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International System of Units overhauled in historic vote (npl.co.uk)
834 points by daegloe 26 days ago | hide | past | web | favorite | 576 comments



See, the US wasn't being stubborn in not adopting metric, it was just waiting patiently for it to progress from beta to 1.0. :)

(Fun fact: all the US customary units have been officially defined in terms of their metric counterparts since 1893: https://www.nist.gov/sites/default/files/documents/pml/wmd/m...)


I'm one of the weird people that actually really likes imperial units. For instance:

1 foot -- base 12. This is a superior base to 10. It can be easily divided into 4ths, 3rd, and 2nds. Base 10 can only easily be divided into 2nds.

1 inch -- an easily identifiable unit of measure for smallish things. About the width of my thumb. A pretty good unit.

For low precision, inches become 1/2, 1/4, 1/8, 1/6, 1/64, etc. Each one is half the size of the previous one. I actually like this one a lot. An eight being half of a quarter is a really easy way to work with things when you're building stuff. Think about drilling a bolt hole in the center of a piece (half the width), or drilling two bolt holes with something in the center (divide those halves in half again) etc. Fractional is really good for building stuff.

For precision: thousands of an inch. Harder to visualize, but precise (has the same problems as mm imho). Millionths of an inch when you get into serious metrology.

Okay temperature: In imperial units:

0 = REALLY cold. 100 = REALLY hot. 50 = somewhere in the middle. Put on a sweater, but not dangerous.

100 = about the temperature of a human body.

Water boils at 212F and freezes at 32F. There are 180 degrees (degrees!) between freezing and boiling. 180 is, again, base 12. It's the 15th order of 12.

I actually love imperial units. I greatly prefer them to metric (even though I do use metric very frequently, and can see the appeal). I think I just actually prefer base 12 to base 10.

I also think that F is seriously superior to C.


You're right - imperial is far superior for precise building or manufacturing work.

Take drill bits, for example. Obviously it's much easier to figure out that 11/32" is less than 3/8". Or is it more? No, I'm pretty sure I was right the first time. The metric ones with their 5.5mm, 6mm, 6.5mm sequencing are just too complicated to work with, in comparison. And half a millimeter isn't very precise - it's much bigger than 1/64". Well, a bit bigger. Let's not get into tenths of millimeters.

And at larger scales, of course, base 12 is much easier when it comes to dividing distances. Taking a distance of 2'7" and dividing it by three in your head is much easier than dividing 79cm by three, because... well, 2' divided by three is 8", obviously. If you need to be sure, just tap it into a calculator. That supports base 12...

Anyway, you'll quickly determine that it's 10 1/3", which is much more precise than 26.3333cm. Now I just need to subtract the radii of these two 5/16" holes from that, which is easy - imagine trying to subtract 8mm from 26.3333cm! What folly.


Do I detect sarcasm here? I'm pretty sure I detect sarcasm here.


I detect 1.23 furlongs of sarcasm.


Much of the sarcasm targets the mixing of multiple units that is everpresent in imperial measurements. Feet + inches instead of one or the other?


Whether decimals or fractions are used is not necessarily related to metric vs. customary units.

I just weighed myself on my bathroom scale -- 191.2 pounds.


People use "stones" for weight of humans. As if 14 pounds is a convenient amount.


These are problems you actually pretty much never have in actual precision manufacturing in metric... Most general machining is done to a tolerance of +/- 0.1 - what does half a millimetre have to do with anything?

As for building, that's mostly just rounded to the millimetre, centimetres aren't usually ever used.


The gp was being sarcastic.


I understand, that you know the metric system, and, judging by your reasoning for your love for the imperial system, I understand, that you know what you are talking about (better than me). So, please, do not understand my comment as wanting to advise you! It's just, that I found this (on the web, one day) to express so much the way I (having grown up with the metric system) feel about it:

"In metric, one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade -- which is 1 percent of the difference between its freezing point and its boiling point. An amount of hydrogen weighing the same amount has exactly one mole of atoms in it. Whereas in the American system, the answer to 'How much energy does it take to boil a room-temperature gallon of water?' is 'Go fuck yourself', because you can't directly relate any of those quantities."

From: "Wild Thing" by [Josh Bazell](https://en.wikipedia.org/wiki/Josh_Bazell).


Actually, assuming room temperature is 60° and you’re at sea level, it’d take 1,216 BTUs to bring a gallon of water to a boil. A BTU is the amount of heat (which is energy) required to heat one pound of water one Fahrenheit degree; a pound of water is a pint; there are 8 pints in a gallon (2 pints in a quart, 2 quarts in a pottle, 2 pottles in a gallon). So, 8 * (212-60) = 1,216.


1 US liquid pint is defined as the volume of 1.041 lb of water at 62F. The British imperial system is a bit cleaner where 1 imperial pint is defined as 20 oz or 1.25 lbs, at 62F.


"A pint's a pound the world around." I never knew whether that came from the fact that both are 16 ounces or because a pint of water weighs a pound (approximately). I prefer to think it's the latter. Makes it so I can remember that a gallon of water is approximately 8 pounds. 5 gallon pail mostly full, probably 35 pounds. Nice.


Except it's not, as a pint is 20 fl.oz, while a pound is only 16 oz.

UK resident here, in case you couldn't tell :).


You know what is worse than either metric or imperial?

Having both in use simultaneously like we have in Canada, where we work with lots of things manufactured in the US or in Canada for export to the US.

So any technician will have to have both metric and imperial tools, occasionally things of very similar size will get interchanged accidentally - using a 3/4" socket on a 19mm bolt for instance, which will work for a while but eventually round off the head because 3/4" is slightly more than 19mm.


I think we can all agree that mixing systems of measurements is the worst possible thing you can do with measurements. Just ask NASA...

(Look up what happened to the Mars climate orbiter)


And least I forget, because nobody mentioned it, yet, what about the beauty of the DIN A papersize? It has been adopted as an ISO, even! Where everything is simply a half of the previous size.


I suspect that only a minority of people in metric-using countries -- those with basic chemistry knowledge fresh in their mind -- know that "one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade".

Probably a similar number of Americans know the same facts. And any of them would answer "How much energy does it take to boil a room-temperature gallon of water" in the only sensible way -- look up the conversion of gallons to liters, do the calculation in metric, and convert back from calories to whatever unit you want (BTUs, I guess).

The point is: nobody, including Americans, uses the customary system in chemistry labs. Nobody ever has cause to calculate how many BTUs it takes to boil a gallon of water without reference to the metric system. So the argument is a bit specious.


> I suspect that only a minority of people in metric-using countries -- those with basic chemistry knowledge fresh in their mind -- know that

This is not the case. This part: "one milliliter of water occupies one cubic centimeter, weighs one gram" is known by most people, even kids in primary school. In other words everyone knows that a litre of water weighs one kilogram, and that there are 1000 litres in a square metre. I concede, though, that at least in Italy, which is the country where I was born and raised, most people wouldn't know the next part: "and requires one calorie of energy to heat up by one degree centigrade".


"Everyone knows there are 1000 litres in a square metre"

;)


Ooops :-(


You probably meant cubic metre?


Ouch, yes I did


It's common knowledge here; in the UK I was taught it in two classes at school: Science and Cooking.

We are taught to use the scales for measuring ingredients - and thanks to this trick you can weigh water (and milk) and vegetable oil (using 5-10% less) if you don't have a measuring jug.


> I suspect that only a minority of people in metric-using countries -- those with basic chemistry knowledge fresh in their mind -- know that "one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade".

They taught us that in 4th grade in cooking classes. Then they made us remember that in physics and chemistry classes 2 years later.


There are plenty of things that everyone learns in 4th grade that not everyone remembers.


The point is that this particular concept of metric units is taught really well (repeatedly on many practical examples and then evwn theoretical ones) and so virtually everyone knows and uses it. It's deeply ingrained in cooking books, recipes, etc.

Of course I don't remember a lot of things from the 4th grade. This one stands out.


>I suspect that only a minority of people in metric-using countries -- those with basic chemistry knowledge fresh in their mind -- know that "one milliliter of water occupies one cubic centimeter, weighs one gram, and requires one calorie of energy to heat up by one degree centigrade".

I wouldn’t be so certain about that. I’ve used that to conceptualize volumes and weights ever since I first learned that in school.


You comment on HN threads about measurement systems. You are not normal. None of us here are.


Nice point, but it is really the typical elementary school topic "one cubic centimeter of water is one gram, one cubic decimeter is one kilograms, one cubic meter is one THOUSAND!!! kilograms" Then in highschool it is used for physics and unit of measurements and everyone knows that you can just weight milk and water when you cook with 1kg = 1liter


Normal people don’t do that. They just know that a gallon is a gallon, a meter is a meter, a pound is a pound, etc. People rarely have need to convert between mass and volume. And they don’t weigh their milk or water.


Because if they had to, they'd rather find a jug than a calculator.


Also most people (in the US at least) do not have kitchen scales!


We study it in high school.


Hmm, good for usage you say. Ok, let's stick to "standard" imperial units. How many feet in a yard? Yards in a mile? What the hell is a quart? And since base 12 is great, what is 12 feet called? 144 feet? A 12th of an inch?

Or, ounces: How many ounces in a gallon? A pound? And how many _kinds_ of ounces are there, anyways?

Fun fact: The term “ounce” is of Latin origin from the word “uncia” which means “a twelfth part.” http://www.differencebetween.net/science/mathematics-statist... So...what's an ounce a twelfth of?

Or, say, a pint. What's the definition of a pint?


> So...what's an ounce a twelfth of?

It's a twelfth of a troy pound, or Roman libra (lb).

These two episodes from The History of English podcast trace these seemingly arbitrary units through history and give them some context. My favorite is the derivation of 5280 feet per mile. Also, that "mark twain" is a depth sounding of two fathoms.

http://historyofenglishpodcast.com/2018/07/26/episode-114-th... http://historyofenglishpodcast.com/2018/08/21/episode-115-th...


