• UsernameIsTooLon@lemmy.world
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    8 months ago

    Technically you can’t measure anything accurately because there’s an infinite amount of numbers between 1 and 0. Whose to say it’s exactly 1? It could be off by an infinite amount of 0s and 1.

    Achilles and the Tortoise paradox.

  • guywithoutaname@lemm.ee
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    8 months ago

    Not true. If you define the circumference in terms of pi, you can define the circumference exactly.

        • h3ndrik@feddit.de
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          8 months ago

          Was going to say the same. Also π isn’t infinite. Far from it. it’s not even bigger than 4. It’s representation in the decimal system is just so that it can’t be written there with a finite number of decimal places. But you could just write “π”. It’s short, concise and exact.

          And by that definition 0.1 is also infinite… My computer can’t write that with a finite amount of digits in base 2, which it uses internally.

          So… I’m crying salty tears, too.

          [Edit: And we don’t even need transcendental numbers or other number systems. A third also doesn’t have a representation. So again following the logic… you can divide a cake into 5 pieces, but never into 3?!]

      • HopFlop@discuss.tchncs.de
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        8 months ago

        That doesnt make a difference. You can find the exact circumference of a circle, you just cant express it in the decimal system as a number (thats why we have a symbol for it so you can still express the exact value)

  • ns1@feddit.uk
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    8 months ago

    More likely a mathematician would correct you instead of crying. Pi is not infinite, its decimal expansion is infinite!

    • zkfcfbzr@lemmy.world
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      8 months ago

      Plus even that isn’t enough: 10/3 has an infinite decimal expansion (in base 10 at least) too, but if π = 10/3, you’d be able to find exact circumferences. Its irrationality is what makes it relevant to this joke.

      A mathematician is also perfectly happy with answers like “4π” as exact.

      Plus what’s to stop you from having a rational circumference but irrational radius?

      Writing this, I feel like I might have accidentally proved your point.

      • danc4498@lemmy.world
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        8 months ago

        Mathematicians taking a physics class and being told they have to round things. That’s when the tears start flowing.

    • Carnelian@lemmy.world
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      8 months ago

      The actual punchline here should have been “there is no known equation to calculate the exact perimeter of an ellipse”, then sucking tears from an astrophysicist

      • marcos@lemmy.world
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        8 months ago

        Try it when you find some physicist that cares about exact values. Or when you see pigs flying over your head, both are about as likely.

    • LanternEverywhere@kbin.social
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      8 months ago

      Exactly, a fraction is completely as valid of a way to express a number as using a decimal.

      1/2 = 0.5

      They’re both fully valid ways to write the exact same quantity

    • chillhelm@lemmy.world
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      8 months ago

      This is the correct answer. Pi is known. What it’s decimal expansion looks like is irrelevant. It’s 1 in base Pi.

      • cogman@lemmy.world
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        8 months ago

        Yup, similar to the square root of two and Euler’s number.

        These are numbers defined by their properties and not their exact values. In fact, we have imaginary numbers that don’t have values and yet are still extremely useful because of their defined properties.

  • bstix@feddit.dk
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    8 months ago

    Easy. Take a wire that is exactly 1 meter long. Form a circle from the wire. The circumference of that circle is 1 meter.

      • RandomStickman@kbin.run
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        8 months ago

        I think it’s because no matter how many corners you cut it’s still an approximation of the circumference area. There’s just an infinite amount of corners that sticks out

        • marcos@lemmy.world
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          8 months ago

          There’s just an infinite amount of corners that sticks out

          Yes. And that means that it is not an approximation of the circumference.

          But it approximates the area of the circle.

      • Zerush@lemmy.ml
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        8 months ago

        It’s a fractal problem, even if you repeat the cutting until infinite, there are still a roughness with little triangles which you must add to Pi, there are no difference between image 4 and 5, the triangles are still there, smaller but more. But it’s a nice illusion.

      • Armok: God of Blood@lemmy.dbzer0.com
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        8 months ago

        Because you never make a circle. You just make a polygon with a perimeter of four and an infinite number of sides as the number of sides approaches infinity.

  • Dippy@beehaw.org
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    8 months ago

    Nasa uses 15 digits of pi for solar system travel. And 42 digits is enough to calculate the entire universe to atomic accuracy

    • Malgas@beehaw.org
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      8 months ago

      And 65 digits is sufficient to calculate the circumference of the visible universe to within a Planck length.

      • dukk@programming.dev
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        8 months ago

        I know enough digits of pi to calculate the circumference of the universe??

  • janAkali@lemmy.one
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    8 months ago

    Who said Pi is infinite? If we take Pi as base unit, it is exactly 1. No fraction, perfectly round.

    Now everything else requires an infinite precision.