The paragraph on the meter should mention that their measuring error from the pole to the equator was .02%, which, without using satellites or even electricity, is fucking impressive.

That is impressive & a nice amendment on your part. Thank you for the added detail

*aluminium

"We decide when history starts" is a hell of a sentiment.

It's only consequencial if you want to get rid of anything that was imposed by the church.

Is someone really arguing that prime numbers are a thing because we have 5 fingers?

i think it is ok, as meter more correctly matches the pronounciation

Maybe you've never heard of decimal inches. Anything under 1/32" people start using 'thou' as in thousandths of an inch.

Subtracting fractions is something you can learn. Children can even do it.

Watch or I'll go nucular on your ass

Uncle John's bathroom reader! I know this has nothing to do with the metric system, but I saw the toilet paper roll around the page number and got a surge of happy brain sauce due to the happy memories of all the copies I owned through the years: 2

Heyyy I've got two of Uncle John's books on the commode right now!

So how the hell was it done? Long piece of rope? Hot air balloon? Or having a bird fly from one point to another and timing it?

Calculations. In 240 BCE, Eratosthenes used a stick. He basically found a place where the sun was directly overhead, and measured the shadow from a stick a known distance to the north of that location. He approximated the circumference of the earth to be 25,000 miles, which was off by 99 miles.

Literally because it scaled

How do we know the conversion of whatever length unit he was using, in modern units?

Lots of triangulation and extrapolation

https://en.wikipedia.org/wiki/Arc_measurement_of_Delambre_and_Méchain

It would have worked so well. 2 digit timestamp gives you 15 (old)minute accuracy which is just perfect for appointments and organizing your day. Digital minutes would be a bit longer than old minutes which is fine for bus/train times etc. Digital seconds a bit shorter than old seconds which is great for timing things. I always thought a second was a wee bit longer than it ought to be anyway.

Uhh, educated guesses. The stadion wasn't exactly standardized. Most of the conversions I see put 10 stadia at 1 mile so that's what I went with.

https://en.wikipedia.org/wiki/Stadion_(unit)

The main thing is his methodology was precise.

I have this book, its great! Some funny bullshit in there

Hmm... What We Did Before Smartphones. I should write a book so the Young's dont forget ye olden ways.

Got two letter 'e's in it, and they're both pronounced differently. To be fair, it's far from the most divergent spelling-to-saying word in English. Some wrong-looking abomination like 'meetir' would be even better.

It doesn't even weigh a kilogram. It masses one kilogram. It's weight will be something like 9.8 Newtons.

Someone so consistently responding to themselves is pretty entertaining.

The metric prefix system is a fantastic invention, akin to the arabic number system. Honestly it's surprising no one came up with it sooner... but (and I'm sure I'll catch some flak for this) the metre is an awkward length - it's too big for human scale measurements. The decimetre is not as bad but still not very good, and it's also not commonly used. The centimetre has the opposite problem - it's too small for the human scale but too big for precision work.

Don't get me wrong, the horrible conversions between imperial units make the system unusable for me, but the unit lengths themselves are scaled to humans because they weren't initially defined arbitrarily by some committee (why should the distance from the pole to the equator be used as the baseline for a measurement used by humans?). I think the inch and foot are great lengths to use on a daily basis, they feel quite natural.

What annoys me the most is that we could have had the best of both, since the foot and inch are only a factor of 12 apart, so we could have had a metre measuring about one foot and a decimetre measuring about an inch.

I think the inch and foot are great lengths to use on a daily basis, they feel quite natural.

Well that would be because you use them on a daily basis. I find meters and centimeters perfectly natural too, and would be hard pressed to think of a situation where the scale of inches and feet would be strictly better.

Nice try! I live in a metric country and use exclusively metric units.

why should the distance from the pole to the equator be used as the baseline for a measurement used by humans?

For both philosophical and scientific reasons, they wanted a definition that could be recreated any where in the world, certainly not the thumb or foot of any one man. With the "distance from pole to equator" definition, you just need to measure a long north-south axis (say a few hundreds km), and knowledge about the figure of the Earth helps you scale that to the full definition. You can do that anywhere on Earth.

Another considered definition was the length of a pendulum whose half period is 1s, but even at the time the effect of local gravity was deemed to be too much

How do you know how it feels to use imperial if you exclusively use metric? And daily!

That's not the point I'm trying to make. You can derive a length from any number of physical constants to make it reproducible, but considering the divisor of exactly ten million suggests the metric committee were far more interested in making something 'clean' than something human-friendly. They could have basically done what they do with the modern redefinitions of the metre - the distance travelled by light in 1/299792458 ths of a second. Obviously they chose that number to keep the definition in line with the original, but they could have done that with the original definition to make the metre basically any length they wanted, but they didn't.

Because I have had to work with American companies as part of my job for the past couple years. For the entirety of my personal life and the rest of my professional life I use metric. I'll grant you I should have said 'almost exclusively' in my previous comment, but I think that's just splitting hairs.

All measurements are arbitrary. This feels like that Fahrenheit debate where "60 feels natural for room temperature" as if anyone has any idea what number a room should be. A meter is just a chunk of distance about this size (holds hands apart). There's nothing a foot can add to a measurement that a meter can't. You'll need fractions and smaller or bigger units in all real world cases anyway, so having easy conversions is much more useful than a "natural" base unit.

