Edfilho said:
GeeBot said:
And about that liter; the liter is a cubic decimeter, and the SI unit is the kilogram, with a mass equivalent to a cubic decimeter of water. Surely, if we're being purely scientific here, a cubic meter and the megagram would have made better base units. As a practical matter, though, both quantities are unwieldly for everyday use (personally, the choice for volume/mass units never bothered me much; I never use the volume units in scientific computations, just convert everything to cubic meters; and the only time mass and volume interact is with density computations, where the density is generally given).
Well, your assumptions here go well against what I experienced my whole life... It's really easy to measure volume with liters and weight with grams. Not only both units fall within human scale, but it also easy to divide and multiply. It's quite easy to infer the volume of something by rule of thumb, and even easier if you have any reference, like a simple box of milk.
Sorry if there was any confusion, but what I meant was that the cubic meter and megagram are impractical for everyday use, despite being more "natural" metric volume/mass units in terms of computations. I was using liters and kilograms as an example of SI units where rationality yielded to practicality, to bolster the idea that the metric (or specifically, SI) system isn't completely rational, either.
Edfilho said:
Well, I'm sorry to say, but the celsius scale fits just nice in the "temperature ranges that most people encounter", because it MAKES SENSE, as opposed to the Farenheit scale. 0° celsius = frozen water, 100° celsius=boiling water. 99% of human life is snugly within these confines. It's pretty easy to know if it's cold or not, even for someone who has no "live" familiarity with celsius. if it's close to 0°, it's cold. if it's close to 100°, it's hot. If it's around 25°, it's room temperature. Quite sensible.
And the Kelvin uses the same scale as Celsius, the only difference is that it starts on ABSOLUTE zero. 0 Kelvin is the coldest possible temperature in the universe. Which is exactly -293.73°C, IIRC. But the "interval" of one Kelvin is the same as 1°C.
Yes, I know that 1 kelvin = 1 degree Celsius (although for the nitpickers out there, note that a kelvin is a unit, while Celsius temperatures are degrees on the Celsius scale). What I was trying to show here is that the 0 C = freezing point of distilled water at 1 atmosphere of pressure was somewhat less rational (from a scientific point of view) than using 0 K = absolute zero.
Also, I take umbrage with the idea that 99% of human life fits snugly between 0 and 100 Celsius (mainly with the term "snugly"); I think this actually points out how separated from meterology the Celsius scale is. For one thing, the outside temperature on this planet has never exceeded roughly 65 C; for another, it routinely goes far below 0 C. And room temperature is closer to 20 C than 25 C. With those guidelines in mind, 100 C is indeed hot; so is 1 million C; so is 30 C. And 0 C is indeed cold, but so is 10 C, as well as -10 C, as well as -200 C.
The Farenheit scale, taken at face value, is much more applicable to temperatures experienced by humans: 0 F is the freezing point of concentrated salt water (and thus the lowest point
any aqueous solution can reach), while 100 F is the average human body temperature (well, not really, but that's more due to a measurement error in the original definition)--in Celsius, it's 37 C.
Celsius is fine for cooking and chemistry and thermodynamics (as far as 1 C = 1 K, not that the Celsius scale is particularly appropriate for thermodynamics), but I think you'd have to have blind faith in the folks who came up with Celsius in the first place to automatically assume that it's a good fit for meterology as well. Remember, just because it's an accepted standard doesn't mean it makes sense for everything; I mean, that's how we got the English system in the first place. The Celsius scale was originally devised a couple centuries ago for people who wanted to use it when the freezing and boiling point of water at 1 atmosphere were important numbers; these endpoints don't make sense for everything.
Don't get me wrong; if you're going to use 1 temperature scale for everything, it makes sense to keep all your temperatures in the same scale, so you don't have to worry about converting from one system to the other. In that respect, Celsius makes as much sense for measuring the temperature on a sunny day as any other. But that's just a matter of what you're used to; I'm sure if physicists with a knowledge of thermodynamics had invented the first temperature scale, we'd be talking about how 314 K is roughly room temperature (or whatever, it'd probably be unlikely that 1 K = 1 C in a truly independently derived system), and how "natural" it was to express temperatures that way, since it's easy to see that 600 K is twice as hot as 300 K (but 200 C is not twice as hot as 100 C).
Edfilho said:
I agree with being down to what we're used to. But your conclusion about "naturalness" fails to notice that, being a logical system with perfectly regular units, you can chose the multiple that suits you better. for instance, if you want to measure the diameter of a pencil, you can use milimeters. If you want to know how long is the road from alaska to patagonia, there are kilometers, but the beauty of it is that you can translate both measurements without effort.
I generally prefer to use explicit powers of ten, rather than metric prefixes, for intermediate calculations (that way, I don't make the mistake of turning 1 m^2 = 1000 mm^2, instead of 1000000 mm^2); I've seen a number of mistakes in this department, even in the second or third editions of textbooks (it is a lot easier to say 10 mm than 0.01 m).
One of my original points was that multiples of 10 aren't the best for everything, though; I originally mentioned degrees of arc and time as examples of where metric hasn't penetrated. The main problem here is that metric doesn't make for particularly convenient fractions, and sometimes the gap between 0 and 10 (or 10 and 20, or whatever) is too large (my main example in this area was Celsius, but since we don't agree on this, I guess I can't use it--maybe I can come up with a better example later). People tend to have a poor sense for how many 0.167's there are in between 0 and 1, for example, but they can work with 1/6th's fairly easily.
But returning to the topic at hand...
Delance said:
Are all WC references in meters or does confed use any different system? (Not including Kilrathi halfs of eights).
I'm pretty sure everything is in meters. As for the "Battlestar Galactica" system, that just sounds like a cop out to me.
