Talk:Temperature/Archive 2

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Internal and External Temperature

There is no such distinction I am aware of, except the idea that weakly coupled subsystems may be at different temperatures, eg, spin temperature and lattice temperature might be different, but this is not what the article is talking about. " "internal energy" or "internal temperature" ". ARGH!!! MISCONCEPTION ALERT LeBofSportif 19:58, 5 June 2006 (UTC)

“Spontaneously give up energy” and other errors

The first sentence of the definition, where it says: In thermodynamics, temperature is a measure of the tendency of an object or system to spontaneously give up energy. seems to be omitting critical wording such that it is misleading to the point of being incorrect. To take out its first-order error, it ought to say "…to spontaneously give up thermal energy.” Without this addition, the potential energy of holding an object off the ground would qualify as “temperature” since potential energy is very arguably the “tendency of an object to spontaneously give up energy.” Secondly, even with this correction, the tendency to give up (thermal) energy is really and actually the product of two characteristics: 1) a substance's temperature, and 2) a substances thermal conductivity. Even if they are at the same temperature, silver has a fabulous tendency to give up thermal energy whereas carpeting, fiberglass, and air, have poor capability.

I suggest that someone should dig through an authoritative text book and quote a classic definition. It seems inescapable that any definition should address the laymans’ needs by saying something along the lines of “temperature underlies the common notions of hot and cold.” It should also quickly follow up with the broad, but technically correct definition of temperature. All I can propose is as follows: “temperature is a function of the average kinetic energy of a certain kind of vibrational motion of matter’s constituent particles called translational motions.” Any contributing author should note that in the case of thermodynamic temperature (either Rankine or Kelvin), absolute temperature is a proportional function of this kinetic energy; for any non-absolute scale, temperature is a slope-intercept (y = mx+b) function of the kinetic energy. Greg L 21:11, 9 October 2006 (UTC)

OK, I gave my attempt at fixing the first two paragraphs of the article. The first paragraph of the Overview section sure seems to be in need of work though. For example, it is incorrect where it says [Temperature arrises from degrees of freedom. And with] “an ideal gas, the relevant degrees of freedom are translational, rotational, and vibrational motion of the individual molecules.” The best analog for an ideal gas is the smallest of the monatomic atoms: helium. An ideal gas doesn't have any rotational and [internal] vibrational (as distinct from “translational”) movements; that's precisely why it's called “ideal” in this context. Secondly, even for complex molecules (not monatomic atoms), rotational and vibrational motions store heat energy but are not motions that contribute to temperature. It was seemingly written by someone who was confusing heat-related phenomena with "temperature." This paragraph is wrong on so many levels, it’s FUBAR. An expert needs to step up to the plate and rewrite this article. Greg L 00:09, 10 October 2006 (UTC)

OK, so I had to do that too. That FUBAR paragraph was best fixed by wholesale deletion. The rest of the section stands well enough on its own. I also added the animation I created for the thermodynamic temperature article. Greg L 16:44, 10 October 2006 (UTC)

Temperature and translational motion

The statement in the Overview that "The translational motion of the fundamental particles of nature gives substances their temperature" is incorrect. For example, translational motion of atoms or electrons has nothing to do with the well-known thermal properties of magnets (try a google search or see http://www.coolmagnetman.com/magstren.htm). Rather, it is the electron spin states in a magnet that change their equilibrium polarization as the temperature changes. Electron spin is a quantum phenomenon, with nothing to do with translational motion, and is best described as a "degree of freedom."

I'll probably wait until the current contributors "cool off" before attempting any changes to the article.

I couldn't agree more. Don't let anything stop you. LeBofSportif 13:08, 17 October 2006 (UTC)

Looks like PAR did a good job for that fix. Thanks, PAR. 137.78.59.167PhysicsPhD

The anonymously contributed comment above (someone in the Los Angeles CA area) is completely wrong. He or she confuses heat with temperature. The magnetocaloric effect has to do with how randomizing the electron spins of a plurality of atoms absorbs heat energy. Magnetic materials heat up upon application of a magnetic field and cool when the field is removed. When the substance is cooling, the heat energy stored in vibrational motion (the translational motion of atoms and molecules) is absorbed by the randomizing electron spins as the magnetic field is removed. The magnetocaloric effect is one of several mechanisms that comprise heat energy. Another is the creation of molecular bonds during phase changes. These all have to do with entropy. The statement “The translational motion of the fundamental particles of nature gives substances their temperature” is 100% true and 100% complete. Don't confuse heat with temperature. Heat arises from several phenomenon; temperature is the result of just one.

This relationship between temperature and the kinetic energy of the translational motion of a given particle is perfectly established by the Boltzmann constant. The Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows:

E_mean = 3/2K_bT

where…

E_mean = joules (symbol: J)

K_b = 1.380 6505(24) × 10⁻²³ J/K

T = thermodynamic temperature in kelvins

If someone's got a problem with the statement “The translational motion of the fundamental particles of nature gives substances their temperature,” go take it up with Ludwig Boltzmann and all the physicists of the world who rely on his constant. Greg L 02:11, 15 December 2006 (UTC)

No. The most basic relationship involving temperature is:

$T=\left({\frac {\partial U}{\partial S}}\right)_{X}$

where U is internal energy, S is entropy, and X are all the other extensive variables. The internal energy (U) is not composed of just the translational energies (or translational degrees of freedom) of the particles, it involves their internal energies (degrees of freedom) as well. For example, a complex molecule can have all sorts of internal vibrational motions going on.

I could just as well say:

"The relationship between temperature and the kinetic energy per degree of freedom of a given particle is perfectly established by the Boltzmann constant. The Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy per degree of freedom of its constituent particles as follows:

$E_{mean}={\frac {n_{dof}}{2}}\,\,K_{b}T$

where $n_{dof}\,$ is the number of degrees of freedom of the particle."

For a point particle, there will be only three translational degrees of freedom, giving the original equation, but for a diatomic molecule with translational vibration only, there will be four, and so on. PAR 04:59, 15 December 2006 (UTC)

• PAR: Your too are confusing heat issues with temperature. Perhaps you didn't thoroughly read what the issue is about. Again, the issue is: What phenomenon underlies temperature? The answer is the thermodynamic temperature of any bulk quantity of a substance (a statistically significant quantity of particles) is directly proportional to the average—or “mean”—kinetic energy of translational motion. Period. Full stop. In your supporting arguments above, you consistently and properly kept on using the term "energy" and described how heat energy is stored in the internal degrees of freedom of molecules. Good. That much is correct. But somehow, you seem to think that undermines what I said temperature is.

Remember, the heat energy stored in all such mechanisms as 1) group nuclear spin moment (a magnetic effect), 2) group electron spin (magnetism), 3) molecular bonds that haven't formed yet (phase changes of cooling), and 4) the internal degrees of freedom in molecules do not contribute to the temperature of a substance. Really really. These simply are all places heat energy is stored.

