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posted by chromas on Monday May 20 2019, @07:42PM   Printer-friendly
from the progress-is-centimetering-along-nicely dept.

We measure stuff all the time – how long, how heavy, how hot, and so on – because we need to for things such as trade, health and knowledge. But making sure our measurements compare apples with apples has been a challenge: how to know if my kilogram weight or metre length is the same as yours.

Attempts have been made to define the units of measurement over the years. But today – International Metrology Day – sees the complete revision of those standards come into play.

You won't notice anything – you will not be heavier or lighter than yesterday – because the transition has been made to be seamless. Just the definitions of the seven base units of the SI (Système International d'Unités, or the International System of Units) are now completely different from yesterday.

[...] The challenge now though is to explain these new definitions to people – especially non-scientists – so they understand.

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  • (Score: 3, Insightful) by AthanasiusKircher on Tuesday May 21 2019, @12:31AM (5 children)

    by AthanasiusKircher (5291) on Tuesday May 21 2019, @12:31AM (#845678) Journal

    The challenge now though is to explain these new definitions to people – especially non-scientists – so they understand.

    Um, why? I mean, I'm all for science education. I'm all for education in general. But why is this a particular "challenge" that needs to be explained to most people, rather than all the other things people could be educated about?

    Most people didn't know already that the kilogram was defined by some hunk of alloyed metal in France. Even fewer people probably knew that the meter is defined in relationship to the speed of light (and that depends on the definition of the second, which relates to cesium transitions). Even fewer people knew the obscure definition of base units like the ampere or the candela. (Seriously -- even among nerds on this site, how many of you seriously could tell me the definition of the candela without looking it up? How many of you didn't even know it was one of the 7 fundamental base units of the metric system? How many don't even know what it is?)

    In the grand scheme of things, are these something the average person needs to understand?

    See, this is the reason metric adoption fails. It's the reason why even in countries that adopted the metric system decades or even centuries ago, everyday weird local units remain in common use alongside metric units. It's because the utility of standardized units -- while incredibly useful and important to science -- is basically irrelevant to most people everyday life. The ultimate usefulness of the metric system comes into play in two situations: (1) communicating units with people outside your country, and (2) conversions.

    Unless you're involved in international trade, the first probably impacts your life rarely. If you live on a border and commute, you probably are fluent in different units across the border, just as you would be if you dealt with different languages across a border.

    As for the second issue of conversions, the usefulness of them in everyday life is overrated. Most things tend to be measured in one particular unit. If you buy milk in the U.S., you care about how many quarts it is. If you buy soda, you care about liters (in a big bottle) or ounces (in a small one). Occasionally people need to convert one level -- and it mostly comes into play for people in food measurements (pounds/ounces or pints/cups/fluid ounces) and in feet/inches. Basically, for most people, you remember about three or four conversion facts, and you're set for 99% of situations in everyday life. Who cares if a mile is 5280 feet? Very few situations where that actually comes up. Who cares if there are 1728 cubic inches in a cubic foot? The few people who deal with situations that this is important can just type them into Google or have memorized formulas (or, back in the day, had little books or cheat sheets of conversions on their desks).

    Note that I think standardized measurement is a very good thing, and I lament the fact that the U.S. hasn't adopted a common international system. But I also know that remnants of old measures survive in a lot of other countries too that pretend they've completely "converted" to metric. It's because real estate agents always measured apartments in square feet and stores measured refrigerators in cubic feet and grocers measured produce in pounds and people measured weight in stones. People don't actually know how big a "cubic foot" is usually -- they just want to compare their refrigerator to their previous one... you might as well call it "18 refrigerator units."

    So when I see someone saying we have a challenge to explain to non-scientists why the kilogram is defined in terms of Planck's constant -- WHY? There are hundreds of better things about measurement I wished they already understood. Start by explaining to people in London why they should list apartments in square meters instead of square feet -- most people have finally transitioned to metric there, but it's still common to see sq. ft., or even yards or miles on road signs. Everyone can make fun of the U.S., but really look around in the world and see how many non-metric units survive in places.

