What is heat?

[swansont]

Therefore, I am requesting specific quotations from ANY source, preferably authoritative, that specifically backs up your specific assertions as I have already outlined. Such as: "A laser is not a thermal source".

 

You say to me: "If you go to Google and choose the "books" option, and type in "blackbody radiation" you get more than 400,000 hits"

 

So what?

 

Great, so you should have NO PROBLEM backing up your assertion with a direct authoritative quotation that reads, in substance: "A laser is not a thermal source".

 

 

Google books does not allow copy/paste. Books generally do not list things that are not examples of a phenomenon under discussion. I provided you with a link to Serway's Physics textbook, but it really doesn't matter which one you pick. Any textbook that includes basic thermo will discuss blackbody radiation.

 

But here's the Princeton University Laser Safety Guide

http://web.princeton.edu/sites/ehs/laserguide/sec2.htm

 

The laws of thermodynamics do not limit the power of lasers. The second law states that the temperature of a surface heated by a beam from a thermal source of radiation cannot exceed the temperature of the source beam. The laser is a non-thermal source and is able to generate temperatures far greater than it's own. A 30 mW laser operating at room temperature is capable of producing enough energy (when focused) to instantly burn through paper.

[DrRocket]

 

As to your other example with the boat, remember that internal energy does not include kinetic energy from the motion of the entire system. A glass of water at 298K at rest and a glass of water at 298K moving at 10 m/s have the same internal energy (neglecting the super tiny relativistic effect).

 

 

That depends on how the problem is formulated.

 

It is rather typical in gas dynamics to speak of both static temperature and stagnation temperature. The former is the local gas temperature in a frame of reference at rest with respect to the local flow. Stagnation temperature is the temperature in rest frame if the gas were to brought to zero velocity isentropically. The difference is the "kinetic energy of motion of the entire system". While static conditions would be of interest to a chemist, both static and stagnation conditions are of great interest when designing rockets and rocket components, where kinetic energy of the entire system can be of great interest..

 

Chemists, physicists and engineers tend to look at thermodynamics in slightly different (but not inconsistent) ways. Chemists and to a lesser extent physicists tend to consider closed systems (i.e. systems without mass transfer). Engineers tend to consider open systems (systems allowing for mass transfer). No confusion arises so long as the assumptions are clearly stated, but communication does require clear agreement on assumptions and terms.

 

It is worth remembering that the formulation of classical thermodynamics by J. Willard Gibbs predates both quantum theory and relativity, and indeed the acceptance of the atomic theory. Classical thermodynamics is rather abstract and independent of the atomic hypothesis, the link being the modern theory of statistical mechanics. Thus it is rather easy to throw atomic phenomena into the mix that at first blush are difficult to classify in classical terms. What is amazing is how well the theory has held up despite the revelations as to how nature works since the time of its invention.

[finiter]

That is not at all what swansont is suggesting. What he is stating very clearly is that thermodynamics does not allow what you are suggesting.

I posed this question to spin1/2, and not swansont (spin1/2 suggested different temperatures). Anyway, I think what you are suggesting is that 'both containers will be at the same temperature, and so will have the same average kinetic energy, but the actual energy possessed will be different'. Is it?

 

— There is no discussion about how you arrived at that condition. Thus, not being able to arrive there via one specific process is not disproof

 

— There is no mention of the pressure. It is a variable in this scenario, not a constant.

 

— Since the average KE is specified to be equal, this is the same as saying that T1=T2. finiter wants to know if this can happen. If it is not, we should expect some contradiction in manipulating the equations, like a negative value or divergent solution.

 

PV=nRT

 

Since n1=n2 and T1=T2, we can then state that P1V1=P2V2

 

Any contradiction here? I don't see one.

So far, there is really no contradiction. The question that I would like to ask now is whether there is any other energy (other than the kinetic energy, which is same in both containers) for the atoms. That is, whether the internal energy is partly kinetic and partly in some other form, and thus the total energy of the atoms will be different for the two containers.

 

 

[DrRocket]

I posed this question to spin1/2, and not swansont (spin1/2 suggested different temperatures). Anyway, I think what you are suggesting is that 'both containers will be at the same temperature, and so will have the same average kinetic energy, but the actual energy possessed will be different'. Is it?

 

Your question is rather poorly phrased and makes little sense. But perhaps this will help.

 

[math]PV=nRt[/math] for an ideal gas.

 

[math]PV[/math] is proportional to the total internal energy of an ideal gas. T is proportional to internal energy per mole, which by the equipartition theorem is proportional to the kinetic energy of translation per mole.

[Tom Booth]

Google books does not allow copy/paste.

 

It is possible to provide links to specific pages though a simple title and page number would be fine if not too much trouble. Or just a title and author as I can search the book or read it myself if you can give assurance that there is some relevant information to be found therein.

 

Books generally do not list things that are not examples of a phenomenon under discussion. I provided you with a link to Serway's Physics textbook, but it really doesn't matter which one you pick. Any textbook that includes basic thermo will discuss blackbody radiation.

 

But here's the Princeton University Laser Safety Guide

http://web.princeton.edu/sites/ehs/laserguide/sec2.htm

 

The laws of thermodynamics do not limit the power of lasers. The second law states that the temperature of a surface heated by a beam from a thermal source of radiation cannot exceed the temperature of the source beam. The laser is a non-thermal source and is able to generate temperatures far greater than it's own. A 30 mW laser operating at room temperature is capable of producing enough energy (when focused) to instantly burn through paper.

 

Ummm... well thanks.

 

I think I understand what you mean by, or what is meant in general by "Thermal Source" at least in this context and why a laser is a "non-thermal source". Thanks.

 

I would like to point out one thing from earlier in this same text though:

 

"improperly used laser devices are potentially dangerous. Effects can range from mild skin burns to irreversible injury to the skin and eye. The biological damage caused by lasers is produced through thermal, acoustical and photochemical processes.

 

Thermal effects are caused by a rise in temperature following absorption of laser energy..."

 

Taken together with your earlier comments regarding lasers and "work", it would appear to me that in regard to lasers at least, this material serves to prove or support my point in regard to light or electromagnetic radiation in general being a form of Kinetic energy not "Heat".

 

I've been doing a bit of additional Googling on the subject of light and heat and have found some arguments put forward by others in support of the my statement that light (in any form) is NOT "heat".

 

I'm presenting these arguments from mostly non-authoritative sources (as far as I know) simply because the individuals making the statements sound at least as sure of themselves as you do and put forward some rather convincing arguments.

 

There are, just by way of comparison, some 50,000 "hits" for the exact phrase (in quotes) "light is not heat".

 

Ummm... "Thermal Source" means basically that the light generated is the result of heating something up to a hot enough temperature so that it gives out light. Like a hot piece of metal in a blacksmiths forge or a light bulb filament. I'm not sure this makes sense either as I thought a laser could be generated from any light source including sunlight but maybe I'm thinking of Indiana Jones creating a laser from sunlight with a ruby to open a tomb and that sort of thing is just fiction (?) Or does only the intermediary "source" count i.e. the Ruby or whatever, and not the original "source".

