The only "seeming" violation is in your imagination.

 

It seems a great deal about the general theory of thermodynamics involves the imagination and includes what seem to me to be arbitrary definitions with no clearly fixed boundaries.

 

No "seconds" of entropy decreasing took place at any time.

 

Assuming you did manage to stack the wood in such a way that the firewood itself was lower in entropy as a system than it had been previously, it was not an isolated system. Your entropy (and/or your lunch) increased even more.

 

At no time, not even temporarily, did you violate the second law.

 

For example: "isolated system" in particular I've been having some trouble with.

 

Granted, the sun was shining. I had eaten something previously, I was breathing air, etc.

 

If a so called "isolated system" is found to have negative entropy, the argument goes that you just move the boundary until you come up with the right numbers to satisfy the formula. (Or imagine that you have.)

 

The definitions of "System", "open system", "isolated system" don't seem to have any governing rules. It is impossible to win an argument against the second law of thermodynamics not because it is true but because the game is fixed. Heads I win, Tails you lose. This kind of moving boundary argument is something I've seen repeatedly in discussions of the topic practically from its first inception. It seems to me that this is changing the definitions to satisfy what amounts to a belief, I think.

 

If the numbers don't square right you can just redefine your "isolated system". Move the boundary line.

 

So, lets go ahead and do that.

 

Now we include my "lunch" or consumption of "fuel".

 

At this point we have introduced another case of negative entropy. Metabolism.

 

And another. Since my food consisted of various complex organic compounds we would have to include the processes involved in growing plants. Inert molecules (dirt) combining with air and sunshine to assemble themselves into the highly complex cellular formations to be found in the tomato on my sandwich for example.

 

We may have shifted the problem further away from the immediate area but I don't see how this solves the "problem" of life in all its varied forms exhibiting "negative entropy" or creating order out of disorder.

 

We can continue moving the boundary. Redefining what constitutes our "closed system" until we reach the ends of the universe, but by this time I think we have left reality and gone off into literal flights of the imagination.

 

Can it be, or has it ever been "proven" that "the universe" is an "isolated system" ?

 

If the ashes that constitute the inert remains of a human being are scattered around my wood pile and "fuel"; (air, sunshine and a BLT sandwich) is added to the mix, does the pile of wood that was dumped out of a truck then assemble itself into stacks ?

 

But this is all getting rather philosophical and pretty far removed from the subject of heat I think.

 

BTW, I benefited from the exercise. Breathed fresh air and was considerably invigorated by the wood stacking. So how did my entropy increase during the process ?

 

Also, in regard to my lunch. It went from a state of relative disorder as a sandwich to a state of considerably greater complexity as part of my blood and bones, muscles, general cellular structure, mitochondria, ribosomes, lysosomes, enzymes, DNA etc. so how did the entropy or state of disorder of the sandwich increase ?

[swansont]

The definitions of "System", "open system", "isolated system" don't seem to have any governing rules. It is impossible to win an argument against the second law of thermodynamics not because it is true but because the game is fixed. Heads I win, Tails you lose. This kind of moving boundary argument is something I've seen repeatedly in discussions of the topic practically from its first inception. It seems to me that this is changing the definitions to satisfy what amounts to a belief, I think.

No, they are pretty well-defined. A closed system does not allow mass transfer across the boundary but can allow work and heat; you can further restrict the system by calling the boundary adiabatic (no heat) or rigid (no work). An isolated system allows none of those.

 

The arguments presented have been pretty consistent. Your perception is flawed.

[Tom Booth]

 

Life does not violate the 2nd law. You are continually burning food to be able to do work, and do so at about 25% efficiency. Much of that energy is rejected as heat, meaning that you are a continual source of entropy. Further, the energy that fuels you ultimately comes from the sun, so you don't have a closed system. Even when you are able to find local decreases in entropy (like the firewood) it is balanced by a larger increase elsewhere.

 

I find this very interesting. In particular

 

"Further, the energy that fuels you ultimately comes from the sun, so you don't have a closed system."

 

What I am really interested in in regard to all this is how it might apply to a particular design for a Heat Engine of my own invention.

 

I've been told repeatedly by various persons over the years that it cannot work because it would be a violation of the Second Law of Thermodynamics.

 

One of my arguments to the contrary was that the engine is not a closed system and that the fuel to run the engine is ultimately heat from the sun.

 

This seems to be the same as the argument you are putting forth here that Life does not violate the Second Law of Thermodynamics for the same reasons

 

I came to find out recently that Tesla conceived a similar engine that he believed could operate on ambient heat he called a "Self acting engine" - able to run on indirect heat from the sun stored in the medium.

 

He seems to be saying that it would be possible under some special circumstances which he describes quite clearly IMO, to extract heat from the atmosphere (heat ultimately coming from the sun) and convert that heat into a different form of energy so as to leave behind a "Sink" or "Cold Hole" for additional heat energy to flow into and thus be able to extract additional energy from that heat. The energy gained could then be used to expel any residual heat not converted so that the "cold hole" could be maintained indefinitely - so long as at least some of the incoming heat continued to be converted to some other form of energy.

 

It seems to me that my engine design is conceptually identical to what Tesla describes.

 

My question is, regardless of any particular design, conceptually, is Tesla's (or my) idea "a violation of the second law of thermodynamics" ?

 

I posted excerpts from Tesla's article here:

 

http://www.scienceforums.net/topic/46143-stirling-turbine/page__view__findpost__p__619315

 

There are also some diagrams and a GIF animation providing a conceptual "working model" of the engine.

 

I'm sure some posting here have already viewed this, but I would be interested in getting any opinions regarding this 2nd Law question.

Edited August 23, 2011 by Tom Booth