# Thread: Heat explained...

1. ## Heat explained...

Heat, entropy and engines:

We all know what heat is - it's the stuff that burns you if you get too near it. It burns because it's "energetic" and if you get near it you do too.
Temperature is a measure of heat which we see as a mark on a ruler. If, over time we plot such measures, a shape appears because heat "flows" in and out of objects and their environment. A hot fluid will have a temperature decay over time, if you measure temperature points you measure this curve as well.

You have a 1-dimensional line with a curve in it, that depends on the rate of flow and the remaining content of heat in the fluid - a differential curve.

The phase space is measured by time and heat content. This space has an invariant in the rate that heat can flow, through a surface bounded by the fluid and the environment. This invariant is Boltzmann's constant k, which we can rewrite in other terms, or we can normalise k to "one constant", by making it unitary in terms of h (convert temperature to energy); we then measure a unitary mole of heat, say.
The dimension of the phase-space is then unitary heat content in dimensionless moles (a number), and time (another number). The curve is the same.

Boltzmann's k 'vanishes' from the frame it gauges, replaced by a dimensionless gauge with units of "other fundamental constants". Absolute zero in Kelvins becomes zero energy in Joules.

Entropy however, has a simple phase-space geometry; you have a potential, in a volume which has a shape. There are 2 generator/annihilator transformations V and S, which transform the volume and shape.

We might call the first "pressure", and the second "a limit or bound". That is, the ersatz

$\Omega_{\phi}\, =\, S_{\phi}\, +\, V.S_{\phi} <=> \Pi(\phi)\, =\, \mu(\phi).\Delta\; \pm\, \kappa$

...which says: A potential's phase space is changed by a pressure operator, which transforms as a volume, and by a limit operator which transforms as a shape (with arbitrary dimensions), a constant K may limit the measure operator (if K is large it can 'swamp' the signal).

The potential's ansatz also has arbitrary dimension, but it 'requires' at least 1. Then content is simply an integral, of linear discrete potentials, over the time dimension from zero energy; a sum that looks like a product.

Power is then the "ability" of a volume to change shape (V) inside the limits it is bounded by (which are K and S, an 'elastic' constant and a shape), over linear time.

Doh!

2. It burns because it's "energetic"
that's quite enlightening. Heat burns because it's energetic, it's energetic because it heats

Temperature is a measure of heat which we see as a mark on a ruler.
Temperature is a measure of body's affinity towards heat.

3. Heat burns because it's energetic, it's energetic because it heats
en.wikipedia.org/wiki/Energetic_inner_product
Temperature is a measure of body's affinity towards heat.
Affinity, in etymology, is the opposite of infinity . These two words have the same root coming from the Latin: finis = end. “Affinity” meaning: is near to the “finis” e.g. close to the “zero point” in a before assumed space.

On the other hand, from the Latin, affinis = connected with, having things in common, and it is utilised to interpret the effective possibility that some substances can or cannot mix together, in terms of sympathies and antipathies.

Also, it can mean a natural attraction of feeling or kinship. A relationship by marriage.

More precisely, affinity may refer to:

 Science and technology

* Chemical affinity - the force of attraction between chemical species.
* Biochemistry, protein-ligand binding affinity

See also

* Affine

Temperature is a mark on a ruler, but this mark exists because the ruler is in thermal equilibrium; the temperature 'number' we use as a gauge is in fact a small interval of heat content - we measure only the depth of this 'energy', but not the width, which is assumed negligible. However the energy 'width' exists, and in fact there would be no 'heat number' measurement if it didn't. Any signal needs 2 dimensions.

4. of course heat can also be the result of friction

5. Then friction is an entropy generator.
There is a friction shape and volume, with v and s generators, as in the ersatz.

6. Is dysplasia channelling the essence of reiku?

7. Is Alphanumeric channeling the essence of scientific enquiry at this forum?

8. Do you have a question, dysplasia, or a point to this thread?

9. Originally Posted by dysplasia
We all know what heat is
Your post disproves this conjecture.

Temperature is not a measure of heat. Temperature is a state variable. It is a measure of the thermal energy contained in some object. Heat is a process variable. It is a measure of the transfer of thermal energy between bodies. Bodies do not contain heat. Heat transfer depends not only on state but also path.