 

At any rate some other peoples arguments: (a series of three dots ... BTW indicates my editing out of what I consider irrelevant but feel free to read the excerpts in context (links provided) Also I have Bolded or otherwise highlighted some passages or statements I thought were particularly relevant.)

 

 

SCIENCE MISCONCEPTIONS IN K-6 TEXTS

 

INFRARED LIGHT IS A FORM OF HEAT

 

CORRECTED: NO, INFRARED LIGHT IS NOT A KIND OF HEAT

 

Infrared light is invisible light. When any type of light is absorbed by an object, that object will be heated.

 

...Just because human eyes cannot see the light which causes the heating does not mean that the light is made of some mysterious entity called "heat radiation."...

 

In his book "Clouds in a Glass of Beer," Physicist C. Bohren points out that this "heat" misconception may have been started long ago, when early physicists believed in the existence of three separate types of radiation: heat radiation, light, and actinic radiation.

 

Eventually they discovered that all three were actually the same stuff: light.

 

"Heat radiation" and "actinic radiation" are simply invisible light of various frequencies. Today we say "UV light" rather than "actinic radiation." Yet the obsolete term "heat radiation" still lingers. ...

 

https://www.msu.edu/user/boswort9/cep817web/amasci/scimis.htm#mis

 

 

------------------------------

 

"Light is not heat, light produces heat when it strikes an object.

 

For this reason, solar heating tubes work extremely effectively, even in winter months, because the light strikes heating elements vacuum sealed inside the heating tubes, protected from the outside temperature. Even in temperatures of -30 degrees F, the heating elements can reach 180 degrees F."

 

http://www.emmyenergy.com/green-energy/How-Solar-Heating-Works.cfm

 

-------------------------------

 

phildonnia

Master Poster

 

Infrared light is not heat, although that myth is probably still being taught even today. This probably got started because radiant heat felt from warm objects is primarily from infrared radiation.

 

Heat is molecular motion. Light is an electromagnetic disturbance.

 

 

http://forums.randi.org/showthread.php?t=49689

------------------------------------------------------

 

Light is electromagnetic radiation, as are radio waves, x-rays, etc… Heat can be transferred by electromagnetic radiation, but electromagnetic radiation is not heat. Heat is rather a form of kinetic energy in which individual atoms (that is, matter) vibrate and move in other ways. Absolute zero is the temperature at which this motion would cease.

 

Just as it would be inaccurate to call a warm breeze ‘heat,’ it is inaccurate to call light ‘heat.’

 

 

Milan October 26, 2009 at 8:39 am

 

...all objects in the universe emit electromagnetic radiation at a wavelength inversely proportional to their temperature). Still, this just means that hot objects emit light – not that light and heat are the same thing.

 

Milan October 26, 2009 at 11:54 am

 

‘Heat’ is how fast molecules are moving. Bombaring molecules with radiation does (usually) make them heat up, but that doesn’t mean that heat and light are the same thing.

 

Matt October 26, 2009 at 1:48 pm

 

I think a good way of illustrating that radiation is not ‘heat’ is to use the example of an antenna:

 

electromagnetic radiation striking an object, will heat it up, sure, but when it strikes something like an antenna, it will also produce electricity. That doesn’t mean that radiation is electricity. Similarly, it is not heat.

 

... if we want to be really technical, it is also wrong to say that radiation is heat. For heat to exist, there needs to be matter.

 

 

Tristan October 26, 2009 at 4:22 pm

 

Again, this is a technical definition of heat which is internally consistent, but which doesn’t correspond to the everyday semantic content of the term.

 

According to this meaning, when I say a fire is “giving off heat”, I’m technically incorrect – a fire is giving off radiation which turns into heat when it hits objects.

 

 

Milan October 26, 2009 at 4:29 pm

 

As Matt points out, light can turn into other things. Radio waves get turned into electricity by antennas.

 

Similarly, photovoltaic systems turn light into electricity.

 

Light can also be converted into kinetic energy (also).

 

As such, it is as much ‘potential electricity’ and ‘potential motion’ as potential heat.

 

Milan October 26, 2009 at 4:38 pm

 

It is also vital to all life on Earth that light is potential chemical bonds.

 

 

http://www.sindark.com/2009/10/23/led-lighting-effectiveness-and-efficiency/

 

----------------------------

 

This is just from the first page or so of search results.

 

I do not know where any of these people get their opinions from, (except where specific sources are cited) but from what seems to be and purports to be some sort of authoritative source of sorts, (the first cited) the idea that light in any form is heat is just plain old "Obsolete" as I read it. A "Science Misconception" in some old sixth grade text books.

 

I'll await your swift rebuttal as I sift through the other 50,000 or so "light is not heat" results.

 

To be fair, though, the phrase "light IS heat" returns nearly as many search results. Some 40,000 or so, So opinions differ, though on the first page of results I notice #1 This forum and #2 there are statements to the effect of "Misguided science students may wrongly believe light is "heat radiation" " so at this point it is a little difficult to say which way the pendulum swings.

 

As far as "Blackbody Radiation" I wonder about this statement from one of your sources previously cited:

 

"The concept of the black body is an idealization, as perfect black bodies do not exist in nature."

 

The concept apparently refers to any radiating source of EM to one degree or another so really, of what significance is that to our discussion ?

 

According to the above statement the Sun would not be a source of "black body radiation" as such a perfect idealization does not exist. Except perhaps the hypothetical "Hawking radiation" emitted by a Black Hole.

[spin-1/2-nuclei]

So far, there is really no contradiction. The question that I would like to ask now is whether there is any other energy (other than the kinetic energy, which is same in both containers) for the atoms. That is, whether the internal energy is partly kinetic and partly in some other form, and thus the total energy of the atoms will be different for the two containers.

 

Hello Finter,

 

Yes there is other energy required to get the containers to this state of having the same temperature but having different pressures. See Boyle's experiment, where holds both mass and temperature constant while changing pressure and volume to prove their relationship. This is called an isothermal process which in most cases cannot occur naturally when compressing a gas. What I was describing was adiabatic heating/cooling - which is the concept that describes the natural - i.e. - un-manipulated behavior between kinetic energy, temperature, pressure, and volume.

 

What I think may have confused you here is

a.) many people have chimed in giving opinions of the conditions I presented you with - adiabatic heating/cooling - from the argument of isothermal conditions. Which does not apply to the explanation I gave to your answer.

 

b.) The people that are using isothermal conditions to answer your question are neglecting to tell you that the equilibrium - i.e. holding temperature and mass constant - must be obtained via adding external energy sources or energy sinks whatever the case may be.

 

This is why I said the following earlier:

Hello,

 

No, there is no extra energy put into the system. The work comes from the force applied when changing the container size. This is how adiabatic compression works.

 

The only way you can change the temperature of a system is to change it's kinetic/thermal energy. A system can absorb energy and use it for many things, but if the temperature of the system increases then there must have been an increase in the kinetic/thermal energy. Now, there are situations when equilibrium can result in no observed change in energy, but that is not the case here. In the example you gave everything was fixed but the size of the container.

