The metre originated in the French Revolution
abc.net.au126 points by Tomte 10 months ago
126 points by Tomte 10 months ago
Another fun fact dating from French revolution is the 10 hour-day, each hour had 100 minutes and each minutes 100 seconds : https://historyfacts.com/world-history/fact/france-had-a-cal...
Fun fact... or not so fun?
For 12 years of the revolutionary era, France did use decimal time. And the calendar and clocks were organized around a 10 day week and a 10 hour day. But those changes, coupled with the loss of Sunday worship, had other effects on the population.
Here’s an assessment of what was really meant and then lost by the elimination of Sunday:
“‘The elderly ladies took advantage of the long journey (to church) to exchange old stories with other old gossips … they met friends and relatives on the way, or when they reached the county town, whom they enjoyed seeing … there then followed a meal or perhaps a reciprocal invitation, which led to one relative or another….’ But if that was the way it was for the old ladies, what did Sunday mean to ‘young girls, whose blood throbbed with the sweetest desire of nature!’ We can well understand their impatience, ‘they waited for each other at the start of the road they shared,’ they danced.
“Now, however, when the Tenth Day came around, ‘the men were left to the devices they always had:’ the old men went to the tavern, and they bargained. The young men drank and, deprived of their ‘lovely village girls’, they quarrelled. As for the women, they had nothing left to do in village. The mothers were miserable in their little hamlets, the daughters too, and out of this came their need to gather together in crowds. If the need for recreation is necessary because of moral forces… there is absolutely no doubt that village girls find it very hard to bear privations which are likely to prolong their unmarried state: ‘in all regions the pleasure of love is the greatest pleasure.'”
– from The Revolution Against the Church, From Reason to the Supreme Being, by Michel Vovelle, pp 158-159.
I know the real goal of the republican calendar was to undermine the Church's power by making it so Sundays would fall at random days of the week, and also screw over the workers by leaving them with a worse weekend-to-week ratio.
However, all I ever read about this part of the revolution seems to indicate that people just didn't comply and went to church anyway on Sundays, and also didn't work that day. On that account, I feel likr your quote is kind of partisan. People wouldn't have been left lost and aimlessly drinking on their tenth day because of a lack of God, because they never quit going to church!
Not sure I understand what you mean. At least, I thought that (most? all?) the churches were closed for the worst part of the French Revolution aftermath.
For example, the new state transformed Notre Dame and other Catholic churches into Temples of Reason, from which the new state religion, the Cult of Reason, would be celebrated. It didn't last long. Hard to create a new religion quickly. Maybe some echoes of recent history there.
It was much more nuanced than that, and the vast majority of the French people stayed Christian during the period. Also, keep in mind the revolution was mostly a Paris thing, the rest of the country was left relatively unaffected at first.
https://en.wikipedia.org/wiki/Dechristianization_of_France_d...
Is the difference "stayed Catholic" vs the churches had to close?
Pretty sure it mattered when and where you were. Armies and militias were sent to put down defiant regions who had set up their own armies and militias in order to keep the Revolution out.
https://de.m.wikipedia.org/wiki/Sowjetischer_Revolutionskale... did the divide and conquer of people better by asigning them non overlapping weekends by colour
If you’re interested in a what an analog clock in decimal time might look like: https://decimal-time.netlify.app/
The USPS uses decimal time for it's time keeping system. It serves almost no functional advantage.
Decimal minutes instead of seconds, to be precise.
The way it should be.
So imagine we get to Mars, establish a colony.
Mars has a day which is 24h 36m.
We could have all of our Martian colonists adhere to an Earth day of 24 hours, with sunrise and sunset drifting around the clock, or we could have them observe an extra 25th hour of the day that lasts 36 minutes.
Or, we could define the Martian day as 24 Martian hours of 60 Martian minutes of 61.5 seconds, with seconds the invariant interchange time between planets.
In turn, seconds stop being a unit of human timekeeping, and everyone just uses decimal minutes as the final subdivision.
