The “flaw” in your argument – that because one side of the aluminum foil is “shiny” with respect to visible light that it will also be “shiny” to infrared radiation – ISN’T due to the fact that you were limiting yourself to a “college textbook answer.” EVERY college physics book I’ve ever seen (for that matter every high school physics book I’ve ever seen) thoroughly discusses absorption, emission, transmission, etc differences according to wavelength (or frequency). My first answer carefully distinguished between aluminum foil’s infrared as well as visible light properties. Besides, the right answer is the right answer. It’s independent of the level of science used to explain it.

I have a feeling that you’ve never even had a calculus based physics class. While I don’t think you need one to discuss AGW, I do think you need one before you cast dispersions on other’s knowledge of science.

You should probably go back and tell your college professor (or whoever conveyed this little example to you) and explain the flaws with their analysis.

Also, I meant to state that you want the side facing the pipe to have lower emissivity.

You might disagree, but you are 100% wrong. Furthermore, I think you know that you’re wrong but are trying to save face.

1. You are conductively heating one side of your system. Therefore, you want the radiating side (the side not facing the pipe) to have higher emissivity than the side being conductively heated. Are you implying that all conduction-to-radiation insulators are bi-directionally equal? Are you implying that a pipe covering which is carbon on one side and silver on the other would be bi-directionally equal? If so, this is laughable.

2. I clearly stated laser DIODES for a reason. Laser diodes are not energized by means of radiated energy yet emit much radiated energy. Therefore, much like your dorm room system, THERE IS NO BALANCE BETWEEN ABSORPTION AND EMISSION. Detailed balance might, as you stated, “help.” Many, many principles “help,” but there is no balance!

Seriously, lgm, I think you’ve realized you’ve lost this one. You are discussing science with someone that is quite capable of understanding the supposed mechanism by which carbon dioxide heats the earth. Stop yourself and ask why nobody is willing to discuss it with me. You seem like a smart person. Why won’t you even consider skeptic evidence?

I’m not cocky enough to describe this as “basic”.

Basic means something from college level physics. Advanced is something from graduate school or postgraduate training. This is basic. Modern climate modeling is advanced.

It is completely INappropriate to apply ‘detailed balance’ to the dorm room situation you described.

I disagree. We want to know whether the shiny or dull side has a smaller emmission coefficient (the constant in Newton’s, not Fourier’s, law of cooling). We do an Einstein style gedanken experiment. In thermal equilibrium, the aluminum foil would emit as much as it absorbs (detailed balance). The shiny side has less absorption, hence less emission. But the emission coefficient is the same whether the system is in equilibrium or not, hence shiny has less emission, in or out of equilibrium. There is a flaw in this college textbook argument. What’s shiny at optical wavelengths may not be so in the infrared.

Don’t ever attempt to cite ‘detailed balance’ when discussing a laser diode or LED.

The relation between absorption and emission coefficients in an LED (or any other laser) is determined by detailed balance. That’s why lasers need to be pumped to bring the excited population out of equilibrium. Detailed balance helps you figure out exactly how much pumping is needed.

One more thing. Don’t ever attempt to cite ‘detailed balance’ when discussing a laser diode or LED. These are example systems of great imbalance between absorption and emission. In fact, the whole point of a laser diode is to create a great imbalance of emission (that’s where the “e” in laser comes from). Again, the system is open. It relies on energy from a constant electric field (not the absorption of radiated energy).

The only point made is that YOU are the one that doesn’t appear to understand (or wish to discuss) science (I’m not cocky enough to describe this as “basic”).

This is the problem with attempting to memorize science. It doesn’t work that way. It is completely INappropriate to apply ‘detailed balance’ to the dorm room situation you described. Detailed balance only applies to closed systems. You clearly described an open system. The continuous supply of hot water is an open energy input to your system. A detailed balance equation would be IMbalanced.

For the record, I stand firmly behind my answer. Do you care to go on the record and answer the question as well?

I’m sure your mistake is in good faith. Again, I think you were hoping that I wouldn’t answer at all. Either way, feel free to explain the mechanism by which carbon dioxide heats the earth. Does this mechanism rely on some obscure atmospheric convection?

BTW, I think that the readers have noted that I do the opposite of dismiss science (the geek in me). You might want to quell their suspicions that, like many AGW proponents, you avoid discussing the science at all costs. They might be sensitive to proponents that point to a scientific paper’s funding source rather than any mistakes in the paper itself. Along those same lines, you appear to be claiming that I don’t understand science enough for you to describe a simple mechanism to me. Well, I think I’ve demonstrated to them, that I am capable of understanding your explanation. So, please, humor me.

But still, there’s that principle, which is related to the science of global warming, for all you who feel qualified to debate the science.

lgm –

I’m just a lowly engineer so I don’t have a detailed knowledge of advanced physics, although I did study quite a bit of heat transfer and use it fairly often in my work (thus my reference to Fourier.) It came up once in some interminable math or physics class long, long ago. After doing some more reading as far as I can tell detailed balance actually falls under the category of probability of processes with applications in various technical areas including quantum mechanics. We are talking about a rather advanced topic that only math/physics majors understand or are even aware of. This is your criteria for discussing global warming with someone?

Now I’m taking a wild guess here but I’m going to assume Al Gore, Hollywood eco-celebs, rock musicians, all leading Democrats and a host of others such as David Lindorff that lecture us on global warming have no understanding of detailed balance, quantum mechanics, Fourier and heat transfer equations or even the most basic fundamentals of physics. Using your logic these people should not be addressing the public on this issue. I’ll go with that. The non-technically trained conservatives will shut up about global warming when the non-technically trained eco-warriors end their crusade.

If this issue had been left to experts and not politicized it would never have seen the light of day and would remain an obscure theory discussed only among experts with uncertain implications, where it rightly belongs IMHO. It is because of highly emotional liberals with minimal technical training that it has become a crisis. We will not stand by and let these people make the decisions for us, most likely bad ones that we will all be suffering with for years.

I am sure there are many technically literate posters here, although it seems very few have knowledge of how detailed balance influences weather patterns or emissivity of aluminum foil. Nonetheless, all of us have a right to sound off on this issue which we feel has been hijacked by the left for political gain.

My point was not that detailed balance is important for climate science, though it is. My point was that some people here write as thought they have a detailed technical understanding of the issues and the basic science, but they do not.