https://en.m.wikipedia.org/wiki/Obsolete_German_units_of_mea...
/S
(honestly, once the US empire is gone for good, historians will have a good laugh about their stubborn refusal to adopt the metric system. Must be the worst case of NIH in history)
A foot is the distance light in a vacuum travels in 1.01 nanoseconds. A meter is the distance light travels in 3.33 nanoseconds. It is not really a big deal what you name that, they are both totally arbitrary. They have no relationship to any core feature of the Universe except by some reverse-engineered arbitrary constant. (You start by defining that there are 9192631770 transitions between the two hyperfine ground states of caesium-133 atoms in a second. You then build the meter by saying that light in a vacuum travels 299792458 meters in 1 second. There is no special meaning to 9192631770 or 299792458; they are totally made-up bullshit constants that mean nothing. Kilograms are even worse; before 2019 it was just a big arbitrary ball of metal in a museum. I won't even mention how the base unit has the prefix "kilo". How crazy someone is for not using the elegant kilogram/meter/second unit system. It's just so pure and natural!)
It seems pointless to me to argue over (or worse, get high-and-mighty over) what these constants are called. SI has a bunch of bullshit constants. The imperial system has a bunch of bullshit constants. It's bullshit all the way down, my friend. As long as you know what constants to use, which is why we name units, then it doesn't really matter which you use. None is better than the other.
Arguments about units usually devolve into how crazy it is that people use fractions with imperial units. But nobody using the units for real things uses fractions; for low precision applications, sure, people will say "a half inch", but when precision matters, it's "500 thou". And people use fractions with meters/kilograms/seconds, they say "half a second" when they really mean "500ms" or "500.000000000ms" or whatever. (This is all weird to me because fractions exist in real life -- you can fold a sheet of paper into thirds. But there is no way to express it in a decimal dimension. You can make three sections that are 33mm, 33mm, and 34mm, but that's not quite right. So I guess you make them 33.33333333333mm, 33.33333333333mm, and 33.33333333334mm?)
It gets weirder when you start using the SI prefixes. There are names for every power of ten, but people only use certain prefixes with certain base units. Nobody ever talks about centiamps, but they'll happily use centimeters. Nobody ever uses deci-anythings, but there it is on the trivia test for SI prefixes. And of course, computer people thought that prefixes would be pretty useful, but we make bytes from 8 bits and not 10, so a kilobyte is 1024 bytes... for some reason. (It's 8192 bits, of course!) Decades later someone decided this was stupid and invented new words for every SI prefix just for computer people. The best case is that you sneak in an extra letter for every quantity ("1KiB") and people will think you made a typo and interpret it as 1024 bytes... exactly as they would if you wrote "1KB". If you want to refer to 1000 bytes you ... just say 1000 bytes because there is no byte prefix that means 1000 unambiguously. (The only people smart enough to benefit from this were marketers. They could write 1K and say "well we thought you were using SI prefixes" and convince customers that they were getting 1KiB of storage for the price of 1000 bytes. If it sounds too good to be true it probably is.)
So this all continues to be arbitrary. What about fastener sizes? The metric system gave us the intuitive ISO metric screw thread. How big is an M4 screw? The minor diameter is 3.242mm, which is obvious from the name. An M4 socket head cap screw accepts a 3mm wrench. An M10 screw accepts an... 9... erm... 8mm wrench. (The SAE/UTS system makes even less sense, if that's possible. It's wire gauges and threads per inch, I think.)
Anyway, my point is that it's all super arbitrary and to do anything you need a lookup table. You can go look at a cesium atom and you'll have no idea how that defines the meter, kilogram, second, or inch without a lookup table. You'll never be able to make a screw with just one number ("M4"). So it's not really worth making snide comments about.
To answer your actual question, why does the US use the metric system? Because we started doing science and engineering before the metric system was invented. There was no reason to switch because there are no benefits in switching. It's all arbitrary.
In general, yes. Though like everything else in the US education system, it’s really up to the local school boards. When I went through a couple of decades ago, we did almost everything in SI units with the occasional oddball problem in traditional units to make sure we knew how to do the conversions.
How long does it take immigrants in the US to "go native"?
Also, here in the UK, for the purposes of identifying COVID-19 symptoms, a fever is being defined as 38.6 °C = 100.0 °F, so US recommendations are clearly having an influence in other countries.
Sometime in the 2100s it would be half what it is today and my country could easily fit everyone!
You just need to glance at China's current demographics to see that hard limits on number of children is not a good idea, both societally (in terms of treatment of women and prospects, for want of a better word, for large numbers of single men) and economically (such as the burden of numbers of children and pensioners per working age adult).
The Economist did a brief piece on Africa's demographics recently. It's an interesting read.
https://www.economist.com/special-report/2020/03/26/africas-...
https://en.wikipedia.org/wiki/List_of_sovereign_states_and_d...
Average volume of a human is 66l [1]. Make it 130l to allow some unused space due to imperfect packing.
7.6 billion * 130l = 988 000 000 000 liters.
1 cubic kilometer = 1 000 000 000 000 liters.
[1] https://www.wolframalpha.com/input/?i=average%20volume%20of%...
"What would happen if you were to gather a mole (unit of measurement) of moles (the small furry critter) in one place?"
Singapore's density at 20,445/sq. mile is less than 1/2 that of Monaco, says its reference 5, which is https://en.wikipedia.org/wiki/List_of_countries_and_dependen... .
Thus, only 10% of the land is needed, giving plenty of space for roads, etc.
Of course, if you include walls then you can place people on either side of the wall without an infection problem, so that changes the calculation considerably.
FWIW, I wondered if Vatican City could reach the limit during a papal audience. It looks like perhaps 15,000 people could be there for one? That alone gives a density of 88K/sq. mile (bearing in mind that Vatican City has nearly 6 popes per square mile - or nearly 12 if we include Popes Emeritus.)
Then there's the staff, and the people visiting the museum, and others beyond the estimated population of 1,000.
Even with those, it doesn't seem like it comes close to 223,563/sq. mile.
That means circles of radius 3ft, for a total of 8,693 square miles.
You have a ridge with discontinuous bands of acceptably sloped terrain, usually highly irregular shapes and you have to fit wind turbines along it, taking into account the minimum clearance between turbines and pack as many as possible within. This type of problem is NP-Hard and almost always ends up being done manually due to additional constraints. These include, access road placement, viewsheds, and turbulence modelling.
Would be interesting to learn how other disciplines have applied such a tool to solve real-world problems.
A lot of this is private property. Offices, people's houses, a farmer's farmland. We can't go inside, or trample on the crops of farmers. Then you need to subtract roads - because you can't walk on a road and definitely not a motorway.
So really, shouldn't the land area used be the publicly accessible pedestrian area?
And I dunno about others, but my footpaths are less than a metre long in width in my residential area. In the commercial areas, they tend to be less than 6 metres.
Memories of enjoying it with that one.
