From Spectrum to Heat Transfer

· blackbody radiation
Print Post
Authors

This is a continuation of the previous post Two Proofs of Planck’s Law vs Backradiation with a clarification that the spectrum is like a boxing weigh-in giving information about potential before match rather than actual exchange during match.

It is a common belief that the spectrum of blackbody directly translates to transfer of heat energy according to Planck’s radiation law

  • E(T,\nu ) =\gamma T\nu^2\theta (T,\nu ) ,      (Planck’s Law)

where E (T,\nu ) is the heat energy radiated from a blackbody as a function of temperature T and frequency \nu, \gamma is a universal constant, and \theta (T,\nu ) is a high frequency cut-off factor (with suitable normalization) defined by

  • \theta (T,\nu )=\frac{\bar\nu}{\exp(\bar\nu )-1}, \bar\nu =\frac{\nu}{T},

so that \theta\approx 1 for \bar\nu <1 and \theta \approx 0 for \bar\nu >10.

The corresponding formula for the heat transfer E(T_1,T_2,\nu ) between two blackbodies B1 and B2 of temperatures T_1 and T_2, is commonly written

  • E(T_1,T_2,\nu ) =E(T_1,\nu ) - E(T_2,\nu )    (Gross Transfer)

suggesting that B1 emits E(T_1,\nu ) to B2  and absorbs E(T_2,\nu ) emitted from B2 as backradiation. If T_1>T_2, then backradiation would correspond to heat transfer from a cold body to a warmer body seemingly in contradiction to the 2nd Law.

The contradiction is resolved by rewriting (Gross Transfer) as

  • E(T_1,T_2,\nu )= \gamma (T_1\theta (T_1,\nu )-T_2\theta (T_2,\nu ))\nu^2,   (Net Transfer)

expressing the net transfer from B1 to B2, from warm to cold.

We can thus view (Net Transfer) as the actual transfer, while (Plank’s Law) and the form (Gross Transfer) can be viewed as potential of transfer.

We thus make a distinction between potential and actual transfer, and we understand that the confusion concerning backradiation comes from mixing up potential and actual heat transfer. What counts in the end is the actual transfer, not the potential of transfer.

Backradiation can thus be seen as a potentiality, not as an actuality and thus is not physical reality but only fiction. Potentiality without actuality is not science, only science fiction.

93 Comments

Comments RSS

  1. Tor

    Are you aware that heat transfer is nothing more then energy transfer?

    It seems that you claim that local optical properties, like reflection depends on surrounding objects and not Fresnel’s equations.

    What do people working with spectroscopy think about this?

    Reply

    • iceskaterfinland

      Tor, heat cannot be transferred by radiation. Heat only exists as atomic vibrations in a body.

      Similarly you cannot transfer the vibrations of a piano wire via radio to a listener at a distance.

      All you can achieve is a replication at a distance of the heat or sound.

      Most people do not say ‘i am transfering my voice to the other phone’ because they realise their voice only exists as movement in air which cannot be transferred over great distances.

      The human voice at the microphone is unique and whatever is at the other end is a different thing.

      You can though argue that heat can be transferred because statistically it appears to be the same thing when we measure it at the other end – unlike the voice which is always distorted by the human contrived pick up, sending and receiving apparatus.

      Reply

      • iceskaterfinland

        Which is then the curious thing about this theory. It says something is impossible because of the 2nd law and yet the impossible thing is never happening anyway, unless a very small statistical sample of molecules is taken, where statistically it is possible for more than one object to heat another in apparent contradiction of the laws created by those who talked of statistics when creating the laws.

  2. iceskaterfinland

    Infrared cameras

    It is claimed that an unheated thermally and vacuum isolated microbolometer used in a thermal camera is *heated* by the emissions being focused upon the absorber which is being measured for resistance changes.

    Since there is a clear relationship between temperature and resistance and the camera can detect images from both hotter and colder objects than the detector, *and* display their temperature *accurately* if their emissivity, is known this appears to be a demonstration of a cold object warming a warmer object.

    It appears to be possible via the optics

    For example, A part of a cold object one degree colder than the distant camera, can only communicate with the camera by sending approximately parallel emissions towards the cameras Germanium lens which then focuses this part of the objects image on an absorbing detector.

    Therefore the energy arriving from the distance object is a subset of the objects emissions for that part of the objects image. However, the detector emits in all 360 directions and can only send back a tiny amount of energy to the colder object one degree colder than the detector.

    Therefore more emissions come from the colder object than come from the detector to the warmer object.