Hopefully this was helpful.

Cheers

 

This is why I continued to assume that you were referring to two isolated containers in your original question and were thus trying to ask what happens under normal conditions. When I stated this, you did not come back and state any specific laboratory conditions, and earlier when I stated this:

 

This doesn't mean that temperature is not related to heat capacity/specific heat, but it does not arise from them. As I said in earlier posts, that is to say that temperature can be changed via many different external forces acting on the molecular system, but these external forces (whether or not they are directly or indirectly measurable) MUST change the average kinetic energy/thermal energy - if they are going to change the temperature.

 

and as I said before,

Energy taken into the system from an external source can either go to internal energies (such as bond making/breaking, etc) or it can be converted into kinetic energy, which is the motion of the molecules, which gives rise to the temperature. That is to say things like entropy don't cause the increase in temperature, but rather cause the increase in the kinetic energy of the system, which in turn cases an increase in the temperature.

 

From your responses I felt that using adiabatic heating would be the best way to answer your question. I think adding in laboratory conditions without explaining them only confuses the process and in order to understand that explanation one would have to first understand the relationships clearly given by the adiabatic process. Thus I decided to explain the relationship between pressure, temperature, kinetic energy, and volume with that process. This is because even in an isothermal process the adiabatic relationships apply - they are just artificially held constant via external heating/cooling sources. Without those external sources you will return to the adiabatic systems.

 

Please read this link for more clarity: - http://en.wikipedia.org/wiki/Isothermal_process#Applications

"In Isothermal non flow Process, the work done by compressing the perfect gas (Pure Substance) is a negative work, as work is done on the system, as result of compression, the volume will decrease, and temperature will try to increase. To maintain the temperature at constant value (as the process is isothermal) heat energy has to leave the system and enter the environment. The amount of energy entering the environment is equal to the work done (by compressing the perfect gas) because internal energy does not change. The thermodynamic sign convention is that heat entering the environment is also negative. Thence Q = W.

In equation of work, the term nRT can be replaced by PV of any state. The product of pressure and volume is in fact, 'Moving Boundary Work'; the systems boundaries are compressed. For Expansion the same theory is applied."

 

Thus, because I described my conditions as adiabatic heating, and some people who did not read the thread in it's entirety and just chimed in after Swansont quoted me answering your question - they did not understand that they were arguing against the validity of adiabatic heating/cooling... which most accurately describes what will happen to a system when it is absent of laboratory/external heating/cooling sources.

 

That is to say.

Always - whenever you change the volume you will change the pressure, which will change the temperature. This change in temperature can either have an impact on the kinetic energy or can be held constant artificially via adding/removing the energy from the system in the form of heat transfer via an external heating/cooling source. This is the explanation that I think has been missing from the descriptions of the isothermal process. The why - of how the temperature remains constant - isn't that the temperature is not rising as a result of the change in pressure, but rather it is because the rise in kinetic energy which leads to the rise in temperature is kept at equilibrium (i.e. the temp and mass are kept constant) artificially via external means.

 

Hope this helps..

Cheers

Edited August 22, 2011 by spin-1/2-nuclei

[swansont]

"Infrared light is not heat" is something I've advanced a number of times — I agree. I've explained it in this thread already, in this post http://www.scienceforums.net/topic/59202-what-is-heat/page__p__622500#entry622500

 

Not all light is emitted because of an objects temperature, so not all light is heat. When an object does emit thermal radiation, if is often in the IR, but it is not constrained to be so. Thermal radiation follows Planck's law for the distribution and the Stefan-Boltzmann law for total power. All of the EM radiation emitted under those conditions id heat. So equating IR with heat is wrong for several reasons — it implies that all IR is from thermal sources, and it implies that only IR carries away energy from the hot object.

[spin-1/2-nuclei]

Ummm... "Thermal Source" means basically that the light generated is the result of heating something up to a hot enough temperature so that it gives out light. Like a hot piece of metal in a blacksmiths forge or a light bulb filament. I'm not sure this makes sense either as I thought a laser could be generated from any light source including sunlight but maybe I'm thinking of Indiana Jones creating a laser from sunlight with a ruby to open a tomb and that sort of thing is just fiction (?) Or does only the intermediary "source" count i.e. the Ruby or whatever, and not the original "source".

 

Hello Tom,

 

I've been following the laser discussion a little bit, and I think I might be able to help you in some regard. I too think that the semantics surrounding what is a "thermal source", vs. what is "heat" detract from the clear understanding of the topics. Unfortunately science seems content to use the terms interchangeably without regard for the amount of confusion it causes. I think the following might help explain why some physicists call lasers "thermal sources" - i.e. they think lasers - in some conditions - are a different type of thermal source (given that the behavior between the two at that point is indistinguishable) and other physicists point to the differences in the photon statistics and 2nd-order coherence as explanations for their position on lasers - not being thermal sources.

 

In laser physics,

The laser and a "thermal source" have different photon statistics despite having the same average number of photons. So both can have the same first order spatial and temporal agreement, bandwith, intensity, and frequency - but in physics they are still considered two different things. So the photon stats are the same for laser light below the threshold of oscillation and a thermal source. So below the threshold the photon counting probability distribution function is utilized and above the threshold the Poisson distribution is utilized to describe the photons.

 

So, in the 1st-order coherence does not discriminate between a "thermal source" and a laser, despite the different photon statistics.. Thus, it is the 2nd-order coherence properties that gives rise to the difference between a laser and a "thermal source". So basically those that think lasers are a "thermal source" are speaking of the lasers below the threshold of oscillation where 1st-order coherence properties apply and those who believe lasers are not a "thermal source" are referring to both the difference in the photon statistics and the 2nd-order coherence properties. I think the Brown and Twiss experiment describes the 2nd-order coherence properties of light.

 

Other key points:

Normal optics cannot describe the difference between laser light and light from a thermal source. So it's the statistical fluctuations in the beams of light that describes the difference between laser light and light from a thermal source. So basically the photon counting just describes the quantum nature of light. This is why Swansont is talking about blackbody radiation... This is the common way to measure the differences between the brightness of radiation from a laser and radiation from thermal light sources. It basically describes the degeneracy factor of a photon.. which can often be much greater for a laser than it is for light from a thermal source. So since "thermal sources" can emit light that is temporally/spatially equivalent to that of a laser some scientists refer to lasers as "thermal sources" - in fact many are starting to do this - BUT -

because "thermal sources" cannot produce the same "amount" of degenerate photons without the "thermal source" being at temperatures we have not see in the universe so scientists say that lasers are not "thermal sources"..

 

So, the question becomes what is a "thermal source", do we adhere to the old school definition of "thermal source" which came about before we had lasers and make up a new definition for the similarity between the "thermal properties" of the "thermal source" and the laser, observed when using lasers below threshold, or do we modify that definition of "thermal source" to include lasers? So far, from what I can tell - there has been no consensus - as the physicists that we work with refer to lasers as "thermal sources" on a regular basis, as do many chemists, and some do not.

 

For more information on photon statistics, I've provided some sources below..

