Guest Post by Willis Eschenbach
Pushed by a commenter on another thread, I thought I’d discuss the R. W. Wood experiment, done in 1909. Many people hold that this experiment shows that CO2 absorption and/or back-radiation doesn’t exist, or at least that the poorly named “greenhouse effect” is trivially small. I say it doesn’t show anything at all. Let me show you the manifold problems with the experiment.
To start with, let me give a curious example of the greenhouse effect, that of the Steel Greenhouse. Imagine a planet in the vacuum of space. A residue of nuclear material reacting in the core warms it to where it is radiating at say 235 watts per square metre (W/m2). Figure 1 shows the situation.
Figure 1. Planet in outer space, heated from the interior. Drawing show equilibrium situation
This planet is at equilibrium. The natural reactor in the core of the planet is generating power that at the planet’s surface amounts to 235 W/m2. It is radiating the same amount, so it is neither warming nor cooling.
Now, imagine that without changing anything else, we put a steel shell around the planet. Figure 2 shows that situation, with one side of the shell temporarily removed so we can look inside.
Figure 2. As in Figure 1, but with a solid steel shell surrounding the planet. Near side of the shell temporarily removed to view interior. Vertical distance of the shell from the surface is greatly exaggerated for clarity—in reality the shell and the shell have nearly the same surface area. (A shell 6 miles (10 km) above the Earth has an exterior area only 0.3% larger than the Earth’s surface area.)
[UPDATE: Misunderstandings revealed in the comments demonstrated that I lacked clarity. To expand, let me note that because the difference in exterior surface area of the shell and the surface is only 0.3%, I am making the simplifying assumption that they are equal. This clarifies the situation greatly. Yes, it introduces a whopping error of 0.3% in the calculations, which people have jumped all over in the comments as if it meant something … really, folks, 0.3%? If you like, you can do the calculations in total watts, which comes to the same answer. I am also making the simplifying assumption that both the planet and shell are “blackbodies”, meaning they absorb all of the infrared that hits them.]
Now, note what happens when we add a shell around the planet. The shell warms up and it begins to radiate as well … but it radiates the same amount inwards and outwards. The inwards radiation warms the surface of the planet, until it is radiating at 470 W/m2. At that point the system is back in equilibrium. The planet is receiving 235 W/m2 from the interior, plus 235 W/m2 from the shell, and it is radiating the total amount, 470 W/m2. The shell is receiving 470 W/m2 from the planet, and it is radiating the same amount, half inwards back to the planet and half outwards to outer space. Note also that despite the fact that the planetary surface ends up much warmer (radiating 470 W/m2), energy is conserved. The same 235 W/m2 of power is emitted to space as in Figure 1.
And that is all that there is to the poorly named greenhouse effect. It does not require CO2 or an atmosphere, it can be built out of steel. It depends entirely on the fact that a shell has two sides and a solid body only has one side.
Now, this magical system works because there is a vacuum between the planet and the shell. As a result, the planet and the shell can take up very different temperatures. If they could not do so, if for example the shell were held up by huge thick pillars that efficiently conducted the heat from the surface to the shell, then the two would always be at the same temperature, and that temperature would be such that the system radiated at 235 W/m2. There would be no differential heating of the surface, and there would be no greenhouse effect.
Another way to lower the efficiency of the system is to introduce an atmosphere. Each watt of power lost by atmospheric convection of heat from the surface to the shell reduces the radiation temperature of the surface by the same amount. If the atmosphere can conduct the surface temperature effectively enough to the shell, the surface ends up only slightly warmer than the shell.
Let me summarize. In order for the greenhouse effect to function, the shell has to be thermally isolated from the surface so that the temperatures of the two can differ substantially. If the atmosphere or other means efficiently transfers surface heat to the shell there will be very little difference in temperature between the two.
Now, remember that I started out to discuss the R. W. Wood experiment. Here is the report of that experiment, from the author. I have highlighted the experimental setup.