Slightly unnerving seeing seconds pass by 15.74% faster.
Feels like living in the future. Progress marches on faster than ever.
Honestly a brilliant marketing move by the French revolutionaries, just a few hundred years too early.
If they were truly revolutionary they would have gone for base 12 or 60 instead of 10
Uncanny valley. Never seen a clock do it before.
Never played most of the super mario games, then? Or is that timer too abstracted?
I think platform games already warp the sense of time a little. You get into the rhythm of the game. Or, say, a musical beat.
As I habitually mention when the revolutionary calendar comes up, emacs calendar mode will give you the date with p-f. For what it's worth, today is Quartidi 4 Prairial an 233 de la Révolution, jour de l'Angélique. (Prairial I had heard of, jour de l'Angélique is news to me.)
[edit: corrected spelling of Quartidi]
I hadn't heard of this and it's fun to think about.
It's 100,000 s/day as opposed to our current 86,400 s/day which is not far off.
Hours, however, were twice as long.
They had time pieces that displayed both together.
Their seconds must have been about 864ms though, otherwise they day is more than 3 hours too long which would be very annoying for any kind of scheduling I’d imagine.
It also messes up the original proposal for defining the meter, which predated the revolution and was "the length of a pendulum with a period of 2 seconds" (i.e. the pendulum would be at its lowest point once per second). Which is ironic considering that the meter was also adopted during the revolution, though with a definition not based on the length of a pendulum).
Latitude, mass concentrations, and climate also messed with the half-period/metre ("seconds pendulum") definition; with increasing frequency precision, one would need an almanac, an accelerometer, and probably other tools. Additionally, stabilizing the length of the pendulum under environmental conditions was already known to be tricky, with materials science unable to produce reasonably low thermal-expansion rods prior to the 20th century.
Consequently, the seconds-pendulum/metre relationship gets in the way as one might want to go to sub-millimetre length precision for parts made in different locations or at different times of the day or year. Precision copies of a prototype was more reliable in practice.
(In practice we mostly still generate precise and accurate physical artifacts and make copies from those, it's just that there one can in principle generate such an artifact just about anywhere and anywhen, calibrating with (for example) interferometry <https://iopscience.iop.org/book/edit/978-0-7503-1578-4/chapt...>)
Finally, the Trinity Clock <https://clock.trin.cam.ac.uk/main.php?menu_option=theory> is a neat examination of a well known pendulum clock that's surprisingly accurate (if not really precise; it's been reliably accurate to within two seconds over the course of a month for a very long time, but it's not going to give you a 10MHz sine-wave, and it's not a good for disciplining an oscillator which does so). Do check out the various plots.
> Latitude, mass concentrations, and climate also messed with the half-period/metre ("seconds pendulum") definition
Probably not by 15% which was the difference between the traditional second and the decimal second.
Sure but using a physical pendulum as a frequency standard is unreliable; an unreliable frequency standard is a bad basis for any sort of time-of-travel definition of length.
Many difficulties of using pendulum clocks (and in transporting any sort of chronometer) in real circumstances were also known before the revolution, with French clockmakers competing for the prize money in Britain's Longitude Act 1714 (13 Ann. c. 14) and the ancien regime's various prize offers in the 1740-1770s.
Prior to Harrison's marine chronometers, minimum longitude errors introduced in multi-degree changes of latitudes were indeed on the order of 10% across an oceanic part of a great circle or other more favourable route under cloudy conditions, and sufficient that in the early 18th century it was common for ships to navigate by dead reckoning along a single line of latitude -- a boon to pirates and other enemies, and also often adding many days to the travel time, in an effort to avoid the common problem (eg. HMS Centurion, 1741) of not knowing whether one was west or east of a landmark at a known latitude.