    The detector is incidently part of an array of detectors so that a detector block of about 1.5″ by 3″ (inches) can contain about 320,000 detectors *each* equivalent to a single radiation thermometer!

    Reply

    • iceskaterfinland

      Correction: Therefore more emissions come from the colder object than come from the warmer detector to the *colder* object

      Reply

  3. Tor

    @iceskaterfinland

    “Tor, heat cannot be transferred by radiation. Heat only exists as atomic vibrations in a body.”

    Ok, I admit I expressed that one rather clumsy. Since heat is a word used in so many ways I tried to use it in the sense that I guess mr Johnson uses it.

    I’m not sure that I agree with your definition though. Not if we want to define it in a stringent manner.

    I would say that heat is the energy in transition over a level curve of the temperature gradient in relation to conduction.

    This is a more stringent way to look at it. How does radiation energy fit into this?

    Radiation is one body influencing another body with a force. Hence energy transmission by radiation is better seen as one body doing work on the other. No heat is exchanged.

    This is all seen in the differential expression of the first law of thermodynamics

    dU=dQ+dW

    That is the internal energy U is changed by a heat process dQ and the work done dW. dQ comes from conduction of energy due to a temperature gradient.

    Reply

    • iceskaterfinland

      but one body does not influence another body with a force according to the standard theories of radiation. radiation from your body around the time of your birth that managed to get out of a window to space is still travelling thru space and will be for the next millions of years.

      Does a gun influence the target with a force?

      Reply

      • Tor

        There’s no reason to get all semantic here =)

        I think we both agree that the important thing is that there is no heat transmitted. Not in the stringent sense.

        Electric charges interact with electromagnetic fields that transmits the Lorentz force. So sure, one should maybe say that it is the electromagnetic field that does the work, in the same way as the bullet from a gun does the work.

        The analogy has a flaw though, the bullet will create a temperature gradient due to friction and hence there is heating. While the electromagnetic field deposit all its energy when interacting and this energy gets thermalized later.

    • iceskaterfinland

      the laws of thermodynamics dont work all of the time.

      Here is Lord Kelvin:

      http://zapatopi.net/kelvin/papers/kinetic_theory.html

      “It is a strange but nevertheless a true conception of the old well-known law of the conduction of heat to say that it is very improbable that in the course of 1,000 years one half the bar of iron shall of itself become warmer by a degree than the other half; and that the probability of this happening before 1,000,000 years pass is 1,000 times as great as that it will happen in the course of 1,000 years, and that it certainly will happen in the course of some very long time.”

      So maybe the next time we accuse somebody of leaving the stove on we need to remember this!

      Reply

      • iceskaterfinland

        Sorry. In my haste i was forgetting this was a thought experiment where that bar is covered with a heat impermeable varnish

        “But let it be remembered that we have supposed the bar to be covered with an impermeable varnish. Do away with this impossible ideal, and believe the number of molecules in the universe to be infinite; then we may say one half of the bar will never become warmer than the other, except by the agency of external sources of heat or cold.”

  4. Tor

    Claes Johnson,

    in your model do you agree to that the external field does work on the oscillators?

    Reply

  5. claesjohnson

    Yes, the external field interacts with the oscillators and heats them above their cut-off freq.

    Reply

  6. Tor

    But energy transmission by work is not heating.

    dU = dQ + dW

    Here dQ=0.

    Maybe confusion about the second law and radiation originates when there is no stringent use of what heat is.

    Reply

  7. claesjohnson

    Heat is internal energy, and internal energy is total energy minus kinetic/potential energy.
    Read my book on Computational Thermodynamics if you want to understand the 2nd law.

    Reply

  8. Tor

    You claim

    “Heat is internal energy, and internal energy is total energy minus kinetic/potential energy.”

    Wikipedia may not be an fully authoritative source but there we have easy access to a modern definition of heat.

    http://en.wikipedia.org/wiki/Heat#Definitions

    “Any spontaneous flow of energy from one system to another caused by a difference in temperature between the systems is called heat.”

    So here it is not internal energy.

    Reply

  9. Tor

    Interestingly I also looked at Planck’s investigation in the matter of radiation interaction between two blackbodies with different temperature. This is in his Theory of Heat Radiation p. 97-98.

    His conclusion there is that from the 2nd law,

    “Emission without simultaneous absorption is irreversible, while the opposite, absorption without emission, is impossible in nature”

    How is this possible with a one way transfer??

    Reply

  10. claesjohnson

    Tor, you have to make a distinction between absorption followed by emission, and absorption causing heating (instead of emission). Planck’s model is incomplete since it does not contain the completely fundamental aspect of heating as increase of internal energy. In Planck’s model whatever is absorbed is emitted directly, without possibility of heating, and half of the story is thus missing.