Still don't believe me? Consider this: Imagine a box filled with steam (water gas) at 120 °C. Steam molecules have three internal degrees of freedom and these degrees of freedom can store just as much heat energy as do the three degrees of freedom that comprise translational motion. Now get this. This is why steam has twice the specific heat capacity as do the monatomic gases such as helium. Focus on this important point: the heat energy absorbed into the internal degrees of freedom of the steam molecules is contributing neither to the translational motion of the steam molecules nor to the temperature of the steam. That's precisely why steam absorbs more heat energy for a given amount of temperature rise. Remember the Ideal gas law? That equation doesn't have a term for molar heat capacity (heat energy or joules), it is a simple formula describing the relationship of temperature, pressure, and volume of gases. All three of these gas attributes are the result of one phenomenon: the translational motion of the molecules or atoms comprising the gas.

One final time for the record now. Focus. Here's the statement I was rebutting from the anonymous reader: The statement in the Overview that "The translational motion of the fundamental particles of nature gives substances their temperature" is incorrect. And I say the quoted text is perfectly and wholly correct. I further said that [The] relationship between temperature and the kinetic energy of the translational motion of a given particle is perfectly established by the Boltzmann constant. The Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows: E_mean = 3/2K_bT

Temperature arises from the translational motion of the fundamental particles of nature. Period. All the other mechanisms you cited are places heat energy is stored into without increasing translational motion (the temperature of the substance). Do you get it now? Greg L 17:37, 15 December 2006 (UTC)

It is a shame, Greg L, that during your time away from this page you have become even more convinced by the fallacies about temperature that you promote. There is nothing unique about translational motion when we talk about temperature. I think I can suggest your misconception: when we measure the temperature of something with a normal thermometer, it is the translational motions of the system which most strongly couple to the thermometer - in this situation you are conflating thermometry with temperature - a grave error. In fact, some systems have temperature which do not have translational motions, eg the spin system in a magnetised solid. It is imperative from a pedagogical point of view that this page does not give a muddled account of what temperature is. Have you read any good physics books recently? LeBofSportif 21:17, 15 December 2006 (UTC)

Effects such as nuclear spin temperatures are well beyond the bounds of this article. "Temperature" as the term is used in thermodynamics for its fundamental physical underpinnings such as the Ideal gas law (pV = nRT), applies only to translational motion. The heat energy stored in all such mechanisms as 1) group nuclear spin moment (a magnetic effect), 2) group electron spin (magnetism), 3) molecular bonds that haven't formed yet (phase changes of cooling), and 4) the internal degrees of freedom in molecules, do not contribute to the thermodynamic temperature of a substance. These are all simply places heat energy is stored. Translational motion is what gives us all the common thermodynamic effects (pressure, the vast majority of gas volume, and temperature). If you take one mole of a molecular gas such as nitrogen and heat it up one degree Celsius, 20.7862 joules of heat energy will be absorbed into the translational motions and 8.33 joules (@ 25 °C) will be absorbed into the molecules' internal degrees of freedom. The heat absorbed internally does not contribute to the thermodynamic temperature of the gas. But as a consequence of absorbing heat internally into its molecules, the molecules then have an internal temperature that is, on average while in equilibrium, equal to the thermodynamic temperature of their translational motions. As of today, this poor article says Temperature is a measure of the average energy of the particles (atoms or molecules) of a substance, or a measure of how hot or cold something is. This energy occurs as the translational motion of a particle or as internal energy of a particle, such as a molecular vibration or the excitation of an electron energy level. These two sentences completely fly in the face of the entire concept of specific heat capacity (how different substances absorb different amounts of heat energy as they are heated up the same amount to the same temperature). Those two sentences are saying that nitrogen (29.12 J mol⁻¹ K⁻¹) must be hotter than helium (20.7862 J mol⁻¹ K⁻¹) because it has more total energy. This article has suffered from common misconceptions and, unfortunately, it shows. I certainly have no intention to change it. It's clear any further discussions with you are a colossal waste of my time. I've accomplished my objective of getting the facts here-memorialized for other, contributing authors to consider. Fini Greg L 22:56, 16 December 2006 (UTC)

Ok, now I am starting to understand. Maybe. If we have an ideal diatomic gas, then we could define temperature as PV/nR. We just measure pressure, volume, moles, and that would be our thermometer. The pressure only comes from the translational motion of the gas, so the temperature reading is only the result of the coupling of the translational motion of the gas to the pressure sensor. {Diatomic, monatomic, doesn't matter. And it's the result of coupling to the temperature sensor, not pressure sensor. Other than that, you've got the concept! — Greg L 00:11, 17 December 2006 (UTC)}

If we can find a situation in which temperature is measured by some means other than a device which couples to the translational degrees of freedom of the particles of the object being measured, would you then be convinced that temperature does not arise from translational motion alone? PAR 22:46, 15 December 2006 (UTC)

Greg L - please answer the above question before you leave. PAR 23:07, 16 December 2006 (UTC)

PAR: See the early part of my above response to you-know-who above. As for your second paragraph, of course; all the other places into which heat energy is absorbed (except for the potential energy of phase changes as materials transition from a less ordered state to a more ordered state), have temperatures that are, on average, equal to that of their translational motions. These temperatures can be measured and I even referenced such concepts when I had the misfortune of having a go at it with you-know-who above on the discussion topic regarding internal temperatures of molecules. Further, a quantum phenomenon such as nuclear spin temperature can be isolated and reduced in magnitude. For instance, the Helsinki University of Technology's Low Temperature Lab achieved a nuclear spin temperature of 100 pK in 2000. But unless someone is using specialized lab magnets to accomplish tricks like this, all these temperatures are equal and simultaneously diminish as a substance is cooled. You know as well as I do that details such as these are entirely beyond the scope of this article—at least in its current, unfortunate state where it has huge errors such as asserting that temperature is the measure of all the various energies of molecules (“translational motion of a particle or as internal energy of a particle”). What a mess! This article sorely needs to get heat issues separated from temperature issues.

Now, I'll directly address your final question (sentence): “…would you then be convinced that temperature does not arise from translational motion alone?” In a word, no. But the answer must be qualified. By "temperature” I'm talking about the common notion that underpins thermodynamics and its laws such as the Ideal gas law (pV = nRT). Do these other mechanisms that store heat energy (such as the internal degrees of freedom of molecules) have temperatures of their own? Yes. The important point to remember is that when you measure the "temperature" of a substance using a thermometer (mercury bulb, alcohol bulb, SPRTs, thermocouples, thermisters, etc.) you are measuring only the effect of the translational motions ("coupling" as you put it). Translational motions are the only motions that create pressure and give gases their volume. All the other motions and phenomena are places where heat energy is absorbed into. This is precisely why some substances have higher molar heat capacity than others; that is, absorb more heat energy for a given amount of "temperature rise" than other substances. Anyone who asserts that the temperature of a substance is caused by anything other than translational motion, is also asserting that the concept of molar heat capacity is incorrect.

