• not_woody_shaw@lemmy.world
        link
        fedilink
        English
        arrow-up
        5
        ·
        2 个月前

        It’s a room made from platinum-iridium, and kept in a triple-locked vault at the International Bureau of Weights and Measures in France.

        • cartoon meme dog@lemm.ee
          link
          fedilink
          English
          arrow-up
          3
          ·
          2 个月前

          unfortunately, opening the door changes the temperature, so in practice instruments are calibrated from copies of the room built at other metrology institutions around the world.