A pint is what British people drink in pubs while chastising the US for not adopting the metric system.


And then complain about gaining a stone?


568ml, as god intended. Not some 450ml abomination!

We don't really use pints for measuring anything else these days.


If only US pints were a 450ml abomination.

That's about 50ml more than I'm used to getting when I order a "pint".


You are benefitting from the true Imperial pint where there is 4546 mL per gallon.

And of course 4 quarts to the gallon and two pints to the quart.

Otherwise like in the US in what is commonly known as the English system there is only 3785 mL to the gallon.


The metric pint?


When they pour 500 mL into your 1 pint (473 mL) glass.


A yard is three feet, or about the length of a man's stride.

A quart is about the maximum amount of whiskey one can drink without dying.

A pint's a pound, the world around.

My favorite is the cord, which is 128 cubic feet, or more often a stack of firewood 4 feet tall by four feet wide by eight feet long.


A pint is a pound so long as you're in the US. Everywhere else, it's 20 fl.oz, while a pound is 16 oz.


The cord is also the size of the standard US pickup truck bed with the wood stacked up about cab height.


A yard is not just a measure of length, but of volume and in a manner, constitution if you will, as it is also 2 1/2 pints[1], good sir or ma'am. Oy!

1. https://en.wikipedia.org/wiki/Yard_of_ale


Between that and the GP, we could establish a conversion between yards and quarts.


You are definitely (and thankfully) not the norm. Imperial units are awful. They're more ... human, maybe, in that a foot is about one human foot long, and that an inch is about one human thumb width, and how 0F feels "pretty cold" and 100F feels "pretty hot", and to me the charm of imperial units begins and ends right there.

Those are literally the only redeemable qualities about imperial units, and they have nothing at all to do with their utility as a tool for measurement.

I am glad that you like them. Use them all you like. I won't.


>They're more ... human, maybe, in that a foot is about one human foot long, and that an inch is about one human thumb width, and how 0F feels "pretty cold" and 100F feels "pretty hot", and to me the charm of imperial units begins and ends right there.

As far as we know, humans are the only thing in the universe that care about any of this stuff. A computer couldn't care less if you are using 1 foot or 0.3048 meters.

Why not optimize for humans, the things actually using these things? Optimizing for the computer just seems...silly. It seems like something somebody from the 1970s would have thought was a futuristic idea.


Because adding 7/16ths of an inch to 7/8ths of a mile and getting an answer in inches isn't easy for a human. Adding 1cm to 982m and getting an answer in centimeters is dead easy for a human.

THAT'S why human intuition about measurement doesn't mean a damn thing.

Using metric means using the system optimized for humans. Period.


Your absolutism is a bit silly. I don't think the Imperial system is good for anything beyond construction or cooking, but there's a reason it excels those areas. And it's exactly because it's more usable by humans in certain contexts (like construction or cooking). 1/3 of a meter should not be an irrational number - how is that "optimized for humans"?

A scalable system that shares the divisibility of the foot would certainly trump both systems.


It is appalling for cooking. Don't get me started on the shitshow of using "cups" to measure weight.


If you want to measure ⅓ metre, go ahead. Nothing stops you from doing that.

The usual convention in construction in Europe is multiples of 150mm, for example a typical large appliance is 595mm wide to fit a 600mm wide space.


Nit: 1/3 of a meter is rational. You're looking for "whole number."


Correct - I've admittedly had a few beers.

Which might be obvious due to me debating the merits of the number 12 on the internet.


Well 12 is amazing, but arguably there are too many other negative aspects in the imperial system as a whole.


But 1/2 isn't a whole number either.

Base-10 absolutism rears its head again. The objection to 1/3 is that it has a non-terminating decimal expansion. This is not a problem if you're using base-anything-with-3-as-a-factor.


What about 1/5 instead? There's always going to be problems with some base, the point is that unit conversions are super easy with metric, and it's easier to teach to children.

As for temperature, 0 is really gold and 100 is really hot in pretty much every scale, that's just a very subjective way of describing things.


The imperial system is not good for construction. Try measuring a 2x4 sometime.

It's just an established convention. And it sucks.


A 2x4 is cut to 2" by 4" wet and shrinks when it is dried. I'm no huge fan, but this is not an issue with the imperial system.


Uh, no. The final 2x4 product is milled mostly dry. Mills allow the timber to air dry, then mill, then post-kiln, and may mill the final product after that e.g. by cutting 2x4s out of a 12x4. The reduction of a 2x4 from 2x4" to 1.75x3.5" is done on purpose, because modern mills can put guarantees on the density of knots in the wood, thus requiring less wood for the same engineered strength guarantee. So the 2x4" product is not actually 2x4 because the mill is asserting that while there is less wood than just cutting a 2x4, the board they're selling is as strong as a 2x4 would have been at the turn of the 20th century, when they didn't have a way to guarantee the density of knots.


The imperial system is terrible for cooking, in my experience as a home cook and baker.

Measuring dry goods by volume instead of by weight? Good luck ever getting consistent results.

Base 10 math is the most intuitive for humans. Fractions are an abomination.


Math isn't intuitive for humans. It takes a lot of work to learn it and most people don't remember any of it past school age. If we taught base 12 instead of 10 it would be just as intuitive.


But we don't. The number system used in the western world is base 10. So why add base 12 on top of that?


1/3 of a metre is 333mm, which is generally precise enough for construction.


How is the system good for cooking? Literally the first thing amazon echo was showcasing was unit conversions while cooking.


In what situation would you be adding 7/16ths of an inch to 7/8 of a mile? If you have such crazy tolerances you shouldn't be using fractions from the start. And even if you did, with imperial system you could just write '7/8 mile and 7/16th of an inch' or '7/8 mi. 7/16 " ' and when they measure it out they will measure 7/8 of a mile, then add on that 7/16 inch.

And whatever you are measuring that length with, fucking awesome job getting 1/16 or better tolerances over that amount of distance with .


Do people in metric-using countries commonly need to know what 982m + 1cm is? It never seems to come up here in the US...


Perhaps not, but nonetheless I instantly worked it out in my head without even trying.


These units are terrible for humans too.

Humans are good at base 10.

For this human, the relationships when (for instance) talking about water are great -

1g = 1ml = 1cm^3


Humans are naturally bad at base 10. This is noticeable when learning counting and arithmetic - children often skip 7 and jumble 6, 7, 8. Base-10 is not so bad once one has learned it, though.

Humans are really good at doubling and halving, which the Imperial system excels at.


That's false, the Imperial system is pretty bad at doubling or halving.

What's double of 3.7 feet? Or half of 1.5? What is 3.7 feet even? Is it 3 feet 7 inches or 3 feet plus 7th of a feet (This last question is a nitpick)

Any of these in metric are super simple, but just harder to do in base-12.


And I would add, it is not immediate to go from 200 inch to 18 feet 2 inches


In practice, as the previous poster pointed out, Imperial numbers are rational, not real. You wouldn’t normally experience ‘3.7’ feet.

Don’t get me wrong, I’m certainly not a proponent of the Imperial system (for instance, calculating prices for groceries is painful). I am just pointing out that the metric system doesn’t take into account many Human use cases (Base-10 isn’t great for Humans). It was a system forced upon people by an ‘ivory tower’, and consistent with US philosophy, it makes sense that they rejected it.


Americans are pretty awesome.


The imperial system is not even in a consistent base!


I should add to the discussion somewhere that when I write code (or even do calculations) that deals with Imperial units, I just use the SI prefixes and end up with things like centifeet and kiloinches (miles are banished forever). It makes the code a lot easier and the people who are used to Imperial can tell what you're going on about.


Also, the statement that metric is more useful for measurement largely ignores the fact that Imperial has stuck around so long because of its usefulness in trade work.

It's definitely ONLY because of base12, but being base12 - imo - positions it far beyond metric for daily use. There's a reason why food items so commonly come by the dozen. Why would anyone prefer to build a house using a system that can't even accurately measure 1/3?


1/3 can easily be measured in metric... it's just not a whole number.

Far out I can invent a system that is unique to everything, and I can create my own abominable conversion ratios all I like. It doesn't make the system superior, it makes my system necessarily inferior.

My TV is now 12 Settos in size. My surround system consumes 12 audots of power. My fridge holds 12 cubic fudo of room.

There. Now everything is easily divisible by 12ths.

I won't even go into conversion factors on this insanity.

Metric is objectively the better system to anyone that doesn't have a decades-long familiarity with the stupidity that is the imperial system. That's coming from an american without a college education, by the way. I am the target demographic for the pro-imperial people. I wasn't abducted into any metric-only education system and forced to convert or fail and disappoint my family. I was a disappointment by my own hand, thank you very much.


I challenge you to make a 1/3 cut in meter length wood using a metric ruler. Must be accurate to 1/128 inch (0.2mm), the tolerance used in fine woodworking.


Not only is it trivial to just cut at 33.33 or what have you, your argument breaks down at cut it into 1/5s.

Good luck with imperial. And has to be accurate to .02mm. In metric? This is a no brainer


That doesn't really hurt the argument at all - you're just arguing about factors now, and if you're really going to go there, 12 wins due to having more factors. The mathematical correction you'll have to do to measure 1/5th will be displaced by all the correction you don't have to do for other cases.


You're bent on the whole number thing. Why?

Whole numbers don't make things easier to measure or cut or reason about. I can measure in thirds or fifths of a meter or a foot or an inch or any unit you want with a compass and a straight edge.

You're arguing that the mark on the tape measure is possible for imperial and impossible for metric, when thirds are involved. Not true.


Because infinite numbers are not a natural expression of discrete measurements, and when it comes to being price 1/3 = 4 is always going to be easier to put your finger on than 1/3 = 3.333.

I work in software and data analysis in the construction industry. A continuous measurement is good for some things, but it's definitely not good for discrete measurements. Furthermore, a lot of the people who work in the field for construction greatly prefer Imperial for a reason. They have no bias towards systems beyond what works fast and easy.


