I am wrong in thinking the circumference or the diameter of a circle has to be rational?

  • Moobythegoldensock@lemm.ee
    link
    fedilink
    arrow-up
    8
    arrow-down
    1
    ·
    edit-2
    9 months ago

    In the real world, you’re measuring with significant figures.

    You draw a 1 cm line with a ruler. But it’s not really 1 cm. It’s 0.9998 cm, or 1.0001, or whatever. The accuracy will get better if you have a better ruler: if it goes down to mm you’ll be more accurate than if you only measure in cm, and even better if you have a nm ruler and magnification to see where the lines are.

    When you go to measure the hypotenuse, the math answer for a unit 1 side triangle is 1.414213562373095… . However, your ruler can’t measure that far. It might measure 1.4 cm, or 1.41, or maybe even 1.414, but you’d need a ruler with infinite resolution to get the math answer.

    Let’s say your ruler can measure millimeters. You’d measure your sides as 1.00 cm, 1.00 cm, and 1.41 cm (the last digit is the visual estimate beyond the mm scoring.) Because that’s the best your ruler can measure in the real world.

    • HobbitFoot @thelemmy.club
      link
      fedilink
      English
      arrow-up
      1
      ·
      9 months ago

      And this comes up in some fields like surveying. The tools are relatively precise, but not enough to be completely accurate in closing a loop of measurements. Because of the known error, there is a hierarchy of things to measure from as continual measurements can lead to small errors becoming large.

    • Klear@lemmy.world
      link
      fedilink
      arrow-up
      1
      ·
      edit-2
      9 months ago

      I used to think that “1 + 1 = 3 for high enough values of 1” was a joke until I realised it’s actually true when it comes to real-world measurements.