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Who the heck invented the Metric System?



  • Actually, it seems that the SI time unit (seconds) isnt based on planetary activity... The unit of time is the duration of exactly 9 192 631 770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the caesium-133 atom at a temperature of 0 K. Defined by: 13th CGPM (1967-1968) Resolution 1, CR 103 So god knows where that came from?!
  • What's more (hatrick yay!) Mark already seems to be running in metric time, what with his Weekly Update being 10 days after his previous one... :D
  • I think they just tried to find something stable to measure that took as long as a second, and then picked that as the definition.
  • NickENickE New
    edited September 2006
    Mini: Apparently the metre isn't officially based on the metre rod any more, either:
    "The standard metre, in 1960, was defined as the length equal to 1650763.73 wavelengths of a particular orange-red line of Krypton-86 undergoing electrical dicharge. Since 1983 the metre has been defined in terms of the speed of light. The current definition states that the metre is the length of path travelled by light in a vacuum during a time interval of 1/299792453 second."

    As far as I know, only the kilogram is still defined by its original prototype, but I could be wrong.
  • So a metre is now defined as the inverse of something which is measured in metres per second? Surely that's a somewhat circular situation?
  • NickENickE New
    edited September 2006
    I'm not too sure, I'm just repeating what I read. It's kind of odd as well, that Maxwell's equation for c includes a constant (permittivity of free space) which is, in turn, defined in terms of c.
  • I love physics! It's all relative after all.
  • It's pretty amusing that Americans can't understand the metric system, yet they use it daily with their currency.

    Kilo means thousand. Confusing!
  • I dont think the issue is understanding the metric system, just converting imperial units into it. Which is unsurprisingly difficult with the limitations bergamot seems to have. To be fair I'm only 18 so the metric system has been round my whole life and i still prefer to weigh myself in stones and pounds and check my speed and distances in miles. That's probably just cause it's still a nationwide standard though.
  • No, I get all that.

    The UK still hasn't officially adopted the metric system, so it makes sense that you'd use it. Despite being raised in Canada, I still prefer miles over kilometers, and I never was able to get into kilograms for weighing heavier things.

    My point, which I arguably didn't make - although I tried to allude to, was that Americans seem scared of the metric system. It doesn't seem to be a case of not understanding the units - many things here are being slowly replaced with metric measurements. It just seems that as soon as metric is mentioned, they lock up and act like it's such a hideously impossible concept that you're practically asking them to convert to Islam and speak Swahili RIGHT AWAY.

    I'm sure there's a contingent of Americans who would welcome catching up with the rest of the world, but those I've spoken to about metric seem scared.
  • Oh, and converting from Fahrenheit to Celsius, and miles to kilometers and all the other daily use measurements takes practically no time to get up to speed with. I've done it, probably, a dozen times now. Each time I completely forget how to translate, even so it only takes a couple days to get up to speed with the heavily used measurements.

    Other than that, I'm sure it sucks for what's-his-face who stated this thread. If there was a sympathy emoticon, I'd make it right now.
  • About Time: ------------- "Having a measurment system with multipliers in the same base as the numbering system is just plain common sense. That being said, I wonder why we don't have a metric version of time..." My thoughts exactly, wallphone. Once or twice I spent a rather long amount of time considering how would time keeping work properly in base10, something where each time subdivision is invariant (each month with the same days, each and every day has the same length) but the problem is daylight would drift all over the place. This is why we have daylight saving time, which is cumbersome but useful. The sun always rises around the same time, at 12:00 it's always straight up. It would be difficult to guess the time with a more numerically sound time measure. It would be easier to make calendar algorithms tho :D About Circular Definitions: -------------------- Physical measures are all about circular definitions. Ok not so circular... they are a mesh of dependencies so you can simplify one with another and go to the basics. However, there are some things that are elemental, such as energy and distance. Currently energy is defined by a relation of pressure and... water (calories, celcius degree and atmosphere), while distance is measured with light speed (as stated above), which is constant. About conversions and 10 fingers: ----------- I've always used the SI, and I can't for the life of me figure why would someone prefer using a system where you need to do calculations to change between different magnitudes of the same measure. In SI you just move the decimal spot: Mega, Kilo, Deca, etc etc. add or remove zeroes (1 feet = 12 inch? wtf!!) I can give you my height in kilometers or milimeters without whipping out a calculator. All that said... changing the measuring system to something different to what you've been using all your life must suck. Embrace it though, SI is much comfier. =)
  • My experience with different systems is: I was brought up in Brazil, and never heard of an non-metric measurement system until I started learning (American) English. We then had to learn about 'yards', 'miles' and such - and it all just sounded a bit absurd and unnecessarily complicated. When I came to Australia for the first time, as an exchange student, and went to live for a year in the country, I met a lot of people (the older generation) who had grown up with the imperial system, and had witnessed the change to metric. While among those there were still some die-hard fans of the old system, the vast majority had adapted pretty quickly to metric - specially where currency was concerned. The generation after that was pretty much like 'Denied' described above: while they were totally comfortable with metric, for a few things (usually personal things, such as a person's height, or distance between home and school) they would still use the old imperial system. This was almost 20 years ago. Needless to say, nowadays the young generation, as far as I can tell, thinks totally in metric measurements. My experience with the rest of the world has been, that in just about every country - except the US and UK - the metric system is the standard, and widely understood. I will probably be flamed for saying this, but my personal feeling is that it is a foregone conclusion that the few countries who still choose to be different, will eventually conform to the rest of the world, for simplicity and practicality's sake.
  • >I want to punch him in the face.

