How could SI units be derived from scratch without the use of modern technology? - eviltoast

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.

  • janus2@lemmy.sdf.orgOP
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    1 year ago

    Interestingly, if you have your meter measure you could use that to measure atmospheric pressure by seeing how far you could raise water in a column by suction. At standard atmospheric pressure you should be able to lift fresh water 10.3m.

    Oh yeah! I should have remembered that actually, since I was just rewatching an episode of Connections 2 that mentions this height limit in the context of vacuum pump history (I think it’s detailed more in season 1 but I forget which episode). So 10.3 m is another key measurement that you want at least one human to have memorized :]

    Gravity is altogether too unreliable and should be abolished.

    This reads like a Douglas Adams quote and I love it.