    Oh, and a last pet peeve -- one place where conversion is really useful for everyday people is in culinary recipes. And that's one place where stupid non-metric units survive, though they've been pigeon-holed into metric rough equivalents. Why continue the stupid practice of 3 teaspoons per tablespoon, for example, along with fractions of such units? Well, I used them to teach my kid fractions when he was preschool age, so I suppose they have their utility. And heaven help you if you need to convert tsp/tbsp into cups or some larger measure (and have to deal with the conversions and how they work differently in U.S. vs. UK vs. Australia, etc.

    It's all a mess. Let's clean that up first. Then maybe in a few decades we can worry about how to explain the definition of a kilogram in terms of Planck's constant to the average person.

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  • (Score: 2) by Hartree on Tuesday May 21 2019, @01:39AM (4 children)

    by Hartree (195) on Tuesday May 21 2019, @01:39AM (#845693)

    " People don't actually know how big a "cubic foot" is usually "

    I'll take a wild guess that it's a block about a foot on a side.

    Do I win a cookie?

    Of course, I've been known to tease someone that their foot isn't cubic so this mythical cubic foot must be a spherical cow approximation to reality.

    • (Score: 2) by AthanasiusKircher on Tuesday May 21 2019, @03:14AM (3 children)

      by AthanasiusKircher (5291) on Tuesday May 21 2019, @03:14AM (#845704) Journal

      That's not really knowing intuitively how big a unit is. That's stating a definition. Can you estimate how many cubic feet your shower is without measuring or estimating all three dimensions? Do you have a sense of how many cubic feet your fridge can hold without looking at the sticker? Could you look at a pile of dirt and estimate how many cubic feet it is? People who work with bulk materials (soil, stone, gravel) etc. generally how an intuitive feel for how much a cubic yard is, for example. Most other people don't.

      Compare that to how many people intuitively have a sense of how big an inch or a foot is, and they can estimate a distance with some accuracy. They know what those units mean.

      I know roughly how much a teaspoon and a tablespoon are and could measure them in my hand freely. I could probably estimate a cup of flour by eye. But if you asked me to shovel out five cubic feet of sand, I don't know that I'd be very accurate by eye. Would you be? If not, you don't intuitively know what a cubic foot is.

      • (Score: 2) by AthanasiusKircher on Tuesday May 21 2019, @03:18AM (1 child)

        by AthanasiusKircher (5291) on Tuesday May 21 2019, @03:18AM (#845706) Journal

        (And by the way, I say all this because my point is that people use units they know intuitively. If someone has a sense of how big a 600 sq. ft. apartment is and how big a 900 one is, etc., they may have less a sense of how big a 75 square meter apartment is without doing some sort of conversion. People use units practically for comparing measures that have some meaning. That's what real-life measurement is usually about.)

        • (Score: 0) by Anonymous Coward on Tuesday May 21 2019, @09:57PM

          by Anonymous Coward on Tuesday May 21 2019, @09:57PM (#845947)

          This is exactly the argument I make to those who prattle on about the superiority of the metric system for everything. No, it is superior for science and commerce where calculations are done all the time. It is useless for everyday life where this obsession for dividing by 10 trumps the need for being able to relate to a measurement. All those weird units come from actual useful things; cups, pints, bushels. They are all units that one can relate to.

      • (Score: 2) by Hartree on Tuesday May 21 2019, @12:41PM

        by Hartree (195) on Tuesday May 21 2019, @12:41PM (#845783)

        You can say the same thing about a gallon. You know about what a gallon is in liquid measure from the container that it's in. But as a raw volume, say of sand, you're in the same boat as with a cubic foot. I'd rate that I could come closer to the shower question in cubic feet because I know that it's a good but taller, and about half again as wide and deep as a 20 cubic foot freezer. I can easily come up with, roughly, 3 feet by 3 feet by 8 feet tall, so 72 cubic feet. But I would have guessed about 2 to 3 times as big as a large freezer. That's as close as most people come to intuition on measures.

        Gallons? Forget it. I'd have to figure it out from knowing a cubic foot is about 8 gallons roughly (and no, I didn't google it).

        One of the things I used do at work is retrofit freezers for chemical storage so I've got a pretty good idea of about what size a freezer is. That said, I'd bet that most people have a better idea, in terms of raw volume rather than a container, what a cubic foot is compared to a gallon. They may think they know gallons better because they measure gasoline in it, but mostly they don't even see the fuel as it goes into their car. They might have some idea of it from the size of their, say, 2 gallon gas can that they use to fill the lawnmower.