And remember, the "ideal" gas law isn't dependent on whether a gas is monatomic, diatomic, or triatomic. The extra degrees of freedom with non-monatomic gases only absorb more heat energy for a given temperature rise. The "ideal" part of the name only pertains to treating the particle as a point-like entity. As can be seen in the animation I made (and which is now included in this article), at a pressure of 136 atmospheres, even the diameter of helium atoms take up a relatively significant portion of the volume. Greg L 00:11, 17 December 2006 (UTC)

Hi - Ok, one more question that I forgot to ask which would help me immensely in understanding your point - can you think of an actual experiment in which you would give a correct answer to the outcome, while someone who disagreed with you on this subject would give an incorrect answer? You know what I mean, not like an answer to a question on an exam, which tests whether two people agree on the answer, but an experimental outcome, which tests who has the better ability to predict the future outcome of an experiment. PAR 02:21, 17 December 2006 (UTC)

PAR: Let's try. I can prove my point based on math. Anyone who thinks I am wrong must show how the below math and/or logic is incorrect.

Let's calculate the particles’ mean kinetic energy using two different techniques.

The Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows:

E_mean = 3/2K_bT

where…

E_mean = joules (symbol: J)

K_b = 1.380 6505(24) × 10⁻²³ J/K

T = thermodynamic temperature in kelvins

Now let's calculate the mean energy another way. Let's start by calculating the speed of particles. The rate of translational motion of atoms and molecules is calculated based on thermodynamic temperature as follows:

${\tilde {v}}={\sqrt {\frac {{K_{b} \over 2}\cdot T}{m \over 2}}}$

where…

${\tilde {v}}$ = vector-isolated mean velocity of translational particle motion in m/s

K_b (Boltzmann constant) = 1.380 6505(24) × 10⁻²³ J/K

T = thermodynamic temperature in kelvins

m = molecular mass of substance in kg/particle

Note that the above formula again uses the Boltzmann constant (a fundamental underpinning of thermodynamics). Now…

The mean speed (not vector-isolated velocity) of an atom or molecule along any arbitrary path is calculated as follows:

${\tilde {s}}={\tilde {v}}\cdot {\sqrt {3}}$

where…

${\tilde {s}}$ = mean speed of translational particle motion in m/s

Note that the mean energy of the translational motions of a substance’s constituent particles correlates to their mean speed, not velocity.

Now let's calculate the kinetic energy of translational motion using an entirely different method. Substituting ${\tilde {s}}$ for v in the classic formula for kinetic energy, E_k = ¹/₂m • v ² produces precisely the same value as does E_mean = 3/2K_bT.

The above are well-accepted formulas in physics. Both techniques convert thermodynamic temperature into kinetic energy. Ah… but what comprises this kinetic energy(?): translational motion as well as other kinds of motions? Have I proven that the kinetic energy arises only from translational motion? So here's the test: If you plug the values for nitrogen (a diatomic gas) at 25 °C into the above, and then repeat it for helium (a monatomic gas), I say you will end up with precisely the same value of kinetic energy per particle. Repeat again at 26 °C. You will obtain a slightly greater kinetic energy value than at 25 °C but… the nitrogen and helium values will again be identical. Yet raising the temperature of a mole of nitrogen by one kelvin requires 40% more heat energy (see table) than does helium. Therefore, the thermodynamic temperature of a substance is a function of kinetic energy associated only with translational motion; it is independent of how much heat energy is absorbed into all internal degrees of freedom of molecules. Greg L 03:31, 17 December 2006 (UTC)

But that's an "exam" type question. It consists of writing down equations, paper, pencils, so forth. I'm looking for an actual experiment. Something where you take an actual thermodynamic system and measure something and get a number. I mean, suppose we have one person who says the acceleration due to gravity is 32 feet/sec/sec, and another says its 100 feet/sec/sec, then we ask them how long will it take for a ball dropped from 100 feet to hit the ground. They will give different answers. Thats the kind of experiment I am looking for. A real one. Can you think of an actual experiment in which you would give a correct answer to the outcome, while someone who disagreed with you on this subject would give an incorrect answer? This is not like some kind of challenge. I am trying to think of such an experiment too, because it would help me to understand the problem. PAR 04:34, 17 December 2006 (UTC)

Not really. Perhaps the best answer to your question is to turn it around and ask you a question: Why must one put more heat energy into molecular-based gases vs. the monatomic gases in order to cause the same quantity (by volume or moles) to increase by the same increment of temperature? Please explain why the diatomic gases such as N₂, O₂, and H₂ (see this table) require roughly 28.5 joules of energy to increase the temperature of one mole of them by one degree C, whereas all of the noble gases require only 20.7862 J. Seriously. Would you please write the proper explanation below? Greg L 05:34, 17 December 2006 (UTC)

P.S. If you want to do some reading before answering, read this. Greg L 05:40, 17 December 2006 (UTC)

The explanation I would start with is that the N2 and O2 gases have internal degrees of freedom and the monatomic gases do not. In fact they have four internal degrees of freedom (two rotational, two vibrational). If they were triatomic molecules, they would have 9 internal degrees of freedom (If I remember correctly). The second part of the explanation is the equipartition of energy. In equilibrium, each degree of freedom acquires an energy of kT/2 unless there are quantum effects which "freeze out" or uncouple certain internal degrees of freedom from the three translational degrees of freedom. So, if you add energy to the gas, that energy must be distributed to more internal degrees of freedom, and so the temperature will rise less per amount of heat added. Assuming no internal degrees of freedom are frozen out, for a diatomic gas, there will be a total of 7 degrees of freedom (3 translational, 4 internal) and so the specific heat will be dU/dT = 7k/2 per molecule.

Note that in the above, there is no need to distinguish between internal temperature and translational temperature, since equilibrium is assumed, and therefore they are identical. (Please let me call it "translational temperature" so there is no confusion over the word "temperature".) If we are going to come up with an experiment which we disagree on, it has to be one in which the internal and translational temperatures are different. Suppose we have a case of a multi-atomic gas where the internal and external degrees of freedom require a time of ΔT to equilibrate, and we manage somehow to drop the translational temperature in a time that is small compared to ΔT. Then, for a short time, we could have a gas in which its translational temperature was different from its internal temperature. We might be able to monitor the radiation from such a gas, and see that its spectrum reflected this fact. I'm not sure what the spectrum would look like, maybe two superimposed black body curves, reflecting the two different temperatures.