Note on the Theory of the Greenhouse
By Professor R. W. Wood (Communicated by the Author)
THERE appears to be a widespread belief that the comparatively high temperature produced within a closed space covered with glass, and exposed to solar radiation, results from a transformation of wave-length, that is, that the heat waves from the sun, which are able to penetrate the glass, fall upon the walls of the enclosure and raise its temperature: the heat energy is re-emitted by the walls in the form of much longer waves, which are unable to penetrate the glass, the greenhouse acting as a radiation trap.
I have always felt some doubt as to whether this action played any very large part in the elevation of temperature. It appeared much more probable that the part played by the glass was the prevention of the escape of the warm air heated by the ground within the enclosure. If we open the doors of a greenhouse on a cold and windy day, the trapping of radiation appears to lose much of its efficacy. As a matter of fact I am of the opinion that a greenhouse made of a glass transparent to waves of every possible length would show a temperature nearly, if not quite, as high as that observed in a glass house. The transparent screen allows the solar radiation to warm the ground, and the ground in turn warms the air, but only the limited amount within the enclosure. In the “open,” the ground is continually brought into contact with cold air by convection currents.
To test the matter I constructed two enclosures of dead black cardboard, one covered with a glass plate, the other with a plate of rock-salt of equal thickness. The bulb of a thermometer was inserted in each enclosure and the whole packed in cotton, with the exception of the transparent plates which were exposed. When exposed to sunlight the temperature rose gradually to 65 oC., the enclosure covered with the salt plate keeping a little ahead of the other, owing to the fact that it transmitted the longer waves from the sun, which were stopped by the glass. In order to eliminate this action the sunlight was first passed through a glass plate.
There was now scarcely a difference of one degree between the temperatures of the two enclosures. The maximum temperature reached was about 55 oC. From what we know about the distribution of energy in the spectrum of the radiation emitted by a body at 55 o, it is clear that the rock-salt plate is capable of transmitting practically all of it, while the glass plate stops it entirely. This shows us that the loss of temperature of the ground by radiation is very small in comparison to the loss by convection, in other words that we gain very little from the circumstance that the radiation is trapped.
Is it therefore necessary to pay attention to trapped radiation in deducing the temperature of a planet as affected by its atmosphere? The solar rays penetrate the atmosphere, warm the ground which in turn warms the atmosphere by contact and by convection currents. The heat received is thus stored up in the atmosphere, remaining there on account of the very low radiating power of a gas. It seems to me very doubtful if the atmosphere is warmed to any great extent by absorbing the radiation from the ground, even under the most favourable conditions.
I do not pretend to have gone very deeply into the matter, and publish this note merely to draw attention to the fact that trapped radiation appears to play but a very small part in the actual cases with which we are familiar.
Here would be my interpretation of his experimental setup:
Figure 3. Cross section of the R. W. Wood experiment. The two cardboard boxes are painted black. One is covered with glass, which absorbs and re-emits infrared. The other is covered with rock salt, which is transparent to infrared. They are packed in cotton wool. Thermometers not shown.
Bearing in mind the discussion of the steel greenhouse above, I leave it as an exercise for the interested reader to work out why this is not a valid test of infrared back-radiation on a planetary scale … please consider the presence of the air in the boxes, the efficiency of the convective heat transfer through that air from the box to the cover plates, the vertical temperature profile of that air, the transfer of power from the “surface” to the “shell” through the walls of the box, and the relative temperatures of the air, the box, and the transparent cover.
Seems to me like with a few small changes it could indeed be a valid test, however.
Best regards,
w.
Bevan’
One does not need a knowledge of physics to realise that the original proposition is absurd
>>>>>>>>>>>>>>>>>>
Well now I have seen the light. Well not actually since you can’t see light, Plato proved that in the 5th centurt BC. But now I understand that there is no need to study physics in order to explain physics. The absurdity of the proposition is obvious. This is why people who have never had children can look down their noses and sneer at all the mistakes people who have children are making with their kids. Back seat drivers serve the exact same purpose. They exist so that people who have never driven a car can explain to the driver what the driver is doing wrong.
It is now just so obvious, I don’t know why I failed to grasp this before.
David Hoffer says
” But now I understand that there is no need to study physics in order to explain physics. ”
Well you certainly proved that on this thread.
