I’ve lived with three systems. I grew up with the imperial system in Britain and Australia, moved to metric in Australia, then have had to move again to US customary in the US.
So I get used to “quarts”, which I’ve never used before, which are closer to litres than anyone would real care about, and are definitely not the same as the 2 pints that I used to know about.
And I now what a litre of water weighs, so I know that a litre of milk would weigh roughly one kilo. So how much does a quart of milk weigh? Well, that 32 fluid ounces – but a fluid ounce of water in these parts doesn’t weigh one ounce, it’s 29 point something ml, which is a bit more than a real fluid ounce, so 32 fluid ounces weighs a bit more than 32 ounces, or 2 pounds.
And carpentry is so much easier in millimetres than in 1/16th’s of an inch, because the multiplications and divisions are some much easier to do. You want 11 shelves in 8 feet? That’s 96 inches divided by 11, or 8 inches plus 8/11 of an inch – so what the nearest 1/16 to 8/11?
Except negative on the Celsius scale isn’t what I think of as “cold!” To use the same number as my previous post, 28 degrees F just isn’t either uncommon or remarkably cold, but in the Celsius scale it’s a negative number. That means I’d be using a negative number to describe the weather of a significant number of days per year. 0 degrees F is “cold!” 0 degrees C is chilly. 100 degrees F is “hot!” 100 degress C isn’t important in weather terms.
In other words, I care about the temperature pretty much only as it relates to my environment. And for my environment, 0-100 degrees F pretty much covers it. 0-100 degrees C starts too high and ends way too high. Scientists can use whatever scale appeals to them without impacting me in the slightest.
I’m not very familiar with ammunition either. But if we imported the 9mm standard caliber bullet, and built guns around it, wouldn’t that be for the same reason that American soda makers had for bringing out two-liter bottles? Or car makers had for switching to metric parts? I assume it was to accommodate the international market — to the small extent that we try to be accommodating.
Maybe someone keen on gun history can better explain these things.
In any case, that remark of mine probably should have had a smiley after it. I was cracking a little joke, and didn’t mean to seriously imply that metric ammunition is one of the great success stories of the metric system in the U.S.
[dorky scansion joke] Ah, so the scientific method is actually written in iambic pentameter? [/dsj]
Science isn’t defined by the units someone uses. Science is defined by the method someone uses. So unless you can find a metric way of forming a hypothesis and testing it, I would say that your argument isn’t a strong one.
One factor that played into the failure of the 70s-era “think metric” campaign —
Instead of focusing kids on the ease of conversion between different metric units, they tried to make the metric system accessible to us by teaching us how to convert from inches to centimeters and vice versa, from cups to milliliters and back, from kilometers to miles and feet and inversely, grams to and from ounces, and so on.
Having 1000 millimeters in a meter or knowing that a centimeter cubed contains the same volume as a milliliter may be a lot more elegant than having to figure out how many tablespoons are in a gallon or how many square feet in an acre, but there’s nothing at all even remotely elegant about conversion formulas for getting from metric to American standard and vice versa.
Zillions of American schoolkids in grades 3-6 came home with page after page of math problems that required conversion between systems, and it didn’t take long before lots of folks wanted it all go just go away.
Fine. I still don’t see what the big deal is with negative numbers. Do you find it difficult to do certain calculations with them? Or is there ambiguity? Is it less intuitive (e.g. -10 sounds warmer than -5)?
Science is also about having a universal, standard way of understanding the world. That’s because modern science is built upon free and rapid exchange of information and knowledge. The standard unit of science is SI.
Besides, many formulas in physics textbooks will only work under SI (or cgs). I’ve never even seen Maxwell equations in Imperial units.
Metric is superior to the Imperial system in only one area, ease of conversion. It’s easy to convert milliliters to liters and meters to kilometers etc. etc. However, in day to day life, conversion is mostly a non-issue.