    Reply

  11. Tor

    Is it really? It doesn’t say where the energy for the emission comes from, just that it has to emit to compensate for decrease in entropy.

    Reply

  12. Tor

    On top of that, your model does not model blackbodies in the sense that everybody else defines them.

    And further, it is far from certain that materials have the optical properties that is required from your model.

    Reply

  13. Tor

    And you seem to use a definition of heat that differs from how everybody else defines it these days.

    Reply

  14. Richard T. Fowler

    #1158

    But Claes’ theory assumes that entropy is not real. So isn’t the theory accounting for that? Then the only remaining question is: Is it reasonable to suppose that there is no entropy? That it was just a mistake from the beginning?

    Do I have that right, Claes?

    Reply

  15. Richard T. Fowler

    #1160

    That is not true. There were two modern definitions given on that page. You only quoted one. There is a diagram just to the right of that that is clearly applying the other one.

    Reply

  16. Tor

    “But Claes’ theory assumes that entropy is not real. So isn’t the theory accounting for that?”

    Saying that doesn’t invalidate the second law. It is not entropy that forbids one way transfer according to Planck, it is the second law.

    “There is a diagram just to the right of that that is clearly applying the other one.”

    The system sketch says the same thing, heat can change the internal energy, it isn’t internal energy.

    Reply

  17. Richard T. Fowler

    “The system sketch says the same thing, heat can change the internal energy, it isn’t internal energy.”

    Sir that is a false statement. Since you seem unable to read the statement corrctly, I will quote it here for the benefit of other readers:

    “Heat may flow across the boundary of the system and thus change its internal energy.”

    That is clearly using the other modern definition, the one you don’t want to talk about.

    Reply

  18. Tor

    You mean that one?

    “The energy transferred from a high-temperature system to a lower-temperature system is called heat.”

    That one is fully equivalent and says that heat is a conduction process.

    Reply

  19. Richard T. Fowler

    No, it says heat is a certain type of energy. I have been assuming you know English. Perhaps that was premature.

    Reply

    • iceskaterfinland

      Richard, I dont see it is helpful to talk like this. It did not work for me.

      Reply

  20. Tor

    I assume you are not a physicist.

    It is a little bit sloppily written because the heat only exists in the transition over the system border. You can never identify where the energy came from after it has thermalized in the system.

    Reply

  21. claesjohnson

    Entropy has no clear physical meaning. I use the definition of heat as internal energy of thermodynamics. And internal energy + kinetic/potential energy = total energy which is conserved.

    Reply

  22. Tor

    “Entropy has no clear physical meaning. I use the definition of heat as internal energy of thermodynamics.”

    Do you have a moder source on that?

    Reply

  23. Tor

    The definition of heat that is.

    Reply

  24. Tor

    I thought I’d sum up the important unanswered questions so they don’t scatter around (pun intended).

    1) How does the spectra for black light look according to your model? How does it compare to measurements and Planck’s law?

    2) Modern source on the thermodynamical definition of heat. Is it possible to find any that is consistent with yours?

    Reply

  25. claesjohnson

    1 it looks like the usual Planck spectrum and thus conforms to measurements.
    2 heat in thermodynamics is internal energy and internal energy = total energy – kinetic/potential/chemical energy, and this is the definition I use.

    Reply

  26. Tor

    1. Does it have the same exponential cut of as seen in measurements? Could you show some plots for representative temperatures?

    2. Kinetical + potential energy = sensible energy

    Chemical energy = energy in molecular bonds

    So left is nuclear energy, latent energy associated with phase changes and electric and magnetic dipole moments.

    Inner energy is the sum of these energy types.

    What of them are the heat then in your opinion since you define heat as internal energy – sensible energy – Chemical energy.

    Reply

  27. claesjohnson

    The cut is similar to that seen in

    The set-up is thermodynamics with internal energy = vibrational energy of resonators = sum of kinetic and potential energies of resonators. In addition there is radiation energy and forcing energy, and there is a balance between all these energies.

    Reply

  28. Tor

    “The cut is similar to that seen in”

    Seen in what? Why don’t you just show your plots?
    ——————————————————————

    Am I getting you right that you mean that heat is sensible energy in matter?

    Reply

  29. claesjohnson

    More computations are on their. As of now the theory shows the cut-off for anyone interested in reading theory. Yes, I use heat as sensible energy.

    Reply

  30. Tor

    So the computations where you show that your theory gives

    Planck’s law = lambda^-5 * 2hc^2/(exp(hc*beta/lambda)-1)

    including fundamental constants is not done yet?

