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.

  • neptune@dmv.social
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    1 year ago

    https://www.howtoinventeverything.com/

    This book was interesting.

    Are you asking about how you reinvent the exact same meter? Well that won’t happen. Our units were arbitrary, useful, widely adopted, and then rigorously defined.

    The book walks you through it all. You can don’t need to redo civilization exactly the same (the author even suggests some very important things to invent differently, especially in better orders)

    • janus2@lemmy.sdf.orgOP
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      1 year ago

      It’s one of my favorite books of all time 😁 to the point where I own a hardback of it despite being staunchly pro-just-read-books-on-my-phone

      IIRC they actually printed a centimeter ruler in the back of the book as an answer to this specific problem.

      • neptune@dmv.social
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        1 year ago

        What’s the point of recreating our arbitrary system? It just has to be useful and universal

        • janus2@lemmy.sdf.orgOP
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          1 year ago

          That’s a fair point. Most likely if a group of people did some kind of Long Term Naked & Afraid experiment they’d just start with some length of particularly well-crafted cordage, call it a New Meter™ and go from there