There are places like on product labels where both units should be mandatory. Hopefully in a few generations people will gradually switch over.
It is, but it can be done in just one generation. The generation that is raised metric finds it even harder to think in imperial measurements, since the imperial measuring system is significantly more complex. Source: I grew up in a fully metric country.
I just looked it up, apparently the conversion to metric happened around the time that I was born. I had no idea, I thought that it was a decade or two before that.
i.e. if the USA had tried a bit harder in 1975, they would be done now.
Also, the UK is not "fully metric". If it was, there would not be road signs showing numbers in miles and miles per hour. You can't stop people from buying beer by the 568ml, but if the UK was serious about metric, official communications and education would be all in metric.
But after more than a decade I still find myself converting back to the old currency in my head from time to time. Only to remind myself that inflation has made that exercise pointless. The older generation has trouble with it, though.
It can be done; it just takes the determination to just do it.
The resistance seems to be largely: (a) older people who doubt their own ability to adjust (b) right-wingers who are convinced it's a socialist conspiracy or somesuch (these are people who think international cooperation is taking sovereignty from the US, or something like that - they're a bit incoherent) and (c) politicians perceive it as unpopular and risky to advocate (presumably because of a and b) or just not a vote-getter.
I've occasionally tried to promote SI by using units in casual contexts, but it's perceived as pretentious or obnoxious. The situation is better online as I participate only in fora like this where US obtuseness is not necessarily expected. It is hard to even find products like thermometers and measuring cups (for cooking) with all-SI.
We did fine! Even my grandma got accustomed quickly. Of course one could argue that is precisely because of the importance of a currency that we adapted so quickly...
Yes, it's difficult to make people think about it. At the same time, sometimes the units "don't matter" (like speed limits, 50 is 50 in the speedometer, just make sure you're not looking at the mph scale)
I want to slap somebody when I hear about "pounds" or "feet/sq ft", or even worse, Fahrenheit (since this is a non-linear transform)
At least everything in the supermarket is marked per pound and kilo
huh?
1. F(c1 + c2) = F(c1) + F(c2)
2. F(k*c1) = k*F(c1)
F(c) = 9/5 * c + 32
F(c1 + c2) = 9/5 * (c1 + c2) + 32
F(c1) + F(c2) = (9/5 * c1 + 32) + (9/5 * c2 + 32) = 9/5 * (c1 + c2) + 64
F(k*c1) = 9/5 * (k*c1) + 32
k*F(c1) = k * (9/5 * c1 + 32) = 9/5 * (k*c1) + k*32
Because it's harder to calculate mentally
One can approximate 2lb to 1kg roughly, 1mi ~ 1.6km, but for Fahrenheit this is harder
One solution is to establish a set point ( 70F = 21.1C, approximate to 20C ) then work in differences, since 1.8deltaF = 1deltaC so, 2dF ~ 1dC (or 10dF ~ 5dC)
Hence, 90F is approximately 30C (exact value, 32.2C)
I would think this would be called linear, but that mean something more specific?
For example, yards to meters is a linear transform. 3 yards converted to meters + 2 yards converted to meters = 5 yards converted to meters. This is not true of temperature. Adding 32F to 32F gives 64F, which is not the same as adding 0C to 0C.
Unfortunately, my brain won't fully switch over because everything else in my life is 12-hour time. Having both means I can't help but stick to the old way. When my computer clock says 17, I know people will start leaving the office. But, when it says 19, I don't think of supper. Supper is when my kitchen clock says 7.
Having a short adjustment period would be good, but at some point you just have to commit. Generations is too long in my opinion.
In Australia we use 12 hour am/pm almost all the time, even on official documents. We've been metric since the early 70's. I still have to pause and convert when I see a time greater than 12 (or, sadly, less than 1.)
It seems much more a cultural thing, that one.
Now if we could only stop anybody using m/d/y date formats...
I think of beer in pints, wine in ml, driving distance in miles, walking distance in km, height in feet and inches, but weight in kg. Lengths are in m/cm/mm as are weights and volumes for cooking. Mountains in Scotland in feet and mountains in the Alps in metres...
Oddly, my teenage son uses m/cm for height and stones/pounds for weight...
I agree. But for science and engineering (where metric is really useful), I believe that everything is metric here now.
The measures for which we still use Imperial units are ones that generally are just directly and subjectively compared by humans, rather than any real engineering work.
Another way of making my claim is that nobody really has to input Imperial measures into a calculator any more, or make any conversions [involving non-metric units] for engineering purposes.
I suppose there are some exceptions (eg. BMI), but these calculations are generally isolated and have no wider unit-incompatibility impact.