In fact your explanations of thermodynamics are quite creative.
The second law can be discarded and cold bodies can heat warmer objects
Bart:
At February 9, 2013 at 1:28 pm you say
Sorry, but that ignores a fundamental principle of communication; viz. a transmitter intending to be received needs to transmit in a manner that the receiver can receive. I explain as follows.
Many people have a message they want to proclaim. Hence, their primary purpose is to be heard, and they have no interest in listening. There are many reasons for people wanting to proclaim a message, and these reasons include beliefs, emotional commitments, political values and religious values.
In this thread there are people trying to proclaim their message that all of radiative physics and quantum mechanics is wrong so energy cannot move from a cooler object to heat a warmer one. Why they want to proclaim that is not relevant to the fact that they do.
But, as David Hoffer said, their proclamations are so wrong that they are easily ridiculed with resulting discredit of all AGW-sceptics. Therefore, we need to get them to listen if we are to correct their misunderstanding and, thus, stop the discredit of AGW-scepticism which their proclamations provide.
A person with no interest in listening will not make an effort to listen. Only, somebody who wants to hear will attempt to ‘tune in’ to the language of the speaker. And a person interested in proclaiming a message is not interested in hearing – or allowing to be heard – those who point out that the message is wrong.
Somebody who wants to be heard will attempt to ‘tune in’ to the language of the listener (because a transmitter intending to be received needs to transmit in a manner that the receiver can receive).
The listener has to be engaged before details can be discussed. Clearly, I and others have failed to engage those proclaiming their ignorance as fact, although I and the others have each tried to talk the language of the proclaimers.
Mathematics is not the language of those trying to proclaim that energy cannot move from a cooler object to heat the hotter one. Clearly, anybody with knowledge of mathematics sufficient to discuss the natures of EM radiation and its interactions with matter will know that EM radiation energy is transmitted from a cooler object to an adjacent warmer one.
If we were to engage with the proclaimers then mathematics would be a useful tool for precise descriptions and discussions (which is why science uses it). But mathematics is not their language and we first need to talk to them in their language, not ours, if we are to achieve getting them to listen. We are nowhere near that. At present we listen to them and explain their errors while they ignore the explanations and iterate the errors.
Richard
Bryan;
In fact your explanations of thermodynamics are quite creative.
>>>>>>>>>>>>>>>>>>.
Well obviously. It took many years of study to come up with an explanation that was consistent with the oth, 1st, 2nd, and 3rd laws of thermodynamics, the law of conservation of energy, stefan-boltzmann law, wien’s displacement law, planck’s law plus the work of Einstein, Millicken and Bohr. All I has to do was ask someone who never studied any of it and I would have understood what a complete waste of my time that was. Why didn’t you say something before I wasted all that time?
I’d like to learn how to fly a plane. Are there any people out there who have never flown a plane who would volunteer to teach me how?
Richard,
Bart just might be right. Let’s produce the math showing that Willis’ model is actually a logarithmic function that approaches a limit.
Then we can get some people who have never studied math to explain what limits and logarithmic functions are to us. At that point we will see the light. Except we won’t be able to actually see the light because Plato proved that was impossible in the 5th century BC. Modern photography proves his theory btw, that’s what the “red eye” effect is, the camera captures the rays emerging from people’s eyes.
I’ve decided to learn how to swim. Are there any people out there who have never learned out to swim who can teach me?
davidmhoffer:
re your post to me at February 10, 2013 at 11:36 am.
Yes, of course you are right. I have been p**ing into the wind.
As you say rational argument cannot dispel lunacy. Perhaps confronting them with similar lunacy will reveal their own behaviour to them, but I doubt it. Anyway, I will observe their responses to your Platonic (pun intended) arguments.
Richard
richardscourtney;
Your last comment reminded me of a long since forgotten story that is germane to this thread and which I believe you in particular will get a chuckle out of.
Some decades ago I moved into a new neighbourhood. As it turned out, there were a large number of houses of worship within a few blocks, and mine was the first new family to have moved into the area in about 15 years. As you can imagine, there was considerable competition to recruit the new folks….
