this post was submitted on 24 Sep 2023
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Think "you wake up in the woods naked," Dr. Stone-style tech reset. How could humans acquire a 1-gram weight, a centimeter ruler, an HH:MM:SS timekeeping device, etc. starting with natural resources?

My best guess was something involving calibrating a mercury thermometer (after spending years developing glassblowing and finding mercury, lol) using boiling water at sea level to mark 100 ° C and then maybe Fahrenheit's dumb ice ammonium chloride brine to mark -17.7778 ° C, then figuring out how far apart they should be in millimeters on the thermometer (er, somehow). I can already think of several confounding variables with that though, most notably atmospheric pressure.

I feel like the most important thing to get would be a length measurement since you can then get a 1 gram mass from a cubic centimeter of distilled water.

That's as far as I got with this thought experiment before deciding to ask the internet. I actually asked on Reddit a while back but never got any responses.

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[–] [email protected] 19 points 1 year ago (30 children)

The metre was originally defined in 1791 (...) as one ten-millionth of the distance from the equator to the North Pole along a great circle, so the Earth's circumference is approximately 40000 km.
https://en.m.wikipedia.org/wiki/Metre

The kilogram was originally defined in 1795 during the French Revolution as the mass of one litre (1/1000 m³) of water.
https://en.m.wikipedia.org/wiki/Kilogram

... and the last major SI unit is the second which of course you know is (originally was) 1/86400 day.

Please notice about the Celsius scale : the second reference point isn't a mixture of ice and salt but rather pure water freezing point.

Now how can we as naked humans develop technology to figure this out is something of historical proportion, that's a quite amazing story !

[–] [email protected] 10 points 1 year ago

Your definition of the meter leaves out the most interesting part. Yes, it was 1,000, 000th the distance of the equator to the North Pole, but how far is that? That wasn't known accurately in the 18th Century. So, two Frenchmen, Delambre and Mechain conducted the longest meridian survey every attempted. They also did so while half of Europe was at war with one another. It was an amazingly dangerous endeavor. There is also significant evidence they totally flubbed and hand-waived their results. So, although their science ended up being questioned, the process and method was accepted and the Meter was defined.

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