Example: Suppose you want to bring a quantity of gas from 270 kelvin, 1 atmosphere to 300 kelvin, 1.111... atmosphere. One way to do this is to transfer heat to the gas while holding the volume constant. Another way is to compress the gas to 1.111... atmosphere while holding the temperature constant and then heat the gas to 300 kelvin while holding the pressure constant. The two paths have the same starting and ending points but will involve different quantities of heat being transferred to the gas.

Originally Posted by AlphaNumeric
Is dysplasia channelling the essence of reiku?
Maybe. But given the title, we can't discount channelling the essence of Farsight.

10. From what you've posted, I can surmise you've read your own conjecture into my OP. Sorry, but the first sentence in your response is churlish rubbish. old man.
Originally Posted by D H
Temperature is not a measure of heat.
To most people who "know what heat is", temperature is an 'instantaneous' measurement, of heat.
Temperature is a state variable. It is a measure of the thermal energy contained in some object.
You mean, thermal energy and heat are "the same thing"? Heat content is something we measure (with temperature)? I think I said that already, dude.
Heat is a process variable. It is a measure of the transfer of thermal energy between bodies. Bodies do not contain heat. Heat transfer depends not only on state but also path.
Uh huh. Heat is also a scale, like temperature? If bodies don't contain heat, why do they change temperature, and why do they 'stay' hot? It isn't because energy is stored, or contained by a body?
Example: Suppose you want to bring a quantity of gas from 270 kelvin, 1 atmosphere to 300 kelvin, 1.111... atmosphere. One way to do this is to transfer heat to the gas while holding the volume constant
But, if the gas isn't going to retain or contain any of this transferred heat, why would you bother?
Another way is to compress the gas to 1.111... atmosphere while holding the temperature constant and then heat the gas to 300 kelvin while holding the pressure constant.
So, you mean "pressure" deforms a volume like I said already?
The two paths have the same starting and ending points but will involve different quantities of heat being transferred to the gas.
The two paths result in the same changes to the entropy volume, you mean?

11. Originally Posted by dysplasia
You mean, thermal energy and heat are "the same thing"? Heat content is something we measure (with temperature)? I think I said that already, dude.
No, and no. Thermal energy and temperature, not heat are the same thing. Heat content is a meaningless concept, meaningless because the concept of heat as something an object held was falsified 200 years ago.

You don't understand heat at all.

12. ???

13. But you don't understand that thermal energy and heat are the same thing.

Heat is just a part of a much larger energy spectrum. Heat is when this part of the EM spectrum flows through objects it is opaque to. The objects respond by changing their shape and volume - heat has a shape and a volume, q.e.d.

Temperature is a signal; we measure a heat depth, but with a small width (in time). A signal has to have two dimensions minimum. If one of the dimensions is actually n-dimensional, it doesn't change the geometry (you could imagine the n-dimensional 'depth' of the signal is just a single depth, what the hey).

Maybe you can point out the blunders these guys have made:
The temperature and phase of a substance subject to heat transfer are determined by latent heat and heat capacity. A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature.
If there's a capacity, isn't a capacity a storage? Then heat is stored, according to these guys... Where have they gone wrong?

Oops, I guess I should try to be more specific and say something vague like: "heat is energy, a part of the EM spectrum; heat is also when this energy makes a body respond to EM energy, by storing it over time - heat in a body measures energy over time, just like a thermometer does."

14. any substance above absolute zero has "heat"
"heat" has no shape.

15. Originally Posted by dysplasia
But you don't understand that thermal energy and heat are the same thing.
No, they are not. Heat is not stored. The concept that objects store heat was falsified 200+ years ago. Google "phlogiston" and "caloric theory of heat".

Heat is just a part of a much larger energy spectrum. Heat is when this part of the EM spectrum flows through objects it is opaque to. The objects respond by changing their shape and volume - heat has a shape and a volume, q.e.d.
Wrong. One more time, objects do not store heat.

Temperature is a signal; we measure a heat depth, but with a small width (in time). A signal has to have two dimensions minimum. If one of the dimensions is actually n-dimensional, it doesn't change the geometry (you could imagine the n-dimensional 'depth' of the signal is just a single depth, what the hey).
The above quoted text is complete nonsense. Alphanumeric was right. You're Reiku.