I work a lot with wood in the metric system and the third thing is bot a problem at all. I never had even remotly any trouble finding 333.33 mm or a 666.66 on a tape measure. For anything that needs extreme accurcay I’d go with my iron ruler with 0.1 mm ruling and beyond that I would go for a caliper.

If you consistently have to use a weird measurement over and over again, you usually end up making a temporary ruler (paper, wood, metal) anyways


What is stopping people from making meter sticks with 3000 lines, i.e. every third of a millimeter is marked?

(The point is, there is nothing any more "infinite" about the rational number 1/3 than 1/4, 1/5, 1/2 or what have you. It just can't be written in the arbitrary base 10 system, just like 1/5 can't be written in base 12)


There is nothing stopping you from writing 1/3 meter.


> and when it comes to being price 1/3 = 4 is always going to be easier to put your finger on than 1/3 = 3.333.

Am I missing something? Wouldn’t it just be putting your finger on the 10 cm mark? This is approx 4”.

I realize this is not exact conversion, but it’s trivial to come up with examples where metric is easier: say you have a piece of wood 7 7/8” long that you want to cut in half. Is it easier to put your finger on 3 15/16” or 10 cm?


"price" is an autocorrection of "precise"


The factor argument is not really something that stands up, because you need to consider factors for an arbitrary length of something in the world, not a well defined unit of your own making.

How about 1/3rd of a tree? It's likely to be in some ungodly fractional amount of an inch, that's extremely hard to convert into feet, but in metric the decimal system just makes it super easy.


Can I pick the blade thickness?


Sure, kerf is less important than the thickness of your pencil line in terms of accuracy


Place the center of your line at the correct location.


wasn't going to use a pencil


You're missing the point if you don't see the problem of an infinitely repeating measurement. That doesn't translate to a tangible action. You can't cut 1/3 of a meter, and there's no subunit to roll down to that can express the right number. It's not like Imperial system exists for uneducated people - it exists for trades people. Metric is the "simple" system, because it ties back to 10, a number we're all used to. I like the metric system for its scalability, but as somebody who works in a math-y area of computing, I have nothing but distaste for base10.


I can cut 1/3 of a meter just as accurately as you can cut 1/3 of a yard.

Not being a whole number does not make it harder to find where it is.


Ha! I'm happy for your apparent virtuosity, but the whole of America's construction industry is quite a few years into disagreeing with you.


So THAT'S why U.S., Liberian and Myanmar architecture is centuries ahead of the rest of the world.

By the way, why isn't your currency base 12? All the purported benefits that apply to length would certainly apply to money as well.


This is just silly. People in most of the world are able to build things just fine without using the American system of units.


Yeah just line it up with that non-existant mark on your measuring stick. Is it enough of a tolerance problem to really worry about? Likely not. But you still can't point to a specific line to measure too unless they have specially added 1/3 marks.


> you still can't point to a specific line to measure too unless they have specially added 1/3 marks.

You also can't point to a line to measure a quarter of an inch, unless they have specifically added 1/4 marks. What's your point?


I have a project where I need 3 wooden blocks, each perfect squares, to fit width wise in a 10” wide gap. I don’t want any space between these blocks sides of the gap they fit in. It’s an important project to me and I’m willing to pay a substantial sum of money.

But from what I am reading it sounds like you’re not able to do the job, the blocks need to be 3 1/3” wide each. It’s a no-go if I see someone try to cut them to 3 5/16”

What kind of system doesn’t let you cut such a fundamental length into thirds. Crazy.


I bet you that if I cut the blocks to 84.7 mm they would do just fine. If they don't, you take a file to one of them. And you have to do it like this with wood, anyway - because of imprecise saws, and moisture changes.


Yeah my point was every measurement system has some value you can’t easily divide into thirds. How you measure depends on your tolerances. I have no qualms using either system, but metric is a much better system in my opinion.


Counterpoint, the us already had undergone industrial revolution and had standardized size on inches. It would have been expensive to restandardize everything


> They're more ... human, maybe

I think both systems of units typical cases are dominated by human factors. Anecdotally, humans tend to use one of three scales for their preferred choice of measurement and they tend to be smaller-than-human, human, larger-than-human.

For example, the km. I see mm, m and km used quite often.. but the other bases are almost never used. A prime case for this is "what is the distance to the sun?" If you're going to round your answer then the most concise form is 150 Gm, yet most people will still say something like "150 million km" which is unnecessarily long and non-canonical, but is much more familiar to the human mind and makes comparisons to everyday experiences much simpler.

You can see this factor occur with just about every other metric base unit, even though the conveniently prefixed part of the system would be "better" for all technical definitions. Just as easily you could use imperial units and just overlay the metric prefix and scaling rules on top of them and it would be no more or less accurate or better than the metric system of units.

> Use them all you like. I won't.

I use whatever is convenient or common for the application.. if it gets complicated or I need a conversion, I use a unit-system aware language or environment to do my calculations. It really obviates the importance of the choice of unit and allows you to think about the fundamental problem more clearly along with many other benefits including conversion of units at any stage of calculation.


> A prime case for this is "what is the distance to the sun?"

I was attending a kids planetarium show as a volunteer and the professor asked this question and a kid proudly shouted “1 AU!”


Nitpick: centimeters are also used often.


In Norway hectograms are frequently used. We use them for things like potato salad at the deli counter, pick'n mix candy, berries and small-time-dealer quantities of hash.


For mass, distance, area, and volume metric has an obvious advantage because for all of those we regularly deal with such a range of values that we want subunits, and basing those subunits on powers of 10 fits in much better with our number system and makes computation and conversion easier.

This lets one make a pretty good argument that metric has advantages sufficient to justify having to buy new rulers and scales.

For temperature, what is the justification for switching from F to C? We don't usually subdivide temperature units, so really all C does different from F is change the size of the degree and what physical process the scale is calibrated to.

One can argue that the physical processes chosen for C calibration are more convenient than those for F. C was 0 == water freezing, 100 == water boiling. F was 0 == temperature of a mixture of water, ice, and ammonium chloride, 100 == body temperature of a healthy man.

But that could have been fixed without changing the scale at all. Just redefine F so that 32 == freezing of water, 212 == boiling of water. That would fix the one problem F had without requiring anyone to get a new thermometer.


> what is the justification for switching from F to C?

The rest of the world already using ℃. Imagine no more dual scale thermometers, no more switches in weather apps, etc :D


Sorry, I guess I was not clear. I didn't mean what would be the justification for switching from F to C now in the US.

I meant what was the justification for adopting C initially for the metric system instead of using F?

For other metric units, there were serious problems with the pre-metric units. For example, Wikipedia says that by the time of the French Revolution, the existing system had become impractical for trade.

It doesn't say why it had become impractical, but my guess would be it had a lot to do with no good standard values for the units. If the units are not well defined in a way that gives the same values everywhere, it makes long distance trade harder.

I base this guess on doing some research once to figure out why they did not defined the meter to make conversion to Imperial easier. Since they were free to define the meter any way they wanted, they could have made 1 meter == 1 yard, which would have made conversions of long distances easier. Or they could have defined the millimeter as 1/25th of an inch, which would have made conversions of short distances easier than the 1/25.4th of an inch that we ended up with.

As far as I was able to determine, this was never an option because, as far as I could find, there was no widespread agreed definition of inches, feet, yards, etc. All that was standard was the relationships among them (1 foot == 12 inches, 3 feet == 1 yard, and so on).

There probably was no way to fix that without adopting a completely new unit, because if they tried to just make a new standard for, say, the yard I'm sure it would have gotten bogged down in arguing over whose yard to base it on. The French would think everyone should adopt their yard, the English would think everyone should adopt theirs, and so on.

So, a new unit, based on something not tied to any one region or nation, makes sense.

Temperature did not suffer from this, or did not suffer from it in a way that was not easily fixable. F was based on a reproducible physical 0 point based on the temperature of a brine with a self-stabilizing temperature. The only problem F had was that there had been some waffling over the other calibration point, which had been fixed well before the first attempts at a metric system.

So...why did they pick C?


What are the redeamable qualities of metric units?


The metric prefixes we know and love are a huge plus. If you convert from Volt to kV or to mV, you just need to move your comma. Ah see what I did there? I uses a metric prefix on a unit that is also used in the US.

The thing is 1V is also 1Nm or 1J or 1Ws. So suddenly we have the meter there right besides the Newton. In fact if you look beyond "I build my own shed in the US"-scenarios, you will find the meter everywhere intertwined in the definition of other units. In fact the definition of imperial length units is based on the metric definition of the length light travels through vacuum in 1/299792458s. So the foundation of the meter is light speed, which helps with all kind of practical issues in physics.

The metric system has maximum compatibility to all these unit systems (except the °C which is a more-practical-for-every-day-use offset version of Kelvin).

Unit systems are always something you grow up with and are therefore an emotional topic. People will take fractions of inches as an example of how metric fractions fail to deliver, when in fact no european woodworker has even remotly a problem with doing their thing in mm. In front of me lies a ruler with a 0.1mm scale and a caliper with 0.01mm or 1/128In accuracyIf I really wanna be ±0.01mm accurate on a cut of 1/3m or 333.33mm getting that accuracy would not be easier in inches. My saw blade is precisely 2mm wide anyways..


V=J/C

V*C = J = Nm = Ws


They're globally standard, decimal, and internally consistent. One never needs to wonder how many meters in a kilometer or how many grams in a kilogram. They have some human usable qualities as well; it's convenient that water freezes at 0°C and that a kilogram of water is also a liter.


a kilogram of water is also a liter

I have never, in around four decades of living, had an actual need to determine the mass of a given volume of water, or the volume of a given mass of water.

When cooking, I routinely need to split some quantity of an ingredient into thirds or quarters.