 

There is an experiment that was done to describe the photon statistics, and I cannot remember for sure what the name of the Scientist who did the first experiment was, but here are some references that you might find useful. I would also suggest obtaining a book that specifically deals with laser physics and not thermodynamics because the typical undergraduate thermo book will not go into enough detail about the why. A good graduate level book on laser physics will explain the majority of these questions much better - although without reaching definite yes/no positions when viewed from the perspective of each camp, unfortunately.

 

1. "Phys. Rev. Lett. 15, 943–946 (1965)

Photoelectron Statistics Produced by a Laser Operating Below the Threshold of Oscillation" - http://prl.aps.org/abstract/PRL/v15/i25/p943_1

 

2. This book on laser physics - http://www.amazon.com/Physics-Oxford-Master-Atomic-Optical/dp/0198506929/ref=sr_1_2?s=books&ie=UTF8&qid=1314006397&sr=1-2

 

I hope this was helpful...

Cheers

Edited August 22, 2011 by spin-1/2-nuclei

[swansont]

As the blurb I had quote earlier points out, the second law of thermodynamics dictates that you cannot make the light from a blackbody make anything hotter than the source. It doesn't matter how you try and collect and concentrate the light — if you use the sun, you will not be able to heat anything above the surface temperature (~5800K). If you could, it would be possible to spontaneously transfer energy from a colder source to a hotter one, a violation of the second law. If you tried to reclassify laser light as heat, you'd have to toss out that law.

[DrRocket]

As the blurb I had quote earlier points out, the second law of thermodynamics dictates that you cannot make the light from a blackbody make anything hotter than the source. It doesn't matter how you try and collect and concentrate the light — if you use the sun, you will not be able to heat anything above the surface temperature (~5800K). If you could, it would be possible to spontaneously transfer energy from a colder source to a hotter one, a violation of the second law. If you tried to reclassify laser light as heat, you'd have to toss out that law.

 

Right. For those who think that all you need to do is focus the sun's light to a point, the problem is that the sun's rays are not perfectly parallel and won't focus to a point. The best that you can do, in the ideal case, is a disc that replicates the surface temperature of the sun. The second law wins again.

 

This issue is not too different from the situation in which a resistor is heated by current from a (lower temperature) battery. Call it work and all is well.

[spin-1/2-nuclei]

Hello Tom,

 

The comments above reminded me that I forgot to address the ruby and Indiana Jones in my previous post, sorry. I'm quite sick with a head cold and have been working long hours in the lab lately, so I'm a little forgetful at times..

 

So....

Yes, they do have lasers powered by sunlight. NREL has made one, and a scientist from Tokyo has as well. I found a really good summary article on google, and I will link you to it here. They are making great strides now, the tokyo researcher has found a way to increase the amount of light focused by utilizing small Fresnel lenses in lieu of mirrors..

 

"The other innovation of Yabe's laser is the use of a small Fresnel lens instead of large mirror lenses. Fresnel lenses reduce the size and amount of material needed to build a lens by breaking it into concentric rings of lenses. Typically, 10 percent of incident light is focused on the crystal, whereas with the Fresnel, it's around 80 percent." - http://www.technologyreview.com/Energy/19402/

 

and this link to info on the NREL laser: http://www.nrel.gov/news/press/1995/solar.html

 

hopefully this was helpful..

Cheers

Edited August 22, 2011 by spin-1/2-nuclei

[Tom Booth]

Well, a few thoughts, given the new information.

 

I'm going with the hypothesis that "Thermal source of radiation" is an "obsolete" phrase or hold over from before scientists realized that so-called "Thermal Radiation" was, in actuality just light that was at a wavelength not appreciable by the human eye.

 

This, to me, quite effectively simplifies the whole equation when thinking about such matters in a general way. i.e. anything said about "Thermal Radiation" can, from hereon, in my personal information censure be taken with a grain of salt.

 

I have no problem with discarding the second law of thermodynamics. It is statistical, like the number of car accidents. Accidents happen. They can also be prevented.

 

Violations of the second law have been postulated. (Maxwells Deamon etc.) And to one degree or another, I think also demonstrated to a very limited degree, though I wont go there at the moment.

 

Yes, I did notice that swansont earlier pointed out that Infrared Light being heat was a misconception, but IMO misinterpreted this to mean that Infrared light is not the only kind of light that is heat when what was really meant is that Light is not heat PERIOD. Infrared light is not heat. There is no such thing as "Heat Radiation". There is no form of EM emission that is pure "Heat" period as was once considered to be the case. The whole concept of "Thermal Radiation" has been obsoleted. "Thermal Radiation" has not been replaced by "Blackbody Radiation" or "Infrared Radiation" or anything else it has been effectively thrown out the window.

 

Anything ever said about "Thermal Radiation", including expariments performed to "prove" anything related to it could have only been approximations.

 

Why ?

 

Light is almost 100% kinetic energy is seems to me. But not really 100% so it is very close to being pure "heat" or Pure "kinetic Energy" but it is not.

 

Photons can be used to propel a spaceship. (Solar Sails). Light has "pressure" (Radiometer). It exhibits characteristics of a "particle". (Photon). It has many attributes that "Heat" does not have.

 

One of my quotes above said: "For heat to exist there has to be matter".

 

Is light a form of "matter" ?

 

There is some "residual heat" or some form of heat in the vacuum of empty space which is apparently due to the light zipping around in it.

 

So, have we come full circle?

 

Light is not heat. it is mostly kinetic energy but as heat is defined as kinetic energy light is mostly "heat". Though for the sake of simplicity I think it is easier to discard "heat" as a concept altogether as an obsolete or unscientific term based on flawed human perceptions and stick with "kinetic energy" period.

 

There is no such thing as "Heat". It is just a subjective human impression that takes place in the nervous system when there is an increase in (kinetic) energy impacting the nerves.

[swansont]

I have no problem with discarding the second law of thermodynamics.

Game over. Just be sure that you know that you are not discussing physics. Call it whatever you want, but it's not physics.

[spin-1/2-nuclei]

Hello again Tom,

 

If you're interested in violations of the second law of thermodynamics I have some papers that you might like to review. The first one is from 2002. When I used to TA, I liked to give excerpts from papers like these to try to encourage my students to think outside of the box. Personally, in addition to having a solid understanding of the first principles, I also liked to teach my chemistry and physics students to understand what the data is saying and draw conclusions based on the data and not from any preconceived ideas (even if those preconceptions are based on the first principles).

 

I think it is necessary to teach objectivity along with the basics because many students first starting their graduate work will overlook discoveries simply because their method of thinking about their research is too rigid. Surely apparent contradictions of well established science require careful investigation, but the point is to investigate objectively rather than disprove. Typical disproof will follow, but on rare occasions it does not!

 

Either way,

Needless to say, very few students were ever willing to consider a violation of the second law of thermo, but a few did and even correctly deduced apparent violations.

 

As with many things approaching the frontiers of scientific research, there are differing opinions in science about what is and is not a violation of the second law of thermodynamics and whether or not any violations have actually occurred.

