A science question

Holmes,I think (I could be wrong) that all heat is IR, which is one form of EMR (light); therefore, heat is light and can be "lost to space" according to your criteria.A quick google seems to confirm my hazy notion about all heat being IR.AbE:
I'm not saying you're wrong about this...it's just that I've never heard that a vacuum is an insulator...where did you get that information from? Perhaps it is only an insulator of electricity?--TheLitThis message has been edited by TheLiteralist, 03-06-2005 05:57 AM

TheLit tries to remember how physics works...The problem would seem to work out like this:(Assumptions)

1. The earth, at some point in the past, was completely or nearly completely molten. (Something that I don't actually believe, btw).
2. The sun produces joules at a constant rate (on average)
3. The earth produces joules at a constant rate (on average)
4. The earth loses joules at a constant rate (on average)
5. Overall, the earth is losing heat energy faster than it gains it (I'm not too sure I believe this, but that would be the necessary assumption if you are starting with a molten earth and ending up with a solid earth, right?)

(Constants)S = Joules per second received from the sun
E = Joules per second generated by earth (whatever the process)
L = Joules per second lost to space from the earth
J_max = Maximum joules that could be contained by a completely molten earth
J_current = Joules contained by earth currently(Variables)t = time the earth has been cooling(The initial equation)J_max + (S t) + (E t) - (L t) = J_current
The initial energy of the molten earth plus the total energy ever recieved from the sun plus the total energy ever generated by the earth minus the total heat ever lost by the earth equals how much energy the earth has now.(Solve for t)J_max + t(S + E - L) = J_current
t (S + E - L) = (J_current - J_max)(The final equation)t = (J_current - J_max) / (S + E - L)
The time period required for the earth to go from a completely molten body to its present partially solid state equals the change in the earth's total energy from its molten to its current state divided by the overall rate by which energy is lost from (or gained by) the earth.S, E, L, and J_current can all be measured, can't they? I would think that J_max could be figured out to a close approximation. This would give the "worst-case scenario" or oldest age possible (starting from the time that the earth was molten)--given the assumptions are all true.It seems doable to me...though I certainly don't have the resources to get the numbers to replace the varibles. But I certainly could have made some stupid error...it's been a long time since I took level I physics.Just foolin' around...
--TheLitThis message has been edited by TheLiteralist, 03-06-2005 05:39 AMThis message has been edited by TheLiteralist, 03-06-2005 08:18 AM

Percy,I agree that heat can be transferred by conduction and convection as well as by radiation (I mean the act of radiating, in this case). However, Holmes appears to think (and no one except me appears to correct his thought) that there are different kinds of heat, only one of which is infrared light. In fact, unless I am mistaken, ALL heat is infrared radiation (invisible light with long wave lengths).Holmes IS correct in that heat can move around within the earth system via conduction or convection as well as radiation (the act of radiating) but that the ONLY way it can be lost to space is via radiation (the act of radiating). However, he is INCORRECT if he thinks there are two or three different forms of heat energy. Either that or *I* am wrong in asserting that ALL heat is light, a point about which I would readily accept correction--myself not being an expert in the science of heat or light.--TheLit

Okay guys,I am actually confused, now. I thought all heat was IR (which I thought was part of the light spectrum).From this online dictionary heat is defined as: While this seems to be what Percy said (in much abbreviated format), this definition doesn't UNCONFUSE me at all. I would think that IF heat can be "transmitted...through empty space by radiation," then heat is, in fact, radiation (light)--regardless of whether it can be transmitted other ways or what different radiation wavelengths occur as the temperature (amount of heat?) increases.I likely have some fundamental misunderstanding of "heat." My last technical dealings with "heat" was in level I physics, in which case it was usually regarded as energy lost from a system due to friction.--TheLitThis message has been edited by TheLiteralist, 03-07-2005 00:15 AM

Percy,Are you saying that kinetic energy IS heat energy? I thought heat was merely a by product of kinetic energy.

Hi Sylas,I'm still convinced that IR is heat (I will readily concede if I can be made to understand...this ISN'T about theology after all). But the IR must continue to be radiated, also, I think--or else there would be no heat radiated from the object, right? I think that both temperature and the wavelengths emitted depend on the amount of kinetic energy present in the system; however, only the IR radiated is the heat of the object. (I could be wrong, I readily admit). This link seems to disagree with you guys (or I'm reading it wrong...entirely possible). While I agree that ALL wavelengths are energy...it appears to me that only (far) infrared wavelengths are HEAT energy (which I have always understood to be a type of energy all its own and different from, say, potential, kinetic, mechanical, or chemical energy). Apparently not even all of the infrared spectrum is considered to be "heat." Heat is also "just a form of energy." If all heat is actually IR, then all heat is light; however, not all light would be heat, if that makes sense. Now, if there are different kinds of heat (I don't believe this, yet), then not all heat is light...but no one has yet demonstrated that all heat isn't IR.I really don't think that kinetic energy (of molecules) IS heat; rather, molecular kinetic energy GENERATES heat (IR). I may be wrong, but if the amount of molecular kinetic energy increases (for whatever reason), IR will increase in amount radiated (temperature increases) and also the molecules will begin radiating in other wavelengths (including visible and beyond). However, the IR must continue to be generated or else there would be no heat felt from the object in question (the sun, for example, generates nearly the complete, if not the complete, light spectrum--including IR--and it VERY hot).Feel free to point out my ignorance...I'm truly curious why several very knowledgeable people are disagreeing with me...I can only surmise that I misunderstand the concept of "heat" fundamentally, in some way.--TheLit

