Harro, That's still not right. Your billiard ball model does not explain radiative heat transfer, but it does explain conductive and convective heat transfer. It appears that you are making a typical mistake. Heat is not stored. An object does not contain heat. Heat is instead what is called a process variable. Suppose you want to bring a gas from some initial pressure and volume (and hence temperature, since PV=nRT for an ideal gas) to some final pressure and volume. There are many ways to do this. For example, you can Change the volume to the final volume while keeping the pressure constant at the initial pressure, and then change the pressure to the final pressure while keeping the volume constant at the final volume, or Change the pressure to the final pressure while keeping the volume constant at the initial volume, and then change the volume to the final volume while keeping the pressure constant at the final pressure, or Make the gas follow a straight line path from the initial state to the final state, or Make the gas follow some curved path through the pressure-volume state. The amount of heat transfered to/from the system depends on the path followed. If objects contained heat, the amount of heat transfered would depend only on the difference between the final and initial state.
No, heat is the energy upon that mass and in all cases em in one 'f' or another. Ie.... all mass between any 2 points in time has em upon it no matter what the mass, no matter what the volume. Heat is the em upon mass!
ah... measuring the exchange does not share what the 'it' is. then why does splitting an atom cause so much heat. that is an error of comprehending even the simple stuff like E=mc2 and like reality conveys; the old are still measuring energy as a potential difference; this comes from the laws of thermodynamics; in which to comprhend the first law, shares that the 2nd law is moot; conservation rules. Which shares that energy is not created or destroys but exists upon mass; and the old school measured the difference between points but that does not share what 'it' is even when people say; 'well it's radiating' when the math does not share what that 'it' is radiating.... Em is the energy upon mass; in all cases! That is what the paradigm shift will unfold; Energy is the light upon mass, in time. The three combine in a simple form (theorem) of mass, energy and time. and to understand light as the energy between all mass, then entangled energy between mass is that other unknown 'it' ........... gravity Gravity is entangled energy between mass; the missing potential is based on the varied wavelengths of energy (light).
ahh so heat is relatively higher energy state condenced in a small area of space. Its effects on matter is motion energy (exited matter), if the matter cant escape it casues higher pressure? I still think matter can store energy, including heat energy, although if the atom reaches an over energized state it would emmit the energy as radiation. I guess the high energy state can be explained, like if you consentrated a light beam into a small volume of mass it would heat up due to the relatively higher energy input. But it wont instantly get hot, it would warm up. I assume the warming up time is the matter storing the energy till it reaches a point it cant store any more and radiates that energy out to neihbouring atoms. Surely some of this energy is expessed as motion energy which starts a chain reaction or excited atoms bumping and colliding all over the place..this would be cause of high preasure would it not. Heat can be lost via lower preasure or radient energy? after all we measure temperature with a pressure guage (thermometer), the liquid expands in a tube, and we measure how far it expands.
I am sure DH knows, but for accuracy his post 18 statement below is not always true: "A better way to look at heat is as energy transfer other than work, i.e., energy transfer that changes temperature." For example: Slowing melting ice requires heat flow, but the temperature does not change. It is not even necessary to change form liquid to solid etc. to transfer heat at constant temperature. For example, solid iron exist in the body centered lcubic atice and in the face centered latice and heat at constant temperature is required to convert the lower temperature one (I forget which that is) to the higher temperature one. Some solids have several solid phases, but as I recall, iron has only these two. Ice is also interesting as when it forms work is done againist the atmospheric pressure so making ice in the high pressure atmosphere will have different heat requirements. Likewise if you have ice and quickly do work on it (too little time for significant heat flow) it will melt - that is how iceskates work - your are often not skating on ice but a very thing film of water made by the work done (and then undone as the compression is removed for it to refreeze.)