Prominent pre-revolutionary figures also disliked the idea of relying on chronometry for position/length/angle measurements generally -- most notably the excellent geometer and astronomer Pierre Bouguer (after whom the relevant <https://en.wikipedia.org/wiki/Bouguer_anomaly> is named) -- so it's not as if messing up a seconds-pendulum-based definition of a metre (and its consequences for the neat pole-to-equator 1/4 great circle length or mass of a cm^3 of water at STP, both of which now are just approximately round numbers) would have been universally outrageous.
And anyway surely one could consider a solution in which the half-period of the metre pendulum might not be exactly one decimal second. After all, at the time in practice one had to measure across many swings to obtain the effective length with reasonable precision. And Earth's rotation was known to be unstable (Richer, Newton, Maupertuis).
Yes. Obviously.
Or more to the point: since they had no use for milliseconds at that time, their milliseconds would have been 86.4% of standard milliseconds.
What about 90° per right angle and not 100°?
It made sense to keep some things like angle measurement and time as disruption was too great for very little practical benefit.
It's called a "gradian", and it's 1% of a right angle.
It's still used in some industries, where convenient.
Yeah, sure. The last person I heard discuss it was my highschool math teacher and he did so only in passing—and that was quite some decades ago.
Anyway, my non-metric preference is the radian unless I'm doing something manual like woodworking.
Still France and French revolution context : https://en.m.wikipedia.org/wiki/Gradian
Another "fun fact" somewhat more relevant to the article is the gradient (aka. grad, or gon), it is a unit of angle equal to 1/400 of a turn, slightly smaller than a degree.
It goes well with the metre because 1 km is 1/100 grad of latitude on earth. It mirrors the nautical mile in that 1 nautical mile is 1/60 degree (1 arcminute) of latitude on earth.
The grad is almost never used on a day to day basis, even in France. It is still used in specialized fields, like surveying.
I believe it was one out of three possible options (other than degrees and radians) to represent angles on my high school scientific calculator.
Accidentally staying in "grad" mode when cycling through them (DEG -> RAD -> GRAD) was always a concern, especially since the difference between RAD and GRAD was easy to miss on the small LCD display (the indicator was via partial selection of the letters within a mask spelling "DEGRAD").
Ah, this brings back fond memories of Swatch's attempt [1] at a decimal division of the day at the height of the dotcom boom.
I still must have one of these digital wristwatches in some box in a closet, with a big button that starts a glorious monochrome LCD animation of "going online" (while of course the watch stayed as offline as any other Quartz watch).
The thought of a watch that could actually go online seemed ridiculously utopian back then, even when everybody was otherwise dreaming of cyberspace. But only a few weeks ago, in a moment of closure spanning a quarter of a century, I finally downloaded a "Swatch Internet Time" complication – from the Internet, directly onto my wristwatch.
Sadly, the 100 day year never worked quite right.
No but they had a clean year of 12 months, 30 days each (3 ten-day weeks) plus 5/6 holiday days at the end of the calendar (around the September equinox).
Also, the months were given names by a Poet, and the days had minerals, vertues or plants instead of Saints. The calendar itself was pretty cool.
Honestly, if they had 5 weeks of 6 days each instead of the 3 weeks of 10 days, I'd even call it the perfect calendar.
Better would be an even more fundamental change: instead of trying to standardize everything on base 10, recognize that base 8 or 16 is much more convenient in both computing and everyday life, and standardize around that.
Historically, the most convenient are numbers with large numbers of factors.
60 can be split into 2, 3, 4, 5, 6, 10, 12, 15, 20, 30 evenly for example
The other number that accomplishes this is 12: 2, 3, 4, 6 are all factors.
That's why 12 and 60 are so common for real life systems.
Definitely not, but very composite numbers are! Like 6, 12, 24, or the best of them all, 60.
Base-60 for everyday life would be nuts; you really think it would be more convenient to have 60 independent digit symbols?
There's an argument for 12 for sure, but I still think having a power of 2 would be more beneficial than having the extra factors. 8 would give you the same number of integer factors as 10, plus all the benefits of being a power of 2.