Need to convert teaspoons to gallons? WTF for? You suddenly using grandma’s fried chicken recipe to feed an army? Going one or two steps isn’t difficult anyway. 3 teaspoons to a tablespoon, 4 tablespoons to a 1/4 cup, 4 cups to a quart and 4 quarts to a gallon.
Converting feet to miles? There’s nothing that I’d measure in feet that I’d want to measure in miles, not even quarter miles. You do have to be careful with inches and feet, I’ll grant you that. Generally speaking, though, you discuss the distance in whatever you use to measure it, such as 1/4 mile for drag racing and 35,000 feet for airliners.
Temperature? Who needs to convert temperature?
Now, when you’re doing science and engineering, you do all sorts of conversions, and use one measurement to develop others, so metric has a distinct advantage.
I had to help an American who was taking a chemistry course in college and had never learned SI – he really had never learned anything, not even the really common prefixes like centi- and milli-. I don’t know why they don’t at least teach the basics of SI earlier, because it’s really very necessary to do anything technical.
One of the greatest strengths of SI (aside from the fact that multiplying by 10 is easier than multiplying by 16 or 32) is the way the SI units work in physics and other technical fields. A newton is a kilogram-meter-per-second. A joule is a newton-meter, a watt is a joule-second. Many SI units can be written out in terms of fundamental units, which makes it possible to treat the units as mathematical operators. For example, if you multiply a quantity of newtons (kg·m·s[sup]-1[/sup]) by a quantity of meters, you get a result in joules (kg·m[sup]2[/sup]·s[sup]-1[/sup]. This makes it much easier to understand how force, energy and work are related. SI is also better-suited to scientific notation and makes the physical constants make more sense.
Unfortunately that has no bearing on everyday life. For the kinds of things you encounter daily, SI only offers some minimal advantages (making it easier to work with weights and lengths, for example). But it’s not all that difficult to add up 2 lbs 6 oz and 1 lb 4 oz, just as it wasn’t that difficult for the British, pre-decimalization, to add pounds, shillings and pence in their heads. So, while I use SI for everything technical and always have (and so does everyone else – try doing chemistry in drams, grains and minims and see how far you get), I still use the old system for everyday things.
I give estimated distances and heights in feet and inches and measured distances in meters. (Never yards; if something is appropriate to measure in yards, I’ll use meters.) The weather is in degrees Celsius; my oven (and only my oven) is in degrees Fahrenheit. Weights are in grams or kilograms if I know them; estimates are ‘half a pound’, ‘ten pounds’, but ‘a few grams’. Liquids are almost always in liters and milliliters unless I’m cooking, when I use cups. Long distances are always in kilometers and speeds always in km/h, but I still use ‘mile’ as an indeterminate long distance. These are probably fairly typical usages for Canadians. Things that have been totally changed to metric (road signs, weather forecasts, food packaging, etc.) are SI, and the rest is still Imperial (people’s heights and weights, estimated measurements). Proximity to the US makes SI units less common, and French Canadians use more SI units.
But where does “science and engineering” stop and “day to day life” begin? Are carpenters, plubmers and hobbyists “engineers”? What about weekend home improvement projects? And why should Americans handycap their children by having them grow up in Imperial, but convert to a different unit as soon as they start learning science and engineering?
Besides, it’s already pointed out that decimal system leads to easier calculations than the base-12 system. It’s evidenced by the fact that every country in the world has switched to a decimal currency system (that I know of, at least).
That’s as meaningless as saying “40C is uncomfortably hot. 104F is pretty vague for all its apparent precision.”
Only because you’re not used to the Celcius scale. To me, 32F understates how cold it is.
Look, you guys are all paying extra for keeping SI and “English” units both in use in the United States.
Scientists are smart and can memorize things. I remember that PI is 3.14159265358979323846, but do you have any idea how many conversions you have to remember to do, say, convective heat transfer calculations in both systems? I AM a scientist, and it is huge pain in the ass. Every layer of complexity you add to a problem is one more thing to manage, one more opportunity for errors. Remember the planetary probe that crashed because one of the speeds was in knots and the conversion was missed? It doesn’t mean NASA can’t convert knots, it means multiple unit systems are truly burdensome.