A few more comments on Heat: I define heat as a type of energy associated with the random motion of many atoms (or molecules). Thus, for me "heat radiation" is not heat. It is IR radiation, but it is not a different form of energy from light or UV or X-rays or even gama rays. This division of the electromagnetic spectrum into wavelength groups is arbitary and very much the IR/light/ UV boundary are just reflecting human neural capacities. Heat is a lower form of energy in the sense that all other forms can be converted 100% into it but it can only partially be converted into other forms. Individual atoms can store energy (in there excited states and in their motion, but that motion is not random, so it is not heat.) When one considers "Brownian Motion" the boundary between heat and directed kinetic energy get a little fuzzy. The energy in 1000 marbles shaken steadly and confined in a box would not normally be consdered heat either, but is sort of large scale Brownian like motion and if one wants to for some reason this fuzzy boundary could be pushed to called either heat, except for the fact my definiton specifically said "random motion of atoms (or molecules)" not, "polen pieces or marbles."
Hi thanks for your informative post. Heat is a usefull form of energy, as it is easy to convert into work. Why is that? because the excited particles trying to get from a high preasure environment to a lower pressure environment. You can capture the motion energy of the matter (it collides with other matter which can be a piston in a car engine for example) So to define heat. The more particles of mass per volume of space plus input of energy will yield higher temperatures. Which goes back to my pool table anology, rack the balls in a cluster (high pressure) and smash them with a cue ball (input energy) and they all scatter around like crazy (high temp) now the balls are spread around the table (lower preassure) and less balls should collide (yielding lower temp).
Presure and density are not in any direct way related to heat. Both are high near the surface of Jupitor (say 100miles below the surface) but the heat energy per gram of mass is probably less than the air around you. (I am just guessing, to illustrate the point, and do not want to get too close to the core as the primortal gravity collapse energy, now converted to heat, still has not dissipated. - I.e. it is hot at the core still. (Jupitor radiates significantly more energy than it recieves from the sun still. Jupitor failed to make the cut to become a very long lived faint companion star of the sun.) "Easy" is a relative word. Converting other forms of energy nearly 100% into heat is easier than converting even part of the heat into other forms of energy. An engine is not always required - for example, thermo-electric generators exist with no moving parts. One needs to "streech" to see how "pressure" is used (but that POV is possible by considering the "electron pressure" inside of solids conductors. Thermionic converters also exits. You no doubt own a few - incandesent light bulbs "boil off" electrons and a slight negative charge develops on the inside surface of the glass bulb. When enough electric field is generated there is no longer any net flow to the surface, but heat has been converted into electic potiential. In vaccum ceasium leaves red hot tungsten, which has a high "work function" as a positive ion, which is massive compared to these electrons. Because momentum and kinetic energy scale differently with speed, these ions can be collected and neutralized to make a nearly practical "battery" that runs on thermal power, not chemical energy. They (the neutral ceasium atoms) are then returned, perhaps by gravity, (no work needed against the electric field) to the hot tungeston. There have been some studies of using sealed Ceasium vapor vaccum cells with nuclear reactors to directly generate electric power. I have not looked at this idea for 40 years. - why not search and tell the status of it now?
The truth is nobody knows exactly what is heat, energy, work, time, space, etc., etc. (circulatory definitions aside) but everybody has some kind of general grasp of these concepts. General vague idea is ALL you can get. Chances are that your particular vagueness is as good as that of Einstein, etc. Sure, lots of braniacs show off their learned feathers using cryptic language (too mesmerize less educated) trying to define those things (and to cover utter failure with all kind of learned BS). Idea of heat&energy is vague and intuitive, it cannot be strictly defined. If you are looking for some ultimate definition, you'll never find it.