    happened 1791.
    you're a tad to late, but just a tad.
  • About time mesure, there have been a try to change it. It had the advantage to be a base 10 unit, but it diseappeared because there wasn't any needs for it, everybody were using the same system.
  • In fact, we (french) also created so called French Revolutionary Calendar and used it 2 centuries ago. It lasted twelve years (began 4 years after 1789 Revolution till Napoleon's Empire in ~1805)
    It is really weird and it has ONE major disavantage: no more 7 days-long weeks, there are 10-days long "decades". No more "5 days work 2 days off" rythm, it would 4-1-3-2 or sth like that ... Two centuries ago, it was one day off each 10 days replacing sunday off. I guess popular enthusiasm was hard to obtain! :-)
    Days lasted 10 hours, each hour divided in 100 minutes, each minute divided in 100 seconds. Pretty useful but 60 can be divided by 2, 3, 5, etc; 100 can't be divided by 3. Sexagecimal system is well suited for division. Duration of second is more or less a heart beat, you can't change such an important human reference.
    Years were written in latin: "An I" corresponding to 1793-1794 till "An XII" in 1805. Just imagine writing "year CLXXVIII" (178) or "year CXCIX" (199) ...
    3 decades per month (30 days per month), 12 months per year: 5 extra days were added in order to stick to observed seasons, equinoxes and so on. Planet Earth orbits around star Sun in 365.2499 days and it can't be changed by law :-)
    Imagine that once per year the "next sunday" is 15 days after and not 10 ... Or even 16 days every 4 years (due to the .2499 part). This problem of avoiding shift is observed in each type of calendar, whether based on moon, sun or a mix of both. 1900 had 366 days but 2000 only 365 in gregorian calendar, so simple isn't it? :-)

    French Revolution had to completely overwrite "Ancien Régime" habits so the names of days and months were completely changed. Months seems quite romantic and well organised (the termination of the word indicates the season and you can guess Flor-/flower is in spring; therm- is hot, etc) but disturbing too when you are used to 'Janvier, Février, Mars, Avril, Mai, Juin, etc)
    Autumn: Vendémiaire, Brumaire, Frimaire
    Winter: Nivôse, Pluviôse, Ventôse
    Spring: Germinal, Floréal, Prairial
    Summer: Messidor, Thermidor, Fructidor

    It has been used again for a short period of time in 1871 but is completely abandoned and only learnt in history class now.
    I wonder how difficult it would be to change time references. In 2002, 12 countries of European Union changed their currency (french francs to Euro for us) but we were accustomed when travelling from one country to another to mentally change 10 FF for ~3 DM (Germany), for example. We (in America or Europe) never have to convert a time interval or a date to another system, and it's something important in our lives and very emotional (kCal/mol to eV in physics isn't :-) )
    Translation from "18 Brumaire An VIII" to "9 November 1799" must be a hell to do without paper and pencil!
  • I would imagine that a 10 day week would annoy the hell out of Christians, Jews, Muslims, and any other major religion that includes the concept of a Sabbath.
  • Yes. And two days off out of ten (instead of the usual seven) would certainly annoy everyone else. ;)
  • Well, you'd change it to three days off out of ten. At least, that's what you'd get in Europe, I bet. (not that we'll switch to 10 day weeks in any forseeable future...)
  • And the 7th day for work rithm is rather important, I believe. Seems to be the right measure.
This discussion has been closed.