    Why do you then claim to have proven Planck’s law? Your theory looks semi-phenomenological as for now.

    Reply

  31. Tor

    Heat in that sense is used in engineering of heat transfer. Let me quote Wikipedia since there is an easy access there

    (http://en.wikipedia.org/wiki/Thermal_energy)
    Thermal energy is distinct from heat. In the strict use in physics, heat is a characteristic only of a process, i.e., it is absorbed or produced as an energy exchange, but it is not a static property of matter. Matter does not contain heat, but thermal energy. Heat is thermal energy in the process of transfer or conversion across a boundary of one region of matter to another.[1]

    (http://en.wikipedia.org/wiki/Thermal_energy#Distinction_of_thermal_energy_and_heat)
    Distinction of thermal energy and heat

    In engineering and technology, and particularly in fields that deal with civil energy use and conservation in building construction, heating systems, and power generation, heat and thermal energy are often indiscriminately used interchangeably.
    In thermodynamics, heat must always be defined as energy in exchange between two systems, or a single system and its surroundings.[5] According to the zeroth law of thermodynamics, heat is exchanged between thermodynamic systems in thermal contact only if their temperatures are different. For the purpose of distinction, a system is defined to be enclosed by a well-characterized boundary. If heat traverses the boundary in direction into the system, the internal energy change is considered to be a positive quantity, while exiting the system, it is negative. Heat is never a property of the system, nor is it contained within the boundary of the system.
    In contrast to heat, thermal energy exists on both sides of a boundary. It is the statistical mean of the microscopic fluctuations of the kinetic energy of the systems’ particles, and it is the source and the effect of the transfer of heat across a system boundary. Statistically, thermal energy is always exchanged between systems, even when the temperatures on both sides is the same, i.e. the systems are in thermal equilibrium. However, at equilibrium, the net exchange of thermal energy is zero, and therefore there is no heat.
    Thermal energy may be increased in a system by other means than heat, for example when mechanical or electrical work is performed on the system. No qualitative difference exists between the thermal energy added by other means. There is also no need in classical thermodynamics to characterize the thermal energy in terms of atomic or molecular behavior. A change in thermal energy induced in a system is the product of the change in entropy and the temperature of the system.
    Heat exchanged with a system may cause changes other than a change in thermal energy. For example, it may cause phase transitions, such as melting or evaporation, which are changes in the configuration of a material. Since such an energy exchange is not observable by a change in temperature, it is called a latent heat and represents a change in the potential energy of the system.
    Rather than being itself the thermal energy involved in a transfer, heat is sometimes also understood as the process of transfer, i.e., it functions as a verb.

    This really matters if you want to address more fundamental issues, like energy transfer with light under thermal equilibrium, which is exactly what Planck’s law is about. Reading Planck’s work in the matter really emphasizes this.

    One good example how this really matters can be seen in the article about thermal radiation

    (http://en.wikipedia.org/wiki/Thermal_radiation)

    In engineering, thermal radiation is considered one of the fundamental methods of heat transfer, although a physicist would likely consider energy transfer through thermal radiation a case of one system performing work on another via electromagnetic radiation, and say that heat is a transfer of energy that does no work.

    Under normal circumstances, none of this matters. But now you are discussing and make claims about very fundamental issues, it is dead serious that you have full compliance with what fundamental theory claims.

    Reply

    • iceskaterfinland

      Tor, I have never heard that Heat is not contained in an isolated system. And neither had John Tyndall back in 1860 when he was making foundation observations about emission and absorption of molecules. Heat for him was molecules in motion or radiant heat/heat rays

      It could be the Wiki version is an ISO introduction.

      Reply

      • Tor

        What is your scientific background?

      • iceskaterfinland

        Tor, I have a scientific background. I suspect I am older than you and either never learnt the Wiki way or over the years whatever i learnt over 30 years ago has been forgotten.

        I think it is a valid thing to say that older people will not have the same conceptions of heat as Wiki. John Tyndall for example was one of the outstanding scientists of his day who is still well regarded and remembered.

      • iceskaterfinland

        Dont forget that in the old days, heat travelled in the ether as a calorific ray or heat ray and was essentially the same thing that was contained in an object.

        If molecular motion is today called thermal energy, todays view is that heat gets transfered in one direction by radiation and thermal energy travels in both directions.

        Heat is to my way of thinking today a way of describing things with mathematics rather than a concrete thing as it was in the past.

        In modern terms for example we can properly say the Sun is hot, not because it contains enormous thermal energy but because it can transfer energy to other systems that have less thermal energy.