About the 10th knock on the door in the first month was by a young man from one of the nearby churches, inviting me to attend services. I politely declined. He asked why. I politely suggested that my reasons were personal. He asked me if I knew that the bible instructed me to do certain things. So, I decided to humour him. I asked him if he could show me where in the bible it said to do those specific things.
He responded that “everyone” knew that’s what the bible said. Really? I asked him what specific version of the bible he ascribed to. King James he said. So, I promptly produced my copy of King James, handed it to him, and asked him to show me where it said what he claimed.
After some furious leafing through the pages, he became more agitated, and repeated his claim that it was in there, and everyone knew that. Really? Have you actually read it, I asked him? I mean not just some here and some there, but actually read it, cover to cover. He admitted that he had not. I told him that I had, which was why I was confident that what he claimed was not true.
At this point he became even more agitated, and began shouting at me using words like “heathen” and “den*er”. I had forgotten the story until just now.
So Richard, I have a question about a passage in Exodus that has always intrigued me. Knowing how well versed you are in scripture, I of course must exclude you from the list of people I might ask to help explain it to me.
Is there anyone out there who has never read Exodus who can help me instead?
richardscourtney says:
February 10, 2013 at 10:42 am
“Mathematics is not the language of those trying to proclaim that energy cannot move from a cooler object to heat the hotter one.”
Net heat energy CANNOT “move” from a colder object to a hotter one. In this, they are correct. Whether radiated, conducted, or convected, the net flow IS always from the hotter object to the colder one. But, that is not the entire story.
In Willis’ setup, that requirement is fulfilled. The shell is colder than the planet, and heat is always moving outward.
But, that movement can be temporarily slowed, and it must respond by establishing a new equilibrium. When that new equilibrium is established, the energy which failed to get out before it could be reestablished is retained, and the planet is hotter than it otherwise would have been.
It is the problem of Watts versus Joules which I have been trying to explain. The Watts can rebalance and go to zero, but the integrated Watts over time, the Joules, do not in general go to zero, as well.
People are arguing past the true issue, and both sides are wrong because they are not viewing it from the proper physical perspective.
MikeB – hold tight. I am working through your write-up to find the flaw in one of our reasonings.
Bart:
In your post at February 10, 2013 at 12:56 pm you say to me
With respect, you are misunderstanding the issue.
They are denying the existence of “net flow” and claiming there is no flow of energy from the cooler to the hotter. Indeed, that is the basis of the disagreement.
Also, I doubt your equilibrium argument will convince them although I hope it will. My doubt is because their argument is not based on evidence and/or logic: their argument is a rationalisation of their desire to believe there is no atmospheric GHE.
Richard
David Hoffer says
” All I has to do was ask someone who never studied any of it and I would have understood what a complete waste of my time that was. Why didn’t you say something before I wasted all that time?”
You are implying that you have studied physics at a university level.
This I doubt from your garbled attempt on this thread.
My university thermodynamics textbooks were
Heat and Thermodynamics by Zemansky
Equilibrium Thermodynamics by Adkins.
I have them still if you want to page and book quote.
I have several others (maybe even one you claim to have).
Your errors are so gross that it is not a question that separates either side of the global warming debate.
Anyone who has successfully passed thermodynamics 101 knows heat does not spontaneously flow from a colder to warmer object.
TJ Folkers agrees
Joel Shore agrees
Both are well known ‘warmists’ who HAVE studied physics so you have no credible support for your erroneous conjecture.
To sum up
If two objects are coupled in a purely radiative exchange ;
Radiation transfer is a two way process
Energy transfer is a two way process
Heat transfer is a one way process always from the higher to a lower temperature object.
Infra Red radiation is not in itself heat.
Heat IS the net radiative flux and is capable of doing thermodynamic work.
All this is apparently above your comprehension but perhaps helps some who follow this thread.
Bart;
People are arguing past the true issue, and both sides are wrong because they are not viewing it from the proper physical perspective.
>>>>>>>>>>>>>>>
I don’t think so Bart. I think the people who understand the physics are using somewhat different terminology from one person to the next, and also explaining the exact same concepts but from different perspectives. tjfolkerts for example said a few things that the nay sayers immediately jumped on as being in disagreement with me. I didn’t see any disagreement at all. But I understood his explanation in the context of both his explanation and the physics, and agreed with it on all fronts.
