[umanwizard]

Is there any compelling reason why the US should switch to the metric system for daily use?

Metric is already used universally in science and engineering, which seem to be the main fields in which consistency across countries matters. I completely agree that in physics, chemistry, engineering, medicine, etc., it is important to use standard units. But what harm is it doing in practice if in everyday life, Americans say things like "I weigh 180 lbs" instead of 81 kg?

The argument that the metric system makes unit conversions easier (e.g., the fact that it's immediately obvious how many meters are in 20 km, but not how many feet are in 12 miles) is true, but not very compelling to me. I virtually never find myself wanting to do these conversions in a non-scientific or non-engineering context, and on the very rare occasions where I need to, I can always look them up on Google.

A good comparison is degrees Celsius, which are just as arbitrary/unscientific (the standard metric unit is the Kelvin). Somehow people around the world get along fine using Celsius.

[jbay808]

Why should there be any separation between science and daily life?

Think about it not for the benefit of the current generation who would be forced to burden the switch, but for the next generation who could reap the benefits.

I think one issue is that by growing up with US units and then using a second system for science and engineering, it can make American students studying those topics feel like they are in an unfamiliar territory and interfere with their intuition. Most will eventually overcome this through practice and become fluent in both systems, but it's still a barrier. Science becomes a Special Discipline requiring Special Language different than what your family uses at home. Like if all science were still done in French or Latin, and you needed to study those to read a paper.

Until you have met people who grew up abroad measuring their height in cm and their weight in kg, preparing food from recipes listing ingredients in grams and mL, to whom those units are completely natural for daily life and are also the same ones they use at work when designing machines and filling test tubes, it's easy to feel that US units simply "are" the units suitable for daily life, as though that were a universal truth and not just a local cultural oddity.

Not to mention the massive net costs of having suppliers worldwide making extra sets of almost identically sized components that nonetheless aren't interoperable. Screws with 3 mm and 3.175 mm diameter, etc.

[ward]

> Science becomes a Special Discipline requiring Special Language different than what your family uses at home. Like if all science were still done in French or Latin, and you needed to study those to read a paper.

You realize this is still a problem for most of the world and needing to learn English, right? :P I'm hoping we can solve this in my lifetime with everyone knowing one standard language through education as a child, but as it stands the struggle is real for many of my fellow non native English speakers.

That said I agree with you, all these differences are a pain and I'm confronted with them way too often in my daily life.

[umanwizard]

> I'm hoping we can solve this in my lifetime with everyone knowing one standard language through education as a child

It seems like this is rapidly becoming the case in the Western world, and that that language is English.

[jbay808]

Absolutely! America is very lucky to have come out on the right side of that lottery. But then it unnecessarily goes and handicaps itself by making measurements into a foreign language.

[reaperducer]

A good comparison is degrees Celsius, which are just as arbitrary/unscientific (the standard metric unit is the Kelvin). Somehow people around the world get along fine using Celsius.

You don't realize how arbitrary Fahrenheit and Celsius are until you try cooking at altitude. When I make breakfast in a particular town I frequent, it takes almost an extra minute to boil an egg.

[macintux]

My Jeep is a bizarre combination of metric and SAE. ISS needs to have two sets of tools[0]. NASA lost the Mars Climate Orbiter due to confusion over the units of measure[1]. Patients are given the wrong dosages[2].

It seems safe to say it's a point of ongoing friction, especially on things like international trade.

[0]: https://space.stackexchange.com/questions/12391/iss-nuts-and... [1]: https://mars.jpl.nasa.gov/msp98/news/mco991110.html [2]: https://www.chihaklaw.com/Articles/Confusion-over-metric-mea...

[umanwizard]

I already made it clear that I totally agree metric should be standard in engineering or scientific applications. I wasn’t aware that this isn’t the case in the US — thanks for the info. I believe it is at least 95% the case in the US and I think we should make every effort to get that to 100%.

I still stand by my argument that it does not matter much for everyday life.

[Oletros]

Why have two separate sets of unit systems?

[umanwizard]

Well, the point I was arguing was "why not" have two separate systems ?

As for "why" to have them, well there isn't a good reason intrinsically -- if there were a way to magically convert the US to metric overnight, it wouldn't bother me. It just seems very unlikely and difficult in a country as huge and culturally diverse in the US. Especially since, by the standards of the rich/developed world, the US is pretty poorly educated, and also very difficult to govern (Obamacare, a law that would have seemed like a moderate reform, relatively simple to pass in any parliamentary system, is the most radical change in any area of policy enacted by the US federal congress in the last decade).

The thing a lot of people miss about the ultra-gridlocked US system is that there's a huge gulf between it being obvious to most people that "we should enact some policy" and anything actually changing. The best answer to "why doesn't the US do this or that" is often just "its political institutions can't".

Since it's so unlikely to change, and given my argument that it isn't a big deal in practice, I guess my main point is that we rationally-minded people should stop worrying/complaining about it so much.

[tpush]

> A good comparison is degrees Celsius, which are just as arbitrary/unscientific (the standard metric unit is the Kelvin).

Celsius is literally the same scale as Kelvin, just shifted so that 0c = water freezing.

[umanwizard]

Yes, and water freezing is a totally arbitrary value.

Fahrenheit is scaled such that 0 is about the coldest it gets where I live, and 100 is about the hottest. (Very approximately, but close enough). That strikes me as a lot nicer in practice (since 99% of the time people are talking about temperature, it’s related to weather) than something based on the physical properties of a particular substance.

Also water freezing at 0 and boiling at 100 is only valid for a specific, non-metric, air pressure.

[ars]

Celsius is a particularly bad metric unit. It doesn't have enough units in the range most commonly encountered by humans, and it goes negative, which is also to be avoided in a good unit.

So you end up needing negatives, and decimals.