International System of Units overhauled in historic vote • Hacker News Board

Re: International System of Units overhauled in historic vote

#401

Post by School-Cotton » Sat, Nov 17, 2018, 6:32 AM UTC

jameshart wrote: post #364

blhack wrote: post #232

Earlier quoted context omitted.

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…

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 t…

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.

Re: International System of Units overhauled in historic vote

#402

Post by School-Cotton » Sat, Nov 17, 2018, 6:34 AM UTC

naikrovek wrote: post #287

blhack wrote: post #256

Earlier quoted context omitted.

>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.…

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.

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

Re: International System of Units overhauled in historic vote

#403

Post by School-Cotton » Sat, Nov 17, 2018, 6:36 AM UTC

Just_Smith wrote: post #325

naikrovek wrote: post #319

Earlier quoted context omitted.

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.

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

Re: International System of Units overhauled in historic vote

#404

Post by garmaine » Sat, Nov 17, 2018, 6:39 AM UTC

Zarel wrote: post #395

garmaine wrote: post #345

Earlier quoted context omitted.

Nope, it is fixed to be N_A = 602,214,076,000,000,000,000,000 exactly (6.02214076x10^23 to units precision). It used to be the case that the mole was an experimental value equal to the number of atoms in a certain mass of a certain something. That is no longer the case with this revision. It is a fixed, never changing integer constant. This does mean that 1 mole of carbon-12 is no longer exactly 12 grams. But it is a…

No, that's not the part we disagree about. Yes, I know, Avogadro's number is a fixed constant now. It's not a _fundamental constant_: https://en.wikipedia.org/wiki/Fundamental_constant A fundamental constant isn't just any fixed constant. It's specifically a constant that describes a fundamental property of the universe. For instance, c describes the speed of light in a vacuum, and is a fundamental physical property…

Fair enough. I was using a different definition, but arguing over definitions isn't a good use of time :)

Re: International System of Units overhauled in historic vote

#405

Post by School-Cotton » Sat, Nov 17, 2018, 6:40 AM UTC

Just_Smith wrote: post #326

naikrovek wrote: post #321

Earlier quoted context omitted.

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 fo…

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)

Re: International System of Units overhauled in historic vote

#406

Post by AmericanChopper » Sat, Nov 17, 2018, 6:47 AM UTC

School-Cotton wrote: post #399

zmix wrote: post #366

Earlier quoted context omitted.

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…

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-…

>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.

Re: International System of Units overhauled in historic vote

#407

Post by School-Cotton » Sat, Nov 17, 2018, 6:47 AM UTC

DareRight wrote: post #391

Just_Smith wrote: post #283

Earlier quoted context omitted.

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.

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

Re: International System of Units overhauled in historic vote

#408

Post by mastazi » Sat, Nov 17, 2018, 6:52 AM UTC

School-Cotton wrote: post #399

zmix wrote: post #366

Earlier quoted context omitted.

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…

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-…

> 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".

Re: International System of Units overhauled in historic vote

#409

Post by School-Cotton » Sat, Nov 17, 2018, 6:56 AM UTC

int_19h wrote: post #340

bkanber wrote: post #328

Earlier quoted context omitted.

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.

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.

Re: International System of Units overhauled in historic vote

#410

Post by jpindar » Sat, Nov 17, 2018, 6:56 AM UTC

csihar wrote: post #269

blhack wrote: post #259

Earlier quoted context omitted.

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.

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.