Does this all sound like a scenario you agree could happen? PAR 14:57, 17 December 2006 (UTC)

PAR: Yes, as far the distinction of internal energy & temperature of molecules vs. the mean kinetic energy of their translational motions and thermodynamic temperature. No, in reality as regards the experiment. It appears you have a good command of the principals underlying heat energy, molar heat capacity, and temperature. But…

I would expect that when one quickly chills a gas, the cold plate — upon which the gas is impinging— will instantly chill both a molecule's translational and internal temperatures. This is because heat exchange mechanism that excites the internal degrees of freedom is instantaneously quick and efficient. All it takes is a single collision with something cold for the kinetic energy of both translational motion and internal motion to be transfered into the molecules comprising the cold plate. So a brief exposure to something cold just partially chills some of the gas sample's molecules — both internal and translational. In this case, all you have is a gas sample that momentarily is not in equilibrium. When that's the case, you can't take a valid temperature measurement because the sample will momentarily not obey the Maxwell–Boltzmann distribution of translational velocities. In other words, the ∆T-effect isn't selective beteween internal motion and translational motion.

As regards nitrogen's “four” internal degrees of freedom, you should know that two different conventions are used in science when counting degrees of freedom. The one I use (because it's quite common in science and physics) counts each dimension or mode of movement as a single degree of freedom. The other convention counts each of these as two degrees (back and forth, up and down, etc.). Thus, translational motion has three degrees of freedom according to the convention I've been using, but six degrees according to the convention you used above. To test for yourself which one would be best for you, Google on the water molecules' degrees of freedom. Some will say six, others will say twelve.

You might be interested in Probing the limits of the quantum world at PhysicsWeb. It's about physicists who experimented with the interference patterns created by shooting whole molecules (not photons) through interferometers. There's a point where they were shooting individual, hot C₆₀ molecules through their interferometer. They also write about how thermal photons were being emitted by these individual molecules as they shot through the interferometer. It's very interesting reading.

Now, since you clearly have a grasp of why different gases have different molar heat capacities, it begs the question: Why does this article talk about how temperature is the measure of both the translational and internal energies? Greg L 17:20, 17 December 2006 (UTC)

P.S.: As regards your request: “Can you think of an actual experiment in which you would give a correct answer to the outcome, while someone who disagreed with you on this subject would give an incorrect answer?,” I guess I can. I predict that if you inject 20.7862 J of heat energy into one mole of helium (a monatomic gas), it will increase in thermodynamic temperature by exactly one kelvin. I also predict that if you inject the same amount, 20.7862 J, into oxygen (a diatomic molecule), its temperature will only increase by 707 millikelvins. The thermodynamic “temperature” as it applies to the laws of thermodynamics, won't increase as much for oxygen because 6.08 J of heat energy was absorbed internally into the oxygen molecule and is unavailable to contribute to its temperature (translational motion). Accordingly, any statement along the lines of "the thermodynamic temperature of a substance is the measure of its total kinetic energy — both its translational and internal energies such as a molecular vibration and the excitation of an electron energy level” is incorrect. It is a big goof and flies in the face of the entire concept of molar heat capacity. The above-described experiment (measuring molar heat capacity) is routinely performed in the scientific world and will prove my point. If one doesn't have the necessary equipment, they can look here to see the results of molar heat capacity experiments others have performed.

And to memorialize for the record (for the benefit of those who came late to this debate and don't want to wade through its whole history), the heat energy stored in all such mechanisms as 1) group nuclear spin moment (a magnetic effect), 2) group electron spin (the magnetocaloric effect), 3) the internal degrees of freedom of molecules, and 4) the potential energy of molecular bonds that haven't yet formed (the phase transitions of cooling), do not contribute to the thermodynamic temperature of a substance. These are all simply places where thermal energy is stored. Also, the first three items in this list have temperatures of their own, and under normal circumstances, these temperatures are equal to the thermodynamic temperature of the substance. Further, effects such as nuclear spin temperatures are well beyond the bounds of this article. The temperature of a substance, as the term is used in thermodynamics for its fundamental underpinnings such as the Ideal gas law (pV = nRT), is the result only of translational motion. This relationship between the kinetic energy of translation motion vs. the thermodynamic temperature of a substance is fully described by the Boltzmann constant. More specifically, the Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows:

E_mean = 3/2K_bT

where…

E_mean = joules (symbol: J)

K_b = 1.380 6505(24) × 10⁻²³ J/K

T = thermodynamic temperature in kelvins

Accordingly, the proper statement as to the nature of temperature is as follows: “The temperature of a substance arises from a certain kind of vibrational motion of its constituent particles called translational motions. More specifically, the thermodynamic temperature of any bulk quantity of matter is the measure of the mean kinetic energy of these translational motions.” Greg L 19:11, 17 December 2006 (UTC)

With regard the experiment you mentioned - you are saying that the error someone would make would be that they would assign the same temperature increase to both cases because they thought that temperature was proportional to the energy added. Is that right? {Yes, that's what I'm saying. Greg L 21:46, 17 December 2006 (UTC)}

In that case, I agree with you to this extent - the temperature of a substance CANNOT be used to predict the average total energy per particle until you know how many internal degrees of freedom there are and to what extent they are being excited at that particular temperature. The temperature of a substance CAN be used to predict the average translational energy per particle of that substance without any additional knowledge (except the number of particles). PAR 20:58, 17 December 2006 (UTC)

So what do you think of the first two sentences of the Overview section(?), which currently states as follows:

Temperature is a measure of the average energy of the particles (atoms or molecules) of a substance, or a measure of how hot or cold something is. This energy occurs as the translational motion of a particle or as internal energy of a particle, such as a molecular vibration or the excitation of an electron energy level. (my emphasis).

Can we agree that it ought to read as follows(?):

“The temperature of a substance arises from a certain kind of vibrational motion of its constituent particles called translational motions. More specifically, the thermodynamic temperature of any bulk quantity of matter is the measure of the mean kinetic energy of these translational motions.”

Greg L 21:46, 17 December 2006 (UTC)

Well thats where I start to have trouble. I agree the sentence is not optimum, because it might give the idea that temperature and internal energy are simply related in the same way for all substances. I agree it should be changed somehow.

We both agree that there are two concepts, which I call internal temperature and translational temperature, and that they are equal (in equilibrium).

What I hear you saying is that the term "thermodynamic temperature" should refer to what I am calling the "translational temperature". Is that correct? PAR 22:22, 17 December 2006 (UTC)

Temperature concepts such as nuclear spin temperatures are far beyond the bounds of this article. The term "temperature" in this article, unless it is very explicitly stated otherwise, has got to address the term as it applies to thermodynamics: such concepts as the conjugate variables of thermodynamics and its various formulas such as the ideal gas constant. What good is the Boltzmann constant (which relates “temperature” to kinetic energy), if this article has the effect of broadening the very notion of what “temperature” is? What feels hot, and what thermometers measure, and what makes all gases expand in volume is only translational motion. If one wants to address other phenomenon such as how molecules’ internal degrees of freedom also have a temperature (which, on average, happen to be identical to that of translational motion), then by all means, say so. But do it somewhere else in the article and be clear! As it is currently written, the first two sentences of the overview are simply and completely false because they totally undermine the concept of molar heat capacity by stating that “temperature” is a measure of total kinetic energy (both translational and internal). You and I know this isn't true.