 

Since you've already said you don't care about violating the second law, I'm not going to bother to chime in with my own position on that because I think it will take away from the conversation that is finally going somewhere interesting.. at least from my perspective..

 

Anyway, below are the references. I apologize if you've read some of these already..

 

1. Experimental Demonstration of Violations of the Second Law of Thermodynamics for Small Systems and Short Time Scales - "We experimentally demonstrate the fluctuation theorem, which predicts appreciable and measurable violations of the second law of thermodynamics for small systems over short time scales, by following the trajectory of a colloidal particle captured in an optical trap that is translated relative to surrounding water molecules. From each particle trajectory, we calculate the entropy production/consumption over the duration of the trajectory and determine the fraction of second law–defying trajectories. Our results show entropy consumption can occur over colloidal length and time scales." - http://prl.aps.org/abstract/PRL/v89/i5/e050601

 

2. Probability of second law violations in shearing steady states - "We propose a new definition of natural invariant measure for trajectory segments of finite duration for a many-particle system. On this basis we give an expression for the probability of fluctuations in the shear stress of a fluid in a nonequilibrium steady state far from equilibrium. In particular we obtain a formula for the ratio that, for a finite time, the shear stress reverse sign, violating the second law of thermodynamics. Computer simulations support this formula.

© 1993 The American Physical Society" - http://prl.aps.org/abstract/PRL/v71/i15/p2401_1

 

3. Violation of the second law of thermodynamics in the quantum microworld - "One of the previously reported linear models of open quantum systems (interacting with a single thermal bath but otherwise not aided from outside) endowed with the faculty of spontaneous self-organization challenging standard thermodynamics is reconstructed here. It is then able to produce, in a cyclic manner, a useful (this time mechanical) work at the cost of just thermal energy in the bath whose quanta get properly in-phased. This means perpetuum mobile of the second kind explicitly violating the second law in its Thomson formulation. No approximations can be made responsible for the effect as a special scaling procedure is used that makes the chosen kinetic theory exact. The effect is purely quantum and disappears in the classical limit." - http://www.sciencedirect.com/science/article/pii/S0378437100003459

 

4. A Quantum Violation of the Second Law? - "An apparent violation of the second law of thermodynamics occurs when an atom coupled to a zero-temperature bath, being necessarily in an excited state, is used to extract work from the bath. Here the fallacy is that it takes work to couple the atom to the bath and this work must exceed that obtained from the atom. For the example of an oscillator coupled to a bath described by the single relaxation time model, the mean oscillator energy and the minimum work required to couple the oscillator to the bath are both calculated explicitly and in closed form. It is shown that the minimum work always exceeds the mean oscillator energy, so there is no violation of the second law." - http://prl.aps.org/abstract/PRL/v96/i2/e020402

 

hope you find them interesting..

Cheers

[Tom Booth]

Tom Booth, on 22 August 2011 - 09:10 AM, said:

I have no problem with discarding the second law of thermodynamics.

 

Game over. Just be sure that you know that you are not discussing physics. Call it whatever you want, but it's not physics.

 

Please note that I did not say that I was discarding it or that I have discarded it or that I do not think it is important, just that I have no problem with considering the possibility of discarding it.

 

Many scientists, physicist, theorists etc. have discussed, considered debated "Maxwell's demon" this does not make them, including Maxwell "unscientific".

 

Just picking something at random:

 

Should this sort of thing just be categorically ignored ?:

 

http://www.newscientist.com/article/dn2572-second-law-of-thermodynamics-broken.html

 

Well, yeh, maybe. But go tell it to New Scientist magazine not me. I haven't actually read the article yet BTW but should I just dismiss it offhand ? Or should I consider such information with an open mind ? Which approach is more "scientific". This article was published nine years ago. Any new developments since then since the 2nd law was apparently thrown out the window ?

 

Not possible according to the good Mr. Swansont. This is not Physics. Change and new insights are nowhere on the horizon for Mr Swansont.

[swansont]

Please note that I did not say that I was discarding it or that I have discarded it or that I do not think it is important, just that I have no problem with considering the possibility of discarding it.

 

Well, no, that's actually not what you said. You said "I have no problem with discarding the second law of thermodynamics" and also indicated that you were content to use your own definitions. You are free to issue a retraction/correction/clarification, but denial is kind of ridiculous when there's a record of what you said.

 

Many scientists, physicist, theorists etc. have discussed, considered debated "Maxwell's demon" this does not make them, including Maxwell "unscientific".

 

Not at all. But they have not concluded that the second law doesn't hold.

 

Just picking something at random:

 

Should this sort of thing just be categorically ignored ?:

 

http://www.newscientist.com/article/dn2572-second-law-of-thermodynamics-broken.html

 

Well, yeh, maybe. But go tell it to New Scientist magazine not me. I haven't actually read the article yet BTW but should I just dismiss it offhand ? Or should I consider such information with an open mind ? Which approach is more "scientific". This article was published nine years ago. Any new developments since then since the 2nd law was apparently thrown out the window ?

(emphasis added)

 

Well, you should. Because headline writers and journalists have a way of sensationalizing experiments. If you had read and understood it, as well as thermodynamics, you would know that the second law was not thrown out the window. In statistical mechanics the second law becomes a statistical argument. Low entropy states are less likely than high entropy states, so it is much more likely that the entropy will increase as you watch the system evolve. But fluctuations that lower entropy can and do occur, they just aren't likely. What this experiment showed was the scale on which one could observe these fluctuations — that part was the newsworthy bit. That the entropy momentarily decreased was not.

 

Not possible according to the good Mr. Swansont. This is not Physics. Change and new insights are nowhere on the horizon for Mr Swansont.

 

If you are going to use a title (which is not at all necessary), the correct one would be Dr. rather than Mr. As for insults, well, just say no (I believe you've already been asked to improve your behavior).

[Tom Booth]

Tom Booth, on 22 August 2011 - 11:52 AM, said:

Please note that I did not say that I was discarding it or that I have discarded it or that I do not think it is important, just that I have no problem with considering the possibility of discarding it.

 

 

Well, no, that's actually not what you said.

 

You said "I have no problem with discarding the second law of thermodynamics"

 

True, that is what I said. But I will repeat. I did not say that I was discarding it or that I have discarded it or that I do not think it is important. What is not clear about that ?

 

The following is a clarification of what I did say:

 

"I have no problem with discarding the second law of thermodynamics"

 

I believe that can stand on its own but since you apparently misinterpreted something about that it means:

 

I am not at all attached to it and if it were dis-proven I would raise the flag. I have no problem with discarding the second law of thermodynamics

 

 

and also indicated that you were content to use your own definitions.

 

So ? Whats wrong with defining my own terms and concepts for the sake of clarity ?

 

If there is admittedly NO SUCH THING as "Thermal Radiation" why continue to shackle the mind with obsoleted concepts and terminology ?

 

You are free to issue a retraction/correction/clarification, but denial is kind of ridiculous when there's a record of what you said.

 

Who's "denying" ?

 

Nature shrugs its shoulders and violates "The Law" with impunity, apparently. Since the atoms making up my fingernail have been spinning and revolving and vibrating for a Bazzillion years.