Similarly, you used the words “temporarily slowed” in your comment. OK, I understand exactly what you meant by that, I even agree with it (as I do with your points about joules and watts btw). If I were to make a comment that the speed of light and hence the energy flux is immutable, but there is a temporary energy flux imbalance, you’d probably agree with that while thinking to yourself that you’d just said that. richardscourtney, mikeb, tjfolkerts, would all (i think) recognize that as two different explanations for the same thing. The nay sayers would jump on it as disagreement.
But at days end we have one group of people repeating over and over again that an experiment unrepresentative of the physical problem and conducted with an apparatus too primitive to measure the effect even if the experiment was representative of the problem, insisting that the results are conclusive. We have another group of people insisting that there is such a thing as “back radiation” but that it just doesn’t “do” anything. We have another group of people shout about the 2nd Law as worded by Clausius in 1850, and regard this as immutable in the face of all the physics that has come since.
I had a raging argument once with a physicist about the behaviour of magnetic flux lines in the classic bar and rail problem. I was using an engineering approach and he was using classic physics. We were both convinced the other was wrong. We formulated a problem to demonstrate….and wound up with the exact same answer. That’s what I see here. Several people with solid math and physics backgrounds but using slightly different terminology to explain the same thing. On the other “side” are people who have never studied math or physics, but are quite certain they know what the math and physics text books say. How to get through to them is beyond me.
I’ve decided to learn French. Is there anyone out there who doesn’t speak French that can help me?
Bryan;
Anyone who has successfully passed thermodynamics 101 knows heat does not spontaneously flow from a colder to warmer object.
TJ Folkers agrees
Joel Shore agrees
>>>>>>>>>>>>>>>>>
So do I.
MikeB says:
February 10, 2013 at 8:01 am
Your mistake is here:
It should have been
Let (Inner Area of Shell/Outer Area of shell) = (R_inner/R_outer)^2. Suppose, for example, that the inner radius stays the same so that R_outer = R_inner + d, where d is the thickness. Then the ratio R_inner/R_outer = R_inner/(R_inner + d). As d increases, the ratio decreases.
Suppose the outer radius stays constant, and the inner radius is given by R_inner = R_outer – d. Then R_inner/R_outer = 1 – d/R_outer. Again, increasing d decreases the ratio. I will leave it as an exercise for you to show that if the mean radius stays constant, the ratio also decreases with thickness. I believe the result probably holds for any radius within the shell held constant, but am not feeling motivated to verify it right now.
davidmhoffer says:
February 10, 2013 at 2:04 pm
Fair enough. It seems it is not possible to explain that they are right about the thermodynamic law, but that it is beside the point, as it does not close off avenues for the accumulation of energy.
David Socrates says:
February 10, 2013 at 1:53 am
Well just shows how wrong you can be. I am an arch skeptic. Judging by your generally illogical and scientifically faulty responses here, you don’t get Willis’s thought experiment either . Your loss is Willis’s undoubted gain.
He is right and you, my friend, have a lot to learn about physics.
___________________________________________________
Yes, David, I do have a lot to learn about physics. I need to go back to university, and learn about how, according to Willis, a lit candle on earth will warm the sun. Yes, I apparently was snoozing during my thermo lecture, and missed that bit. Wait a minute. I have a brilliant idea. On Earth Day, everyone should shut off all their energy sources. That way the sun will cool, and global warming will be a thing of the past!
And all these years I’ve been wasting needless energy in my house, because all I needed to do was place an IR reflecting plate next to my wallboard heater to make it even hotter (face palm).
David, you indicated my responses were “illogical” and “faulty”, yet you offered no specifics whatsoever. Have fun at “The Great Debate”, and don’t forget you tin foil hat.
davidmhoffer says (February 10, 2013 at 2:04 pm): “I had a raging argument once with a physicist about the behaviour of magnetic flux lines in the classic bar and rail problem. I was using an engineering approach and he was using classic physics. We were both convinced the other was wrong. We formulated a problem to demonstrate….and wound up with the exact same answer.”