And no, the term “thermodynamic temperature” does not necessarily have the connotation of “the temperature associated with translational motion.” It merely has its null point at absolute zero. As such, it is an absolute scale (so it works well in formulas involving other absolute measures such as energy and pressure). Any "thermodynamic temperature" in kelvins can readily be converted to the Celsius scale by simply subtracting 273.15 from it. Regardless of what scale is used, temperature is temperature. If you are talking about “the temperature of a substance,” it has only one meaning and must be kept completely separate from the notion of thermal energy and its various other forms.

Over 5200 words have been written on this discussion topic. I don't know what more I can offer. Greg L 00:05, 18 December 2006 (UTC)

P.S.: I'm not positive, but I think I can define what the key distinction is that you're wrestling with: what is having its temperature measured. Thermodynamics deals with the temperatures of substances. If you want to talk about nuclear spin temperatures, that's another issue. If you want to talk about the internal temperature of molecules, that's another issue. But if one asks "What gives a substance its temperature?”, the answer is, “The temperature of a substance arises from a certain kind of vibrational motion of its constituent particles called translational motions. More specifically, the thermodynamic temperature of any bulk quantity of matter is the measure of the mean kinetic energy of these translational motions.” If you want to talk about how thermal energy is absorbed into the internal degrees of freedom of molecules, great. We can just look at the molar heat capacity and calculate exactly what portion of the heat energy is borne by translational motion and how much is borne by the internal degrees of freedom of the molecule. And the answer as to what the internal temperature of the molecule is, well, that's simple; for a bulk quantity in equilibrium, it's equal to the temperature of the substance (its translational motion temperature).

All of these issues seem to be beyond the proper scope of this article. I suggest you simply state what phenomenon gives substances their temperature. Then you can state that heat energy is absorbed only into translational motion for monatomic gases. You can also state that for molecular substances, additional heat energy is absorbed into internal degrees of freedom and you can refer them to specific heat capacity to learn more. It's quite simple. Discussing it is what's complex. Greg L 00:45, 18 December 2006 (UTC)

Ok - Two questions

• We agree that most temperature measurements are responding to what I call the translational temperature of the object measured. I don't understand if this is the basis of your argument, though. If I were to find a temperature measurement that measured the internal temperature of a gas of complex molecules, would that change your mind?

• Given that you know more or less how I am thinking about things, in terms of internal and translational temperature, is there now any real-life experiment that you can think of on whose outcome we would disagree? (Remember how I suddenly understood what you were saying when you came up with that last experiment.)

PAR 02:58, 18 December 2006 (UTC)

{PAR and Greg L have spent several days corresponding directly with each other off-line to discuss and debate this issue.} (Greg L 00:05, 20 December 2006 (UTC))

PAR: Here's a straw-man paragraph for you and others to consider for starting the Overview section:

Temperature arises from the random submicroscopic vibrations of the particle constituents of matter. More specifically, the thermodynamic (absolute) temperature of any bulk quantity of a substance (a statistically significant quantity of particles) in equilibrium is directly proportional to the average—or “mean”—kinetic energy of a specific kind of particle motion known as translational motion. Translational motions are ordinary, whole-body movements in 3D space whereby particles move about and exchange energy in collisions. Fig. 1 above illustrates translational motion in gases. The Boltzmann constant relates the thermodynamic temperature of a bulk quantity of a substance to the mean energy of the translational motions of its constituent particles as follows: E_mean = 3/2K_bT. Translational motion is also what gives gases their pressure and the vast majority of their volume, as established by the ideal gas law. The kinetic energy of translational motion is a major contributor of contributes to the total heat energy contained in a substance. For monatomic substances such as the noble gas helium, this kinetic energy arises only from translational motion. Molecules however, are complex objects; they are a population of atoms that can move about within a molecule in different ways (known as a molecule’s internal degrees of freedom). Heat energy is stored in these internal motions. Accordingly, the total heat energy of molecular substances includes not only the kinetic energy of translational motion, but also the kinetic energy bound in a molecule’s internal degrees of freedom. The heat energy stored internally in molecules does not contribute to the temperature of a substance (nor to the pressure or volume of gases). This is because any kinetic energy that is, at a given instant, bound in internal motions is not at that same instant contributing to the molecules’ translational motions. Differences in the number of internal degrees of freedom is one of the reasons why different substances have different molar heat capacities.

Greg L 21:35, 23 December 2006 (UTC)

Hi Greg - As we discussed in our conversation, I prefer to think in terms of a temperature associated with each degree of freedom. Classically, each degree of freedom gets an average of (1/2)kT of energy. So that means we can talk about a translational temperature for the three translational degrees of freedom, and an internal temperature for the rotational and vibrational degrees of freedom. At equilibrium they are all equal.

You point out that:

• Pressure is the result of translational motion. In fact, if T_t is the translational temperature, then the ideal gas law is actually PV=NkT_t.
• Heat transfer between bodies is basically mediated by the translational motions of the particles.
• It follows that most temperature measurements are measuring the translational temperature.
• It also follows that the sensation of heat is caused by translational temperature difference.
• For the translational degrees of freedom, the average energy is always proportional to temperature via E=(3/2)kT except for extremely low temperatures. The internal (i.e. non-translational) energy on the other hand, cannot be said to be proportional to temperature due to quantum effects. Thus, assuming a proportionality between translational temperature and energy is almost always correct, while assuming a proportionality between internal temperature and energy is almost never correct. Temperature is therefore not proportional to the energy of a molecule, only to its translational energy.

If I understand your argument, this is the basis for your saying that the term "temperature" actually refers only to what I am calling the "translational temperature". In particular you make the statement:

The heat energy stored internally in molecules does not contribute to the temperature of a substance (nor to the pressure or volume of gases)

This is a statement I disagree with, simply because it conflicts with my understanding of temperature. If the words "translational temperature" were substituted for "temperature", then I would agree with it. In your above paragraph, I agree with just about everything else.

Importantly, I think that we agree that there is no objective way to resolve this disagreement. In other words, there is no experimental outcome for which we would give different answers as the result of our disagreement. I believe the difference is semantic, or one of terminology. In other words we disagree on how to use words to describe a situation we both have the same understanding of. In this case, we have to conform to the usage of the community at large. I think that your terminology is not "standard" in this sense.

