My brain has a variety of settings; work, home, soccer, Stout Month…..One of the more pronounced divisions in my brain (work and not work) expresses itself in a variety of ways, perhaps most notably in my preference for systems of measurement. Sounds odd, but let me explain.
Scientists, for the most part, love the metric system. People often talk about how much sense it makes and how orderly it is. This is true, when you need to convert measurements, calculate values, deal with orders of magnitude, or communicate with the world community, the metric system rules. My science education has been dominated by metric measurements. My brain carries around a variety of numbers that I use and recite: A good approximate temperature at the base of the crust is about 600°C and basaltic magmas are about 1000°C, give or take. Typical continental geothermal gradients are on the order of 20-30 °C/km, the activation energy of He diffusion in apatite is about 125 kJ/mol, and granites have an average density of 2.7 g/cc.
Although the specifics may differ, I’m willing to wager that all professional scientists have a similar list in their head. So I know these things, but ask me what the temperature at the base of the crust is in Fahrenheit. I’ve known it to be 600°C since I was 18 year old, but ask me Fahrenheit and I’m reaching for the unit converter on my smart phone, same with any of these numbers, or any value in science, for that matter. When it comes to science I am all metric. It is a superior system for science and for international collaboration, and I am sure that the vast majority of living scientists and engineers would agree with me. But here’s the thing, outside of science I really don’t like the metric system. Just like my science brain is wired metric, my non-science brain is wired with good old U.S. standard units. Room temperature in Celsius? Want to know my weight in kilograms, height in centimeters, or my car speed in kilometers per hour? Let me do some conversions. The room is 9 square meters? Awesome, where’s my smartphone, I need to check an app. The only daily thing I know in metric is that 45°C is a screaming hot Australian day, and I only know that because Midnight Oil sang about it once.
There are a few reasons I feel this way. Likely a lot of it has to do with how I was raised. I was raised with U.S. standard units, and they feel natural to me. This post is therefore American-centric, so be it. Despite that I do have some justifications.
But Thermochronic, you say, U.S. standard units are sooooo ddduuuuummmmbbbb. I mean, metric makes sense, water boils at 100°C and freezes at 0°C, but in America you have to remember all of these weird numbers, like 212°F and 32°C. Water boils at 100°C, really? Not where I live. Where I live water boils at about 94°C, and 202°F. When people say that what they really mean, of course, is that at 1 atmosphere, err, excuse me, 101,325 Pa, water boils at 100°C.
Figure from Cohen, J.E., and Small, C., 1998, Hypsographic demography: The distribution of human population by altitude: Proceedings of the National Academy of Sciences, v. 95, no. 24, p. 14009–14014.
Now, take into account that the median elevation that people live at worldwide (as of 1998) is 194 m above sea level, then on average, when people boil water it is sightly below 100°C, something like 99.75°C or so. Only 16% of the world population lives at elevations below 100 m, and for those of us who live at high altitudes, 100°C is rather meaningless. Sure, if you are obsessed with multiples of 10, the 100 and 0 are easier to remember, but what exactly do you need to remember them with any precision for? I’ve used boiling and freezing water to calibrate thermocouples, but I have to account for pressure in those instances, so having to memorize things isn’t really the issue. (Incidentally, my high-elevation home is a great coffee town, and I am convinced that part of the reason is that water boils at the right temperature for making coffee here, not at 212°C where the National Coffee Association warns your coffee will be substandard). This to me is a weird argument, that somehow because water boils and freezes at an even number for some small subset of the human population that somehow the other system is automatically inferior. In addition, it isn’t like sea level is static, especially in today’s warming climate.
Yeah, but Thermochronic, look at how complicated conversion are, I mean in the metric system you can go from nanometers to kilometers by just modifying the exponent, things are just factors of 10! True, and in science unit conversions are common, and the metric system is superior. But outside of science you rarely need to convert teaspoons to acre-feet. The units themselves are rather self contained, and the amount of conversion most people do is minimal. And I am not too obsessed with factors of 10. For example, I don’t argue that time should be broken down into factors of 10. 60 seconds in a minute, 60 minutes in an hour, 24 hours in a day, HOW DO YOU REMEMBER ALL OF THOSE NUMBERS? I expect people who argue for factors of 10 being important should also be arguing to scrap out current time system and impose something based on factors of 10. Beat time anyone?
U.S. standard units, their size and precision, make sense for a variety of everyday things: teaspoons, tablespoons, cups, pints, and quarts are great measurements for cooking. I know some people love weighing ingredients, but I don’t. These measures are about as precise as you need for most cooking, especially if you, like me, alter the amount of an ingredient based on taste or local environmental concerns. But that is kind of the point. U.S. standard units, or British imperial units or whatever iteration you are thinking of are largely based off of human experience. Miles, for example, refer to the fact that they were originally defined as a thousand paces. Science is suppose to take us beyond human experience, so it makes sense that the units don’t fit.
But here is the main reason I prefer the U.S. standard system for everyday things; it’s poetic. Seriously, inch, foot, pound, mile….you want to write a song or a poem, and you’d better just forget the metric system. Maybe it is because they have fewer syllables, or maybe it is because of some weird conditioning we experience growing up, but regardless, it is hard to argue against. There are plenty of examples, but let’s start with one of my favorites.
Original Version
The woods are lovely, dark and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.
Metricized Version
The woods are lovely, dark and deep,
But I have promises to keep,
And kilometers to go before I sleep,
And kilometers to go before I sleep.
No contest, right? Let’s try again
But I would walk five hundred miles
And I would walk five hundred more
Just to be the man who walked a thousand miles
To fall down at your door
Metricized Version
But I would walk five hundred kilometers
And I would walk five hundred more
Just to be the man who walked a thousand miles
To fall down at your door
it gets even worse if you actually assume the Proclaimers meant a literal 500 miles and you have to do the conversion, but I won’t go into that.
It takes a hundred kilograms of clay…
How high’s the water mama? 0.67 meters and rising…
I’d hate to look into those eyes and see 29 milliliters of pain….
and of course that classic early 90’s album 40 deciliters to Freedom.
I can’t think of a single song or poem that violates this rule. I think the only metric units that makes much of an appearance are degrees Celsius (although no one uses Kelvin), and occasionally the words “mill” or “key” when referring to gun caliber or some measure of cocaine. But notice even then the full words aren’t used, they just don’t fit into songs. This isn’t the metric systems fault, it is utilitarian and damn good at it’s job. I am just glad that the songwriters and poets of the world have alternate units to use.
I am slightly embarrassed by this. I hate that I don’t know room temperatures in Celsius, or my height in centimeters. But I think it is time we stop hating so much on the U.S. standard units, and realize that they actually do have a place.
Apparent Dip 