 

I don't personally know enough about it to form a judgement one way or the other, (thank God) but what I do know is that most of what I learned in school was obsolete before I graduated and the pace of scientific advancement is greater than ever before in history to the point where we are apparently still on this board discussing things and using terminologies that have long since fallen into obsolescence without our even knowing it or anyone who does bothering to make mention of the fact.

 

So I do tend to try and keep an open mind about such things and follow new developments regardless of how "sensational".

 

I would not be too surprised if eventually some astute observer of nature figured out just why as some say "perpetual motion is the rule of the universe

"

Tom Booth, on 22 August 2011 - 11:52 AM, said:

Many scientists, physicist, theorists etc. have discussed, considered debated "Maxwell's demon" this does not make them, including Maxwell "unscientific".

 

Not at all. But they have not concluded that the second law doesn't hold.

 

Maybe not. but if some such exception or "loophole" were discovered ? Who would be leading the lynch mob ?

 

And what if they did come to such a conclusion ? Would you launch into an ad hominem attack against the person (as you have done with me) rather than considering or debating the issue ?

 

Tom Booth, on 22 August 2011 - 11:52 AM, said:

Just picking something at random:

 

Should this sort of thing just be categorically ignored ?:

 

http://www.newscient...ics-broken.html

 

Well, yeh, maybe. But go tell it to New Scientist magazine not me. I haven't actually read the article yet BTW but should I just dismiss it offhand ? Or should I consider such information with an open mind ? Which approach is more "scientific". This article was published nine years ago. Any new developments since then since the 2nd law was apparently thrown out the window ?

(emphasis added)

 

Well, you should. Because headline writers and journalists have a way of sensationalizing experiments....

 

Why bother ? If you already know it is just journalist sensationalizing why read any further than the headline ?

 

As for insults, well, just say no (I believe you've already been asked to improve your behavior).

 

That's fine, but perhaps you might explain why others get a pass when insulting spin-1/2-nuclei, accompanied by roaring laughter and knee slapping, when he happens to make some sort of misstatement.

 

I thought I was being rather conservative in my jests by comparison.

 

Not to mention some of your comments towards myself have not exactly been complementary. Like most recently, simply considering a possibility or speculating along some lines you don't happen to agree with is... well... In your words: "Call it whatever you want, but it's not physics." or "headline writers and journalists have a way of sensationalizing experiments. If you had read and understood it, as well as thermodynamics,..."

 

I personally find such comments just a bit insulting and ad hominem.

 

I would say that there is some possibility that your prejudice may have slanted your perceptions of the article just on the basis of the headline.

 

I've read numerous controversies and debates over just exactly what is or isn't a violation. It seems to me to be largely a matter of personal perception and interpretation.

 

For all I know the so-called "Law" is pure mythology. A self imposed restriction scientists have shackled their minds with.

 

How can you take something seriously when it is based on a fallacious belief in the existence of "Thermal Radiation" ?

 

When "Heat" itself is proven to be nothing more than motion. How can there be a "Heat Death of the Universe" as apparently dictated by "The Law" if there is no such thing as "Heat" ?

[mississippichem]

I would say that there is some possibility that your prejudice may have slanted your perceptions of the article just on the basis of the headline.

 

Well then I must have the exact same bias as I reached a similar conclusion on the article. There is no violation of the 2nd law of thermodynamics here. You clearly do not understand the second law. This is not an insult, merely an accurate observation that is completely relevant to the discussion at hand.

 

Start a thread on the second law of thermodynamics. I'm sure there are many here willing to explain it to you.

 

I've read numerous controversies and debates over just exactly what is or isn't a violation. It seems to me to be largely a matter of personal perception and interpretation.

 

Citation?

 

A true violation would be some interval of time where the entropy of the entire universe increased and did not decrease accordingly. A perpetual motion machine would accomplish this. However, this will simply never happen.

 

For all I know the so-called "Law" is pure mythology. A self imposed restriction scientists have shackled their minds with.

 

How can you take something seriously when it is based on a fallacious belief in the existence of "Thermal Radiation" ?

 

When "Heat" itself is proven to be nothing more than motion. How can there be a "Heat Death of the Universe" as apparently dictated by "The Law" if there is no such thing as "Heat" ?

 

(Equivocation fallacy) [imath] \times [/imath] (Strawman) [imath] = [/imath] (disingenuous argument) [imath] + [/imath] (complete incorrectness). What part of the second law requires the use of the term "thermal radiation"? What does heat death of the universe have to do with the second law in this context?

[swansont]

So ? Whats wrong with defining my own terms and concepts for the sake of clarity ?

 

Because it's a barrier to discussing the concepts if e.g. what you mean by heat is different from what everyone else means by heat.

 

If there is admittedly NO SUCH THING as "Thermal Radiation" why continue to shackle the mind with obsoleted concepts and terminology ?

 

There is. You're the only one here denying that thermal sources emit radiation, and that this is considered heat. If you want, you can construct a model on this idea, but it won't be thermodynamics.

 

Nature shrugs its shoulders and violates "The Law" with impunity, apparently. Since the atoms making up my fingernail have been spinning and revolving and vibrating for a Bazzillion years.

 

No, that would be you misunderstanding thermodynamics.

 

Would you launch into an ad hominem attack against the person (as you have done with me) rather than considering or debating the issue ?

 

I have made an ad hominem attack on you? I have no need of an ad hominem. Your arguments are wrong and can be discussed on their merits (or lack thereof)

 

 

Why bother ? If you already know it is just journalist sensationalizing why read any further than the headline ?

 

Because the headline is wrong (sensationalized) and the article actually explains some details that might let you know what happened.

 

That's fine, but perhaps you might explain why others get a pass when insulting spin-1/2-nuclei, accompanied by roaring laughter and knee slapping, when he happens to make some sort of misstatement.

 

"You're wrong" isn't an insult, and if there was any laughter or knee-slapping, I missed it. I saw a lot of "nonsense" and "You are just making stuff up as you go along" but that came from you …

 

I thought I was being rather conservative in my jests by comparison.

 

Not to mention some of your comments towards myself have not exactly been complementary. Like most recently, simply considering a possibility or speculating along some lines you don't happen to agree with is... well... In your words: "Call it whatever you want, but it's not physics." or "headline writers and journalists have a way of sensationalizing experiments. If you had read and understood it, as well as thermodynamics,..."

 

I personally find such comments just a bit insulting and ad hominem.

 

It's not physics. That can't be ad hominem, because it's not an observation about you.

You didn't read the article. By your own admission. You have also demonstrated a serious lack of understanding of thermodynamics. That also can't be ad hominem, because it's the exact subject of the discussion.

 

How can you take something seriously when it is based on a fallacious belief in the existence of "Thermal Radiation" ?

 

Case in point.

[Tom Booth]

Well then I must have the exact same bias as I reached a similar conclusion on the article.

 

Everybody has a bias, IMO. We are all full of assumptions taught to us from the cradle, most of which we never become consciously aware of.

 

There is no violation of the 2nd law of thermodynamics here.

