7 ms·

Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the w

Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the weird conversion factors. The original Roman mile was 5000 Roman feet. In fact, 1 nmi ≡ 1.852 km exactly. Also from the original definition of the metre: 1/60 × 1/90 × 10^7 = 1851.85185185... m. Inter-convertability was a defining trait of SI (or more precisely, its predecessors, MKS and CGS) from the very outset, which is why we have 1 m ≡ 1 s ≡ 1 kg ≡ 1 N ≡ 1 Pa ≡ 1 J ≡ 1 A ≡ 1 C ≡ 1 V ≡ 1 Ω ≡ 1 F ≡ 1 W ≡ 1 Wb ≡ 1 T ≡ 1 H ≡ 1 Hz (I use '≡' loosely here to suggest conversion factors, rather than its usual meaning of equivalence). The only outliers in the SI are the kelvin, the mole, and the candela (and derived units from these). The former two are dealt with straightforwardly with the Boltzmann and Avogadro constants. I have issues with the presence of the candela in the SI.

skissane 3y ago
> Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the weird conversion factors. The original Roman mile was 5000 Roman feet. Pre-metric Europe was full of units with weird conversion factors, based on a shared heritage (mixture of Roman and Germanic), but with lots of divergent evolution subsequently. England didn't really stand out; France, Spain, Italy, Germany, etc, were really no different. Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so. But the fact that people have forgotten that the French/Germans/etc used to have feet/inches/miles/pounds/etc too, [0] albeit with somewhat different definitions, makes people think English units were somehow unique. They never were. The uniqueness is in the slowness in replacing them with metric, not the units themselves. [0] They still have some of these units for certain purposes. In France and Germany, the pound is still used, albeit redefined to be exactly 500 g. Nautical miles are used in maritime and aviation applications; American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation – the foot French pilots use to measure altitudes is the English foot not the old French foot; etc
- delta_p_delta_x 3y ago
  > American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation There are a few notes I have regarding this. The Airbus consortium initially set up the Airbus A300 cockpit entirely in SI units, but they realised this wouldn't sell well in the US, and they switched to feet and flight levels. Airfield weather data, including pressure and temperature readings in everywhere but the US are given in hectopascals and degrees Celsius. Many post-Warsaw Pact countries (Russia, China, Uzbekistan, Belarus, Ukraine until recently) used to have a completely metric unit setup for their air traffic controls. Both Boeing and Airbus cockpits have settings to output altimeter readings in metres. > Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so. If there's one export of the US I despise more than anything else, it is making legacy non-SI units relevant again because of its outsize influence in traditional and social media. I live in a country that metricated half a century ago, but I have Gen Z friends who measure their heights in feet and inches, and their gym weights in pounds. What the absolute hell. The SI units are the pinnacle of standardisation and the culmination of a three-hundred-year long effort to make life easier for everyone. I have no idea why the richest country in the world can't metricate properly. Get rid of legacy units, and we save billions in not printing the (XX fl. oz), (XX lbs), or (XX oz) on food packaging alone. It is ironic that a country that did away with colonialism, a whole lot of tea, and embraced the French and their revolution, never embraced the French units, but stuck with the English units.
  - Mountain_Skies 3y ago
    Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away.
    - skissane 3y ago
      > Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away. I've heard this argument many times before, but I don't think it makes much sense. The US customary / British imperial measurements are not consistently based on base 12. Yes, there are 12 inches to a foot; but there are 16 (not 12) ounces in a pound, and 128 (not 12 or 144) US fluid ounces in a US gallon (versus 160 UK fluid ounces in a UK gallon). Fahrenheit has 180 degrees between the freezing and boiling points of water, with water freezing at 32 degrees – none of which has much to do with base 12 either. There is no widely used unit corresponding to 12 feet or a twelfth of a mile. If you really want a system of units based on base 12, the US customary / British imperial system ain't what you are looking for. Also, it ignores the fact that you can metricate while keeping a foot of 12 inches, if you define a new "metric foot" composed of 12 "metric inches". This has been done before – as I mentioned in an earlier comment, many European countries kept the pound when metricating, by defining a new "metric pound" of 500 g. Given the current standard US-UK inch is exactly 25.4 mm, one option would be to have a metric inch of 25 mm (= 2.5 cm), twelve of which would give a metric foot of 300 mm (= 30 cm, versus 30.48 cm exactly for the standard US-UK foot). Sure, having two different foots and inches (old and new) coexisting for a while might cause some confusion; but if the confusion isn't worth it, maybe base 12 isn't really worth it either. And to avoid the confusion, you could always give the new metric units different names ("moots and minches", maybe?)
earthboundkid 3y ago
China had their own mile. “The journey of a thousand miles begins with a single step” was actually only around 300 English miles long.
- Aerroon 3y ago
  The modern Chinese li is defined as exactly 500 meters.
  - earthboundkid 3y ago
    Laozi had some foresight to use meters in 500BCE.
  - hashmush 3y ago
    And, similarly, the 斤 (jīn) is defined as 500g.
labster 3y ago
Kilogram is also an outlier, as it is the only base unit that comes with a magnitude prefix.
- Aachen 3y ago
  The base unit is gram, not sure what you mean
  - thomas2718 3y ago
    The base unit is indeed the kilogram, see https://www.bipm.org/en/measurement-units/si-base-units https://www.bipm.org/en/measurement-units/si-base-units.

