4 ms·

> "Internal consistency" doesn't matter. The lack of an opinionated stance on internal consistency is exactly how we arrive at traditional measures and also th

by nayuki 3y ago

> "Internal consistency" doesn't matter. The lack of an opinionated stance on internal consistency is exactly how we arrive at traditional measures and also the US Customary set of units. It's far easier politically to be accommodating and allow more units than to put down your foot and say no, this is redundant, this cannot be used. > Virtually nobody ever has to convert miles to yards That's mostly true because it seems yards are only used to measure football fields and fabric. Everything else is measured in feet, from personal heights to furniture to rooms to house yards to building structures (the Empire State Building is 1454 feet tall). But my point still stands. You think you don't have to convert between miles and feet? Okay: https://www.researchgate.net/figure/a-Typical-multi-lane-highway-California-USA-b-5-lane-highway-in-the-simulator_fig1_333658431 https://www.researchgate.net/figure/a-Typical-multi-lane-hig... . There's a highway exit coming up in 800 feet and another in 1/2 mile. How many times longer does it take to reach the second exit compared to the first exit? You have no clue. In metric it's 250 m and 800 m, and it obviously takes about 3 times longer to reach the second exit. > These people never work with each other. This is a fantasy. Tell me you haven't worked in engineering without telling me you haven't worked in engineering. If you eyeball everything and use intuition, I can see why you don't care about units, conversions, and calculations. If you actually need to plan and analyze things carefully before you order materials and cut things, you'll quickly see that having a plethora of units adds complexity and chances for error without adding any functionality that a pure system has (whether you're using millimetres or only decimal inches).

emodendroket 3y ago
> But my point still stands. You think you don't have to convert between miles and feet? Okay: https://www.researchgate.net/figure/a-Typical-multi-lane-hig https://www.researchgate.net/figure/a-Typical-multi-lane-hig... . There's a highway exit coming up in 800 feet and another in 1/2 mile. How many times longer does it take to reach the second exit compared to the first exit? You have no clue. In metric it's 250 m and 800 m, and it obviously takes about 3 times longer to reach the second exit. I’m having a hard time seeing this as much of a problem in daily life. That sounds more like a word problem in math class than something someone would want to typically calculate on the fly. And my sense of how far something at a given distance is in the car is informed more by experience and intuitive sense than measurement.
philwelch 3y ago
> That's mostly true because it seems yards are only used to measure football fields and fabric. Also shooting ranges, but yes. > There's a highway exit coming up in 800 feet and another in 1/2 mile. How many times longer does it take to reach the second exit compared to the first exit? Prior to GPS navigation nobody ever said "there's a highway exit coming up in 800 feet"; road signs in the US consistently use fractions of a mile. When my GPS app switches units from fractions of a mile to feet, that means I can see where I need to exit/turn. Calculating a precise ratio doesn't matter. It's between 6 and 7 since there's 5280 feet in a mile and 86 is 48 but 87 is 56, but who cares? Also, on a highway, I'm usually traveling at least 60 mph, and since there's 60 minutes in an hour, that comes out to one mile per minute. Try that with your fancy metric system! > Tell me you haven't worked in engineering without telling me you haven't worked in engineering. If you eyeball everything and use intuition, I can see why you don't care about units, conversions, and calculations. You're imagining a scenario where a guy who's worrying about fractions of an inch building a cabinet has to talk to the city planner who's worried about miles and they have to convert units to do that. That doesn't happen, and yet you want to optimize the entire unit of measurement for that specific use case at the expense of more common use cases like "dividing by three". When it comes to domains where consistency does matter, we just don't do unit conversions. For instance, flight altitude is measured in feet, even when it's thousands of feet, instead of miles. If you're flying an airplane at 30,000 feet, who cares how many miles that is? That's not what miles are for. Likewise with domains that use feet per second rather than miles per hour. Again, even "metric" countries don't commit to the bit here; name me a country where the highway speed limit is in meters per second.
- nayuki 3y ago
  > When it comes to domains where consistency does matter, we just don't do unit conversions. For instance, flight altitude is measured in feet, even when it's thousands of feet, instead of miles. If you're flying an airplane at 30,000 feet, who cares how many miles that is? Wrong. https://en.wikipedia.org/wiki/Gliding_flight#Glide_ratio https://en.wikipedia.org/wiki/Gliding_flight#Glide_ratio Your plane is up at 30000 feet and your engines are out. The nearest airport is 47 nautical miles out. The plane has a glide ratio of 15. Will you make it? It's easy in metric: 9.1 km altitude, 87 km distance. > Again, even "metric" countries don't commit to the bit here; name me a country where the highway speed limit is in meters per second. I actually much prefer metres per second. It makes things like kinetic energy calculations easier. If I wanted to know the KE of a 1500 kg, 100 km/h car, I would first need to convert to m/s. Ditto the kilowatt-hour; it needs to die in favor of megajoules.