Might I introduce you to visions of what could have been: https://en.wikipedia.org/wiki/Calendar_reform
Given the difference of ( 10 00 00 ) / 86400 ; they made their second ~1.1574 times faster? ( 125 : 108 , or 5 * 5 * 5 : 2 2 3 3 3 )
> (It was later found the astronomers were a bit off in their calculations, and the metre as we know it is 0.2 millimetres shorter than it should've been.)
That's actually impressively good accuracy for the time! Hats off to the astronomers.
I was just about to post same quote but you beat me to it.
I'd go further, I think their work was a remarkable feat for the late 1790s. That they achieved that accuracy given the primitive equipment of the day says much for their abilities and understanding.
Also at the time France was in turmoil, numbers of its scientists were victims of the French Revolution—Antoine Lavoisier, probably the greatest chemist of his time—was beheaded by guillotine in 1794, so the political environment was anything but stable.
Look back 225+ years ago: there was no electricity, no material science to speak of to make precision instrumentation—journal bearings on lathes, etc. couldn't be made with the accuracy of today, backlash would have been a constant worry. All instrumentation would have been crafted by hand.
And the old French pre-metric system of units was an imperial system similar to the British (France even had an inch that was similar in length to British Imperial unit). All instrumentation up to that point would have relied on the less precise standards of that old system.
Traveling was by horse and sailing ship, and so on. Surveying would have been difficult. There wasn't even the electric telegraph, only the crude optical Chappe telegraph, and even then it was only invented in the 1790s and wasn't fully implemented during the survey.
They did a truly excellent job without any of today's high tech infrastructure but they made up for all these limitations by being brilliant.
In today's modern world we often underestimate how inventive our forefathers were.
The pre-metric measurements in France weren’t imperial, but local: units had the same name, but different cities defined them differently. A livre[0] in one village was almost, but not quite, the livre used by the one only a couple toise[1] away.
[0] about a modern pound, depending where you were. Toulouse’s livre was almost 1.3 modern pounds, for example.
[1] about 13853/27000 meter.
You're right, I should have put 'imperial' in quotes as it's not the same as the British Imperial measurement. You'll note however I did distinguish the French system from the British one by referring to it in lowercase, that was intentional.
The issue came up in a round about way on HN several weeks ago and I should have been more careful here because I wasn't precise enough in my comment then. As I inferred in that post 'imperial' nomenclature is used rather loosely to refer to measurement and coinage/currency as they're often closely linked (in the sense that the 'Crown' once regulated both).
Pre-revolution French coinage used the same 1/12/20 number divisions as did the old English LSD and currencies in other parts of Europe, and that system is often referred to as 'imperial' coinage which likely goes back to Roman Imperial Coinage — but to confuse matters it was decimal.
One can't cover the long historical lineage here except to mention the sign for the Roman [decimal] denarius is 'd' which is also used for the LSD penny, 12 of which make the shilling (£=240d).
So for various reasons both 'old' physical measurement and 'old' coinage are often referred to as (I)imperial. To add to the confusion, modern currencies when converting from LSD/1/12/20 to metric and '1/12… measurement' are often done around the same time. Nomenclature overlaps.
For example, I'm in Australia and the 1966 conversion from LSD to metrified coinage occurred shortly before the metrication of measurement. It was all lumped together as Imperial (note u/c) to Metric (that's how the public perceived it). The Government staged both changeovers close enough so that the reeducation of the citizenry wasn't forgotten by the time the measurement program started.
For the record here's part of length in the old French measurement system:
"Pied du Roi (foot) ≈ 32.48 cm (Slightly longer than an English foot, which is about 30.48 cm.)
Pouce (inch) = 1/12 of a pied ≈ 2.707 cm
Ligne = 1/12 of a pouce ≈ 2.256 mm
Toise ≈ 1.949 metres (A toise is 6 pieds.) <...>"
The other units can be found on the same site: https://interessia.com/medieval-french-measurements/
I think I wasn't clear about the point I was trying to make, because your comment seems unrelated to it.
