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Comment by michaelpinto | Hacker News Reader

Nassim Taleb argues that the metric system is too abstract for people to relate to as where measurements like an inch (the size of your thumb) are much more easy to relate to. And as someone who studies usability I have to say that he's on to something.

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To this day I still don't remember the exact number of feet in a mile. I know between 4-5 thousand, but the exact number is just absurd.

exactly 5280. Its not absurd. It has always been that number.

The mile has not even been the same size, it changed in 1959 https://en.wikipedia.org/wiki/Mile and it still is not at sea, where the nautical mile is longer. The Roman mile was 5000 feet.

I stand corrected.

not really. the mile was changed from 5000 to 5280 feet in order to make it an even number of furlongs (a furlong is 40 rods and a rod is 5.5 yard, the closest thing to 5 meters). you're in good company though, as there're also the geographical mile, the british nautical mile, the sea mile, the russian mile, the scots mile, the irish mile, the arabic mile and finally the original 5000 feet roman mile from where everything started, at least it was consistent over the entire roman empire. almost forgot: there's also the nautical mile but I'll spare that as it's really the only one whose definition is an angular measure applied to the earth surface instead of an arbitrarily decided unit.

I suspect it is mostly whatever you grew up with first. (BTW my thumb is 5cm or longer depending on where you measure.) If metric was difficult or less relatable then wouldn't people have noticed in the 190 or so countries that use it pervasively?

An inch is more or less the width of a thumb, not the length. It always surprises me how few people know that (is there a conspiracy in the USA, where parents teach their children about the inch at exactly the time their thumb is an inch long? When do they learn about the foot, then?)

That should be obvious from http://en.wikipedia.org/wiki/Ancient_Roman_weights_and_measu..., which states "The Roman foot was sub-divided either like the Greek pous into 16 digiti or fingers; or into 12 unciae or inches". So, Romans thought a thumb to be longer than a finger by 4:3.

I think it also makes sense when looking at the way one would measure stuff. How would you go about measuring something in thumb lengths with some accuracy? With widths, you can grab it between thumb and need finger of one hand, place thumb and index finger of the other hand next to it, move first pair to the other side, etc.

> An inch is more or less the width of a thumb

My thumb width is 7/8th of an inch, and I'm 1m94cm tall.

> is there a conspiracy in the USA

Although I live in the US, I am an immigrant who grew up with the metric system and consequently not part of said conspiracy.

What if you have big thumbs? In any case, you can always find connections: a cm is about the width of a fingernail, for example.

The most useful one in metric is the width of the open hand, from thumb tip to pinkie tip is about 20cm. It is surprisingly constant from person to person. I measure everything on the order of a meter with that, whether a piece of furniture will fit through a door, the size of rug I need, etc... I'm sure there are more "body measures" like this but this is the most useful to me.

You just use other things to relate to - one meter is a (somewhat larger than normal) step, your pinky is probably about one centimeter width and so on. There are as many things around you having simple sizes in the metric system as in the imperial system.

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