The metric thread

[DanTheMan414]

Big metric fan here.  Of course, being in engineering, it'd be easier doing calculations if we used metric across the board.

Speaking of metric, I saw some Everett Turnpike photos from New Hampshire from earlier this year showing advance exit signs in both miles & kilometers.  These signs looked like they weren't too old, but I'm wondering if these were erected at a previous time, and are just waiting to be replaced with signs showing only miles.  I was curious if anyone had background on these signs.

[Mr. Matté]

Big metric fan here.  Of course, being in engineering, it'd be easier doing calculations if we used metric across the board.

Same here, although I know how stupid the average American is so I know they would not want to switch to that damned socialist measurement system.  I would be fine keeping the current units although I wish in our system, mass would be easier to figure out (it's always kilograms in metric but when we use it here, it's weight and you have to divide the weight by 32.174 ft/s^2 to get actual mass).

[agentsteel53]

Same here, although I know how stupid the average American is so I know they would not want to switch to that damned socialist measurement system.  I would be fine keeping the current units although I wish in our system, mass would be easier to figure out (it's always kilograms in metric but when we use it here, it's weight and you have to divide the weight by 32.174 ft/s^2 to get actual mass).

I tend to remain under generally constant gravity, so I'm okay with using a unit of weight

[vdeane]

For ordinary people, weight and mass would be interchangeable.  Most people don't even know the difference (or that the kg and lbs aren't actually equivalent units).

[agentsteel53]

For ordinary people, weight and mass would be interchangeable.  Most people don't even know the difference (or that the kg and lbs aren't actually equivalent units).

and non-ordinary people use metric approximately 100% of the time! 

(in my physics class, we noted that it is actually correct to say that "on the moon, Neil Armstrong weighed 30 pounds" - and then we did the actual rocket science in metric!)

[Duke87]

To clarify something which confuses a lot of people:

The US does not, and never has, used the Imperial system of measures. What we use was formerly known as and is often still called "English Units", but is now properly known as "US Customary Units".

The major difference is the definition of the gallon. One US gallon is exactly 231 cubic inches (just because that's a nice round number). One Imperial Gallon is the volume occupied by 10 (avoirdupois) pounds of water under standard conditions. The difference is not exactly but very nearly a 6:5 ratio (that is, 6 US gallons = 5 imperial gallons). Of course this also means quarts, pints, cups, etc. differ, too.
It also means that when someone from Europe reports a value in gallons (I see this a lot discussing fuel economy and MPG), often it will be in imperial gallons... and most people won't be aware that there's a difference.


True, the US customary measures aren't exactly intuitive.
3 teaspoons in a tablespoon, 2 tablespoons in a fluid ounce, 8 ounces in a cup, 2 cups in a pint, 2 pints in a quart, 4 quarts in a gallon... number of gallons in a barrel depends on what it's a barrel of (for crude oil, it's 55).
And if you think that's bad, look at your typical measurements of reservoir/lake capacity. Likely reported in acre-feet (1 acre-foot = 43560 cubic feet, same as the number of square feet in an acre).
Metric, which uses nothing but multiple of 10 (well, ideally, multiples of 1000; use of centi-, deci-, deka-, and hecto- is frowned upon in scientific applications) is most certainly simpler.

My key issue with using "metric" is that no country has actually yet done it properly. Post your speed limits in meters per second and record the temperature in Kelvins and then we'll talk.

[vdeane]

Metric doesn't mean that you have to use SI units.

[english si]

given it would cost mega-bucks in terms of re-education, changing machines, signage, labelling and so on and so forth, I reckon that the economic benefits would almost be cancelled out.

In the US, I suspect more people know the customary units, rather than the metric ones (especially when it comes to estimation - a unit that has evolved to be the right size for the job it's for is better than a completely artificial and arbitrary one for remembering and guessing how big it is).

We have these discussions rather often in the UK, where almost everything is officially in metric (even if pseudo-imperial). I think the best response I've heard is "If metric is so much better, how come imperial units have to be suppressed by law for people to not use them instead". People in the UK are varied - some can't use imperial, whereas others can use both systems but use a variety of different units or just one set, and finally there are people who can't use metric.

Given that I was schooled, almost entirely, in metric, the indoctrination failed: heights and weights of people need to be in feet and inches or pounds and stone for me to make sense of them - I convert cm/kg to the imperial units roughly in my head so I can get more manageable numbers - we can't easily visualise numbers more than 12 - perhaps 20 at a push - if we used decimetres and 10^4g (KILOgram being the base unit is very strange) - you could call such a thing as a myriagram, but no one would have a clue what that means - then the numbers would be better, but no one does. I can use metric for these things, but I'm much more comfortable in imperial.

I use a hybrid of units - metric for science, engineering, (maths is easier) and stuff which I'm unable to visualise anyway (very big, very small). Stuff on a more human scale uses imperial. I'm easy whether miles or km are used - they are in a no mans land.

As for the crazy irregular multiples, you don't use more than one of them at a time, and that's in the rare case of you using more than one unit - human height is one of the few, rare, exceptions (and human weight in the UK, where we make the 1stone = 14lbs conversion, so as to get more human numbers - under 20).

Also, I've got to love the pseudo- or neo-customary measures: light years, AUs, ångströms, plank lengths, electron charges, earth radii, kiloWatt-hours. Even hard-core metric fields like physics, energy generation, chemistry and so on aren't fully metric - whatever country you are in. Metric time was tried by revolutionary France and was rejected as a step too far, so we use things like days, weeks, years, hours, minutes (none of which are SI, and have varying conversion rates - just like all other customary units, though we even use several different units at the same time and have no problem - look at my post in a few days, and there'll be an example of it at the top of my post).

[algorerhythms]

One advantage of the majority of the world switching to the metric system is that there is less ambiguity in units when there are fewer customary unit systems. Before the advent of the metric system, there was little to no standardization in units, so a "foot" was different in different places. Of course, now that there are only two systems remaining, most of the ambiguity is gone; an inch is 25.4 millimeters, as only one definition of the inch remains in common use.