3 ms·

If we just needed these quantities as the inputs to an equation, sure, we should express them as 1E12 meters or (whatever x 3.6E6) Joules. But it turns out unit

If we just needed these quantities as the inputs to an equation, sure, we should express them as 1E12 meters or (whatever x 3.6E6) Joules. But it turns out units are not only used for computing, but for communication. I am familiar with the kilometer because I know what it feels like to walk one. I am exposed to watts because I have grown up using 60W lightbulbs. Now, you could call this history and experience needless in the context of science. But in the context of my comprehension of the results of science, they are important, however "weird" they are to compute. I would much prefer for my computer to multiply by an extra conversion factor than to re-calibrate my mind to use "more efficient" units.

chriswarbo 10y ago
> If we just needed these quantities as the inputs to an equation, sure, we should express them as 1E12 meters or (whatever x 3.6E6) Joules. To be clear, I wasn't advocating against the use of km, cm, kW, etc.; only against the common contrivance that "the cm", "the km", etc. are some sort of independent units with remarkable power-of-ten conversion rules. As an analogy, it's like claiming that the number ½ ("one half") is, coincidentally, the same as the result of "1 ÷ 2" ("one divided by two"). In fact, there is no coincidence; the 'claim' is just describing the intended meaning of the "x over y" notation. Likewise, powers-of-ten are the intended meaning of the "kilo", "centi", etc. notation. In other words, expressing quantities in kilometres is expressing them in metres; there's no need to use, say, scientific notation to make it "more metric". My point about "1000 million kilometres" was simply that it's overly complicated (3 different factors, written in 3 different ways: one with digits, one in English and one as a prefix); why not "1 billion kilometres", "1 trillion metres" or even "1 terametre" ;) The problem with kilowatthours isn't the "kilo" or the "Watt", but the "hours"; it introduces an unnecessary factor of 3600 compared to other units. For example, a megawattsecond (AKA a megajoule) has the same order of magnitude (1kWh = 3.6 MWs)

chriswarbo 10y ago

> If we just needed these quantities as the inputs to an equation, sure, we should express them as 1E12 meters or (whatever x 3.6E6) Joules. To be clear, I wasn't advocating against the use of km, cm, kW, etc.; only against the common contrivance that "the cm", "the km", etc. are some sort of independent units with remarkable power-of-ten conversion rules. As an analogy, it's like claiming that the number ½ ("one half") is, coincidentally, the same as the result of "1 ÷ 2" ("one divided by two"). In fact, there is no coincidence; the 'claim' is just describing the intended meaning of the "x over y" notation. Likewise, powers-of-ten are the intended meaning of the "kilo", "centi", etc. notation. In other words, expressing quantities in kilometres is expressing them in metres; there's no need to use, say, scientific notation to make it "more metric". My point about "1000 million kilometres" was simply that it's overly complicated (3 different factors, written in 3 different ways: one with digits, one in English and one as a prefix); why not "1 billion kilometres", "1 trillion metres" or even "1 terametre" ;) The problem with kilowatthours isn't the "kilo" or the "Watt", but the "hours"; it introduces an unnecessary factor of 3600 compared to other units. For example, a megawattsecond (AKA a megajoule) has the same order of magnitude (1kWh = 3.6 MWs)