Pre-metrification there wasn't a French unit system, like we think about those today, where a meter in Paris is the same meter used in Limoges. The actual length of a ligne changed from one region to the next. There was no country wide standard of exactly how much a certain unit is. Such standards were regional, at best, sometimes the regions being as small as a single village.
This is one of the most important results of the French resolution: a consistent system of measurements, regardless of the units chosen for it.
The meter was also a bit of a gimmick, definitionally -- they wanted a unit that was about three (French/Paris) feet, but a definition that wasn't "my personal yardstick" so everyone would agree to it.
So they played around with various definitions like the 2-second pendulum, until they found one which worked and produced a single indisputable length.
(As opposed to picking something fundamental which was unrelated to previous units. Eg (not that they could have derived it at the time), the hydrogen line, the wavelength of the 1420MHz watering hole frequency, is human scale at about 21cm/8.3 inches, fundamental throughout the universe, and unrelated to previous units.)
Right. Essentially, before the Enlightenment systems of weights and measures didn't exist in the standardized way we know it today—measurements traceable to national/international standards, etc.
That's not to say local standards—let's call them weights and measures—weren't strictly adhered to and enforced. They were. There are many recorded instances from history to illustrate the point from, say, Archimedes' eureka moment to that of the obsessive and overzealous Issac Newton† when Warden of the Royal Mint was roaming around London checking for clipped coins and bringing the perpetrators to justice.
I'm fiercely pro-metric, and I've had much to say on the matter on HN over the years. So I'm used to the guns coming out from those in the US defending the Imperial system. I've good reason, at school I learned the Imperial system, CGS and MKS (it was before SI). In say physics learning to do things fluently in three different systems was a recipe for mistakes and confusion.
At the risk of repeating myself (link below), learning foot poundals, dynes and Newtons was bad enough but to have to convert between them in exams really was pretty rotten. The other reasons I've also menrioned, I've sat on standards committees and have writtern standards (nothing as illustrious as the ISO but it was for an intergovernmental organization nonetheless). Writing standards is often a tedious thankless task (I don't have to tell you people don't read them for the fun of it).
The link below is me getting worked up on HN over the metric system over a number of rolling posts, and it's not the first. I've referred to it here more for the sake of completeness than anything else. (I don't like rereading my old posts so I don't expect others to do so.)
https://news.ycombinator.com/context?id=43880977
† Newton. Not exactly weights and measures but a well documented case: https://coinsandhistoryfoundation.org/2021/04/30/sir-isaac-n...
The US doesn't use the Imperial system, it uses US customary units.
They're similar but very different.
An Imperial pint is 568 ml; a US pint is 473.
An Imperial hundredweight is 112 lbs. A US hundredweight is 100.
They're similar but very different.
Right. …And that's even worse—the US wasn't even satisfied with the well-established Imperial system and had to mess it up.
Everyone who takes an interest in measurement matters knows the story of the various aircraft that have run out of fuel because the US 'shortchanged' the gallon.
It'd be funny if it wasn't so serious, the last major incident was an Air Canada flight in the 80s.
The rest of the world shakes its head in disbelief.
Actually, the Imperial system messed itself up, post-1776.
The US did screw up a bit by standardizing on the wine gallon (231 cubic inches) instead of 222 cubic inches. This leads to a fluid ounce that is about 4% larger than an Imperial fluid ounce, and breaks the "a pint's a pound the whole world round" relationship (an Imperial fluid ounce of water weighs an ounce, and a pint of water being 16 fluid ounces is also a pound, which is 16 ounces of weight); in the US, a gallon of water now weighs "a little more" than 8 pounds.
Of course, in the UK, an Imperial gallon of water now weighs exactly 10 pounds. This is because in the 1820s -- which you will note is half a century after the US and UK parted ways -- the UK decided to add more factors of 10 and 7 into their units, and redefined the pint to be 20 fluid ounces instead of 16, and a gallon became 160 instead of 128.
The US and UK systems of measure diverged after 1776, and I'd argue the UK system changed more during standardization and re-standardization from the semi-formal system they shared before.