        The whole thing about the words hot and cold is conceptually different to the way i ever thought about it before.

        However i think you are right to want to ensure there is a consistant definition of heat and so forth.

      • iceskaterfinland

        I found this on physics forum:

        There is general agreement that ΔQ is “heat flow”. But, apart from that, “heat” is a loose term that can be used to refer to different things. The confusing use of the term “heat” may be historical. Heat was originally thought to be some kind of substance that flowed between bodies.

        “Heat flow” is embodied in the first law of thermodynamics

        ΔQ=ΔU+W

      • iceskaterfinland

        And this from an assistant lecturer with a Phd and chemistry background who shares my view of these terms

        Click to access openres.pdf

        “Heat IS thermal energy. It is the energy associated with molecular motion, including translation, vibration, and rotation.

        Infrared rays are a segment of the electromagnetic spectrum. Infrared radiation is not the same thing as heat! Yes, hot things emit infrared, but that is simply “black body radiation”: make them hotter still, and they will emit electromagnetic radiation in the visible, UV, and even X-ray regions.

        Rubbing two rocks together makes them hotter. In thermodynamic terms, heat is being added to the rocks. This is NOT electromagnetic radiation, though the rocks will emit electromagnetic radiation characteristic of their new temperature.

        Richard E. Barrans Jr., Ph.D.”

  32. claesjohnson

    Read my proof and then say something sensible about it or quit. It is a model and the proof gives the first understandable account of the phenomenon of blackbody radiation as a phenomenon of near-reasonance in a resonant system with small damping. If you don’t understand, point to your hang-up and I will explain.

    Reply

  33. claesjohnson

    Tor: I urge to read also my book on Computational Thermodynamics if you are interested in following my argument. If you don’t want to read what I write, please direct your energy to something else than putting friction into the system for the sake of it.

    Reply

    • iceskaterfinland

      Claes, Either you are deleting my comments made in reply to your own comments or there is a bug in your software.

      Reply

      • iceskaterfinland

        That one appeared. Your pdf seems to have the blue and the red mixed up on the front page and on fig 4.1 This is the fourth time i have attempted to notify you of that 🙂 The previous times i used the link of the PDF

  34. Tor

    Iceskaterfinland, so what is your background? (I’m just curious. My own is a master in engineering physics)

    As I wrote, Wikipedia is good because it is accessible. And further it describes exactly the points that was lectured a couple of years ago when I attended lectures relevant for this matter.

    Heat may be the most misused term in science.

    Please read, ‘Heat is not a noun, Am. J. Phys., Vol. 69, No. 2, February 2001 p. 107’, it’s illuminating!

    Reply

    • iceskaterfinland

      I dont think it so relevant that i have a degree in applied analytical chemistry. I think you are forgetting that your foundation experiences are taught by a group of people with opinions and it could be there is a group of people who taught you and also inspired the amateur editors of wiki to produce all that stuff for wiki, and then elsewhere there are another group of people with opinions.

      It seems to me that I was taught differently to you and that it is not my memory that is faulty.

      I will try and see if i can find out how your version of heat has arisen.

      By the way do you have a definition for “sensible energy?”

      Reply

      • Tor

        Sure,

        sensible energy corresponds to the excitation of the inner mechanical degrees of freedom in a quantum mechanical sense, so it includes electron excitation and spin.

        As I wrote, heat is one of the most misused terms in science. When it comes to engineering, it’s not that important. It becomes important when you want to draw more fundamental conclusions.

        Did you read the article?

    • iceskaterfinland

      Tor, The Wiki definition does not make sense

      “Heat is never a property of the system, nor is it contained within the boundary of the system”.

      According to this if you place a bar of metal in a system that is hot at one end and cold at the other, heat is not travelling along that bar.

      Also if you had a lump of lead a few meters high and it falls to the ground in the system no heat is created.

      Reply

      • Tor

        “According to this if you place a bar of metal in a system that is hot at one end and cold at the other, heat is not travelling along that bar.”

        It depends on how you look at it. If you set up the bar divided as two systems, then you have heat at the boundary between the systems.

        If you have your whole as one system, the energy in the hot end are already in the system.

        How does the internal energy change? There is no \delta U ! How could there be \Delta U ??

        Remember the first law, \Delta U = \delta Q – \delta W.

        This is a really important point. Heat is dependent on how the system is described. Say that you attach a resistor to one end of the rod. If you see this resistor as different from your system, there is heat since energy goes from the resistor conducting into the rod, giving it sensible energy, there is \Delta Q and no \Delta W.

        If you include your resistor in the system description, there is work done on your system, you push electrons inside it and that creates sensible energy in the system, there is \Delta W but no \Delta Q.