Furthermore, I have two sets of wrenches in my toolbox, there are two sets of nuts and bolts in the shop, two racks of raw materials (metal rod and so forth), and I don’t know anybody who can eyeball the difference between a 7/16" hex and an 11 mm hex, but if it’s an expensive fitting with tight tolerances, the 11 mm wrench will be really really really hard to fit over the 7/16" nut. It’s not that any of these items is insurmountable - the problem is that every one of them keeps dragging down all the things we have to do, and the total cost of all of that is just enormous!
Moreover, the US is still such an economic and engineering force that to some degree we are practically forcing some of this burden on much of the rest of the world, so the harm goes beyond what we ourselves experience.
In 1215, in the Magna Carta, King John decreed “Let there be one measure of wine throughout our whole realm; and one measure of ale; and one measure of corn, to wit, ‘the London quarter’; and one width of cloth, to wit, to ells within the salvages; of weights also let it be as of measures.” It’s almost 800 years later and we still don’t have it worked out. I have a reputation amongst my colleagues of being quite good at mental calculation, and I just hate having to add this stupid burden to all the other things, many of them clearly more inventive and constructive, that need doing!
Same here, though I’ve lived in Montreal my whole life. Right around second or third grade, our older imperial math textbooks were being replaced.
I tend toward metric distances between places (my car’s speedometer and odometer are in kilometers) but feet-and-inches for home renovations. Pounds for significant weights, grams for smaller weights, metric for liquid measure… overall which measuring system I end up using depends on the measuring tools I’ll be using. I don’t need Metric’s ease of calculation that often, but it sure came in handy when I tried to figure out how much a filled aquarium was going to weigh. Just measure the dimensions in centimeters and figure one gram per cc.
I have an idea of what a liquid ounce is, from seeing a shot glass, but a gallon? Dunno.
It’s a very small garden. Watch the weather on the 6 o’clock news, see that frost is predicted, grab the two or three house plants still in the garden where they have been catching the late autumn sun, light greenhouse heater.
I just find the SI metric system so much more relationally intuitive and rational. Basically, all the units you need to use can be built out of other units, if they are not related somehow to natural constants. A second? The amount of time it takes radiation from a caesium 133 atom making a particular energy transition to oscillate 9 192 631 770 times. A meter? The distance light travels in 1/299 792 458th of a second. A gram? The amount of mass in one cubic centimeter (1/100th of a meter) of H2O. A newton? 1 kilogram (1000 grams) meter per second[sup]2[/sup]. A joule? 1 newton meter. There: I went from units defined by properties of electromagnetic energy up through several units built from those units to a unit I can use to measure the work I can do, a.k.a. energy.
It doesn’t hurt that I can do all kinds of easy conversions with these using straighforward dimensional analysis, in decimal, which is quite familiar and comfortable given the ubiquity of base-ten counting (whether I use metric or not).
Technically there’s SI, from which both CGS and MKS are based. Astronomers for example use CGS normally, while many physicists (or at least physics teachers) use MKS. It’s an irritating complication to work around, but fortunately all the conversion factors between the two systems are just powers of ten.
And, I would argue that a “good” physics equation doesn’t depend on any particular units at all. Maxwell’s equations don’t, unless you pre-expand the constants into numerical unit-dependent forms — which is a no-no. Certainly these equations are most conveniently evaluated in metric, not imperial, but if you’re careful you should get physically equivalent results.
(Come to think of it though, I’m not even sure the imperial system has all the necessary units to do physics. For example, is there an imperial unit for magnetic field strength?)
And hey, I just though of another realm where metric dominates, even in America: electrical circuits. Volts, ohms, and amperes are all SI units, and they are the universal convention here. So are watts, for rating power consumption.