That’s why I keep referring to Dr. Spencer’s “Yes, Virginia” thought experiment, a more down-to-earth version of so-called “back radiation” than Willis’s steel greenhouse (which I think is terrific, but tends to confuse some people)..
“I’ve decided to learn French. Is there anyone out there who doesn’t speak French that can help me?”
Your Plato, piloting, swimming, Exodus, etc examples are priceless. Thanks for adding more humor to an already amusing thread.
davidmhoffer says, February 9, 2013 at 10:30 am: There is so much wrong with the CAGW meme that can be debunked with good solid science. How to get to that when the skeptic side is littered with people that cling to a belief system that can be debunked by the simplest of observational evidence? People who the warmists can point to in order to discredit skeptics?
and: Tjfolkerts, mikeB, bart, MiCro and others are having a conversation amongst themselves that I for one have learned from. They are refining their collective knowledge and learning from each other rather than shouting belief systems at each other while ignoring valid points that someone else advances. That’s science in action and we need more of it.
David,
Well said. Over at the Talkshop we are currently carrying on that debate “refining collective knowledge and learning from each other” at:
http://tallbloke.wordpress.com/2013/02/04/david-cosserat-atmospheric-thermal-enhancement-part-i-the-great-debate-begins/comment-page-1/#comment-43430
Do drop by any time and help us out.
” davidmhoffer says:
February 10, 2013 at 2:04 pm
Bart;
People are arguing past the true issue, and both sides are wrong because they are not viewing it from the proper physical perspective.
>>>>>>>>>>>>>>>
I don’t think so Bart. I think the people who understand the physics are using somewhat different terminology from one person to the next, and also explaining the exact same concepts but from different perspectives.”
I think Bart is more correct.
“We have another group of people insisting that there is such a thing as “back radiation” but that it just doesn’t “do” anything. ”
Back radiation doesn’t warm the surface and/or doesn’t block a significant amount of heat from leaving earth. And that CO2 levels has even less impact in terms of warming the surface and/or preventing heat from leaving Earth.
Those who believe that “back radiation” is important can even agree that it has small effect, but that this small effect is amplified by “feedback”.
So, “back radiation” does not increase the skin surface temperature enough to be measured-
so we call that as being None. Nor is there a theory physics that says it should.
What causes the skin temperature to increase in temperature is sunlight and back radiation
does not make the skin temperature a higher temperature.
The earth’s atmosphere does not increase the highest surface temperature- the atmosphere
inhibits the sunlight from reaching the surface, because the sunlight is inhibited by the atmosphere the skin surface is heated less.
So the intensity of the sunlight determine skin temperature [greenhouse gases do not have any effect in this regard].
Next part is “back radiation” keeps surface warmer for longer time- it traps the heat. It acts like a blanket. This is also not true- it’s not measurable affect.
Rather than discussing skin surface temperature, some prefer to say back radiation keep the surface [skin and air temperature] warm. But let’s instead focus on skin temperature.
What affects the skin temperature is the heat capacity of the surface. A sidewalk “traps heat”.
And sidewalk traps more heat than sand, because the surface of the concrete heated by the sunlight, conducts the heat of skin temperature better than sand.
What the large affect concerning the surface skin temperature is the solar flux, how well the surface absorbs this energy and conduction of heat below the surface, and convection of heat of the skin to air above it, and evaporation of water.
So the temperature of pan of water in sunlight depends upon how much of the sunlight is absorbed [a dark color bottom of pan affected this] how much water is in the pan, how heat in convected by air, and most important how much water evaporated.
A larger amount of water will take longer to warm [has more capacity to store heat]. And larger volumes have less surface area- therefore the more water takes longer cooler to cool by radiation.
[And Earth’s ocean store vast amount of heat.]
So the “back radiation” blanket effect is suppose to slow the amount of energy being radiated
from the skin surface. And there is little evidence of back radiation inhibiting this radiation
as compared to a vacuum condition. A vacuum condition does not have convection loss [it could cool a lot from evaporation] and rather being seen as “cold” it works well retaining heat.