        You see the important point?

        Try to apply it to your lump of lead!

      • Tor

        As a side note.

        I do know of a more modern type of thermodynamics that do model heat as something contained in systems and that flows between them. But there is a big but. They use heat as a synonym for entropy. This should not be confused with “classical” thermo.

        This book is about that approach,

        I do intend to read this one more carefully when I get the time.

      • Tor

        And the really important point then.

        How does this connect with light?

        Electromagnetic waves interact with a volume, so it is necessarily active in the system, it is work done on the system. There is no thermal gradient that drives the energy over the border, hence no heat.

      • iceskaterfinland

        >>Try to apply it to your lump of lead!

        I really cannot follow you so far

        Before the lead falls there is an amount of potential energy. Or ability to do work.

        After the lead falls that previously available energy has dissapeared and additional heat is created.

    • iceskaterfinland

      >> Heat is not a noun.

      I cannot find that article and you supplied no link. Maybe you are at a university?

      However from googling it appears that the ‘heat is not a noun’ is in reference to the first law of thermodynamics

      “”In all cases in which work is produced by the agency of heat, a quantity of heat is consumed which is proportional to the work done; and conversely, by the expenditure of an equal quantity of work an equal quantity of heat is produced.”

      Evidently in a system there *can* exist a quantity of heat.

      And long before wiki came along people who knew about physics thought so too:

      Thermodynamics Enrico Fermi

      http://books.google.fi/books?id=VEZ1ljsT3IwC&lpg=PP1&dq=thermodynamics&hl=fi&pg=PA29#v=onepage&q&f=false

      “By means of friction we could transform this work into heat again, and with this heat raise the temperature of a given body,”

      So obviously the heat exists before the transfer to raise the temperature of the given body

      Reply

      • Tor

        Sorry, you can’t read it if you have no subscription. My bad.

        Let me ask you this instead.

        Heat happens when two systems with different temperature (measure of mean sensible energy per degree of freedom) conducts inner energy due to molecular collision when in contact.

        Before contact there is only sensible energy. After contact and separation, there is only sensible energy. Where is the heat?

        If you want to equate part of the inner energy with heat, what do you gain by doing so?

        Read this again

        “According to this if you place a bar of metal in a system that is hot at one end and cold at the other, heat is not travelling along that bar.”

        It depends on how you look at it. If you set up the bar divided as two systems, then you have heat at the boundary between the systems.

        If you have your whole as one system, the energy in the hot end are already in the system.

        How does the internal energy change? There is no \delta U ! How could there be \Delta U ??

        Remember the first law, \Delta U = \delta Q – \delta W.

        This is a really important point. Heat is dependent on how the system is described. Say that you attach a resistor to one end of the rod. If you see this resistor as different from your system, there is heat since energy goes from the resistor conducting into the rod, giving it sensible energy, there is \Delta Q and no \Delta W.

        If you include your resistor in the system description, there is work done on your system, you push electrons inside it and that creates sensible energy in the system, there is \Delta W but no \Delta Q.

        You see the important point?

        Try to apply it to your lump of lead!

        Let me know when it hits you. I do admit that it is subtle 😉

  35. Tor

    I really like the statement of the first law in that article.

    Adiabatic work is path independent

    So clear, so nice, so elegant. And no reference to heat! 🙂

    Reply

  36. Tor

    Then introduce Q (don’t call it heat) as

    Q = Delta U – W

    Reply

  37. Tor

    Oh, sorry I forgot.

    I have looked at the texts you are referring to Claes.

    You must motivate more strongly why this isn’t a phenomenological model.

    So I further don’t see how this could have fundamental implications.

    Reply

  38. Tor

    “>>Try to apply it to your lump of lead!

    I really cannot follow you so far

    Before the lead falls there is an amount of potential energy. Or ability to do work.

    After the lead falls that previously available energy has dissapeared and additional heat is created.”

    Ok, depending on your view, different things can happen.

    But in the end all the potential energy ends up as inner energy.

    One way to see it. Led is soft. So when it hits the ground it gets deformed. This means that work has been done on the system of lead. This increases the inner energy and therefore the temperature. If the surface of contact to the ground has a positive temperature gradient to the ground then energy will be conducted to the ground, this is heat.

    Reply

    • iceskaterfinland

      All you are doing is finding more and more ways to insist that your *new* defininition of heat is correct and that the one that has been around since the laws of thermo were created is wrong and for no good reason at all

      Heat is far more meaningful and useful than ‘inner energy’.

      Reply

      • Tor

        Oh, I don’t think that the definition can be seen as *new*.