Yet I am also constantly told that I'm ignorant and backwards and irrational for preferring a system that optimizes for the latter, rather than for the former. Base 12 is genuinely better for many real-world applications than base 10, those applications are more common in the lives of non-scientists than the applications metric is optimized for, and I doubt you're going to be able to produce a rational argument otherwise.


But that's because your recipes are built on the easy divisibility, no? If your recipes are built on weight measurements, suddenly "easy divisibility" brings nothing to the table. If you cook with a kitchen scale, "one ml of water is one gram" is used all the time.


So you never went hiking for a longer period of time or did anything that actually involves carrying water.

I remember when some guys thought about building a pool on the balcony, calculating how much water weighs is admitably not ver often used, but when it is the consistency of the metric system is nice.

I work with wood in mm for years and never had any problem with the metric system. Finding the third, fifth or sixth or whatnot is not hard if you are used to it at all. Converting from mm to meters isn’t hard, etc.

Having a number like 666.66 mm probably sounds scary to measure (beyond the religious connotations), but in fact it is a point on a line that is easy enough to find.


> When cooking, I routinely need to split some quantity of an ingredient into thirds or quarters.

Why?


Recipe feeds six. Making it for two.


Recipe feeds five. Now what?


Never seen it. Have You?


Yes, but I live in a country which uses the metric system.


Makes sense. People respond to the systems they live with.


Are they globally “standard?” China uses Mou to measure land area. A pyeong is used in Korea for housing floor area, the British use pints in the pub and stone when weighing themselves. The US uses feet and pounds. We use clocks that have 60 seconds, 60 minutes, 24 hours, weeks, months. If we want to be consistent, “minutes” should perhaps be 100 seconds, for instance. Horses are measured in “hands.”

“Global standard” isn’t necessarily an argument for “good.” Why aren’t imperial units the standard? Who actually decided that metric was the right answer?

And as a previous poster mentioned; why don’t we say a megameter or gigameter when talking about long distances? Because ultimately measurement units are really about human understanding, despite ostensibly being “scientific.” A foot as just as scientific as a meter. NASA went to the moon with imperial units and it worked out just fine. People and countries are entitled to their preferences. We don’t advocate English or Chinese to be the global standard language. Or that all countries use euros or dollars. Weights and measures can be perfectly accurate regardless of the units used; the idea that we should either create or adhere to a global standard is not unlike suggesting everyone speak the same language.


> the British use pints in the pub and stone when weighing themselves.

Using a country that excels in being contrary, to the point of being the national pastime, is a poor example.

Even then we literally use metric for everything else. And although it is referred to as a pint, it is measured in metric.

Weighing yourself in kilos is a more modern thing, but that is really the only thing.


There's a reason measurements have a global standard, NASA attempted to work with a team from elsewhere that used Metric, and this lead to the loss of the Mars Climate Orbiter when they couldn't work well together and had a conversion problem.

Standards make it easy for people to work with each other across borders, and most of the world uses metric already. NASA has since then started all of their new projects on Metric too.

I do agree with your point about the fact that weights and measures can be accurate regardless of the units used, the argument against Imperial isn't about accuracy, it's about ease of conversion and changing bases of the unit scale. (Like 12 inches to a foot, but 3 feet to a yard etc)


> Who actually decided that metric was the right answer?

People who wanted actual definition of units.

Once upon a time if you wanted to sell stuff in my home City you would need to use the city measurements made via a really big stone tablet in the old roman center with various units of lengths.

This was hard to communicate and stuff.

The French decided that one unit of measurement was better than many and made one "easy" (possible) to replicate and validate when the imperial one still used medium sized wheat seeds as measure of pressure.

But now everything is ultimately standardized on the metric system (even the US).

So one need to ask better at what? Better to standardize? Metric no doubt. Better to use? Well this appears to be controversial


Global standard doesn't mean that every person everywhere uses metric. It means that people everywhere can use metric and they know what it means, and that official weights and measures are done in metric. Use whatever glass size you want at the bar, or measure your horses however you wish, but when you get on the road the signs are in km/h.

Plenty of people are "bilingual" with metric and local. Canadians are universally bilingual with metric and imperial. It's not that hard.


Frankly, while mathematically speaking 12 is a great base, people don't think in twelves - you can quickly perform arithmetic and our entire education system of math relies on base 10. Kind of hard to suddenly add two fingers to everyone. Additionally, base 12, would not act like 12 does in base 10, thus if base 12 is your key point of reference, a foot should be 10 in base 12 for inches.....


Additionally, base 12, would not act like 12 does in base 10, thus if base 12 is your key point of reference, a foot should be 10 in base 12 for inches.....

I honestly cannot make any sense of this part of your argument. The symbols 10 would only look like ten they would still mean a dozen and the properties would remain the same. Furthermore people don’t think in twelves because we are not taught in a dozenal numbering system. And there is no need for twelve fingers it would be a simple thing to create two additional hand symbols to teach children to count to a dozen.

Twelve is a great base. I would prefer it but it isn’t the sort of thing that can be changed.


He is saying that you need twelve digits to actually use base 12 and that in every base N with N>1 you write N as 10 (eg in hex 10 is A and 16 is 10)


Understood, his mistake was this “base 12, would not act like 12 does in base 10". That statement is mistaken. A dozen would look like ‘10’ but it would still behave like a dozen.


People don't really think in terms of 10s either - that's just societal conditioning based on the usage of fingers to count. If you can accurately picture 1/3 of set, but your number system cannot, it's not really that accommodating of a system.

By the way, you can count base12 on your hands using the digits of your fingers. We just teach kids to use fingers because it's the norm.


Why are you so obsessed with thirds? If you care about short, clean fractions on a human scale, base 6 is overall better, see this table: https://youtu.be/qID2B4MK7Y0?t=992

Plus you get all the convenience of having five digits on a hand and 5 as the highest counting digit, so you can count to 55 on two hands, and all the rest of the benefits in that (totally serious) video.


A numbering system based on human fingers would be base6.


You've got it backwards. Counting to ten on your fingers predates the concept of our modern positional number system by hundreds of thousands of years. That's why base 10 was already the well-established natural choice when that system was invented.

Thinking that you could represent the quantity IIIIIIIIIIIIIIIIIIIII by the string "21" because it's 2 * 10 + 1, or similarly as "three fingers on left hand, three fingers on right hand" seems obvious to us now, but is actually pretty recent technology relative to the whole timescale of human development


I'm not sure what your point is. A numbering system based on five-fingered hands is still base6. It doesn't make mathematical sense to argue that we learn base10 today because our hands have 5 fingers. Even if you argue that we have 10 total fingers, that's base11. Does anybody advocate that? How did we come to such an arbitrary thing as base ten?


No, counting on the hands is not base anything, because positional number systems did not exist. Just like Roman numerals or tally marks aren't base anything.

People counted on fingers like with tally marks - they could express the numbers one through ten. Thus ten became an important and familiar number to humans. Thus it would have seemed natural to use a base 10 number system many millennia later.


Clearly, people do think in 12s, because it's been a common thread in mathematics and measurement and calendaring through many different cultures going back to the Sumerians.


Let me clear something: how do you count? Can you multiply 63895 by 12? By 6? By 3? By 10? This is an standard, there have been coltures where the base was 60 and they could multiply 63895 by 60 easily. But now the whole world counts in 10.

I would be happy if that number was 12 but the simple fact that we write in base ten makes it not the case (also mathematically speaking 12 is divided by a square which causes weird things)

There is nothing wrong with 12 but as long as you cannot do 63895*12 easily 10 is better


It’s based on the decimal system, which we happen to use in our primary numerical system as well?


We use the decimal system for imperial units too. Thousands of an inch, millionths of an inch, etc.


In most practical applications that I've seen fractions of imperial measurements used, it tends to be in powers of 2, i.e., 3/16 inch, 1/4 mile, etc. Decimals can certainly be used, but for most applications where you'd use something like a "millionth of an inch," it's vastly more common to use metric.


What applications are you talking about? Just for a general example of the sort of thing I'm talking about: https://youtu.be/EWqThb9Z1jk?t=137

They're resurfacing a surface plate, which has to be very flat. If you listen to the exchanges between them, everything is being done in millionths of an inch.


In my experience (electronics manufacturing), both PCBs and machined parts are usually in mils or decimal inches, although millimeters are becoming more common and many drawings show both systems.


This might be specific to where you live though, in my experience in the electronics industry, I've pretty much only seen millimeters.


Or nothing is stopping you from using things like 1.3 inches, 2.7 miles, .6 gallons. I tend to use the fractions when doing measurements in my head. But if things get too complicated and I have a calculator I switch to decimal.


Imperial units are good for describing small items in 'feets' length, and for cooking measures.

I don't think miles have an advantage over kilometers.

In Canada, people have trouble understanding the various measures if '10ml' of this, or '10mg' of that.

They do understand 'a teaspoon' or a 'large spoon'.

I think we need some kind of colloquial measure for food.


Recipes in cups are one thing I cannot understand, I do have a scale, I can measure everything with that


"Recipes in cups are one thing I cannot understand"

??

You drink out of cups every day; this is what humans, even you understand.

'A scale' is inapplicable while you're buying food or reading labels.

Why use a scale when everyone knows what a cup and teaspoon are? They are human measurements.

But it doesn't matter what you use, what matters is what people understand, and they don't understand grams and millilitres.

It's been identified as a health problem: people don't have an intuition for the units on labels - there should be imperial units to help them understand.

As for litre/gallon or pound/kg I don't think it matters ... but consider for a moment that everyone in Canada that I know still uses pounds. And feet/inches for height.

I don't know a single person that can tell you their weight in Kg, maybe heir height in meters but they'd have to think about it.


My cupboard has cups in all kinds of sizes. Which one is the right one to use as a measurement? And for baking there's quite a big difference if my cups are 150 ml or 350 ml, especially when paired with counted ingredients like eggs. That's the problem with cups.


All of your regular coffee cups are exactly 250ml.

