09-12-2010, 11:54 PM
(09-12-2010, 11:29 PM)--Pete Wrote: Indeed, why use a unit based on the freezing point and boiling point of water at all? The Fahrenheit values of zero and one hundred are more useful to the human scale. They are the temperatures (approximately) above and below which humans start to lose efficiency.
While I agree with most of what you've written, this makes no sense to me, and indeed seems to be in contradiction to the spirit of the rest of your argument.
The Fahrenheit values of zero and one hundred are worth nothing. One, or five degrees above or below zero, or one hundred, and nothing special at all happens. It is not a threshold of any relevant kind, practical or theoretical. I don't even know what to make of "start[ing] to lose efficiency" - are you saying that humans operate with no loss of efficiency between these points? How do you know when you "start" to lose efficiency? And why would that be a relevant marker even for a practical temperature system?
The freezing and boiling points of water, OTOH, are of enormous practical, everyday usage. People are mostly water. Our planet is mostly water. We consume water. Water falls from the sky. We travel across water (without which the nautical mile wouldn't have been a hell of a lot of historical use). We drink water drinks, and both freeze and boil water for consumption. Water is a very natural, practical reference point. Zero and one hundred are physical thresholds - you can tell when you've reached them (suitably adjusted for pressure) pretty much immediately by its effects on the water surrounding us. It is precisely defined (in theory, if only roughly in practice), it is observable in everyday life, and it has practical value. Fahrenheit has... uh... well, nothing, really.
Kelvin is no doubt more useful for scientific measurements, because it starts in the ultimate physically justifiable point, absolute zero. But it is damned annoying to use numbers from 250-350 to describe everyday temperatures, and if we have to use a compromise system, Celsius/Centigrade seems like a good one.
-Jester