The 39th Root of 92 • Hacker News Board

Re: The 39th Root of 92

#21

Post by HCIdivision17 » Sun, Aug 07, 2016, 3:13 AM UTC

ysleepy wrote: post #15

MikeTLive wrote: post #8

Earlier quoted context omitted.

Appelbaum: So the people blocking adoption of the metric system weren't backward-looking traditionalists, but cutting-edge industrialists? Mihm: That's correct. While the anti-metric forces included outright cranks, including people who believed that the inch was a God-given unit of measurement, the most sophisticated and powerful opponents of the metric system were anything but cranks. They were engineers who built…

Yeah the engineers love the process of calculating if that wire can carry the specified current. Because it's so industry friendly. This is complete nonsense and sounds like musings of a desperate advocate. If you want to believe something, you start to accept the lamest arguments.

You don't really recalculate that stuff over and over, do you? Every electrician I've worked with has a couple of the main ratings memorized and just applies it to standard. Anything more complex requires a calculator or tables either way, and once you're not doing the math in your head, it really doesn't matter what units you use. They're all arbitrary, so you may as well snap 'em to an integer value of convenience.

You'd certainly also want a universal one for conversion, but not for every day tedium. Fahrenheit is nice because it spans the human experience in a nice range (say damn cold 0 to rather hot 100). But that's bunk if you're in context of chemistry where water's properties are far more comparative (0 freezes to 100 boiling). Though absolute scales are always a bit sporky, since they latch to a scale and wonk it sideways (-273 is a silly number no matter what anyone says).

And so on. Scales and units are merely benchmarks. Literally. Pick the right bench for the job and follow the marks.

(Though with enough effort you can make any scale work. Kinda like hammers and threaded carpenter nails.)

Edited; typing on phones ruins grammar.

Re: The 39th Root of 92

#22

Post by sn41 » Sun, Aug 07, 2016, 3:14 AM UTC

HCIdivision17 wrote: post #20

kevhito wrote: post #18

Earlier quoted context omitted.

If you have never wired a house for electrical, then sure, the units seem arbitrary. But if you do, then the units seem very comfortable. 12ga for most typical 20a circuits, 14ga for light, 10ga or thicker for some heavy-duty circuits. Hey boss, we seem to be all out of 3.31mm^2 romex, all I got left is 2.08mm^2. And why did you mention cross-sectional area? Why not radius? or diameter? Or better yet, circumference?…

That's the trick. In a sense, the units follow the application, and hence English units always feel a bit natural. They have a tendency to have integer multiples and simple fractions. And when I say natural, I don't mean elegant. They often tend to be thoroughly arbitrary. But they match the needs, which is usually reasonably pragmatic. For example, 360 degrees is ideal for simple in-head directional geometry, but ra…

The Sumerians divided the circle into 360 degrees because the Sun's annual path took 360 days to come around a full circle. It's no wonder that 360 degrees feel natural for directions.

Another thing I've encountered: in South India, there is a measure of distance & time called a "nazhika". It is 24 minutes. 2 1/2 nazhika is one hour, 60 nazhikas make a day. A nazhika is also roughly the time taken for a normal person to walk 1 mile. Hence a nazhika is also used as approximately one mile. Seems a bit weird until you remember that light-years involve the same identification of time and distance.

Non-metric units like these and others ("foot") have probably very good reasons behind them, and they could be used by people in their day-to-day activities while not carrying measuring instruments with them. Metric System is more systematic, but people "lose touch" with intuitions of quantity.

Re: The 39th Root of 92

#23

Post by saghm » Sun, Aug 07, 2016, 3:16 AM UTC

dragontamer wrote: post #19

pacaro wrote: post #17

Earlier quoted context omitted.

The thing that always gets me about this is how incomplete it is (at least in most people's experience) What is the unit of mass smaller than an Ounce? Some people know that this is a Grain (7,000 in a pound, which means the awfully convenient division of 437.5 per oz - assuming avoirdupois of course) What if anything is smaller than an inch? Power of two fractions until 1/64 then "thous" - 15.625 thous in 1/64" - al…

> What if anything is smaller than an inch? Then we use Pica and Points. You know, like 12-point font. Which is 1/6th of an inch tall. 72-points to an inch, 12-points to a pica. Get with the program man!