The Gimli Glider?
Wrong size gallons is a terrible analysis of that incident.
The fueler reported that the density of jet fuel at the time was 1.77, which was in lb/L, since other Air Canada aircraft used lb. Pearson and Quintal both used the density of jet fuel in lb/L without converting to kg/L
In fact, Air Canada was in the process of standardizing their fleet on metric, but failed to carefully train their personnel and failed to establish procedures for accurately transmitting measurements.
There was a 12:1 ratio between the foot ' inch '' line ''' and point '''' in pre-decimal engineering. Yes, they used triple prime marks. The typographic point was originally 1/144th of an inch. Watches are typically measued in french pointes.
Have you read the novel Le rendez-vous de Vénus by Jean-Pierre Luminet? If not you might love ite
I always think about what a cool adventure it must have been, for Pierre Méchain and Jean-Baptiste Delambre to roam for 7 years, go wherever they need thanks to an official letter, make calculations and come back successful to Paris. To think that they were only off by .2mm !
“The Measure of All Things” by Ken Adler[0] is a good, extremely readable book about their adventure, which was indeed wild.
[0] https://en.wikipedia.org/wiki/Special:BookSources/978-0-349-...
Yes, this is a brilliant book, and well worth reading. Another other one in the same vein is "Longitude" by Dava Sobel: https://www.amazon.com/Longitude-Genius-Greatest-Scientific-...
Here's a completely random anecdote: my mother often told me that her father, my grandfather, born in France in 1899, sculptor, draftsman and general maker of things, had a strong dislike of the metric system. He complained continuously that anything with round metric ratios was "ugly" and that beauty could only be found in more ancient measuring systems.
He died when I was 4 so it's not a first hand account, I'm not sure how much of it is true or what he really thought, but somehow it feels right.
The metric system is incredibly useful and practical (of course) but there's something rigid and unpleasant about it.
I know modern craftsmen* who lament the same. Being able to divide things in 2, 3, 4, 6, or 12 is mechanically more useful than 2/5/10 (the former being achievable by drafting tools more easily).
*Yes, it should be craftspeople, but that doesn't exactly sound like the same thing, and anyway all of them happen to be men.
Nohting prevent you to use the metric system and use 60cm (for example) as a base unit for your construction. So you can easily divide it by 12 if you want.
Just one example I'm familiar with. Drywall typically comes in widths of 1200 mm and are mounted on studs 600 mm c/c.
Nothing's stopping you from defining beautiful ratios and express the result in metric units, like ISO 216.[0] It feels like an odd complaint about the utility of the metric system, as if it is the only system; ratios aren't even units themselves!
Things that annoy me about the metric system: base-10 numbering system, a liter is not a cubic meter, and 'kilogram' is the base unit, not 'gram'.
That last one is what I have the biggest problem with. When you are doing anything with derived units, 'kilo' suddenly disappears.
> base-10 numbering system
Having decimal numbers, it’s the best solution. Otherwise you’re bound to make mistakes scaling things up or down.
> a liter is not a cubic meter
Well, it’s a dm^3, close enough ;) Conversion is trivial, 1 m^3 is 1000 l. A cubic metre is a bit large for everyday use, but it makes sense e.g. when measuring water consumption or larger volumes. The litre also had the advantage of being close to 2 pints, so it already made sense as a unit when it was introduced. Contrary to hours with 100s.
> 'kilogram' is the base unit, not 'gram'
Yeah, this one is perplexing. It’s an annoying inconsistency on an otherwise beautifully regular system.
I don't understand your issue between gram and kilo gram: gram is the base unit and the prefix kilo, meaning one thousand just says that 1 kg = 1000 grams. It is exactly the same as meters and kilometers: meters is the base unit and 1 km = 1000 meters.
In SI, kg is the base unit, and g is a derived unit.
There's an etymological reason for the word gram. It derives from a greek word γράμμα which roughly translates as "small weight" and made its way into French via the latin gramma to the French gramme, and the English gram. And 1kg is just very chunky. It wouldn't be right to refer to that as small.