PAR 07:29, 27 December 2006 (UTC)

I agree, Greg's terminology is totally non standard. An example where his concept of temperature becomes totally inadequate is a long-chain polymer liquid. Internal and translational "degrees of freedom" get totally mixed up. LeBofSportif 22:02, 27 December 2006 (UTC)

How so? PAR 22:44, 27 December 2006 (UTC)

If someone is swinging a double ended chain around their head and it thwacks you in the face you will feel it. Do you get my point now? LeBofSportif 23:26, 28 December 2006 (UTC)

PAR: I appreciate your thoughts. I'm searching for a way to demonstrate that internal degrees of freedom (and their associated contribution to increased molar heat capacity) is truly very really distinct from external degrees of freedom and its association with temperature. I thought I had made a good case with the intimate association between external degrees of freedom and both the pressure and volume of gases (pV = nRT). Perhaps, it is just an issue of semantics. Greg L 03:27, 29 December 2006 (UTC)

Diurnal Temperature Variation

I have been searching Wikipedia on diurnal temperature variation and have found nothing on the subject so far. I think this is a very important field to be covered when it comes to air temperature. For example, the fact that deserts tend to have very big diurnal temperature variation or that the diurnal temperature variaton decreases when moving pole ward. —The preceding unsigned comment was added by 217.209.60.200 (talk) 18:13, 18 January 2007 (UTC).

Overcomplication

I removed the following from where it had been used to write the introduction. In my view this is way too advanced for the introductory paragraphs. However, I leave it here in the hope that an expert might recycle it into the more detailed parts.

The absolute temperature of a system is defined as the energy of microscopic motions in the system per particle per degree of freedom (with half of the Boltzmann constant to be the proportionality factor between unit of energy and unit of temperature). For a solid, these microscopic motions are principally the vibrations of the constituent atoms about their sites in the solid. For an ideal monatomic gas, the microscopic motions are the translational motions of the constituent gas particles.

Notinasnaid 16:19, 15 March 2007 (UTC)

Congratulation! Now - when you removed my definition of T (which is actually not my but simply the accepted definition of T in science) everyone can see that now this article has NO consistent definition of temperature at all. We all can safely and loudly laugh at the "definition" dT = dQ/S which you (or someone else) put in the article without understanding that entropy in thermodynamics is in turn defined via temperature - as dS = dQ/T (dS=dQ/T can be derived from the statistical definition of entropy S=wkln(w) but again PROVIDED that temperature T is predefined first). The circle (or better to say, the circus) is complete and perfect. Good entertainment. Enormousdude 21:17, 27 June 2007 (UTC)

[Copied from user talk page]:

Please do not revert definitions - clear definitions are important as everything follows from them. Some definitions are not elementary. Temperature is a statistical parameter of large ensemble of identical particles. Its definition can not be understood without proper background (at least statistical mechanics or statistical physics must be taken, well understood, and passed with good grade prior to contributing to the matter of this subject).

What is seen as "fantastic overcomplication" to you is actually starting chapter in any standard statistical mechanics text.

Sincerely, Enormousdude 16:40, 15 March 2007 (UTC)

Mathematical definition

This section I removed is just plain inaccurate. As a working understanding of temperature in people's everyday experience it is fine, but what was quoted is the result of the classical equipartition theorem. It fails when dealing with non quadratic contributions to the energy, like you get for relativistic particles (eg a very hot plasma or photons), and in quantum mechanical limits. Bottom line, there are two accurate definitions of temperature: the zeroth law definition that appeals to equilibrium and lets us set a standard and the statistical mechanical one where it is defined in terms of entropy and energy. So, if you're going to appeal to the microscopic properties of the system, go the second route, if you're not stick with the zeroth law definition. BlackGriffen 20:56, 13 June 2007 (UTC)

Hold on, there no temperature for relativistic or QM system anyway (and if in some cases it is possible to define it, then T is defined as I said - average energy of particle per degree of freedom: T = 2<E>/k.

And you also are incorrect about entropy definition of temperature. Fundamental definition of entropy is statistical one: S=-kwlnw from which then t/dynamical definition dQ/T follows as a corollary PROVIDED that temperature T is already defined (so, t/d definition of entropy REQUIRES T to be pre-defined BEFORE t/d entropy can be defined). Thus t/d entropy CAN NOT be used to define temperature.

Zeroth law is obviosely NOT a definition of T - it can not even give units of T (not to say about other properties of T).

So, your revert is incorrect.

Sincerely, Enormousdude 20:46, 22 June 2007 (UTC)

---

My apologies for not knowing how to sign in.

I tried to use the statement in "overview" that scientists achieved a temperature of 700nK (nanoKelvin) by getting Cesium atoms to move at 7 mm per second. By my math, 100 degrees Kelvin would then be achieved if Cesium atoms were moving at 1000 km/second. I know that this extrapolation would fail completely if atoms were traveling faster than the speed of light. So, how would you explain the translational motion of atoms versus temperature? What happened?

I got 83.7 m/sec for 100 K, which is rather consistent with the average kinetic energy of Cs atoms at that temperature. Remember that kinetic energy is proportional to SQUARE of speed.

Sincerely, 161.28.196.101 21:16, 26 June 2007 (UTC)

maximum limit of temperature?

Is there any theoretical maximum limit of temperature? Say due to relativistic limit on speed of particles? manya (talk) 05:28, 1 September 2008 (UTC)

No, temperature is proportional to energy per particle and there is no limit on the energy a particle can have. Dragons flight (talk) 06:15, 1 September 2008 (UTC)

That's a good question, and, AFAICT, the article doesn't really answer it. There is a brief mention of "infinite temperature" in the summary section on Temperature#Negative temperature that cites Kittel & Kroemer, but that section is buried in the middle of the article. ISTM, the lead could say something about the limits of temperature. BTW, Zemansky's Temperatures Very Low and Very High has a chapter called Beyond Infinity to Negative Temperatures. --Jtir (talk) 20:19, 3 September 2008 (UTC)

• Yes, there is a theoretical maximum limit of temperature. It is the Planck temperature, which is 1.41679(11)×10³² K. Greg L (talk) 22:06, 4 September 2008 (UTC)
  • No, that's a temperature at which existing physics ceases to make sense. Like Planck length, Planck time, etc. it is not at all clear if those measures are fundemental limits or merely limits beyond which our existing physical understanding is inadequate to probe. In each case a theory of quantum gravity is necessary to describe phenomena under those conditions. Dragons flight (talk) 22:11, 4 September 2008 (UTC)

• Your argument splits hairs a bit too finely and is almost one of those “classic and theoretical physics isn’t good enough for me”-answers. The Planck temperature is the closest known thing there is to a “theoretical maximum limit of temperature” and is considered to be the temperature of the Universe during the first instant (the first unit of Planck time) of the Big Bang. If that isn’t the maximum possible temperature, I don’t know what is. If you don’t think the Plank temperature is a theoretical maximum limit on temperature, tell us, what is? Greg L (talk) 02:21, 5 September 2008 (UTC)

Thank-you both for your informative comments. It sounds like you agree that the Planck temperature is a theoretical limit, which is what the original question asked for. Could either of you cite a reliable source on this limit? Planck temperature cites a web site; it would be better to cite a physics book. --Jtir (talk) 19:58, 5 September 2008 (UTC)

definition of temperature scale

The article states that the triple point of water is 273.16 degrees Kelvin. This is an obvious clerical error. I have a newly established account on wikipedia and have not yet learned how to fix such things. I hope someone more knowledgeable than I will do it. Georgeisomorphism (talk) 00:58, 10 January 2009 (UTC)