A jar of warm water in space works almost as well as a thermos bottle- you give the jar silver coating it’s as good or better than thermos bottles on Earth.
What does may a difference is having warm enough air- warmer air will effect how much heat is lost from the skin temperature.
So that’s means we have address whether back radiation keeps the the surface air warm.
And this generally gets us into discussion of lapse rates.
Greg House says:
February 9, 2013 at 6:28 pm
I assume, their reflector might redirect light and one can get a certain spot brighter, but not because of alleged higher temperature of the filament caused by trapped/back radiation.
I suggest you read it again, the white light which is emitted is not effected by the dichroic coating and carries on as if the coating wasn’t there, it is the IR which is reflected and returned to the filament.
“Is there anyone out there who has never read Exodus who can help me instead?”
I read it once.
So Egyptians with help of a smart Jew, developed a welfare state, the state stored
food for times bad harvest. The Jews went to Egypt and everything was wonderful,
but over time they became enslaved, and so they left Egypt.
Seems like good lesson in there.
Bart says:
February 10, 2013 at 2:20 pm
davidmhoffer says:
February 10, 2013 at 2:04 pm
You never realize how something might be read when you write it. I meant “It seems it is not possible to explain to them…” I wasn’t being snarky.
” MiCro says:
February 10, 2013 at 8:07 am
” However a cup of water at an intermediate temperature, placed between the two, would slow the rate of cooling of the hot cup of coffee.”
This is how the Earth is, space is about 3K, the atm over my house on a 35F (274K) clear sky day was 233K. The atm doesn’t warm my house, but it does keep it warmer than if there wasn’t an atm.”
Keeping a house warm is space is easy.
The problem with say the international space station [ISS] is getting rid of heat.
You won’t read any about the ISS having some exotic powerful heater, instead
the big component is the large radiators to shed heat. And designed not absorb
much heat- it isn’t black, it’s white and reflective.
Both cooling and heating are quite simple things to do in the space environment.
A refrigerator is dead easy- no motors required. And heating is as easy.
So in space your heating and cooling energy cost are minimal- would be 1/10th
of places of Europe.
The heating used to heat of house in the permanent dark crater of the Moon with
surface temperatures around 30 K, would be less than in the UK.
The only reason the Apollo 13 crew were cold, was because their vehicle was designed
to be cold in the space environment [because that is the hard part- keeping
it cool enough- heating it was easy [assuming you didn’t need to conserve all
the battery power]
gbaikie commented
That is a very good point!
It does reminds me of something that goes nicely with your explanation.
In the 80’s I was a Application Engineer for some electronic design tools, and one of my customers was NASA GSFC. One of the groups I worked with was redesigning circuit boards for the Space Shuttle, as many of the original components where no longer available. In many cases hundreds of chips would now fit into a single programmable array, while reducing power dissipation and heat generation at the same time. But while looking at one of the designs, I noticed a big resistor on a board from power to ground, and asked why, thinking saving power and heat would be a good thing. I was told that the Shuttle was design around a certain power and heat load, and changing either would require extensive analysis and a lot of re-engineering, it was simpler and a lot cheaper to just dissipate the power with a resistor.
Gary Hladik;
Your Plato, piloting, swimming, Exodus, etc examples are priceless. Thanks for adding more humor to an already amusing thread.
>>>>>>>>>>>>>
Well thanks! But I am re-thinking the whole enterprise. I mean, why should I take piloting lessons when I can teach them instead? I mean, isn’t that the saying? Them’s that can do, and them’s that can’t teach? Well I can’t, so I’m qualified!
Who wants to learn how to fly? How’s $150 an hour sound?
davidmhoffer says:
February 10, 2013 at 6:47 pm
Flying is dangerous, something you’d want the best teacher available for, and everyone knows getting the best costs more, so could I pay you $300/hr? I want the best teaching me!
davidmhoffer:
David, this is a reply to your anecdote at February 10, 2013 at 12:51 pm. It is somewhat off-topic and is not intended to initiate a religious discussion. Indeed, I have taken time to consider whether to make this response for fear that it could divert the thread. On reflection, I have decided to make the point but I will refuse to be side-tracked into religious discussion.