Maybe you can point out the blunders these guys have made:
The temperature and phase of a substance subject to heat transfer are determined by latent heat and heat capacity. A related term is thermal energy, loosely defined as the energy of a body that increases with its temperature.
What guys? Good grief, Reiku. When you quote someone, give a reference.

That said, what you quoted looks fine. They talk about
• Heat transfer.
Heat is a process variable, not a state variable. The First Law of Thermodynamics is $\Delta U = Q - W$. The Q is the heat transfered to the system in question. The First Law of Thermodynamics a path-dependent differential equation. It is not an equation of state.
• Latent heat.
You can google that term, of course. Latent heat is energy released or absorbed during a phase transition.
• Heat capacity.
You can google that term, too, of course. There are different measures of specific heat (e.g., cv and cp) because heat transfer is a process variable.
• thermal energy, loosely defined as the energy of a body that increases with its temperature
Bodies do indeed have thermal energy. This stored energy is a property of the body -- a state variable. Temperature is a state variable and is a measure of that stored thermal energy.

If there's a capacity, isn't a capacity a storage? Then heat is stored, according to these guys... Where have they gone wrong?
They haven't gone wrong. You have.

16. Originally Posted by D H
what you quoted looks fine. They talk about

* Heat transfer.
Heat is a process variable, not a state variable.
OK then, let's see what it does in the next part of your exposition as a direct substitution:
The Q is the process variable transfered to the system in question.
The First Law of Thermodynamics [is] a path-dependent differential equation. It is not an equation of state.

* Latent process variable.

You can google that term, of course. Latent process variable is energy released or absorbed during a phase transition.

* process variable capacity.

You can google that term, too, of course. There are different measures of specific process variable (e.g., cv and cp) because process variable transfer is a process variable.

* thermal energy, loosely defined as the energy of a body that increases with its temperature

Bodies do indeed have thermal energy. This stored energy is a property of the body -- a state variable. Temperature is a state variable and is a measure of that stored thermal energy.

17. An object = a container
Heat = thermal energy
Hot object = container with thermal energy

A container has a shape and a volume. Temperature is a measure of "heat" or maybe it's an integral over time of the thermal energy = an entropy change? Maybe it's just a "timed" signal with only 1 dimension? Who the hell knows what heat is?

How about what entropy is? Does it have a volume or a shape?
Does this forum? Does anyone actually know what dysplasia is?

18. That (post #16) was truly idiotic.

If you really want to understand thermodynamics, pick up a book. Lacking a book, you can poke around on the 'net. The underlined text that follows links to some key wikipedia articles. A good place to start is to understand what thermodynamic state means. Heat (and work) are not a thermodynamic state variables because they depend on the path taken between states. Mathematically, heat and work are "inexact differentials". Quoting from the Inexact differential article, "In thermodynamics, an inexact differential or imperfect differential is any quantity, particularly heat Q and work W, that are not state functions, in that their values depend on how the process is carried out."

19. Originally Posted by dysplasia
Heat = thermal energy
This is incorrect. You are confusing the internal energy of an object (thermal energy) with energy transferred between two objects (heat).

Hot object = container with thermal energy
Fair enough, but hot object does not equal object with heat. See?

Temperature is a measure of "heat"...
No. Temperature is a measure of (internal) thermal energy.

... or maybe it's an integral over time of the thermal energy = an entropy change? Maybe it's just a "timed" signal with only 1 dimension? Who the hell knows what heat is?
Any 1st-year physics textbook will provide you with a concise definition of heat. Maybe you ought to read one.

How about what entropy is? Does it have a volume or a shape?
Does this forum? Does anyone actually know what dysplasia is?
dysplasia (n.): Abnormal development (of organs or cells) or an abnormal structure resulting from such growth.

20. Hot object = container with thermal energy

Fair enough, but hot object does not equal object with heat. See?
Yes, I see that you're playing with metaphor, like most people when they try to form pictures of something.

"Heat != body with heat in it"

But, it does mean this colloquially, we associate the heat in a flame with the flame. As somebody pointed out, we talk about states and processes in physics. Assigning the same name to something which is a state (instantaneous and time-independent) and to something which is a process (which in a physical domain is time-dependent by definition), is the problem.

But there is a state, and there is a process. There would be neither if either were non-existent (AND is a selection or a measure). There is also a potential, with arbitrary dimension, which looks different when it's measured 'in' objects, than when it's "out".
In the latter case, it has different degrees of freedom, for some reason or other.

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