As the name kilogram implies, gram is actually the unit here. But it was derived from the mass of a standard 1 kg chunk of metal that lives in a museum somewhere near Paris. This is the literal base unit of mass (at least historically, the definition has since been redefined using the Planck constant). A 1 gram chunk would have been tiny and be tedious to work with doing e.g. experiments with gravity.
They also have the original prototype meter in the form of a length of platinum-iridium alloy bar. And because the specific reference object for mass weighs 1kg instead of 1g, it means 1kg is the base unit in SI.
But quite obvious in the system of measurements, the gram is the logical unit here that you augment with prefixes and people commonly handle a lot of mass quantities that are in the order of grams rather than kg.
Derivations are simple. Simply apply powers of ten and their commonly used prefixes (kilo, milli, mega, micro etc.). The base unit is something physical that you can point at as the base unit. Or at least historically that was the intention.
There's also convenience. A 1l of water is about 1kg and a volume of 10x10x10cm. or 1 dm3. That's not accidental but intentional. It makes it easy to work with volumes and masses for people. Never mind that a liter of water isn't exactly a kg (because water purity, temperature, and a few other things).
Kilogram is indeed the base SI unit and not gram. It’s an exception.
Every formula using SI will expect mass in kg and you will be off a factor of 1000 if you use gram as the base unit. Same with derivative units like the newton which all use mass in kg for conversion.
It’s an historical artifact, as it was easier to manufacture a reference kilogram than a reference gram.
Considering today we set the kilogram by fixing the Planck constant and deriving it from there, we can just divide each side of the definition by 1000 and use that as a base unit. Using kg as the base unit is completely arbitrary, as we can derive each unit of weight directly from the meter and the second, not from the base unit.
Why not call the thing that weighs ~2.2 pounds a 'gram'?
For the same reason it was not renamed "Wug".
It's not the same reason. Gram is already part of the nomenclature, wug is not. The change I asked about would shift the relation of the prefixes to the masses: kilogram would represent a mass 1,000 times larger than it does now.
It's exactly the same reason: gram referenced a known quantity. Changing it by a few insignificant digits because of the kilogram update wouldn't force people to realign their perception of it.
Changing it to ~1,000 times what it used to be, or giving it a new name, would force people to realign.
There's reason many people still prefer customary and imperial units, and it's not just bigotry and nationalism (even if they play a part in that preference).
I think they mean that the gram is defined as 1/1000 of a kilogram. With a kilogram having a definition based on physical constants.
The kilogram is no longer defined by a physical artifact, fwiw.
Anyway, the point is the inconsistency in the system due to the kilogram being the base unit. So derived units are defined in terms of kilogram rather than gram. Say, the unit of force, Newton (N), is defined as kgm/s^2 and not gm/s^2). Or pressure, Pascal (Pa) which is N/m^2 which inherits N being defined in terms of the kilogram). And so on. Anyway, an annoying inconsistency maybe but doesn't really affect usage of the system once you get used to it.
Reportedly, the kg was going to be called "grav", but it sounded too similar to "Graf", a German feudal rank, and these guys really hated feudalism.
Er, `gram` most definitely is the base unit. Kilogram is what's handy for humans given how light a gram is.
EDIT: Yes, yes, SI defines the kg and then the g by reference to kg, but so what, notionally it's still the gram that's the base unit.
Why is base 10 annoying?
Too few divisors of place values. The idea you would pick something that isn't evenly divisible by at least 3 or 4 was a mistake.
This one isn't metric's fault to be fair. That's just what you get for inventing numbers before inventing math.
Makes me wonder what would have happened if 'French numbers' in base 12, 36 or 60 were introduced at the same time.
People got used to working in octal.or hexadecimal in the past for computers, doesn't seem like it would have been as big of a change as you think.
>evenly divisible by at least 3 or 4
Irrelevant with a decimal system.