Um, I believe 273.16 K is correct. Dragons flight (talk) 01:19, 10 January 2009 (UTC)

Yes, thank you, 273.16 K is correct. I am a double idiot. Firstly, I misread the article which does correctly state "273.16" K. Secondly, when I typed my comments, I typed 273.16 rather than what I thought I had seen. Pleae forgive me. If I ever summon the courage to make another comment on a wikipedia article, I will try to be more careful.Georgeisomorphism (talk) 01:25, 7 February 2009 (UTC)

Rankine Scale does not have a degree sign

The Rankine scale does not need a degree sign before R as it is listed in this section as °R This is because it is an absolute temperature scale like the Kelvin scale. This error is replicated in all the temperature scale pages in the temperature converstion graph

Temperature/Archive 2 temperature conversion formulae

	from Temperature/Archive 2	to Temperature/Archive 2
Celsius	x K ≘ (x − 273.15) °C	x °C ≘ (x + 273.15) K
Fahrenheit	x K ≘ (x × 9/5 − 459.67) °F	x °F ≘ (x + 459.67) × 5/9 K
Rankine	x K ≘ x × 9/5 °R	x °R ≘ x × 5/9 K
For temperature intervals rather than specific temperatures, 1 K = 1 °C = 9/5 °F = 9/5 °R Conversion between temperature scales

Would someone please correct this. I do not have the ability to edit this article with my account.

Mrjoebob (talk) 01:36, 9 March 2009 (UTC)

I'd like to see a reference for this one way or the other. The discussion at Talk:Rankine scale seems to suggest that even though it is an absolute scale, that nonetheless the degree sign is used more often than not. If there is a "right" and "wrong" way to write this, I would like to know "according to whom" and whether or not there is a reliable convention here? Dragons flight (talk) 01:45, 9 March 2009 (UTC)

Confusing Carnot Equation

In the section "Phenomenological definition based on second law of thermodynamics," the article states

"Carnot's theorem states that all reversible engines operating between the same heat reservoirs are equally efficient. Thus, a heat engine operating between T1 and T3 must have the same efficiency as one consisting of two cycles, one between T1 and T2, and the second between T2 and T3. This can only be the case if:"

   q_{13} = \frac{q_1}{o_7}

The equation q13 = q1 / o7 seems confusing to me because I don't think that the variable o has been defined in this article (I could have just overlooked it, of course.) It seems that this equation may have a typo, or at the least requires additional explanation. Also, I'm not an expert in thermodynamics by any means, but I have never heard of a variable "o" being used in a thermo equation. WilliamJenkins09 (talk) 13:24, 29 November 2009 (UTC)

Rigorous definition of temperature

This section was introduced without any links [1] and it claims "The definition of temperature in modern physics is the other way around". Given the completely weird definition of heat in Wikipedia I think a link to the variety of modern physics the editor has in mind is vitally important to avoid confusion in this section. --Damorbel (talk) 21:08, 29 November 2009 (UTC)

What I wrote can be found in e.g. the book Fundamentals of Statistical and Thermal Physics by F. Reif, i.m.o., the best book on this subject. The point is that entropy can be defined in terms of the fundamental properties oif the system. If you have some gas in a container, then the fndamental laws of physics fix the states the system can be in. Entropy is proportional to the logartihm of this number of states. Temperature is then the derivative of the entropy w.r.t. the internal energy taken at constant volume (and whatever other external parameters the system has).

Work is by definition any transfer of energy from one system to another system as a result of a change in external parameters. Heat is by definition transfer of energy that happens in any other way.

You have to consider that such definitions have to be applicable to completely arbitrary systems or to familiar systems for which you consider doing something completely unusual. E.g. the volume of a system does not need to be the only external parameter. In principle you can consider a system that has trillions of independent external degrees of freedoms. In that case any change in internal energy as a result of changing any of these parameters counts as work. But if you cannot control any of these parameters, then these external parameters will be subject to thermal fluctuations. Energy transfer that happens via these parameters would then be heat transfer. Count Iblis (talk) 22:22, 29 November 2009 (UTC)

I've renamed the section to the "Definition of temperature in Statistical mechanics". --Dc987 (talk) 23:04, 1 December 2009 (UTC)

Yet One More Scale.....

When I studied math in Junior High School we were taught the principles of different numbering systems. That is, numbering systems other than the decimal or "base ten" system.

Many criticized such "new math" priorities as idle and not practical. This was a generation before the cyber-students. Soon even amateur programmers were using four systems: Base Two or binary, base eight or octal-decimal (8 bit processors of the 1980's), base 16 or hexadecimal and the conventional base 10.

My curiosity was raised when I read of the "duodecimal" or base 12 concept that apparently the Babylonians may have used. It made much more sense to use the prime numbers (1), 2 and 3 instead of (1), 2 and 5, especially for subdividing. But I digress....

During College we were trained in a bilingual nomenclature system, converting constantly from the SI/metric units to the much maligned SAE or "Imperial" system. The ability to work in two systems was as probably the greater benefit of the exercise.

For example, the "old" system would express units for Refrigeration equipment as: (1)tons of refrigeration (heat transfer at the evapourator) (2) Btuh for heat transfer at the condenser (3) bhp - brake horse power for the compressor shaft power and (4) Kw for the "electrical" power into the compressor motor. The new system uses Kw to describe all four rates of energy transfer!

So it only seemed reasonable to propose, when possible, new more logical systems of measurement, since the status quo, at times, appeared so tangled anyway - especially to non-technical people. What about temperature measurement?

I thought about a scale that would have 0 (zero) degrees as the freezing point of water and approximate human body temperature as 100 degrees -98 2/3(98.6667) degrees F. That is 66.67 degrees F from 0 to 100 or units exactly 1.5 time degrees F.

The zero degrees for freezing water had an environmental (weather) and physical sciences application. The upper 100 degrees would have a physiological life sciences application. Moderate room temperature would be therefore 54 degrees exactly.

The only question remained what to name this scale. The "Earth" scale (degrees E) the Science Scale (degrees S)..... I don't know.... maybe the Wiki scale (degrees W)??

Peter 142.163.53.194 (talk) 15:24, 25 March 2008 (UTC)

---Rebuttle---

Peter,

Seriously? This scale has less applicable use than any other scale I've ever seen, IMHO. While I am a fan of having a greater degree of precision in the temp readings we take, the average human body temperature is itself in a state of flux and it's value is in debate.

You should never make one end of your scale a moving value, because this only leads to confusion about what a referenced tempature was in the past,present,or future. What happens if the average human body termperature raises or drops by 10 degrees in the next 100 years? The only truely fixed points you can create are abs(0) and a phase-chaneg of a set compound in set circumstances.

