The metric system isn’t that much better

October 20, 2012 by Joshua
in Blog, Humor, Nature

I think it helps to look at the world from a different point of view sometimes. You see things differently. When I did yoga, sometimes my teacher would have us cross our arms left over right instead of right over left (or vice versa, depending on how you did it normally). If you’ve never done it, try it. I doubt it will make you suddenly enlightened, but it feels weird in a way that might make you wonder how many other things you assumed were just one way don’t have to be.

So today’s post is about values, understanding why you have yours, and how you probably have some for reasons you don’t understand or care about. You may think you’re reading about measurement systems, but you’re also reading about how others influenced how you see and value your world.

If you think metric is better, why?

With my physics background, I learned to use metric units despite living in the U.S. But outside science, I rarely used metric. Now, after almost half a year living abroad for the first time in a long time, I’m thinking about metric again, and I’m not so convinced it’s better than imperial — or whatever we call feet, yards, and gallons — for everyday use. For the record, I support metric and I’ll explain why below, but not for any advantage you and I on a day-to-day basis would notice.

I mean, if you were starting from scratch, I would agree metric is better, but not by much. And if you have to convert a nation, benefits have to outweigh switching costs. I’m not convinced they do — all the more so as computers becoming more ubiquitous make calculations easier. For physics you’re crazy not to use cgs or something similar derived from the metric system (though see below, because even physicists use multiple sets of units). People who put down imperial units (I looked it up between last paragraph and this one) think they’re high and mighty, but I’m not convinced.

Claimed advantages don’t help much

The main advantage of metric is quick conversion between units by powers of ten. That’s great in science, but I don’t know many times people convert between units. I know 100 centimeters go in a meter, but in regular-life practice I just know a meter is a lot bigger than a centimeter, just like a yard is a lot bigger than an inch, but I rarely convert between them. I know converting from cups or teaspoons to gallons is annoying, but I doubt I’ve ever needed to convert those numbers in a way that meaningfully mattered.

Nobody converts between inches and miles or teaspoons and gallons. I don’t mind using different units at different scales. I don’t see much advantage to knowing I can measure how much liquid is in my spoon with the same unit I measure the distance to the sun.

So far, no advantage to metric.

Imperial units are often handier

Meanwhile, I have to say, a foot is a very useful unit and the metric system doesn’t have it. For a ton of things, a foot is just about the right length. Centimeters are too small, meters are too big, nobody uses decimeters, and using a thirty-centimeter distance violates the advantages of metric.

Advantage imperial.

I first hit this type of problem this summer. We could set the air conditioner in my classroom to a particular temperature, of course Celsius. Well, it turns out Celsius degrees are about twice as coarse as Fahrenheit. And the class kept having to switch settings manually because it was either too hot or too cold. Yes, the air conditioner manufacturer could have given us half-degree settings, but that’s helps my point — I don’t find metric units better and I see little advantage in being able to convert.

Advantage imperial.

That Mr. Celsius in the eighteenth century calibrated his scale to properties of water doesn’t help me. Nobody lives their life around freezing and boiling temperatures. I live my life around 50 to 90 degrees and if you live yours around 10 to 40, I don’t see the advantage.

No advantage to metric.

Meanwhile, in the only place I’ve noticed it mattering in the past several decades, I preferred the Fahrenheit interval, just like the only times distance scales matter, I prefer the foot, a distance the metric system doesn’t have.

Multiplying or dividing by two is useful, which messes up metric

Oh, and another big difference with distances. When I measure distances, dividing or multiplying by two several times is a big advantage that dividing by ten doesn’t have. When I build things or cut things, halving or doubling happens a lot, which ruins the metric system. You can divide ten by two once, then you start needing fractions too and metric rulers don’t help. Whereas imperial rulers and measuring tapes tend to have halves, quarters, eighths, sixteenths, and sometimes more.

Very useful!

Another advantage to imperial and strike against metric.

Time ruins many conversions anyway

Finally, lets talk about probably the most common unit we all use but that the metric system has no advantage in — time.

Converting between seconds, minutes, hours, days, weeks, months, years, decades, and so on involve factors of 60, 60, 24, 7, 4 and change, 52 and change, 12, 10, and so on. And it’s not just time — time enters speed and rate conversions, ruining many of the metric system’s advantages in those areas. For all your ability to convert centimeters to meters, when you try to calculate how far you’ll drive in a day from km/h, you have to go back to your calculator for those factors of 24 and 60.

And why don’t we convert time to base ten? Probably because if we had ten or hundred hour days we’d have no units like our current seconds, minutes, and hours, all of which are pretty useful. So suddenly metric doesn’t have any great advantages. Unless you plan to drop hours in favor of hectoseconds and kiloseconds.

No advantage to metric. In fact, loss of advantage in areas it used to have an advantage in.

Oh wait, is the hour even in metric? I never thought of that, but Wikipedia says it isn’t so km/h isn’t even in metric! Speeds should be in km/s.

Penalty to metric.

Who converts between speeds and anything else in metric anyway? Just like with temperatures, having speed limits around 100 versus around 60 doesn’t matter much. Not that metric advocates could claim any advantage here anyway, because nobody uses metric for speeds. They use hours.

Science doesn’t use metric all the time either

Did I say finally? I forgot a couple more points. You know how I said in physics we use metric? Well, we often do, but once we get into a specific domain, we adopt units useful for that domain. When we talk relativity we use fractions of the speed of light. When we do atomic physics we use atomic units. Yes, we know how to convert them into metric, but actually, the questions on tests when we have to convert from the handy local units to everyday units tend to be the hardest ones on the test. And we don’t usually think of them as asking about science.

Again, no advantage metric.

Oddball units like hogsheads don’t matter

People talk about how imperial units like hogsheads and barrels confuse things. Well, nobody uses those measures anyway. I know there are multiple types of ounces and other units, but the only places I’ve seen them matter are on school tests designed to show problems in a system that otherwise doesn’t have those problems.

And if you’re in a field where those things do matter, you probably, like scientists, use special units for your field.

Besides, metric people use non-metric oddball units too. Ask your doctor your blood pressure in metric and you’ll get a blank stare. Sorry, but it’s mmHg.

Not to mention hours, days, and years!

No advantage to metric.

Why I support metric anyway, but only barely

Up to now, metric hasn’t had any advantages that matter to people on a day-to-day basis. I support it because conversions from one system to another make a difference so the world benefits from having a single system. Most of the world uses metric (well, a hybrid of metric and bizarre time units), so it wins by some type of majority rule.

But for the U.S. to stay with imperial doesn’t strike me as barbaric or stupid. Most of the time it’s no worse and is sometimes superior.

A better alternative?

If we had to start a new system today, I suspect a binary system might have advantages over metric’s decimal. Binary works in computers. It might be harder than decimal for converting some units, but no worse than time is already, which everyone uses.

Consider this: binary may make more sense today because we can convert with computers easily and would gain the easy divisibility of imperial now. If so, people who prefer metric may be wrong for exactly the same reasons they now consider themselves right.

EDIT: you can find some discussion of this post here — https://news.ycombinator.com/item?id=7062671. I can’t resist responding here to a comment there. Someone wrote

As someone who bakes, I loathe imperial measurements. For one, measuring by weight instead of volume is just much easier and more precise. (I’m looking at you “cups of flour.”) For two, it’s a lot simpler to scale recipes given in metric amounts.

I can imagine using weights helps cooking over volume, but metric has no advantage since imperial has weights too and can use the same scale. For that matter, the scale will almost certainly read units of mass on the metric side, not weight, for those who know the difference. The imperial readout will tell you weight.

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