Regular people use them for basic baking all the time, like making pancakes.

'Cups' are still better measures than ml because even you, in your self-acclaimed ignorance have a sense of how much a cup is whereas people do not have any idea how much '300ml' is.

Canadians have no clue what 10ml of anything is.

Canadians will continue to use feet and pounds for personal measure, despite being surrounded by total metric system - that should tell you something.

Do you order beer in ml? Or pints?

Seriously, do you know anyone that orders a 473ml of beer?

So why pints? And not ml? Because it makes sense.

Everything should be in metric, but many things should also be Imperial because metric is not useful for many common measurements.

The entire construction industry in Canada still uses Imperial, and it also weirdly makes sense. Inches and feet are slightly more approachable at smaller scale.


How can you be sure that "all of your regular coffee cups are exactly 250ml"? And what about teaspoon? And everything else?

Everyone here is obviously biased toward his/her own measurement system based on our experience, but the fact that "3 cups and a half of milk" is more precise than "875mL of milk" is clearly false.


I didn't say anything about Imperial being more precise.

I'm saying it's often more useful.

1 cup mix, 1 cup milk + 1 egg.

1 pint of beer.

1 teaspoon of sugar.

These are things everyone can understand.

You can put the ml on the side of the label.

"That guy is 6 feet tall, about 180 lbs."

Is better than metric for most people.

"I'll have a glass of wine" instead of "I'll have 240 ml of wine"

Any one of you who orders beer by the 'ml' can keep arguing with me, but I suspect you all order 'pints' in which case you should consider for a moment why you do that.


> These are things everyone can understand

Eh, no, here in my country nobody uses that units, all the recipes and in the stores, the units are ml, kg, etc


For 300 ml there are measuring cups that have a scale on the side. Same for 250 ml by the way. Incidentally, I wouldn't be sure I could actually measure 1⅕ cups of anything (under your assumption that a cup is exactly 250 ml (Do I fill them completely? One cm below the top? And while about 50 % of the cups here seem to roughly fit that size, the others are different.)).

I don't order beer at all, but around here it's usually ordered as 500 ml (a little further south, especially around October, they tend to order 1 liter).


> whereas people do not have any idea how much '300ml' is.

No, you get a sense of this if you live somewhere that uses ml for things.

One can of soda is 330 ml.


I live in Canada we use ml and nobody orders beer in ml.

5 grams of sugar? Nobody knows what that means.

They know what 5 tea-spoons is though.

I'll be $100 that if they put 'teaspoons of sugar' instead of grams, people would be shocked. There are videos showing how much sugar in a can of Coke, and it's largely because people are oblivious to the units on the label, which we can all technically read.


And here I thought 1 Imperial cup was ~284 ml... 1 US cup is closer at 240 ml. Might get away with that discrepancy when cooking, but when baking, not so much.


Especially if you're using things like flour where you get different quantities which if you sift it, or spoon it into the cup, or scoop it from the bag.

Cups are fine for rough and ready, but terrible for baking.


Fractional units are extremely useful in construction and machining. Now you could use fractions with meters, but nobody does, and im not sure why other than 10 is a shitty starting point for fractions and you end up with crazy fucked denominators.


The typical woodworker knows by hard all “crazy fucked” denominators like 333.333 mm for a third, 200 mm for a fifth etc.

The idea that not having straight fractional values somehow makes it harder is just plainly false. When you tell anybody to cut a third of a meter they will just happily cut 333.33 mm down to their usual tolerance


While I agree that in many ways imperial is better than metric in the way that you mention. It is absolutely atrocious when it comes to weight and volume. A gallon is still a base 10 unit of measure of water (10 pounds of water). Then only after that, is it in base 8 rather than maintaining that base 12 consistency.

Then if you look at imperial units of weight, it deviates away from base 12 again. It counts upwards from a pound using base 14 with stone and ton. And then when counting downwards it uses base 16 for a little bit with ounces, followed by out of nowhere throwing in a 1/7000 for a grain unit.

Even ignoring the scientific applications, none of this is easier for visualization purposes than grams or kilograms, nor is it all that useful for volumetric units either with maybe the exception of using cups instead of milliliters for cooking.


A gallon is NOT 10 pounds of water.

Rough conversions: 1.1, 2.2, 3.3 for volume (quart to L), weight (pound to kg), length (foot to m).

One gallon is: 4 quarts * (1 L / 1.1 quarts) * (1 kg / L) * (2.2 pounds / kg) = 4 * 2.2 / 1.1, so a gallon is roughly 8 pounds.


>> "A gallon is still a base 10 unit of measure of water (10 pounds of water)."

Not sure what you are getting at here. A gallon is about 8.3 lbs (3.8kg).

A gallon is 128 oz, a nice base-2 number.


You are arguing the difference between an imperial gallon and a US gallon.

Further evidence of how stupid these measurements are.


I understand some of what you say, but the point of standard unit is not so that people can choose which unit they like. It's to make sure everyone uses the same ones. If all but a few countries used imperial as their standard measure then I'd go for it. But right now it's the odd one out. Itu mostly survived only thanks to being associated with an economic superpower, so international companies can't afford to ignore it.


Hate to break it to you, but international companies do ignore it unless they need to print something out for an American to read.


Yes, but I suspect they bother to print anything at all is because the US is a big market. Unfortunately, this helps perpetuate those legacy units.


> I also think that F is seriously superior to C.

Yeah, no. You're just suffering from Stockholm Syndrome or being thinly ironic.

People have absolutely no problem associating numbers to temperature sensations in C. And actually people can objectively feel temperature differences from around 2C/5F so in that way C is superior to F, 1F difference is meaningless.


It's true that (for example) a third of a metre isn't expressible accurately in decimetres, but you can always just say (continuing this specific example) "a third of a metre". Nobody will be confused about what you mean.

This is however perhaps a good argument in favour of non-decimal currency.


It doesn’t matter. Just write 333.333 mm and if you make it evident in your construction drawing that three of these third meter-things need to fit one meter somebody might even calculate the width of the blade into it.

Measurements are just a number and you will always have tolerances and chains of measurements to go with them to clarify what you expext as a end result.


Yes, good point - I was thinking about casual, everyday uses, but if you're going to be precise then the question of divisibility becames even less relevant. Just tack on as many decimal places as you need.

It's true that this applies just as much to non-metric units, of course! But then if divisibility isn't a big deal, this goes both ways - meaning that the disadvantages of the metric system's base 10 orientation may well be minor in practice, and not enough to outweigh the advantages.

(Actually though I think the metric system has you more cleanly covered for this sort of case, with its consistent set of prefixes for scaling up and down by 1,000. Non-metric units tend to be a random jumble of 8s, 12s, 16s, or worse.)


Base 12 is more convenient than base 10. But that argument really only works if numbers were written in base 12. They're not, though, and that isn't changing any time soon. As a result, Imperial has to deal with two bases - the units themselves are defined base 12 (more or less; it's not really consistent e.g. with volume), but then you still have to do arithmetic in base 10.

So, until such time as we switch to base 12 for all numbers, metric is superior, because it is simpler.


You're just familiar with it - as somebody who has grown up with the metric system, I feel exactly the same affection about it, and to me imperial units feel stupid, unworkable and old fashioned.

I think this is the biggest problem with metric/imperial arguments - most of it is actually based on emotional attachment deep down.


No matter what is suggested, no matter how much better the alternative, there will always be a group of contrary people. Look at flat earthers. Look at anti-vaxers.


That's... not the same thing. One is: system that is mostly always better but can sometimes be handy for certain contexts. The other is: objectively true thing versus objectively false thing.


There are actual benefits to some imperial units when working in small amounts. They can often be subdivided much more easily into amounts that are harder to handle (or at least require going to another order of magnitude to do accurately).

For example, dividing a foot into thirds or fourths is trivial, but for a meter it requires either going two orders of magnitude (25/100ths for a quarter) or simply cannot perfectly represent the amount (1/3).

Now, not all imperial units have sane definitions, and they don't even all follow similar rules (8 fluid oz. to a cup, 16 fluid ozz to a pint, you lose thirds but can still easily do fourths).

In a lot of ways, base 10 is really substandard to base 12, we just used base 10 because it's physically easy and socially ingrained. Who knows, maybe 100 years from now we'll teach in base 12 and have a new system that's base 12, and all the metric die-hards will been seen as backwards yokels that cling to a clearly substandard system because of history and it's what they know? I mean, I really, really doubt it, but it would be better than the metric system as long as most people could easily think in base 12 (which would require a massive social upheaval).


"It cannot perfectly represent the amount" you say, and then perfectly represent the amount.

You represent a quarter as the fraction 25/100ths to show how impractical it is, instead of writing 1/4.

Would it be so hard to build a ruler with thirds measured on it, so you don't need to try and guess 0.333333 from mm readings? Like http://teaching.monster.com/nfs/teaching/attachment_images/0... but made of metal


> "It cannot perfectly represent the amount" you say, and then perfectly represent the amount.

Actually, I said "It cannot perfectly represent the amount (1/3)", so I specifically game an example immediately after the statement of exactly what I was talking about, which you then ignored and used an example for a different item to represent erroneously. What's up with that?

> You represent a quarter as the fraction 25/100ths to show how impractical it is, instead of writing 1/4.

No, I represent a quarter as 25/100's to show how it would be accurately represented in metric. 1/4 meter is not pure metric, it's applying a non-metric modifuer to a metric amount. The metric representation of 1/4 meters is 25 centimeters, which is 25/100.

Let me lay it out side by side:

- 1 and 1/2 units Imperial: 1 foot 6 inches or 18 inches Metric: 1 meter 50 centimeters or 15 decimeters or 150 centimeters

- 1 and 1/3 units Imperial: 1 foot four inches or 16 inches Metric: 1 meter 33 centimetersa and 3 millimeters and... or 133.33... centimeters

- 1 and 1/4 units Imperial: 1 foot 3 inches or 15 inches. Metric: 1 meter 25 centimeters or 125 centimeters

That's not to say imperial units are good. They are hard to use for most things because they change across types of things measures, and counting in twelfths when needed is much more painful than in tenths.