skissane 3y ago

> Most other 'mile's are derivatives of the Roman mile which developed somewhat independently of the English units (foot, yard, inch, barleycorn, etc), ergo the weird conversion factors. The original Roman mile was 5000 Roman feet. Pre-metric Europe was full of units with weird conversion factors, based on a shared heritage (mixture of Roman and Germanic), but with lots of divergent evolution subsequently. England didn't really stand out; France, Spain, Italy, Germany, etc, were really no different. Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so. But the fact that people have forgotten that the French/Germans/etc used to have feet/inches/miles/pounds/etc too, [0] albeit with somewhat different definitions, makes people think English units were somehow unique. They never were. The uniqueness is in the slowness in replacing them with metric, not the units themselves. [0] They still have some of these units for certain purposes. In France and Germany, the pound is still used, albeit redefined to be exactly 500 g. Nautical miles are used in maritime and aviation applications; American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation – the foot French pilots use to measure altitudes is the English foot not the old French foot; etc

delta_p_delta_x 3y ago
> American influence (and to a lesser degree British) led to the adoption of the Anglo-American foot as the unit of altitude in aviation There are a few notes I have regarding this. The Airbus consortium initially set up the Airbus A300 cockpit entirely in SI units, but they realised this wouldn't sell well in the US, and they switched to feet and flight levels. Airfield weather data, including pressure and temperature readings in everywhere but the US are given in hectopascals and degrees Celsius. Many post-Warsaw Pact countries (Russia, China, Uzbekistan, Belarus, Ukraine until recently) used to have a completely metric unit setup for their air traffic controls. Both Boeing and Airbus cockpits have settings to output altimeter readings in metres. > Then the Continent did away with most of that complexity by adopting metric, and for whatever reason the English dragged their feet on doing that, and their American offshoots even more so. If there's one export of the US I despise more than anything else, it is making legacy non-SI units relevant again because of its outsize influence in traditional and social media. I live in a country that metricated half a century ago, but I have Gen Z friends who measure their heights in feet and inches, and their gym weights in pounds. What the absolute hell. The SI units are the pinnacle of standardisation and the culmination of a three-hundred-year long effort to make life easier for everyone. I have no idea why the richest country in the world can't metricate properly. Get rid of legacy units, and we save billions in not printing the (XX fl. oz), (XX lbs), or (XX oz) on food packaging alone. It is ironic that a country that did away with colonialism, a whole lot of tea, and embraced the French and their revolution, never embraced the French units, but stuck with the English units.
- Mountain_Skies 3y ago
  Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away.
  - skissane 3y ago
    > Base ten is an unfortunate numeric choice and responsible for much of the hesitation to switch to metric. Maybe someday when we have millions of O'Neill Cylinder colonies, one of them will adopt base twelve instead, at which point the main reason against metric would go away. I've heard this argument many times before, but I don't think it makes much sense. The US customary / British imperial measurements are not consistently based on base 12. Yes, there are 12 inches to a foot; but there are 16 (not 12) ounces in a pound, and 128 (not 12 or 144) US fluid ounces in a US gallon (versus 160 UK fluid ounces in a UK gallon). Fahrenheit has 180 degrees between the freezing and boiling points of water, with water freezing at 32 degrees – none of which has much to do with base 12 either. There is no widely used unit corresponding to 12 feet or a twelfth of a mile. If you really want a system of units based on base 12, the US customary / British imperial system ain't what you are looking for. Also, it ignores the fact that you can metricate while keeping a foot of 12 inches, if you define a new "metric foot" composed of 12 "metric inches". This has been done before – as I mentioned in an earlier comment, many European countries kept the pound when metricating, by defining a new "metric pound" of 500 g. Given the current standard US-UK inch is exactly 25.4 mm, one option would be to have a metric inch of 25 mm (= 2.5 cm), twelve of which would give a metric foot of 300 mm (= 30 cm, versus 30.48 cm exactly for the standard US-UK foot). Sure, having two different foots and inches (old and new) coexisting for a while might cause some confusion; but if the confusion isn't worth it, maybe base 12 isn't really worth it either. And to avoid the confusion, you could always give the new metric units different names ("moots and minches", maybe?)

earthboundkid 3y ago

China had their own mile. “The journey of a thousand miles begins with a single step” was actually only around 300 English miles long.

Aerroon 3y ago
The modern Chinese li is defined as exactly 500 meters.
- earthboundkid 3y ago
  Laozi had some foresight to use meters in 500BCE.
- hashmush 3y ago
  And, similarly, the 斤 (jīn) is defined as 500g.

labster 3y ago

Kilogram is also an outlier, as it is the only base unit that comes with a magnitude prefix.

Aachen 3y ago
The base unit is gram, not sure what you mean
- thomas2718 3y ago
  The base unit is indeed the kilogram, see https://www.bipm.org/en/measurement-units/si-base-units https://www.bipm.org/en/measurement-units/si-base-units.