by nayuki 3y ago

emodendroket 3y ago

> But my point still stands. You think you don't have to convert between miles and feet? Okay: https://www.researchgate.net/figure/a-Typical-multi-lane-hig https://www.researchgate.net/figure/a-Typical-multi-lane-hig... . There's a highway exit coming up in 800 feet and another in 1/2 mile. How many times longer does it take to reach the second exit compared to the first exit? You have no clue. In metric it's 250 m and 800 m, and it obviously takes about 3 times longer to reach the second exit. I’m having a hard time seeing this as much of a problem in daily life. That sounds more like a word problem in math class than something someone would want to typically calculate on the fly. And my sense of how far something at a given distance is in the car is informed more by experience and intuitive sense than measurement.

philwelch 3y ago

> That's mostly true because it seems yards are only used to measure football fields and fabric. Also shooting ranges, but yes. > There's a highway exit coming up in 800 feet and another in 1/2 mile. How many times longer does it take to reach the second exit compared to the first exit? Prior to GPS navigation nobody ever said "there's a highway exit coming up in 800 feet"; road signs in the US consistently use fractions of a mile. When my GPS app switches units from fractions of a mile to feet, that means I can see where I need to exit/turn. Calculating a precise ratio doesn't matter. It's between 6 and 7 since there's 5280 feet in a mile and 86 is 48 but 87 is 56, but who cares? Also, on a highway, I'm usually traveling at least 60 mph, and since there's 60 minutes in an hour, that comes out to one mile per minute. Try that with your fancy metric system! > Tell me you haven't worked in engineering without telling me you haven't worked in engineering. If you eyeball everything and use intuition, I can see why you don't care about units, conversions, and calculations. You're imagining a scenario where a guy who's worrying about fractions of an inch building a cabinet has to talk to the city planner who's worried about miles and they have to convert units to do that. That doesn't happen, and yet you want to optimize the entire unit of measurement for that specific use case at the expense of more common use cases like "dividing by three". When it comes to domains where consistency does matter, we just don't do unit conversions. For instance, flight altitude is measured in feet, even when it's thousands of feet, instead of miles. If you're flying an airplane at 30,000 feet, who cares how many miles that is? That's not what miles are for. Likewise with domains that use feet per second rather than miles per hour. Again, even "metric" countries don't commit to the bit here; name me a country where the highway speed limit is in meters per second.

nayuki 3y ago
> When it comes to domains where consistency does matter, we just don't do unit conversions. For instance, flight altitude is measured in feet, even when it's thousands of feet, instead of miles. If you're flying an airplane at 30,000 feet, who cares how many miles that is? Wrong. https://en.wikipedia.org/wiki/Gliding_flight#Glide_ratio https://en.wikipedia.org/wiki/Gliding_flight#Glide_ratio Your plane is up at 30000 feet and your engines are out. The nearest airport is 47 nautical miles out. The plane has a glide ratio of 15. Will you make it? It's easy in metric: 9.1 km altitude, 87 km distance. > Again, even "metric" countries don't commit to the bit here; name me a country where the highway speed limit is in meters per second. I actually much prefer metres per second. It makes things like kinetic energy calculations easier. If I wanted to know the KE of a 1500 kg, 100 km/h car, I would first need to convert to m/s. Ditto the kilowatt-hour; it needs to die in favor of megajoules.