The boiling point of water and freezing point of water (usually salt water) have been used over the years because of the relationship between the availability of salt water and consistancy of phase change, however I do agree it to be relatively arbitrary as it is not a homogenous substance and therefore far more variable than basing it on say abs(0)=0 and the melting point of Pure Nickle at sea-level = 1000.

However two problem befall my example, it is hard if not impossible to gather an ounce of a pure element, and 1000 may not be a value which lends to understanding the temperature on your day to day, there may need to be many decimal places in order to see the small temp changes humans percieve, making the scale somewhat cumbersome, much the way that the imperial scale F generally needs a single decimal place after it to really account for the subtle temperature changes humans can feel, there may need to be 3 or 4 decimal places on my arbitrary scale.

So it's nothing against you personally, but I hope you see why the arbitrary choices made in temp scale in the past have been with what most consider good reason. I personally would prefer a scale where Abs(0) = 0 and Fresh Water Freezing at sea level = 1000, this would have about double the preciscion of the Rahnkienscale, and in my oppinion would be much easier to understand relative temperatures once adopted. But, that is neigther here nore there, good luck in tweaking your scale to make more sence.

~Q —Preceding unsigned comment added by 69.74.205.178 (talk) 16:17, 29 August 2008 (UTC)

The zero point has significance in the physical and meteorological sciences, the upper scale ("100") is fixed (98 2/3 deg. F) thus it has a more of a nominal than any arbitrary significance in the physiological sciences.

Fahrenheit originally considered the (approximate)human body temperature to be 96 degrees even, making it divisible by prime numbers 2 and 3. "...His third point, the 96th degree, was the level of the liquid in the thermometer when held in the mouth or under the armpit.....". Thus, as you point out, even his scale fell into the pitfalls of using an imprecise, albeit significant, boundary. [2]

Not to be vain, but mine is at least a clever proposal and is at least intriguing to even amateur scientists. Daring of you to rebut, though.....thanks.

Peter 72.139.113.118 ([[User talk:72.139.113.118|talk]]) 19:28, 31 August 2008 (UTC)

P.S.: The "100 degrees" need not be a fixed point, the calibration point would be 270 W(Or E, or S or whatever) - the boiling point of water. 100 W need only be a reference point which may or may not have a useful medical application.

Peter 142.163.53.194 (talk) 21:45, 2 September 2008 (UTC)

Peter, It's been a while, I was just thinking of this scale you had thought up again the other day, let me first say 'thanks' for the complement. Now down to Business. The reason a non fixed scale is bad is because if 98.6 were the 'average' human temp, which it's not, it's lower, and you have people that range from 95 degrees to 101 degrees F lets say, then your 'end-point' would never read right on almost anymore, nearly every human would read something other than 100 (You would have people who range from 94.5 to 103.5, so I’m not really seeing the advantage to the average being 100 there.)

--Also as an aside fevers would be anywhere from 102 to 111, I don’t consider this either an improvement or a disadvantage to the system over Fahrenheit or Celsius, just for reference really.--

Now 54 degrees may be 68 degrees which you consider a comfortable room temperature (this is highly debatable especially considering he time of year and the person involved lol, but besides the point), it doesn’t in any way mean that 54 degrees is about 54 times as hot as 0 and ½ as hot as 100, which I somehow have a feeling your expecting from creating a new scale.. But perhaps I’m reading into things too much. For reference your Absolute zero will be -737.505 Degrees.

So now consider you have 100 years go by ,and in that 100 years the average human body temperature drops by 10 degrees Fahrenheit, how does that affect your temp scale? Are you going to re-center yoru scale so 88.6 = 100? Now what about all the work ever done in the scale before? Now it no longer makes sense because you’ve changed the conversion rate into another scale, you can now never be certain whether someone recorded a temperature in the old or new scale, and how do you compare the changes from the past?

Well maybe you’re thinking well no I’ll just leave 100 be the max = 98.6, who cares that it’s now completely arbitrary to a person’s daily life? Well okay so what happens in 1000 years if the average body temperature of a human changes to be + 100 degrees more, so now it’s 188.6 (yeah I know that’s a bit farfetched as humans would be on the verge of boiling) So now in this world where humans all have faster metabolisms, you’re going to find all temperatures they are interested in for their bodies, and appropriate ‘comfortable’ temperatures all fall above 100 degrees, so now your scale isn’t used because it’s not really applicable in the way it was intended

These are again the problems with a scale that will use a moving point as an end, either the scale constantly changes, and you can never correlate data, or the scale can run out of usefulness because the value at one end has changed so far from he fixed point originally meant to represent it.

Also your scale is not 1.5 F, as you stated-- Instead, your scale converts as: P = (F-32)*(3/2) And to convert back obviously you are needing to use: F = 32+(P*2/3)

~Q —Preceding unsigned comment added by 71.169.9.246 (talk) 04:57, 27 November 2009 (UTC)

Very good of you to contemplate this concept and take the time to reply.

Methinks you must have a medical background, since the criticisms focus largely on clinical applications.

It would, could, be an ambiguous situation when some students might assume that something other than 100 deg, (exactly) would be abnormal. However for lay persons observing any significant deviation from (about) 100 deg would be cause for concern and they would then check with their doctor. They would not have to try to remember if normal temp is 96.8 or 98.6. Celsius increments are too large - you have to focus on 1/10 degree changes to detect a developing complication such as an infection. [BTW the mean typical core temperature, for this scale, would be 98 2/3 F = 100 deg EXACTLY - more a numeric necessity than a medical one.]

You make a good point though, body temperature is the business of doctors and biologists - what if this changes? Then the scale serves as at least an historical reference. Then again, if you have ever travelled to higher altitudes, the coffee is cooler. Water does not boil at 100C everywhere. The scale is still relevant, in fact it now reflects the change in barometric pressure. However, boiling water cannot be used to calibrate a tranducer or an instrument.

With the proposed scale, the scientist only has to place the probe in melting snow for the zero point and under his tongue for the 100 deg point to calibrate the equipment approximately.

Then there is the application for environmental applications, specifically comfort temperatures. 54 deg would equal 68 exactly (numeric requirement).[BTW 54 X 0=0]. However the physiology of human and animal comfort is a science in itself. Actually "comfort" is a misnomer except at resorts, HVAC is more a matter of worker productivity in factories and offices.

Referencing body core temperature to skin surface temperature to air temperature is a significant concept. However heat transfer and humidity complicates the equation.... think wind chill factors and humidex.

The conversion factor of 1.5 X F is accurate (exactly) for Change in Temperature, i,e, "delta T", not the scale temperatures. However your conversion algorithm is correct - flattered by the use of the "P" symbol... thanks!

This exchange of criticisms displays the other feature of the scale...... that of an academic teaching device. Asking the students to propose their own scale, or other system to measure paremeters is clever exercise in itself for the serious science students.

Thnks,

Peter

(aka) Pete318 (talk) 20:18, 6 January 2010 (UTC)