But, if we were taught in a 12 base system we would be able to use it easily, and base 12 has more cases where it can be used easily than base 10. Everything else would be the same except than our sense of scale would be a little different and we would have an easier tome subdividing things in many cases.

Metric isn't an optimal system, it's just the optimal system for right now and the world we currently live in. But for a few historical turns of fate, it might have been very different.

> Would it be so hard to build a ruler with thirds measured on it, so you don't need to try and guess 0.333333 from mm readings? Like http://teaching.monster.com/nfs/teaching/attachment_images/0.... but made of metal

Then it's not metric. That's the point. We use these values anyway, yet you have to step outside the metric system to represent them easily. Adding extra marks that don't correspond to the regular intervals is confusing, so it's avoided. That's why most rulers in the united states show metric on one side and imperial on the other.[1]

1: http://cdn.dickblick.com/items/554/27/55427-1012-3ww-l.jpg


>No, I represent a quarter as 25/100's to show how it would be accurately represented in metric. 1/4 meter is not pure metric, it's applying a non-metric modifuer to a metric amount. The metric representation of 1/4 meters is 25 centimeters, which is 25/100.

What? Fractions aren't exclusive to the imperial system.

1/4 of a metre is metric, just as a 1/4 of an inch is imperial.

Everything below is a perfectly legitimate way of writing metric units:

1/4 m = 6/24 m = 3/12 m = 0.25 m = 25 cm = 250 mm

So easy!


Fractions are mathematical modifiers that can applied to any quantifiable measurement. That said, I imagine they aren't generally used in professional context in metric, because they generally aren't in imperial either. You don't see architectural plans that say 1-1/2 feet, they say 1'-6". Is it common to see fractional amounts in metric when used in a professional context?


Usually we write everything in mm for professional context.


Thanks, that's what I assumed (because it makes sense). For metric you often go two orders of magnitude smaller, but I'm thinking a good amount of the reason to usually go straight to millimeters instead of also using decimeters is that decimeters just can't easily represent many common fractions of a meter (1/4, 3/4, 1/3, 2/3), and a base 10 system can never represent some of those perfectly without resorting to a mixed format.


Buy an imperial rule.

There's some inches that are sub-divided into tenths (maybe 1/20), and others sub-divided into sixteenths (maybe 32nds or 64ths). Often with heavier markings on more significance. For easy division and fractioning of whatever it is you are doing.

If it's imperial only (v. rare nowadays) there's usually a coarser scale or two for easier subdivision or when the 16ths and finer just don't matter.

Buy a metric rule.

There's mm, cm, and metres. Nowt else, not even weighting of marks except usually 1cm or 5mm. For measurement this is fine. For division such as in woodwork, metalwork and building, this is often a pain in the ass.

Metric only usually engraves just one side or exactly duplicates. No coarser scales.

So even when working in metric I often find an older imperial rule a better working tool(!)


How often is the distance you need to divide a whole number of inches anyway?

No more often than it is a multiple of 12mm, 60mm, or whatever.

Real distances are either designed for easy calculation, like my N*150mm kitchen pieces, or are some random length.


As someone who does a lot of woodworking in a metric world: the common fractions (e.g. 1/3) are not a problem at all, they are periodic. Adjusting my saw to 333.33mm or 6.66mm is something I do quite often.

If you use fractions often or work with weirder fractions anybody who is worth their grain of salt will build custom temporary rulers or helper systems anyways. And then it won't matter at all if your unit is hyperinches or fractions of lightspeed traveling through frozen beer in a second.

I can see how anybody who grew up with inches likes that one better, but in the end it is just numbers on a scale.


> If you use fractions often or work with weirder fractions anybody who is worth their grain of salt will build custom temporary rulers or helper systems anyways.

My point is a system with less need for that because it can handle more common divisions easily would be good.

> I can see how anybody who grew up with inches likes that one better

I tried to be very explicit in that I was not promoting the imperial system. I'm not even promoting imperial distance over metric distance. I'm purely using feet because there's a base 13 for inches to illustrate how a full base 12 system might work. Feet and inches are much worse than metric even in this case because that conversion only happens at one spot, not at regular orders of magnitude.

All I was saying is that since it's a fact there are some things that can be done in base 12 that can't be done in base 10 but not the other way aroubd, it would be really interesting (and extremely unlikely) if we somehow shifted to a base 12 metric-like system. That wouldn't be imperial (which has a different conversion every time you blink).

I learned a lesson though. People are very protective of the metric system. Even opining about fictional future possibilities with mathematical facts will lead to downvoting into oblivion and people misinterpreting clear assertions as something they aren't.


> My point is a system with less need for that because it can handle more common divisions easily would be good.

My point was, that from a practicle standpoint this doesn't really matter. If you need to tick of a third of a meter somewhere just a few times, everybody would just happily make a mark at 333.33mm – if you need to do this 50 times, building a temporary ruler is a good idea in any measurment system, because it reduces both cognitive load and the likelyhood of mismeasurement. This is especially true if you are building something that involves many steps that are repetitive, similar, but different enough to ruin your day if you fuck up.

For me one of the best things about the metric system is, that it in fact is base10 because it eases the conversion and calculation between units and has cool effects that imo outwheigh the cool things you would get from going base12.

Going base12 in a good way would mean going base12 fully, including temperatures, currencies, voltages, weight, etc. and this would mean turning a whole culture of knowledge upside down and inside out. If we would have a world dictator they might try something like this. From a distribution perspective it is desirable to have one standardized unit system that makes sense.

So my pain point isn't exactly metric vs imperial, but that in 2018 we still need to deal with these two systems and the conversion between them. Metric is far more wide spread than imperial and this has reasons, some historical, some political, some practical. If you are one who thinks national unilateralisms are a waste of energy and potential, you are certainly in favour of the metric system, just because it would be easier for the world to agree on going fully metric, than it would be for the world to go fully imperial.

And I am not talking about everybody having to use it in their day to day life – just look at the UK. I am talking about certain space agencies, industry, electrical engineering etc, where these things can have real graspable consequences, maybe even deaths.


That's actually my point. Whilst I use metric for almost all things, an imperial rule is, for me, a better temporary custom rule for actually doing stuff like centre finding or sub-dividing, than the metric ones. The units don't matter a jot, the markings and spacings do.

Which is why I keep one of each in the tool chest. :)


> but for a meter it requires either going two orders of magnitude (25/100ths for a quarter) or simply cannot perfectly represent the amount (1/3).

What? you switch to metric and suddenly fractions are not a thing any more?

1/3 m is just that, one third of a meter, perfectly. How is that so complicated? It can also be 333.3mm. And no one would write it as 333/1000 to make it seem more complicated than it is.


0 C = frozen, be careful

10 C = you need a jacket

15-25 C = great outdoors temperatures

20 C = good house temperature in the winter

25 C = good house temperature in the summer

30 C = too hot to go out doing physical activity, good for a picnic or a day at the beach

35 C = too hot to go out, period

40 C = hot bath

100 C = boiling water


I hadn't thought of some of these advantages. Some are subjective, but it's hard to deny the intuitive nature of others. I say bring back the span and the rod as well.


Go walk a job site with a tradesman and youll see why imperial is so useful and natural to them. They walk off long distancrs, use knuckles for small ones and do complex division with ease.


Because they have to since they're stuck using imperial. The imperial system does not make people better, it forces people to use fractions.


My father lays tiles for a living and he always did the same in metric, if he didn’t had something to measure things with him (which any professional should!)

A meter is basically a slightly longer step. I think most tradesmen over here got a pretty good sense how to walk a meter.

0.1m or 1dm or 10cm or 100mm is basically the width of your hand.

1cm or 10mm is roundabout the width of the pinky finger


I'm glad you made this point, because I am the one that usually does and gets hammered for daring to even hint that imperial might not be totally insane! The temperature one I've always found compelling. Most humans only rarely experience temperatures outside of 0-100F. That makes sense to me. Celsius makes little sense, except for 0 being when water freezes. It compacts the scale too much for everyday use.

However, beyond basic human usage, I quickly switch to metric for anything involving actual math: simulation, science, finance, etc.

A "cup" is about what a normal drink is. A liter is an insane amount of liquid for everyday use. I don't sit down and drink a liter of wine, I have a cup of wine.


The last couple of years we have had between -36 F to 97 F. Or -38 to +36 C. I like to be able to tell when the roads might get slippery (below +3 C or so), when the car will get problems starting if you forgot to plug in the heater (about -25 C), When it's time for the shorts (+18 C?).

Also handy to know that I need 3-6-3 ammounts to make pancakes. 3 eggs, 6 litres of milk and 3 dl flour (that will be meassured with grams because easier, can just pour everything into the bucket and press "tara"). Flour weighs 60 g per dl. Put bowl on scale, start it. Pour flour in the bowl until it reads 180 g. Reset and pour in milk until it says 300 g. Mix until perfect. Add eggs. Reset scale and pour another 300 g and mix again. Start frying!


A popular unit for a large beer is the "40" which is what a 40 ounce bottle of beer is called. About 1.2 liters, but not a size found in "respectable" households.


Next you'll be promoting "a better way to count" by Conlang Critic Jan Misali - https://www.youtube.com/watch?v=qID2B4MK7Y0


Divisibility by 12 could have benefits when working with small numbers, but on the other hand multiplying by 12 doesnt sound like operation you can do easily from top of your head...


Presumably, you'd also adopt a base 12 number system, so that decimal 12 becomes 10, and decimal 36 becomes 30, etc.


Good luck with that


0 degrees Farenheit is also the temperature salt stops freezing water. It is a good thing to remember when you are wondering about driving on snowy and icy roads.


Just as a side note, the US system gets worse and worse when you look beyond the everyday units of measure.