The biggest source of communication issues around these unit systems is that in metric, you're supposed to reach for decimals when working with the units, and in imperial, you're supposed to reach for fractions when working with the units.
Which is why the imperial lovers all cry out about their fractions not "working" in metric. Yes, exactly, that is the point. They don't understand that they're reaching for a tool they shouldn't be reaching for, and then they blame the unit system for it.
Irrelevant if you are working with computers and digital equipment.
Highly relevant if you are using T-squares, compasses, and dividing calipers.
It's just a matter of working with base elements that are divisible by 3 and 4 really.
So instead of buying 100cm planks, buy 120cm planks?
And eventually you’re going to want a name for your 120cm unit. But that’s not allowed in metric because any named unit has to be base 10.
It's pretty relevant with computers. If we were used to working in base-8 or base-16 in everyday life, numerous aspects of programming would be simplified.
It's not irrelevant, you can choose something like 12 to make all your factors out of. It's a particular strength of working in feet and yards.
Except now you can't divide accurately by 5. Or 10.
You're making an argument from familiarity. Yes, a 12-base system using fractions works very neatly in a small human-sized domain, but it disintegrates into complete uselessness outside that domain. That's why you get ridiculousness as things being 13/64th of an inch, or that there's 63360 inches in a mile. It's unworkable for very large distances and very small distances. With a metre and standard prefixes, you don't need any conversion factors, and you can represent any distance at any scale with a single unit.
Quick, what's 11/64" + 3/8"?
Quick, which weight is bigger: 0.6lbs or 10oz?
> That's why you get ridiculousness as things being 13/64th of an inch
Such fractions are very rarely used, you're more likely to use mils (1/1000 of an inch) at that scale.
> or that there's 63360 inches in a mile.
Likewise, something that will probably never come up in your life. Inches/feet/yards and miles just remain separate things, never mixed.
> With a metre and standard prefixes, you don't need any conversion factors, and you can represent any distance at any scale with a single unit.
There's no intuition for them. Knowing what a meter is does not help with getting a feel for a kilometer. They might as well be as separate as feet and miles at that scale.
> Quick, what's 11/64" + 3/8"?
That one's not even hard, it's just a fraction. 35/64"
> Quick, which weight is bigger: 0.6lbs or 10oz?
Another arbitrary problem that will probably never come up, but to entertain you: since 0.5 lbs is 8oz, adding 1.6oz to that (another tenth of a lbs) results in 9.6oz. 10oz is bigger than 0.6 lbs. Not hard, but at least mildly harder than the first question.
None of this really had to do with the convenience highlighted initially: 12 inches in a foot and 3 feet in a yard make extremely convenient divisible factors. You can trivially divide things by 2, 3, 4, and 6 and keep with whole integer values. The same definitely cannot be said of metric.
> Inches/feet/yards and miles just remain separate things, never mixed
How tall are you, maybe 70 inches? Or 5⅚ft?
178cm or 1.78m are so obviously equivalent it doesn't matter which is used.
> 12 inches in a foot and 3 feet in a yard make extremely convenient divisible factors.
This requires you to start with 12 inches. If you're making a cupboard to fit in an 18¾" (476mm) space, it's no use, or is only randomly useful.
If you can choose, then you can just as easily start with 36cm. For example, European kitchens are designed around a 300mm base size.
> How tall are you, maybe 70 inches? Or 5⅚ft?
Are you purposely doing this? That is obviously not what I meant. Nobody says "3 miles, 500 feet", they say "3.1 miles". Effectively two systems of distance measurement: inches/feet/yards (near scale), and miles (distant scale).
"5 feet 10 inches" is completely normal and fine.
> This requires you to start with 12 inches. If you're making a cupboard to fit in an 18¾" (476mm) space, it's no use, or is only randomly useful.
So you cut the cupboard to fit a 18¾" space, no big deal. Same as anything else, and just as random as 476mm.
Typically they come in (integer!) 12-inch, 24-inch, 36-inch, or 48-inch variants.