 

The article suggests repeatedly that there is. I don't know enough about hypothetical future nanobots "running backwards" to form an opinion.

 

You clearly do not understand the second law. This is not an insult, merely an accurate observation that is completely relevant to the discussion at hand.

 

No, I admittedly do not understand the second law of thermodynamics.

 

For one thing I would object to anything in scientific circles being referred to as a "LAW". In my mind this is unscientific and stifles the imagination and the possibility of progress.

 

Properly I think it should read the second theory if it is science rather than dogma.

 

Just my opinion of course.

 

I also don't "understand" how a theory that seems to dictate increasing disorder (entropy) is compatible with... well, the Big Bang Theory for one. Life for another.

 

I know all about thermodynamics. I spent most of the afternoon stacking firewood.

 

The pile of firewood went "spontaneously" from a completely disordered pile to a very orderly neat stack. Of course, "I" was involved in the process somehow I think but "I" don't count.

 

Life evolved "spontaneously" on earth. I'm a part of that apparent "negative entropy". You can't hold to the theory of "entropy" (i.e. the second law) without ignoring the obvious fact that you violate it by your existence.

 

I've read numerous controversies and debates over just exactly what is or isn't a violation. It seems to me to be largely a matter of personal perception and interpretation.

 

Citation?

How about this forum and this thread and this conversation. One need not look very far.

 

Sticking with the theme, Take the issue of the evolution of life. You and me.

 

According to the article we are currently discussing it is something of a marvel that some beads floating around randomly in water happened to congregate on one side or the other for a second or two.

 

I say so what ? The eyeball observing the experiment is more organized.

 

Life has become more organized and complex over billions of years it has existed on the planet. Who cares about a brief assemblage of a few beads floating in water ?

 

Arguments to counter this sort of question from thermodynamic or science (particularly evolution) advocates, it seems to me, devolve into mathematical gobbledygook.

 

Take this one for example:

 

http://www.talkorigins.org/faqs/thermo/probability.html

 

Or this:

 

http://www.talkorigins.org/faqs/thermo/entropy.html

 

And the rebuttal from a creationist:

 

http://www.trueorigin.org/steiger.asp

 

I'm not an evolutionist or a creationist so don't bother debating either side of any of these discussions with me. Just pointing out a small fragment of some of the controversy, real or imagined in one small area of interest.

 

Every time some article is published, like the one cited above there are also debates about the article on numerous forums. Why should this be surprising ? I've read and / or participated in a few of them.

 

A true violation would be some interval of time where the entropy of the entire universe increased and did not decrease accordingly. A perpetual motion machine would accomplish this. However, this will simply never happen.

 

Like I say, that is a matter of perception and interpretation.

 

What has taken place since the beginning of the universe other than a movement from the total chaos of the "Big Bang" to the mind boggling and largely inexplicable complexities and general orderliness of the universe to be found at every turn today, including life.

 

If we are supposed to exclude or ignore life I would like to know the basis for doing so. Science is about observation not burying ones head in the sand and ignoring what's plain to see.

 

Do you know anyone who has ever traveled to or seen the end of the universe? What exactly constitutes the "ENTIRE UNIVERSE" ?

 

Have you ever heard of String Theory ? It seems to be the latest rage and postulates some eleven or so universes. Or keeping with something more well established than String Theory: The Many-Worlds Interpretation of Quantum Mechanics.

 

How can a "true violation" be defined in terms of an "entire universe" with multiple hidden dimensions as in String Theory or with a potentially infinite number of "parallel universes" as in some interpretations of Quantum Physics and does anyone even have a real handle on THIS UNIVERSE in its entirety ? I doubt it.

 

(Equivocation fallacy) [imath] \times [/imath] (Strawman) [imath] = [/imath] (disingenuous argument) [imath] + [/imath] (complete incorrectness). What part of the second law requires the use of the term "thermal radiation"?

 

It is not the term "thermal radiation" specifically, it is the whole concept of Heat in general:

 

It is part of the definition of the science.

 

"her·mo·dy·nam·ics

Noun: The branch of physical science that deals with the relations between heat and other forms of energy"

 

"The branch of physics that deals with the relationships between heat and other forms of energy"

 

Well, if "heat" in matter is kinetic energy and "thermal radiation" is obsoleted what does that leave ?

 

But please do not take my philosophical musings on the subject too seriously or personally. I'm not particularly trying to prove or disprove anything.

 

But if the fundamental principle or basic assumptions upon which a science is supposed to be based. In this case "Thermo" (from the Greek: Θερμότητα, meaning heat) is shown to be a fallacy, where does that leave that science ?

 

Open to some question or re-examination I would think.

 

What does heat death of the universe have to do with the second law in this context?

 

Beats me.

 

Practically every text I've ever read on Thermodynamics makes mention of it:

 

For example:

 

--------------clip

Heat death of the universe

Main article: Heat death of the universe

 

According to the second law, the entropy of any isolated system, such as the entire universe, never decreases. If the entropy of the universe has a maximum upper bound then when this bound is reached the universe has no thermodynamic free energy to sustain motion or life, that is, the heat death is reached.

 

http://en.wikipedia.org/wiki/Second_law_of_thermodynamics#Heat_death_of_the_universe

--------------

 

Sounds pretty gruesome.

 

The tendency for entropy to increase in isolated systems is expressed in the second law of thermodynamics-- perhaps the most pessimistic and amoral formulation in all human thought.

 

http://www.principiadiscordia.com/book/54.php

 

If possible, I would prefer not to ignore life.

[DrRocket]

 

I know all about thermodynamics. I spent most of the afternoon stacking firewood.

 

 

"It ain't what you don't know that gets you into trouble. It's what you know for sure that just ain't so. "– Mark Twain

 

 

[finiter]

What I think may have confused you here is

a.) many people have chimed in giving opinions of the conditions I presented you with - adiabatic heating/cooling - from the argument of isothermal conditions. Which does not apply to the explanation I gave to your answer.

 

b.) The people that are using isothermal conditions to answer your question are neglecting to tell you that the equilibrium - i.e. holding temperature and mass constant - must be obtained via adding external energy sources or energy sinks whatever the case may be.

I got it clearly. First you have to compress the larger container, and then remove the heat of compression (either adiabatically or isothermally)

to reach the state of the smaller container. The confusion was mine: I just ignored the fact that applying the force resulted in an increase in energy. (Personally, I do not agree with the concept that energy transfer occurs just because a force acts or a force is applied, and this view interfered and caused the confusion).

[Tom Booth]

Tom Booth, on 22 August 2011 - 04:50 PM, said:

So ? Whats wrong with defining my own terms and concepts for the sake of clarity ?

 

Because it's a barrier to discussing the concepts if e.g. what you mean by heat is different from what everyone else means by heat.

 

What is the topic of this thread?

 

~~ WHAT IS HEAT ~~

 

Defining HEAT is the stated theme of this thread is it not? I think everyone here in one way or another has put forward their definition of the term. What reason would you have for objecting to my doing the same ?

 

Tom Booth, on 22 August 2011 - 04:50 PM, said:

If there is admittedly NO SUCH THING as "Thermal Radiation" why continue to shackle the mind with obsoleted concepts and terminology ?