        I think it was Max Born who introduced it to get a precise meaning of it so it would be wrong to call it new.

        It’s all there in the usual expression of the first law,

        dU = dQ – dW

        and as you know the d:s in dQ and dW are not exact differentials. So no functions of state!

    • iceskaterfinland

      >>Heat happens when two systems with different temperature (measure of mean sensible energy per degree of freedom) conducts inner energy due to molecular collision when in contact

      Who has created this defininition??

      Obviously it is a recent creation

      Reply

    • iceskaterfinland

      It appears the definition has come from

      Zemansky and Dittman (1997) state that “heat is internal energy in transit.”

      In their intermediate text book for undergraduates.

      Apparently by 1997 Zemansky had already died.

      Reply

  39. iceskaterfinland

    I feel like you are obfuscating

    When the lead falls the lead gets hotter.

    The heat exists before it gets tranferred out of the system

    It is crazy to say that heat is something being transferred where we are not allowed to call what is being transferred heat.

    The heat exists before it is transferred

    Reply

    • Tor

      You really do not get the subtle point.

      Have you read the MIT links?

      Reply

    • Tor

      If something is heat from one viewpoint and work from another.

      Exactly how can there exist heat in an absolute sense?

      Reply

      • iceskaterfinland

        you seem fixated by transfers

        It makes no difference if the water is heated by the hot resistor or by electricity!

        The water has what we call heat from either of your viewpoints.

        You say there is some subtle point here. 🙂

        there is none. The water got hot!

      • iceskaterfinland

        if the hot resistor is cooling to heat the water there is no heating.

        But that is not the point

        if the lead falls it gets hotter

    • Tor

      Do you say that work exists in a system before it performs work on another?

      Reply

      • iceskaterfinland

        the concept of potential energy to do work is well established.

        The first law is a statement about conservation of energy.

        “”In all cases in which work is produced by the agency of heat, a quantity of heat is consumed which is proportional to the work done; and conversely, by the expenditure of an equal quantity of work an equal quantity of heat is produced.”

        The lead falls. The work is done. heat is produced

  40. Tor

    This kind of proves my original point. Heat is confusing since it is used in many non-rigorous manners.

    You for instance seem to confuse temperature with heat.

    Reply

  41. iceskaterfinland

    No. You just seem to be in love with a definition of heat that somebody gave you in your lectures and which appears in your undergraduate text books and which seeks to replace all the previous definitions used for the last 150 years.

    Most people have no idea what temperature is. Are you going to replace that too?

    It is a foundation of the first law of thermo that if you do work on a system, heat will be created that is contained in that system and has not yet moved elsewhere.

    No matter how many times you try to shove it up my preverbial, heat gets created in the system when the lead falls.

    Reply

  42. Tor

    First, at least in physics, there is no need to consider what most people have an idea about. something.

    “It is a foundation of the first law of thermo that if you do work on a system, heat will be created that is contained in that system and has not yet moved elsewhere.”

    What is an adiabatic process in your opinion?

    Reply

    • iceskaterfinland

      As explained already if you heat a very thin layer of metal oxide with a rapid on off current it will cool almost to room temperature between heating pulses running at 30 times a second

      If you drop a lump of lead onto the floor in air, after this heating it will be cooling for the next hour or so.

      The fall of the lead is approaching an adiabatic process.

      Reply

      • Tor

        Please stop your ad hoc modifications to object against what I written instead of thinking about what has been written. It’s totally pointless for me to try and explain this view if you’re not prepared to read and ponder what it means.

        It’s all there, no need to add anything more.

        If your not happy with this view, carry on, there’s nothing to see.

  43. iceskaterfinland

    You need to explain what you mean by that comment.

    The first law of thermodynamics is a statement about conservation of energy involving heat and work and total system energy. If the system does work when it has the potential to do work then heat is created according to the law and heat according to the law exists within that system.

    You asked me what i understood by an adiabatic process and i just gave an illustration of a process that was far from being one that was adiabatic and one that was tending to approach that of being adiabatic by comparison.

    You have also made comments about heat and temperature. Temperature is what happens when no heat flows between a thermometer and the object being tested.

    If you drop the lump of lead it has an almost infinite number of different temperatures inside the mass where heat is flowing from hot to cold,

    Clearly heat transfer is happening inside the system and so heat exists inside the system.

    Your definition is just wrong on a number of different levels.

    Reply

    • iceskaterfinland

      And importantly for this blog you are using your definition to attack Claes in what is an unjustifiable manner dispite whatever else we agree or disagree upon .

      However i agree that the blog needs a consistantly correct understanding of what heat and temperature are and so forth.