Too bad we had to go and make displays with different pixel densities...

Re: The 39th Root of 92

#24

Post by einhverfr » Sun, Aug 07, 2016, 3:16 AM UTC

HCIdivision17 wrote: post #20

kevhito wrote: post #18

Earlier quoted context omitted.

If you have never wired a house for electrical, then sure, the units seem arbitrary. But if you do, then the units seem very comfortable. 12ga for most typical 20a circuits, 14ga for light, 10ga or thicker for some heavy-duty circuits. Hey boss, we seem to be all out of 3.31mm^2 romex, all I got left is 2.08mm^2. And why did you mention cross-sectional area? Why not radius? or diameter? Or better yet, circumference?…

That's the trick. In a sense, the units follow the application, and hence English units always feel a bit natural. They have a tendency to have integer multiples and simple fractions. And when I say natural, I don't mean elegant. They often tend to be thoroughly arbitrary. But they match the needs, which is usually reasonably pragmatic. For example, 360 degrees is ideal for simple in-head directional geometry, but ra…

One of the neat things about degrees and plane geometry is how regular polygons you can have without partial degrees.

The number of sides depends on the divisiblity of 360 by the number of angles so:

3, 4, 5, 6, 8, 9, 10, 12, 15, 18, 20, 30, and so forth.

For angle measurement where you want a closed geometry figure at the end, degrees are extremely elegant, and 360 is 2^3x3^2x5

Re: The 39th Root of 92

#25

Post by einhverfr » Sun, Aug 07, 2016, 3:18 AM UTC

sn41 wrote: post #22

HCIdivision17 wrote: post #20

Earlier quoted context omitted.

That's the trick. In a sense, the units follow the application, and hence English units always feel a bit natural. They have a tendency to have integer multiples and simple fractions. And when I say natural, I don't mean elegant. They often tend to be thoroughly arbitrary. But they match the needs, which is usually reasonably pragmatic. For example, 360 degrees is ideal for simple in-head directional geometry, but ra…

The Sumerians divided the circle into 360 degrees because the Sun's annual path took 360 days to come around a full circle. It's no wonder that 360 degrees feel natural for directions. Another thing I've encountered: in South India, there is a measure of distance & time called a "nazhika". It is 24 minutes. 2 1/2 nazhika is one hour, 60 nazhikas make a day. A nazhika is also roughly the time taken for a normal person…

I assume that the Sumerians were observant enough to realize that there were still a few days missing, and that 360 was better because it was a more divisible number actually.

The Sumerians did, in fact, periodically insert intercalary months in order to offset the difference, which suggests that this is in part close approximation and on the other part nice for application.

Re: The 39th Root of 92

#26

Post by einhverfr » Sun, Aug 07, 2016, 3:21 AM UTC

ysleepy wrote: post #14

sgk284 wrote: post #13

Earlier quoted context omitted.

Just like with software, backwards compatibility is a double-edged sword. You can look at almost any land assignment, building or commercial sale ever in the history of the United States and be able to compare / modify / extend it without any conversions. If my great-great-grandfather claimed 160 acres from the Homestead Act, any documentation from that time is just as easily understood today without any conversions.…

Who says people should collectively forget what an inch is? Every other country made unit conversions. The people will use old units for some time to buy cheese at the counter and all is well.

Yeah, right up until your car lease contract limits you to 2000 Swedish Miles per year. (Note, these are about 6x longer than American miles).

Or you buy fruit at the supermarket in Indonesia in ounces and kg (an ounce is an hg).

Re: The 39th Root of 92

#27

Post by sn41 » Sun, Aug 07, 2016, 3:31 AM UTC

einhverfr wrote: post #25

sn41 wrote: post #22

Earlier quoted context omitted.

The Sumerians divided the circle into 360 degrees because the Sun's annual path took 360 days to come around a full circle. It's no wonder that 360 degrees feel natural for directions. Another thing I've encountered: in South India, there is a measure of distance & time called a "nazhika". It is 24 minutes. 2 1/2 nazhika is one hour, 60 nazhikas make a day. A nazhika is also roughly the time taken for a normal person…

I assume that the Sumerians were observant enough to realize that there were still a few days missing, and that 360 was better because it was a more divisible number actually. The Sumerians did, in fact, periodically insert intercalary months in order to offset the difference, which suggests that this is in part close approximation and on the other part nice for application.