 

There is. You're the only one here denying that thermal sources emit radiation, and that this is considered heat....

 

I'm simply pondering the ramifications of what is stated on this website regarding "Science Misconceptions" previously quoted:

 

https://www.msu.edu/user/boswort9/cep817web/amasci/scimis.htm

 

To quote one more time:

 

----------------clip

 

In his book "Clouds in a Glass of Beer," Physicist C. Bohren points out that this "heat" misconception may have been started long ago, when early physicists believed in the existence of three separate types of radiation: heat radiation, light, and actinic radiation.

 

Eventually they discovered that all three were actually the same stuff: light.

 

"Heat radiation" and "actinic radiation" are simply invisible light of various frequencies. Today we say "UV light" rather than "actinic radiation." Yet the obsolete term "heat radiation" still lingers. ...

-----------------

 

It would appear that there is not LITERALLY any "heat radiation" as originally conceived. The belief has been overturned. Heat does not literally radiate.

 

I'm not "denying that thermal sources emit radiation, and that this is considered heat...."

 

I have no particular opinion on the matter.

 

The references previously cited state that to consider such electromagnetic radiation to be heat is erroneous and a holdover from bygone days apparently still taught to High School Students.

 

This is News to me.

 

Do you still hold to the theory of "actinic radiation" as well ?

 

It seems to me that this is more than just a swopping out of one terminology for another.

 

Well, we used to call IT "Heat Radiation" but now we call IT Infrared Light.

 

I certainly don't deny that "thermal sources (as previously defined; i.e. em emitting objects) emit radiation, and that this is considered heat...." apparently by you and others and is a commonly held assumption by nearly everyone including, until now, myself.

 

This reference and others, however, state that this consideration is wrong. EM Radiation is not the same thing as heat.

 

Do you dispute what this reference says ?

 

This seems to me to be a fundamental change in how reality is viewed not just a change in terminology. It was thought that heat itself could radiate. This was discovered to be false, apparently. Something else fundamentally different from heat radiates. This something else is converted to or from Heat at either end but is not itself heat but light. There is no such thing as "Heat Radiation" so why continue to use the outmoded terminology or "consider" something to be something that it isn't ?

 

On the other hand, if you consider heat as universally a substitute term for "kinetic energy" then the problem disappears and the terminology more accurately reflects the reality. Or so it would seem to me.

 

Then you do not have to form arbitrary or artificial distinctions between a photon from a "Thermal Source" and a Photon from any other source when there is apparently no physical basis for making such a distinction.

 

In my mind this clears up a lot of confusion. I'll admit, I could be wrong but that is what makes sense to me at this point trying to reconcile the apparent contradictions.

Tom Booth, on 22 August 2011 - 04:50 PM, said:

Nature shrugs its shoulders and violates "The Law" with impunity, apparently. Since the atoms making up my fingernail have been spinning and revolving and vibrating for a Bazzillion years.

 

No, that would be you misunderstanding thermodynamics.

 

OK, how so ?

Tom Booth, on 22 August 2011 - 04:50 PM, said:

Would you launch into an ad hominem attack against the person (as you have done with me) rather than considering or debating the issue ?

 

I have made an ad hominem attack on you? I have no need of an ad hominem. Your arguments are wrong and can be discussed on their merits (or lack thereof)

 

May I remind you of your earlier statement: "Because it's a barrier to discussing the concepts if e.g. what you mean by heat is different from what everyone else means by heat."

 

Since defining "heat" is the topic of the thread, I would have to perceive this statement as ad hominem and personal even if veiled.

 

You should be arguing with the quote from which the information came, not denying me the right to discuss it.

Tom Booth, on 22 August 2011 - 04:50 PM, said:

Why bother ? If you already know it is just journalist sensationalizing why read any further than the headline ?

 

Because the headline is wrong (sensationalized) and the article actually explains some details that might let you know what happened.

 

I don't mean why should I bother, but why should you.

Tom Booth, on 22 August 2011 - 04:50 PM, said:

That's fine, but perhaps you might explain why others get a pass when insulting spin-1/2-nuclei, accompanied by roaring laughter and knee slapping, when he happens to make some sort of misstatement.

 

"You're wrong" isn't an insult, and if there was any laughter or knee-slapping, I missed it. I saw a lot of "nonsense" and "You are just making stuff up as you go along" but that came from you …

 

I was referring specifically to such comments as: "I'd like to buy a few bottles from his supplier." - "Whatever he is drinking is powerful stuff."

 

Now I don't personally object to a bit of poking fun or whatever now and then but why zero in on me ?

 

You have also demonstrated a serious lack of understanding of thermodynamics. That also can't be ad hominem, because it's the exact subject of the discussion.

 

Tom Booth, on 22 August 2011 - 04:50 PM, said:

How can you take something seriously when it is based on a fallacious belief in the existence of "Thermal Radiation" ?

 

Case in point.

 

I take this personally because I'm discussing a reference to a website that stated that "Heat Radiation" is an obsolete conception but instead of discussing the quotation or arguing your point in reference to the citation you point at my "serious lack of understanding of thermodynamics" which may or may not be true but my understanding is not the issue. The statements made in the references are the issue.

 

-----------------clip

Physicist C. Bohren points out that this "heat" misconception may have been started long ago, when early physicists believed in the existence of three separate types of radiation: heat radiation, light, and actinic radiation.

 

Eventually they discovered that all three were actually the same stuff: light.

 

"Heat radiation" and "actinic radiation" are simply invisible light of various frequencies. Today we say "UV light" rather than "actinic radiation." Yet the obsolete term "heat radiation" still lingers. ...

------------------

[DrRocket]

(Personally, I do not agree with the concept that energy transfer occurs just because a force acts or a force is applied, and this view interfered and caused the confusion).

 

Application of a force does not necessarily imply energy transfer. It is application of force over a distance, work, that transfers energy.

 

What is the topic of this thread?

 

~~ WHAT IS HEAT ~~

 

Defining HEAT is the stated theme of this thread is it not? I think everyone here in one way or another has put forward their definition of the term. What reason would you have for objecting to my doing the same ?

 

 

 

 

There is this branch of science called physics and within in there is a subject called thermodynamics. The term "heat" has a well-established meaning within thermodynamics and that definition is the answer to your question.

 

If you choose to ignore that definition, which you may certainly do, then what you are discussing is something other than physics. But there is no point in usurping a widely recognized term, like heat, and applying it to something else. That is poor communication, and just plain silly. Call it Oscar, and don't confuse the discussion of Oscar with a discussion of physics.

 

You really do need to read a book on thermodynamics.

Edited August 23, 2011 by DrRocket

[finiter]

Your question is rather poorly phrased and makes little sense. But perhaps this will help.

I just got confused with the existing theory and my personal theory (I do not agree with the concept that energy transfer takes place just because a force acts).

Sorry, I saw your reply (post no. 124) just now. My objection is particularly to what you have pointed out "It is application of force over a distance, work, that transfers energy."

Edited August 23, 2011 by finiter