Sure, inches are great, but below 1/4", screws are in a numbered system (higher number is larger) while the corresponding drill bits are in a different numbered system (higher number is smaller) or lettered (A to Z). Wire and sheet metal gage numbers are still different.

An #8-32 thread takes a #29 tap drill...

https://www.lincolnmachine.com/tap_drill_chart.html


F is not superior to C, your argument for it makes very little sense, even from a plain human "everyday" (non-scientific) point of view. Can anyone sense when the temperature changes by a single degree in F? I doubt it. With C you have a chance. With C when it's below zero you know there could be snow and ice.

Each set of 10 degrees in C is a pretty clear temperature range. 30-40 scorching. 20-30 hot. 10-20 warm. 0-10 cool. -10 to 0: cold


For me. 26+ scorching. 25 perfect. 24- freezing. Haha.


I feel almost the same lol. Without looking at my "smart" thermometer (is set at 24), I know what temperature is in the house. If it's 23,9 i'm already cold and I have to put something on. But if it's 24,1 I can stay with my shirt on.


You should be careful about the term "imperial". US customary units do not always match the old British "imperial" units. A US fluid pint is significantly smaller than an Imperial pint, for example.


> I also think that F is seriously superior to C.

Both are not metric though. Metric unit for temperature is kelvin.


True although C is just an offset from K, i.e. only absolute values change, temperature deltas are the same in C and K.


The strength of the metric system shows when you need several different scales. nano- micro- milli- kilo- mega- giga-

The number of inches in a mile is harder to get than the number of millimeters in a kilometer or grams in a ton.


I see you're not liking how many feet are in a mile (and many other silly things).


Well I also don't particularly care about how many feet are in a kilometer, since they are different units.

A mile is...a mile. A half a mile, a quarter of a mile, an eighth of a mile, etc. Yeah, there are 5280 feet in a mile. There are also 25.8 or something like that mm in a inch, some other arbitrary unit of conversion that we all have to memorize.


Your second example is disingenuous. Mm to inch is going to be a weird conversion because they are between different unit systems. Feet to miles is unacceptable considering they're both imperial units.


These differences get important if you do any type calculation in engineering or physics.

Then it suddenly starts to matter if the result is Nm, Nmn or a Newton times a inch

Example: a Volt – which also the US uses with its metric prefixes – is defined as a Joule or a Wattsecond or a Newtonmeter.


Celsius and Fahrenheit may be use for some thing, but I think kelvin is a good system, even if others are use for other purposes sometimes (such as Fahrenheit for oven temperatures).


I feel like imperial units are human units. they are units used on a human scale, where as metric are more 'computer'. example: a human really cant look at something and divide it by 10 very well, but 1/3, 1/2, 1/4, very easy to do. the sizes makes human sense, like a foot being about a human foot, etc.


I don't get that one. It might be just that you are used to it.

A meter is a slightly longish step.

A decimeter is the width of a hand.

A centimeter is the width of a pinky finger.

A milimeter is twice the thickness of your fingernail.

It is actually no less or more intuitive than the imperial system (except when it comes to calculations, unit conversion and interfacing with other SI units like Volts, Joules, Watts etc.) I feel very comfortable working with digits like 12.5 or 33.33. I think a lot of the imperial-versus-metric-debate boils down to the question how big your love for fractions is and how things are measured around you. If everything is built with 2 by 4 wood, then a metric system is inconvinient. If your hardware store sells 4x8cm wood, then going to inches would be inconvinient.


But they're not! My foot is 25cm, far from '1 foot'. My thumb is 1.5 cm wide, far from an inch. The metric system is actually much more human for me. And I never needed to measure 1/3rds to 0.02mm precision without a precise measurement instrument. And if exact precision doesn't matter then all these arguments about fractions are moot, too!


considering your foot is 2 standard deviations from the mean foot length, that hardly proves anything


Well it proves a lot in my opinion. Feet are really non uniform in length by a lot.


go to google and type "about definition"


You can't both say that meter isn't exact enough when meassuring 1/3 and also say that 25 mm wrong on a food is ok...


I didnt say exact, just not easily done aka intuitive. a concept probably lost on you ages ago


10 can easily be divided by into fifths.


Thank you.

I'm glad I'm not the only person who thinks this way.


Most probably because you grew up with it. I’m pretty sure you think the same about your religion, nation, race ... but be sure eveybody else in the world may think the same of their own. And they’d be right too.

What I personally find disturbing is how irrational positions such as yours are commonly accepted in a supposedly advanced society. It leads to a pretty bumpy road, time and time again.


As a proponent of the metric system, I got to say the most disturbing thing is how an honest because openly subjective, intelligible and relatable statement (like the one OP gave) can be turned into something political and offensive. It it is the habit of doing this, that leads to a bumpy road ahead.

But since we‘re talking politics: it were the „progressive“ Bauhaus proponents like Corbusier, that proclaimed that what we build should use human scale as foundation of measurement. What OP said is exactly that.


It’s neither intelligent (as in based in some objective rationale) but subjective and capricious. It’s not relatable unless you’re also into the imperial system. And I’m not talking about politics: you will find the same people everywhere.

But I also find unlikely you support the metric system, at least other than for white knighting random strangers that you happen to agree with.


On top of that I don’t see how imperial is more human than metric. Yeah you have the foot bit a meter is a slighly longish step. Both units make you walk weirdly.


> irrational positions such as yours

This is, frankly, insulting. You may disagree about the merits of blhack's arguments, but that doesn't make them illogical or unreasonable.

It would be one thing if you said, "Here's why I think blhack has got it wrong, and why the arguments presented don't hold water." But you just tossed an insult without bothering to refute. Bad form.


[flagged]


And when he refuted the bias you claimed you dismissed him. Your every comment on this thread has been in bad faith and on at least one instance internally inconsistent. I’m sure you’re unaware but you’re uncharitable and not worth interacting with at any length.


Well I actually grew up with the metric system. I'm also not the religion I was raised. I do love my nation, which is easy because I'm American and there is a lot to love.

Imperial units are just better for humans to use. I would love if somebody could give me a redeeming quality for metric, but so far nobody has.


One reason to avoid imperial units is that people seem to be generally unsure if they're even using them! I might be wrong, but you're probably more familiar with the US system rather than imperial units (given you said you're american). Did you know there are 20 fluid ounces in a pint?


It’s easy to convert between units, miles and yard and feet and inches make my brain have a BSOD


I generally find them easier to manipulate, which is a frequent use for measuring distance. Honestly, I think the big thing hampering metric adoption is that no one uses decimeters. Kilometers are useful for trip distances, centimeters/millimeters are useful for small/precise measurements, but meters are deeply unuseful (for the same reasons you rarely see things measured in yards).

1/10th of a meter gets you a lot of the same usability as a foot measurement, but now adding centimeters onto that is more straightforward. A lot easier to calculate for measuring space for furniture, height, etc. . .


We do actually work in decimeters a lot, we just refer to them in 10cm increments. And conveniently there are 10 units of 10cm in a meter.


That’s usually called the zeal of the convert. First generation immigrants are quite adept at it.


And what I personally find disturbing is your idea that their view conflicting with yours is somehow an indication that they are obstructing advancement. To me, that seems much more problematic than them favoring the number 12 for common measurements.


Weasel words. I could easily justify pretty much any barbaric idea in the same terms, and it’ll fly among a certain subset of US citizens. Which honestly is worrisome to say the least, regardless of you agreeing with such idea.


There isn't anything more rational about demanding base 10 systems.


Last time I checked base 10 was quite common for pretty much everything but the imperial system.


For most things, I think metric makes more sense, but I fully agree about temperatures. Fahrenheit is a superior scale for humans.


While having a "wider spread" of "today's forecast" numbers is nice, that 32-degree offset is a huge negative ding against it.

I mean, there's a big important point where you start getting solid things falling on your head and slick icy roads and ruined fruit-plants, so it ought to be at more meaningful spot, like 0.


I can just barely feel the difference of temperature of one degree Celsius. I really don't feel multiplying that by 1.8 will make a big difference in how good a scale it is for humans.


As an example, the common temperatures in NYC range from 0-100F. In celcius that's like -18 to +38.

I'm a scientist and an engineer, and in those applications C is often better. But in daily life, Fahrenheit makes a ton of sense.


Just think about it by 10s, as you do with the metric system:

20 C - a bit less than room temperature (68 F)

30 C - pretty hot (86 F)

40 C - very hot (104 F)

And going the other way:

10 C - a bit chilly (50 F)

0 C - cold (32 F)

-10 C - real cold (14 F)

-20 C - really really cold (-4 F)

When you hear a temperature in Celsius, don't try to convert it to Fahrenheit, just think in Celsius. 15 degrees is halfway between "chilly" 10 C and "room temp" 20 C. One degree of warming - say 26 C to 27 C - is pretty easy to conceptualize when you have those 10-degree reference points.


This is the right answer for Americans. The reason I prefer Fahrenheit is because it is the one I know what degrees feel like and because Celsius isn’t reported in enough resolution.

If it was always reported to the half point I think we would be able to relate to Celsius better. And if I was making a population wide change I’d ensure reporting was always to the half degree.


We just report it to the degree (high of 34 tomorrow, 32 the next day). That's really plenty of resolution for non-scientific measurement.


And is also more resolution than the error warrants


I think I meant less for forecasts and more for weather apps and thermostats. I really think it could help with adoption. But if it’s not warranted by the error then maybe I’ll reconsider.


The precision on most digital thermometers for home use is (surprice) +-1 degree C :-)


If you live in NYC, maybe. A lot of people don't, and you can find places where ranges in C are "neater" than in F.


> If you live in NYC, maybe. A lot of people don't

Those people are free to use whatever units they like. It doesn't have much bearing on the point that Fahrenheit, which is used in the United States, is a good match for the climate of most of the United States.


Most of the United States doesn't have climate that falls within 0..100 F. There are plenty of places that are more like 30..90 F etc. And I don't see how that's any different from, say, 0..30 C.

