First I’ll point out a deceptive little trick employed by Roy which he used to blunder his point. To quote him:
RS: “The Wikipedia entry for the 2nd Law of Thermodynamics includes the following statement from Rudolph Clausius, who formulated one of the necessary consequences of the 2nd Law (emphasis added):
““Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.”
“The statement by Clausius uses the concept of ‘passage of heat’. As is usual in thermodynamic discussions, this means ‘net transfer of energy as heat’, and does not refer to contributory transfers one way and the other.”
The italicized words are important, and have been ignored by my critics: while it is true that the net flow of heat must be from higher temperature to lower temperature, this does not mean that the lower temperature object cannot (for example) emit radiant energy in the direction of the warmer object, and thus increase the temperature of the warmer object above what it would otherwise be.”
Whereas, Roy left out a the final paragraph in the Wiki quote on the Clausius statement. It fully reads:
“”Heat can never pass from a colder to a warmer body without some other change, connected therewith, occurring at the same time.”
The statement by Clausius uses the concept of ‘passage of heat’. As is usual in thermodynamic discussions, this means ‘net transfer of energy as heat’, and does not refer to contributory transfers one way and the other.
Heat cannot spontaneously flow from cold regions to hot regions without external work being performed on the system, which is evident from ordinary experience of refrigeration, for example. In a refrigerator, heat flows from cold to hot, but only when forced by an external agent, the refrigeration system.”
See that last part? It requires “external work being performed on the system” for heat to flow from cold to hot. Convenient for Roy to leave that part out wasn’t it? Thus, with the full statement from Wiki, his experiment is refuted before it even begins because he is not performing external work on his system. All he is doing is covering or uncovering the ice box, and this does not amount to work being performed by the ice on the heated surface.
As for his experiment, he is using an extremely precise measurement device which is nice for pretending that the results are likewise precise. Just because the measurement device can measure to 0.1°F does not mean that the experiment itself is sensitive to that level. All he actually measured was a 3-4 °F change in temperature which could have arisen merely from increased source lamp input flux onto the heated surface by reflected light from the highly reflective ice box cover. Given a change in temperature from 254 °F to 258 °F, this is a change in input flux on the primary heated surface of only 2.3%. So his experiment only saw a 2.3% (!) increase in flux on the heated surface, and that can easily, and undoubtedly, have come from a change in the input flux from the primary source from reflected input off of the ice cover. So there’s that, plus there’s fast air-temperature changes from diffusive transfer which can affect the result as well; it’s not just convection, but diffusion can change the air temperature too, etc.
To totally debunk it from first principles, all we need to do is step the experiment back a little bit and see that it is actually identical to the one by Curt Wilson for Anthony Watts. Spencer could have just as easily pointed the lights directly at the absorbing surface, and stated that backradiation would cause the lights to get hotter and thus brighter.
Let’s review something quickly:
|Differential in:||Causes action:||Modulated by:|
|Force||Acceleration (mechanical energy transfer)||Mass|
|Voltage||Current (electrical energy transfer)||Electrical Resistance|
|Temperature||Heat (thermal energy transfer)||Thermal Conductivity
Emissivity & Absorptivity
The power emitted by Roy’s lamp is supplied by the outside work of the voltage differential coming to his electrical sockets. That’s the source of power. The power P emitted by his lamp circuit is given by P = V²/R, where V is the voltage differential supplied by outside work, and R is the resistance of the circuit. So, does backradiation increase the voltage across the poles of the electrical outlet? Does it increase the current in the curcuit? Of course not. And since it doesn’t, then backradiation can’t make the source of heat (the filament) get hotter still, since its temperature is determined by the power which is produced from the voltage supplied from outside, and which is constant, and which can not be affected by the backradiation. Backradiation is not additional power…it is passive background without any ability to do work on its source, in accordance with the Laws of Thermodynamics.
Secondly, consider what would happen even if backradiation did cause the filament to get hotter. Every electrical engineer in the world knows what happens to a resister (the filament) when it increases in temperature: its resistance increases. Now look at the equation for the circuit again: P = V²/R. So, if R increased due to the heating from backradiation, then P would decrease given that V is constant (it is supplied from outside). Now think about that. The power P is also the radiant energy emitted by the filament by P = AσT4, where A is the surface area of the filament and T is its temperature. A higher temperature filament has higher P, and a lower temperature filament a lower P. Backradiation would cause a higher resistance, giving a lower power, which would mean lower temperature and hence less bright filament. However, backradiation was supposed to make a hotter filament and brighter filament. So we get a logical contradiction, which originates in the original consideration of the first sentence where we assumed that backradiation could cause warming. If backradiation did work as they desire, it would dim the filament, not brighten it, but they desired that it brightened it.
QED. It doesn’t work that way.