All measurements are arbitrary

Perhaps in a perfectly rational world, but humans are silly creatures. The human brain evolved to deal with small numbers. Distinguishing one vs two lions is important, but distinguishing 14 vs 15 lions is not, so our brain immediately recognises numbers up to about six and has to rely on conscious counting for anything larger. If I told you that "This dog is two ducks tall" you'd have a pretty good idea of how big the dog is, but if I said it was "20 mice tall" you might have trouble visualising, or worse "450 ants tall" at which point I would have no idea. Our brains don't innately have the ability to accurately conceptualise large numbers, which is why the metric prefix system works so well - it keeps numbers relatively small.
I think the same logic applies to decimals and fractions. Simple fractions like halves through to perhaps fifths can be visually conceptualised at a glance, but beyond that it requires calculation.

What that means to me is that ideally your measurement unit should be big enough to be able to measure most things you deal with on a daily basis using no more than say 10 units (arbitrary, I could be persuaded down to 6 or up to 20), and still measuring most things without going smaller than about 0.2 units.
As an example, consider human height (after all, what could be more a more human measurement?). The average person is between 1.5 and 1.9m tall, which is not a great start since we're riding close to the 0.2 'lower resolution' just describing the whole range. You could use centimetres but then you're looking at 150 or 190 which is much too large to visualise nicely. Decimetres is better but not great. Feet is a pretty good fit for this, since that'd be about 4.9 to 6.2 ft. We haven't violated either the max or minimum requirements and we still have a decent resolution within the range too.

having easy conversions is much more useful than a "natural" base unit.

I agree, but my whole point is that we didn't have to choose!

If we were to make a meter today, I would think it would be a fraction of the speed of light.

And on that note, I honestly think a base 12 number system would be easier in the long run.

Coincidentally we accidentally got really close to 1/300 000 000th the speed of light in a vacuum. 299 792 458 m/s.

Honestly, humans are pretty damn lucky when it comes to cosmic coincidences.

Thinking about you, moon and Jupiter.

It bugs me so much that they used the decimeter to define the liter and kilogram instead of using a meter to define a liter and gram

Square-Cube law was gonna fuck with that one way or another. A meter is a very human-oriented unit of measure -- but a cubic meter of water is a fuckton more than most people have to deal with in the normal course of business.

And we're gonna call that one gram of water?

One liter of water being 1000cc or one kilogram keeps the scales much more useful, imo. And personally, being essentially a sentient bag of water with a handful of other elements gluing it together...I appreciate that.

Ultimately it's all the same, anyways. It's just a matter of the words we call them, the math works out the same, if we just give them different names. That's the point. Math is the constant. Assuming a space alien can understand Base10, we can explain the metric system in terms of universal constants that make sense in Base10.

Unfortunately, all number systems are Base10...

about 4.9 to 6.2 ft

Hey! Didn't you just violate your own rule of "0.2 lower resolution"?

You're right about big numbers losing relevance in our minds, but I don't think that's even true for units of measurement. Since all units are arbitrary, they are inherently linked to a mental model with simple maths, quick conversions and rules of thumb. 450 ants is too large to visualize, but 450cm is simply the height where an old chestnut tree's branches start. There are no 450 distinct centimeters involved in any of that, so you don't have to keep them in your mind.

Compress down, guesstimate a piece of physical distance, continue with your day. Whether that mental model started as 15 foot or 450 centimeter isn't really relevant, as long as you have developed a sense for the size of various things in your chosen units, and the units map nicely to other common units you might encounter. If you need any more precision, you take out your tools.

And the fact that Inch is not precisly defined. "Three grains of ..." or "King's thumb" is not a precise definition.

The meter is nowadays literally defined as the distance light travels in a certain amount of time, ie through the speed of light.

In what context do people use metric units of length larger than a kilometer? 🤨

Why this year I drove 1.5 Megameter by car

Technically you can say that, I just don't remember ever hearing it in any context, not even space travel.

It's so impressively thought out. I got my mind blown when the physics teacher told us that 1 calorie is the amount of energy it takes to heat 1cc by 1°C. Suddenly you realise that someone actually put some effort into this whole system

You clearly haven't been a kid measuring a 7m penalty kick on some random field. It works perfectly fine.

I would rather walk-measure the side of a field than tiptoe-measure it.

If you want to be more precise, you need to know your body's measures. Like the span of my hand from thumb to middle finger is 21cm. 20 if I'm not that concerned about accuracy. I can measure quite a lot with that. Or 170cm for my arms spread apart (wingspan).

Kilo just means 1,000, a kilo meter is just 1,000 meters. That last point is simply stupid conjecture by the author, and unlike the metric system, isn't well thought out.

You could measure things in kilo miles if you want...

I will always defend mes amis français against le perfide albion d'outre mer

Astronomy.

Multiple kilometers for example.

I don't think he used miles.

Are you American by any chance? I ask because in the UK we primarily used yards before metricification which are almost the same length as metres and there wasn't any sort of long rumbling "ohhh yards are an awkward length" they were just used. I think you feeling that feet are more suitable is probably just familiarity.

And iirc 1 Joule is the energy required to lift 100g by 1m