      Reply

      • iceskaterfinland

        Your definition is confusing the methods of measuring heat where that can only happen at the boundary of the system via heat transfer such as by having a constant temperature boundary with known variable heating so that heat crossing the boundary can be calculated, with the idea of heat itself which must exist before it crosses the boundary.

        The temperature of absolute zero is the total absense of heat. If you then create heat you then see a temperature rise.

      • iceskaterfinland

        evidently we are both already there unless you are single.

        I have now spent 5 sold weeks full time stuck talking about the existance of backradiation

        It is not exactly something to be proud of. Most people would consider it bordering on insanity.

      • iceskaterfinland

        and probably about 20-50% of that time has been spend pressing refresh to see if there is a crazy response that i can calmly and sensibly respond to. FFS. It is already totally nuts

  44. Tor

    You should unplug your net for a couple of days I guess.

    It would be very unnecessary for you to develop OCD over something like this.

    Reply

    • iceskaterfinland

      It would be nice to progress this.

      I already produced a book by Enrico Fermi who you must have heard of. I mentioned also John Tyndall, and for sure you have heard of James Clerk Maxwell

      http://books.google.fi/books?id=DqAAAAAAMAAJ&dq=inauthor%3A%22James%20Clerk%20Maxwell%22&hl=fi&pg=PA10#v=onepage&q=inauthor%3A%22James%20Clerk%20Maxwell%22&f=false

      “convection is the motion of the hot body itself carrying its heat with it”

      Obviously the definition of heat you are using is relatively new and not shared by most other people, including those who formulated the laws of thermo.

      Do you not have anything to say to that?

      Why is this newer definition so strongly promoted by some people?

      Reply

      • Tor

        You clearly marked that this may not be so healthy for you, and I feel discomfort in participating if this could make your obsession worse.

        Maybe this article can be of help for you to settle on the issue why there is need for a stringent definition.

        ‘Concerning Scientific Discourse about Heat’

        Click to access perc2004_revised.pdf

        Some quotes.

        ‘There are many possible reasons why students thought that the total heat and/or work for the cycle must be zero. Meltzer explains that students believe that work and heat
        are state functions of the system. We wish to investigate this idea further and attempt to explain why students might view heat as a state function. Terms such as “added to” suggest students are viewing the gas/system as a container of heat, and that they are confusing energy and heat as substances and using temperature as an indicator of the amount of heat in the system’

        ‘Thus we hypothesize that students’ confusion with work as a state function comes from inappropriate transfer, while their confusion with heat may have linguistic origins.’

        ‘Although physicists are quite aware that heat should be thought of as a process rather than a substance[15, 16,17], our coding shows that their language does not re-flect this understanding. Our coding scheme also enables us to decide systematically what language more closely reflects the correct underlying ontology of modern thermodynamics.’

  45. iceskaterfinland

    I am noting once again that you absolutely refuse to acknowledge that the giants of the past do not agree with this new fangled heat definition.

    And it evident that you have far more energy to keep up this nonesense than I do.

    Reply

    • iceskaterfinland

      And i note the AGW consensus bullshit that if somebody does not agree with the new science they are in some manner mentally retarded and unfit for publication

      It is like 1984

      Reply

    • iceskaterfinland

      Apparently the American text book writer who started this nonesense had some fools notion that maxwell kelvin Fermi and co were mislead by erroneous ideas from the past, about heat being a substance in a body.

      So when i was taught, heat was the thing that today goes by various names as internal energy or internal thermal energy and god knows what else.

      “Heat. Heat, like work, is a measure of the amount of energy transferred from one body to another because of the temperature difference between those bodies. Heat is not energy possessed by a body. We should not speak of the “heat in a body.” The energy a body possesses due to its temperature is a different thing, called internal thermal energy. The misuse of this word probably dates back to the 18th century when it was still thought that bodies undergoing thermal processes exchanged a substance, called caloric or phlogiston, a substance later called heat. We now know that heat is not a substance. Reference: Zemansky, Mark W. The Use and Misuse of the Word “Heat” in Physics Teaching” The Physics Teacher, 8, 6 (Sept 1970) p. 295-300. ”

      So today we now know what they knew 170 years ago that heat is not a substance, but somehow people today are oh so much smarter than 170 years ago! FFS

      Not once do these fools ever talk in terms of changing long standing definitions for the purposes of clarity.

      The fact is they dont even realise they are changing long standing definitions and creating massive confusion!! All they can believe is that every body else was mixed up and confused.

      Unbelievable.

      Reply

Leave a reply to iceskaterfinland Cancel reply