OTOH, as far as weather goes, C has the nice property that anything below zero is freezing temperature. In any locale where snow and ice is a thing, that's handy to know.


In Ecuador the temperature ranges from ~60 to ~90F, but I'm sure for them is a great relief to know people of New York have a temperature unit that perfectly matches their climate as neatly as going from 0 to 100.


But is 15C to 32C better?


When it is 0 C, you can expect ice/snow outside.

Yesterday it was +20 C, today it is +25 C, so it is noticeably warmer.

-10 C tomorrow, so you'll need your woolen cap and padded jacket. -20 C and add a layer of underwear underneath and maybe a scarf.

When you boil water for tea (100 C) and don't want the water boiling but still hot, aim for 95 C.

When the inner temperature of salmon is +46 C, it is perfect, if it is +56 C or more, it is thoroughly cooked and will not taste soft anymore.

Usually the relevant difference is 5 or 10 degrees.

I don't even want to think what those examples could be as Fahrenheit.

My point is it is eventually a matter of what you are used to, but Celsius is more logical, because it is directly tied to water freezing and boiling.

For the most logical measurements we'd use Kelvin, but it is not practical! "Oh, it is 273.15 K outside, might be black ice on the roads"


Co-signed! The freezing and boiling points of water are also not particularly pragmatic points of reference. I don't think "I need to lower this to 0°", I think "I need to put this in the freezer".


> The freezing and boiling points of water are also not particularly pragmatic points of reference.

I must strongly disagree.

The freezing point of water is an incredibly important and pragmatic point of reference for hundreds of millions of people around the world, who live in places where water can freeze (or thaw) on its own outdoors. Not just for transportation, but also its affect on biology in agriculture.

While the boiling point is (thankfully) not important for weather-reports... Cooking! What would you do if I said to "simmer" something? You aren't supposed to go high enough to reach the obvious boiling point, so how are you supposed to know when you're close enough if you can't remember the magic number?


I'll concede that freezing is very important to a lot of people, but at the same time, I don't think it's particularly onerous to remember that the freezing point is 32 degrees.

As far as boiling and cooking, I would argue that there is no magic number anyways, since boiling point is variable by elevation. At 7500 feet / ~2250 meters, water boils at 198°F.


> As far as boiling and cooking, I would argue that there is no magic number anyways, since boiling point is variable by elevation. At 7500 feet / ~2250 meters, water boils at 198°F.

That's an excellent point, let's examine the relationship between altitude and boiling point, in both American units and everywhere-else-in-the-world units [0]:

5000 feet -> 202.97 F

7500 feet -> 198.33

10000 feet -> 193.6 F

Compared to:

1000 meters -> 96.73 C

2000 meters -> 93.38 C

3000 meters -> 89.95 C

In both cases, the boiling points at altitude are magic numbers. The difference is that with Celsius, you can interpret degrees as "percentage of the way from freezing to boiling". Going from 100 C at 0 meters to 90 C at 3000 meters is immediately meaningful as a 10% decrease. With degrees Fahrenheit, that same 10% drop in boiling temperature that happens at around 3000 meters / 10,000 feet is 212 F to 194 F.

0: https://www.omnicalculator.com/chemistry/boiling-point-altit...


If going from 100 °C to 90 °C was a 10% decrease, then going from 0 °C to 1 °C would be an ∞% increase. Metric units are superior to imperial for many reasons, but this isn’t one of them.


Excellent point.

100 -> 90 is 10% decrease.

212 -> 194 is ~8.5% decrease (and I had to go out of my way to count that).


Also: Celsius converts easier to Kelvin which is sometimes useful


Good thing Fahrenheit's got pragmatic points of reference, like. . . the freezing point of brine water and almost the body temperature of human [1].

[1]: https://en.wikipedia.org/wiki/Fahrenheit#History


So it's fair to rib my American friends with the fact that Imperial is implemented using metric?


I like to commend my American friends for their undying loyalty to the memory of the Empire. U.S. customary units are derived from units that helped the British conquer the world, but even the British themselves have shamelessly abandoned them for the units of a filthy, monarch-less republic. It's good to see that Americans still subconsciously yearn for the firm ruling hand of their rightful Queen.

Note: Americans hate it when I do this.


It just doesn't have the same ring to it.

"He won't move an inch," or "He won't move a centimeter."

"She won't quit until she's six feet under," or "She won't quit until she's two meters under."

"I'll go the whole nine yards," or "I'll go the whole nine meters."

"You can see for miles and miles," or "You can see for kilometers and kilometers."


I need you to understand that those phrases are still used all the time in English speaking countries that have adopted the metric system.

Changing your scientific measuring system doesn't necessitate a change to your colloquialisms; commonly used phrases don't change.


In case you are not joking... in metric countries we still say the same sentences you say, with miles and inches. That doesn't mean we use the olde units to actually measure something...


Well, then you are welcome for us keeping the more poetic units alive and meaningful.


Sorry, but no. They are just our old units that stuck in everyday language. They are probably not even closer to yours than yours are to antique Egypt ones, given that they were not internationally standardized and merely referenced the same body parts.

And we have expressions including other old units that you don't have (lieu, arpent, toise, etc.).


Not really --- in some languages these sayings actually are already in metric units. The SI system is by now over hundred years old, so just by waiting probably will upgrade unit system also there.


In Russian you still have people using colloquialisms and idioms with units that were put out of use almost a century ago, yet everyone here gets the meaning (or at least the intent, which is what matters in the contexts they are used in) since they have stayed in the literature written centuries ago and of course nobody went out of their way to fix measurements in works of fiction.

Heck, most people using them don't even have a rough idea of how much they originally meant, and if you were to press them to give you a number for the sake of an experiment, they might be 2 orders of magnitude off.

https://en.wikipedia.org/Obsolete_Russian_units_of_measureme...


Yes, that's true. Another argument my American coworker had put forth: "American rock-n-roll needed Imperial units... or the lyrics would not work".


I think there's a serious point to what you're saying. I was bought up in the UK so I have metres for short distances and miles for long distances. If you say to me 5 miles I instantly know what you mean. If you say 8km, I have an academic understanding but not really an intuitive feel for what you mean (other than 8km=5mi, feel 5mi).


That's just familiarity though. People in countries that primarily use kilometers have the same intuitions about them.


I doubt that in practice an average person would be able to (reasonably) accurately differentiate between 4 miles and 5 miles or 6km and 8km without external measurement tools in an unfamiliar environment.

The heuristics at play that the human brain would use is likely: "5 miles is way more than I'd normally want to walk on my feet, since the trip would take me about 2 hours."


As our metric British friends say at the end of a long day: "Ah, I can't wait to get down to the pub and have my hard-earned 568.261 ml!"


But Brits haven't completely abandoned them, have they? Maybe for educational, scientific and in manufacturing industries it's all metric but they still seem to use a blend of imperial and metric for day to day stuff. The distance is in miles, speed in miles/hr, they use lbs as well and deg.F from time to time (mostly deg.C tho),"pints" for beer, ft and in for height etc.


Your friends don't like it when you invent reasons to antagonize them? How odd!


I was born and raised in the US and I don't think I've ever met someone who has any sort of complex about the British Empire, or who would be any more insulted by "you should be ruled by the Queen" than "you should be ruled by the President of Uruguay" (or any other random country). The US was last part of the British Empire before most of our ancestors came to this country.

Honestly your comment, assuming it is meant to be taken seriously, strikes me as bizarre, and I suspect you're misinterpreting your American friends' reactions.


That's some well metered ribbing. No worries. We can take it.


> metered

Ah!


*British themselves have shamelessly abandoned most of them, most of the time, when convenient


Our King wears no clothes. We desperately could use a Queen and some manners right about now.


As of today, they are both implemented using fundamental constants. ;-)

But indeed, most people worldwide are surprised when you tell them that there is no standard inch or standard pound sitting in a vault somewhere. Most machines, and most design software, have a button that switches between US and metric, and the machine itself doesn't care. More and more new products in the US use metric fasteners unless it's for something where a standard applies to exactly one thing, such as spark plug thread. I have used my metric tools more than my US tools in the process of doing repairs around the house, on my car, and my bikes.

One fastener on my bike uses Whitworth threads.

For all intents and purposes, it has ceased to matter.


Nope, because we don't use the Imperial system, though. We use American Standard Units. They happen to be just like the Imperial units, except they have more freedom.


Only if we can rib on you for using imperial machining standards and imperial pipe thread forms.


It's stunning to see people debating "ease-of-understanding" of the base 12 imperial system while at the same time happily using a decimal based currency (nearly?) all over the world.

It's easy to understand construction and cooking concepts in imperial? But you just used a decimal based currency to buy the materials for the said uses, and could easily add up the costs of those materials in your head instead of staring blankly at the cashier who was trying to add 77 shillings and 23 half-crowns.


No, it were actually pirates at fault of America not adopting metric: https://www.npr.org/sections/thetwo-way/2017/12/28/574044232...


Where I'm from, it's a hybrid system. kg, celcius, litres and inches


Now can we redefine 1 pound to equal 1 kg?

(the opposite of https://xkcd.com/2073)


Can you imagine the confusion? Having the same word mean a different amount of something would cause a lot of misunderstanding. Saying "This car weighs 2200 poundsm" have two different meanings depending on the year you said it sounds awful.

The new metric definitions work because they don't change the actual amount, they just change the way the amount is defined. (Natural constant vs reference weight)


We could gradually redefine pound to be closer and closer to kilogram, say, over a century, so that people don't notice. ~


That sounds like it would require more coordination than just adopting the kilogram as the primary unit of measure in a short period of time.


See ton vs tonne


Considering the speed at which metrologists create new standards, we'll be about three iterations into the infinite loop by the end of the century.


Nope, 1 pound should equal 0.5 kg.


It does in France already and has done for years, so when you ask for a pound of cheese you get 500g. Simples.

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