In this thread we have people who have convinced themselves that physical laws mean what they want the laws to say, and those laws don’t mean what the laws do say. Your anecdote was about people who have convinced themselves that the Bible says what they want it to say and not what it does. There are many people who demean the Bible by pretending it is all literal truth so their understanding of it alone must be accepted.
You say to me
I don’t know the passage you don’t want me to explain, but I think Exodus 34: 29-35 contains an example which is germane to understanding what is happening in this thread.
Those verses say Moses repeatedly met God in secret and this resulted in his face “shining” (whatever that means). So, he put a veil over his face so people would not be disturbed by seeing his face “shining”.
St Paul gives his opinion of Moses’ “shining” face in 2Corinthians 3: 12-13. Although some translations are not as clear about it as the original text, Paul suggests Moses’ veil was to hide when the “shining” had faded. In other words, Paul suggests that Moses pretended the “shining” effect at least some of the time so Moses was a fraudster.
Ignoring whether Moses was a real or mythical person, this poses a problem for those who claim all of the Bible is literal truth: the two passages cannot be equated within their claim. i.e.
Was Moses genuine so Paul was mistaken?
Or
Was Moses a trickster because Paul’s opinions are divinely inspired?
Moses and Paul can’t both be right if you wish to proclaim the Bible is literal truth.
The paradox (and many similar paradoxes between Biblical passages) only exists for people who want to belittle the Bible as containing only literal truth from which they can select to justify their prejudices. In reality, the Bible contains many truths of many kinds. But they want the Bible to say what they want it to say instead of what it does say. And when the paradox is pointed out they make all kinds of illogical rationalisations.
Similarly, those who want to misrepresent the Thermodynamic Laws on this thread are claiming those Laws say what they want to believe and they are rejecting what the Laws do say. But they cannot see the paradox that if what they are claiming were true then refrigerators, pulse pumps, microwave ovens and several other devices could not exist. And when the paradox is pointed out they make all kinds of illogical rationalisations.
Richard
richardscourtney says
“Similarly, those who want to misrepresent the Thermodynamic Laws on this thread are claiming those Laws say what they want to believe and they are rejecting what the Laws do say. But they cannot see the paradox that if what they are claiming were true then refrigerators, pulse pumps, microwave ovens and several other devices could not exist. And when the paradox is pointed out they make all kinds of illogical rationalisations.”
Right after the explanation of the Carnot Cycle in a thermodynamics textbook comes the explanation of how the refrigerator works.
A refrigerator does not spontaneously transfer heat from a colder to a higher temperature.
It has to be supplied with energy to do this.
So instead of the Carnot heat engine doing work the refrigerator requires work to be done on it.
You obviously have never studied thermodynamics or you would know this.
Still its never to late to learn.
Anyway David now agrees that heat cannot spontaneously go from a lower to a higher temperature.
Bryan says:
February 11, 2013 at 8:38 am
Bryan, as I admitted up the page I still have lots of things to learn, so maybe I don’t understand your point, but let me offer another explanation for the disagreement.
The 2nd Law was developed prior to Quantum Mechanics, and while what you describe is true in Thermodynamics, QM demands the exchange of photons that have a defined energy, and therefore energy does transfer from the colder object to the warmer object, physics demands it. But the net energy flow as Thermodynamics demands does only flow from warmer to colder.
MiCro;
Hilarious!
Richard;
I knew you would “get it”.
Bryan;
I knew you would not.
MiCro says
“and therefore energy does transfer from the colder object to the warmer object, physics demands it. But the net energy flow as Thermodynamics demands does only flow from warmer to colder.”
That’s pretty much how I see it.
I would add the net energy flow is called heat and it is capable of doing thermodynamic work.
As I said above……
“To sum up
If two objects are coupled in a purely radiative exchange ;
Radiation transfer is a two way process
Energy transfer is a two way process
Heat transfer is a one way process always from the higher to a lower temperature object.
Infra Red radiation is not in itself heat.
Heat IS the net radiative flux and is capable of doing thermodynamic work.”