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Not sure what you are saying, but yes all words in any language have circular definitions. Look anyone up and a dictionary and you will find it defined in different words, each of which is also defined in still more words etc. The dictionary is a circular network.* Is that what you are stating? Words acquire their meaning by their use, not by their dictionary definitions. Those printed definition only are reasonably good reflections of the meaning aquired by use. As the way words are used slowly changes with time, the dictionary needs constant up dating. For example "Lady" now mainly means "female" not "wife of a lord" now, at least in US usage. That said and acknowledged, there are few words as well defined by operational proceedures as the word of physics. For example, "work" is the mathematical product of the force component in the direction of motion times the extent (magnitude, or amount) of that motion. If either factor is not constant then infintesimal products of these two factors must be integrated. Both of the factors can be defined, not only by other word, but by operational MEASUREMENT proceedures. Most words can only be defined by other words, in a clearly circular process. Terms of physic are defined operationally as well as by other words. - They are the best definded terms (words) in the language as circular definitons are not required when the / operational procedures / measurments are used. Thus I do not understand what is your point. ---------- *For example, if given a complete dictionary of languange you do not know any words of - it is totally useless for you. The circular nature of dictionaries and their definitions is then very clear to you. Physic is not dependent on these circular terms alone - it can be operationally defined.
Classic example of circular definition: Energy - capacity to do work (the most popular def.) Work - change in the energy of an object Most of physics/thermodynamics textbooks using this circular crap without much thinking. Actually, this is the most screwed up part of most books, since authors should know better that some energy cannot be transformed into work. It is important to realize that in physics today, we have no knowledge of what energy is. The Feynman Lectures on Physics Vol I, p 4-1 Yes, we can calculate & measure "energy", but we don't really understand (and may never understand) meaning of it as we may never define (in noncircular way) force, space, time, work, heat, mass - those are basic physics abstractions, something like axioms in math. Physics requires some phenomenological definition/understanding. Besides the question "what is force & time" are also very interesting.
Yes, but that is not physics. That is philosphy. Physic makes no attempt to tell what anything really IS. Physic is unifying scheme that allows prediction of many special cases by general rules ("laws" if you like). For example: under conditions "A" objects "b & c" will "D" Physics never tries to tell what "b" or "c" "really is." The "unifying scheme" often has a model and some equations, but if the model has sub models and or "componet parts" such as electrons or quarks etc. what they "really are" is also not told. Physicists tend to think they are real objects, as believe it or not physicsists are humans also. This does not imply; however that the thing of the model or of its componet parts, have been explained as to what they "really are." In this sense no one will tell what heat "really is" (and there is the other non-physics meaning of this word also, related to human perception of warmth, which is something entirely different than the physicist's "heat.") For example: Given the geometry of a conductor (say a coil of wire) and a mesured electric current distribution in it, I can predict the magnetic field to be found atr various locations in space and confirm these prediction by measurent of the magnetic field. I can go deeper into what the electric current is (the drift velocity added to the random thermal velocity in the conductor's free electrons etc. or what is the band structure of that type of conductor etc. ... But I still do not know what is an electron or what is a magnetic field, or what heat IS in a philosophical sense. etc. All I know is given condidtions "A" and objects "b" and "c" I can expect "D" but there are zillions of variations on this with all covered by realtive few rules that allow the predition of condition "D."
Welcome to SF. lionwarrior. So do I, if he is only saying that no ones know what anthing really is or that most words have only circular definitions. In first reply to him I said not sure what he was saying at the start of my post. (he still has not made it very clear) In second I said: "Yes, but that is not physics. That is philosphy. Physic makes no attempt to tell what anything really IS. ..." at the start as he now seems to only be saying that one one knows what anything "really IS" and I do agree with that.
So it seems today's physics are 'less than' good. Such that they can build a steam engine by the usage of heat but who has taken the time to define what that 'heat' is upon mass. ie... the thread shares that 'heat' is simply em (light) in every case no matter how you slice it up. Is there any doubt? Is there anything in the whole of existence that can prove that point incorrect?
Lots of doubt about what you are stating or asking. "what point"? Please try again. Is English not your native language? (No insult intended - I just have no idea what you are asking, or even if you are asking something.)
I understand Billy T it was me opening the thread asking 'what is heat' and within the body a proposal was made that 'heat' as far as what 'it' is has been determined to be em (light) no matter how any wish to debate from the resonance, to the momentum or what have you; that 'it' is em causing it in all cases. Em (light) is the energy upon mass.