I did not know this. Thanks.

Re: The 39th Root of 92

#28

Post by einhverfr » Sun, Aug 07, 2016, 3:33 AM UTC

ysleepy wrote: post #3

I continue to be baffled by the arcane units in the US. This uses a measure on the completely wrong abstraction level. An accidental production process now defines a wire unit instead the end result the consumer/engineer/technician wants to know (mm^2 or inch^2 oh no no it's pica^2 ?). There must be some sociological phenomenon going on that keeps the US from adopting modern units. Maybe can't admit a shortcoming and…

I am not sure. American units usually focus on divisibility and factoring of integers, while metric units focus on quick base-10 math. So they are different concerns and this is why, I think, people from elsewhere in the world have so much trouble understanding American units.

If you are brought up with metric units, the units are built around the number system.

A good way to understand the problem by for the HN audience is the problem of using IEEE floats where precise numbers matter in programming. The problem with IEEE floats is that we usually think about them in base 10 but they represent something in base 2, and no lossless conversion across the domain is possible. American units bridge that sort of gap much better than metric ones do because they usually focus on divisibility than on quick representation and conversion.

There are certain areas where metric makes sense. If I have prices in kg and I want to know how many g I can buy for a certain amount of money, because the money and weight systems coincide we are well optimized for that problem.

But, imagine calculating the angles of a triangle or a hexagon if your degree system was base 10.

In other words, American units are abstracted around actual application.

There is of course a happy medium. We could change to duodecimal numbers and come up with a duodecimal metric system. Then everyone would get what they want, right? ;-)

Re: The 39th Root of 92

#29

Post by HCIdivision17 » Sun, Aug 07, 2016, 3:36 AM UTC

einhverfr wrote: post #25

sn41 wrote: post #22

Earlier quoted context omitted.

The Sumerians divided the circle into 360 degrees because the Sun's annual path took 360 days to come around a full circle. It's no wonder that 360 degrees feel natural for directions. Another thing I've encountered: in South India, there is a measure of distance & time called a "nazhika". It is 24 minutes. 2 1/2 nazhika is one hour, 60 nazhikas make a day. A nazhika is also roughly the time taken for a normal person…

I assume that the Sumerians were observant enough to realize that there were still a few days missing, and that 360 was better because it was a more divisible number actually. The Sumerians did, in fact, periodically insert intercalary months in order to offset the difference, which suggests that this is in part close approximation and on the other part nice for application.

I feel like unit debates often result from a misunderstanding between sides of "is perfect the enemy of good?" I thought it suspicious that they would have miscounted the days, but you're right: it's so dang useful that it's worth a little error (with occasional corrections) for such convenience.

Of course, at some point it becomes a huge pain and you buckle down and choose something just as arbitrary but easier to handle. And that's why we don't count angles in the milliseconds since 1970. Or days in a year; though we do sometimes measure 3D angles in solid minutes, which seems like a metaphor taken too far :)

Re: The 39th Root of 92

#30

Post by einhverfr » Sun, Aug 07, 2016, 3:39 AM UTC

rz2k wrote: post #11

MikeTLive wrote: post #8

Earlier quoted context omitted.

Appelbaum: So the people blocking adoption of the metric system weren't backward-looking traditionalists, but cutting-edge industrialists? Mihm: That's correct. While the anti-metric forces included outright cranks, including people who believed that the inch was a God-given unit of measurement, the most sophisticated and powerful opponents of the metric system were anything but cranks. They were engineers who built…

The philosophy seems to be reversed with the ISO 216 paper size standards like A4. Anyway, the main advantage of metric seems to be its universality between different markets, rather than the somewhat silly idea of ideal relationships such as water in one arbitrary form having a certain weight and volume replacing a system that was derived from a hundreds of years process resembling a genetic algorithm.

I wonder if it is an internal/external optimization. The whole point of metric is that it is built around the number system, leading to easy conversion between units.

The whole point of the American unit system is that they are optimized for specific use, but definitely not for conversion.

ISO paper sizes are a great counterexample, actually, because they took an application, rather than a conversion-centric approach. I.e when you print a signature you do so on a larger piece of paper, and then you fold, crop, and bind. Each fold cuts the paper size in half.

So ISO paper sizes are much more like American units than American paper sizes are.