When the world was new, Laotzu and Confucius were potters and they spent long days working the bellows at their kiln to fire the pots. When Confucius kept track of quantities he used the metric system, while Laotzu used human-scale versions of the natural units. It was Confucius' turn to blow so he was pumping the bellows while Laotzu rested. Confucius' plan was to bring the kiln up to 1414.5 Kelvin and then stop blowing and let the temperature coast back down. For Laotzu that meant bringing it up to 10 grade, which was fine with him.
Laotzu had made a hole in the side of the kiln and fitted a plug to it. The plug was about as thick as his little finger. From time to time, when he was curious about how it was inside, Laotzu would take out the plug and look in the hole.
Because he could see in the infrared and judge the keynote frequency in the light, Laotzu already had one good way to tell the temperature. When the target of 10 grade was reached the keynote frequency in the glow would be 10 quadrillion per minute.
But he could tell it from brightness as well. He could judge by eye how many ponies of power came out the square-bone hole and that gave him an idea of the temperature inside the kiln. A square bone area is 10-4 of a square pace.
That morning Confucius had forgotten to bring thge radiant heat thermometer the had ordered from the German company of Boltzmann-Stefan GmbH. After a while he got tired of working the bellows and said to Laotzu: "You take over and I will go back to the house and fetch the thermometer to tell when it's hot enough." But Laotzu said: "Keep on blowing. I'll know when it reaches 10 grade."
Laotzu reckoned what brightness to expect by squaring the target temperature twice (this was easy with 10 grade and gave him 10 000) and multiplying by pi2/60 told him ponies per square pace. Then dividing by 10 000 told him the ponies per square bone—and that turned out to be exactly pi2/60 When the kiln reached 10 grade, he knew 1/6 of a pony of light would be coming from the hole. You didn't have to be a Taoist sage to judge that level of radiant power, you could feel it on your palm of his hand—put in Western terms, since a pony is about 360 watts, it is something like 60 watts.
After a while Confucius was finished with his turn pumping the bellows and Laotzu got up and removed the plug and saw that 1/6 pony was shining from the hole. The sages decided they could leave the kiln to cool, so they closed up the shed and went back to the house for tea.
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Copyright © 2002 Leonard Cottrell. All rights reserved.
Table of Contents
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arithmetic:
In the language of Freshman Physics, pi2/60 pony per square bone per quartic grade would be described as the "Stefan-Boltzmann sigma". It is the constant in the "fourth power radiation law." You might be curious about how the constant looks in metric units. In metric terms sigma is:
5.6704...× 10-8 watts per square meter per quartic Kelvin.
If Confucius had been willing to struggle with the arithmetic he could have squared 1414.5 twice (which gets messy) and multiplied by this "sigma" number (which is even messier) and eventually found out the power from the peephole in watts. Anything Laotzu could do with human-scale natural units could also be done with metric units — merely with more bother.
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