CF,I could be wrong, but I am not convinced, yet. Right now, I see it this way:

• Kinetic energy is NOT heat energy; however, kinetic energy produces heat energy, and the heat energy of a system is always directly proportional to the kinetic energy of the same system
• Kinetic energy (and, indirectly, heat energy) can be transferred to another object by physical contact (i.e., by molecular collisions). If this transferrance of kinetic energy occurs, then the kinetic energy and, therefore, the heat energy of the contacted object will increase (while the kinetic energy and heat of the first object decrease).
• If radiated heat energy (IR light) contacts another object, it indirectly increases the heat energy by increasing the kinetic energy of the irradiated object

Either I'm wrong or you guys are confusing kinetic energy with heat energy. Since the heat energy of a system is directly dependant upon kinetic energy of the system, this would be completely understandable. The two forms of energy, while extremely interrelated and interdependant, are completely different forms of energy...I thought. Temperature is a measurement of kinetic energy only because heat energy is always generated by kinetic energy (and always in dependable proportion to the kinetic energy).OTOH, several knowledgeable people are agreeing with you and finding my assertions problematic; for this reason only, I permit a shadow of doubt in my mind about my position on this matter. It's just that, so far, I haven't seen anything to change my mind.--TheLitThis message has been edited by TheLiteralist, 03-07-2005 00:13 AM

Hi JonF, Well, I was hoping that my constant "L" (the rate at which the earth loses energy to space) would make knowing the complex movements of heat energy within the earth unnecessary.I wonder if understanding the complexities of heat movement within the earth system is necessary for estimating the current energy contained by the earth system or the rate at which the earth generates energy. I was hoping not and thought that a mean earth temperature plus some calculations based on the rotational/revolving motions of the earth might do the trick.Oh well...whether it can be done or not...I certainly can't do it! So, it's pointless anyways, I guess.--TheLit

NosyNed, Okay. I guess that could be batted around for a bit. To prevent that, I will concede (not only due to your post but also due to Sylas's post)--for now, for argument's sake--that no particular light wavelength can be classified as heat.This actually would make the discussion clearer perhaps (for me, anyways)...thanks.
--TheLit

Ha ha.Well, you two are agreeing this time--for what it's worth.

Everybody,Due to the most recent posts by Ned and Sylas, I concede (for argument’s sake) that the wavelength is irrelevant to defining heat.The problem then becomes even simpler.Heat is light--always. All the laws that apply to light apply to heat. Heat can be radiated, reflected, refracted, or absorbed. Therefore, heat, regardless of it’s source, is a candidate for being lost to space via radiation.Kinetic energy produces light--always. Usually this light is invisible and is felt as heat.Heat (or light) is NOT kinetic energy, but heat is very, very closely related to kinetic energy. Kinetic energy produces heat. Heat produces kinetic energy.I think (emphasize: THINK) it is only an illusion that heat is conducted. I believe the kinetic energy is conducted, and the heat results from the increased kinetic energy. Similarly, irradiation increases the kinetic energy--not the light energy--of the absorbing system. However, increased heat results from the increased kinetic energy.(Am I arguing apples and oranges? I feel like I'm making much ado about nothing, in a way--OTOH, it seems fundamental to the discussion--plus I'm having fun blathering on about it, I suppose.)--TheLit

Sylas,Just in case you're curious...From this link: Of course, being absorbed by the earth's atmosphere is still being absorbed by the earth system (it's mighty convenient for us, too, I imagine...I'm only too happy to have a bit of the IR for myself, but I am just as happy to let the atmosphere have the rest...I believe in sharing!).--TheLit

Sylas,Thanks for the link. Thanks for the replies, too. Uh oh. Maybe I'm completely wrong, then. What are the other ways in which energy flows from hot objects to cooler ones? If it's conduction and convection, I'm dead wrong!See, I've been considering heat transfer via conduction to be a sort of illusion. What I mean is that there is actually a transfer of kinetic energy (molecular collisions). This transfer of kinetic energy results in increased heat, of course, which I considered to ALWAYS be light.Oh well...,
--TheLit

Holmes, If I have understood Sylas correctly, then ALL light is heat, but not all heat is light. If this is the case, then we are BOTH wrong, right? I say this because you seem to separate heat utterly from light and kinetic energy per phrases like... Perhaps we will both be enlightened? But just think of how much more typing than you I had to do in order to be enlightened! I can be awfully stubborn, sometimes.--TheLit

JonF,Okay. But couldn't the rate of energy being lost to space from the outer atmosphere be directly measured? Perhaps measured over time just in case it is cyclical or is on a curve (not a constant rate). Wouldn't this negate the need to find out all the complex mechanisms of HOW the heat got to and through the upper atmosphere?I mean maybe it wouldn't...but I thought maybe it could.Thanks for the reply and discussion of it, at any rate.--TheLitThis message has been edited by TheLiteralist, 03-07-2005 10:09 AM