Relative lack of vibration.
Quite.
Or, indeed, quiet.
A quiet molecule has the ability to make surrounding molecules quiet. As the surrounding molecules quieten, they, in turn, have the ability to quieten the molecules that surround them. Thus we have a model that quote adequately describes the flow of cold.
The “flow of heat” and “flow of cold” aren’t competing theories, though. They’re just different ways of describing exactly the same thing.
quite adequately.
Just to add a bit of surrounding context. I know that you, Princhester, have some knowledge of electronics, circuit theory, etc.
It’s always taught that electricity flows from positive to negative. That’s the convention. It’s also always taught that the electrons, the things that actually move, flow from negative to positive. Is that a contradiction? Yes. Does the model work either way? Yes.
Similarly for heat transfer. It doesn’t matter whether you define things in terms of heat flow or “cold” flow. The model works just as well either way.
I tend to disagree (strongly) with this statement. As would writers of Statistical Thermodynamics textbooks (Dagnabbit, I didn’t pass my Themo course for nothin!). Statistical Thermodynamics is a nice big impressive pair of words, but it’s basically just looking at heat from a molecular point of view. It turns out that if you look at what happens when a bunch of bunch of atoms and molecules bounce around, and take an average of their energy, you end up with all the laws of heat that we know about from measuring heat (heat energy flows from hot to cold, etc.). So when you do this, you realize that ‘heat’ is just a kind of average of molecular motion, and there’s no real thing you can call ‘heat’ by itself.
The zeroth law is not axiomatic in the sense that you can’t explain it in more basic terms (you can explain it perfectly in terms of molecules bouncing around). It’s the zeroth law because it defines what we’re talking about when we say heat.
Desmo next time I buy something from you on ebay, rather than me give you money, you give me a lack of money. After all, you can describe it either way. However, I’m interested in how, at a practical level, you are going to do this.
What Desmostylus is claiming is that you could mathematically account for the flow of energy either way. Although I think maybe to use “cold” as the currency you might have to change the sign of energy.
When a hot body is in a colder environment the hot body gets colder and the environment gets warmer. Both originally had some level of energy above zero since both were originally above absolute zero. From a bookkeeping point of view I don’t think it makes any difference whether you say that the hot body transferred x calories of heat or the colder body transferred -x calories of cold.
In your purchase analogy does it matter whether the bookkeeper says that that you transferred $100 to D or that D transferred -$10 to you? In both cases he adds and amount to your bank balance and subtracts and amount from his bank balance and the numbers are the same either way.
It does matter, though, if the bookkeeper can’t read.
Make that: “In your purchase analogy does it matter whether the bookkeeper says that that you transferred $100 to D or that D transferred -$100 to you? In both cases he adds an amount to your bank balance and subtracts an amount from his bank balance and the numbers are the same either way.”
Well, almost. What about the Hall Effect?
I understand all that, that’s my point. From a bookkeeping/math point of view it may be all the same. But from the outset I have been talking about what is actually occurring at a physical level. Tim makes my point beautifully, as far as the electrical analogy is concerned.
I don’t want to run this into the ground, but since Hall-effect devices are not a part of the analog for heat transfer what do they have to do with the question?
The analogy is this: while the model works either way, reality in fact actually only occurs one way.
>I found it, thanks to Understanding Physics by Isaac Asimov (Barnes & Noble), a fine book that I recommend to all non-scientists who would like to know more about physics.
Ack! Ack! Wait, don’t do that. Asimov was a pretty amazing fellow, but he could also be a hack that kept better authorities out of people’s hands. I went through an Asimov phase where I read everything of his I could find that was nonfiction. Fortunately, Amazon.com didn’t exist yet, so “everything of his I could find” was only 30 or so books. Nevertheless, I was amazed to pick up so many mistakes. His book on The Bloodstream (one of his earliest, maybe even THE earliest) is fantastic, as it should be - that was his field. Some of his other books on physiology were also quite good. But by the time he started calling us “Gentle Reader” and writing about everything under (& over) the sun, he was overreaching.
For an accessable and authoritative paperback, check out the Penguin Dictionary of Physics, and put all your Asimov books into Fiction like I do, whether the bookstore does or not.
Whew. Sorry for the rant.
This is irrelevant. In metals, the charge carriers are -ve, because only the electrons are free to move. In say, an ionic solution, the charge carriers are of both signs. In, say, a beam of metal ions, the charge carriers are +ve.
I oversimplified the electrical analogy. Electric current is a flow of charge. By convention, we define it as flowing in the direction of +ve to -ve, regardless of the sign of the actual charge carrier.
What Quercus says is correct. The thing that we define as “heat” is a statistical phenomenon is a physical medium. If we connect a cylinder of hot gas to a cylinder of cold gas, the cold cylinder will get hotter because more energetic molecules from the hot cylinder move into the cold cylinder. But the hot cylinder gets colder becuase less energetic molecules from the cold cylinder move into the hot cylinder. Which is the equivalent of the charge carrier: the more energetic molecules or the less energetic molecules? Answer: both of them. This situation is analagous to the ionic solution I mentioned above.
If I but something from you on ebay, the bank (or paypal, or the credit card company, or whatever) is going to credit your account and debit my account. By convention, we refer to this as a flow “money” from me to you. But what physical phemonenon took place? Did a credit flow from me to you, or did a debit flow from you to me, or both? Makes no difference, does it?
This would be better phrased as:
“In a phyical medium, the thing we define as “heat” is a statistical phenomenon”.
[QUOTE=NapierAck! Ack! Wait, don’t do that.[/QUOTE]
Is disagreement allowed regarding the value for non-scientists of Understanding Physics?
You’re talking about mixing, which isn’t the subject.
Whether there is a difference or not depends on what we are talking about. If we are talking about accounting, then it makes no difference because accounting is concerned with describing the results (do you end up with the money or do I?). If we are describing physically how what occurred was effected, then yes, it makes a difference. Because what happens is I give you money (or ask my bank to do so). What does not happen is you give me some absence of money.
Just as a molecule suffering an absence of heat can’t give that absence to a warmer molecule. You can’t give an absence.