• Tavarin@lemmy.ca
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    1 year ago

    I don’t like the Ramanujan explanation at all because c - 4c doesn’t equal the divergent series, since 4c is only supposed to subtract from every other number, so it has more terms at every single limit of n, and thus more terms at infinity. So c - 4c is just -3c, not a divergent series.

      • Tavarin@lemmy.ca
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        1 year ago

        Except it is. Infinities can have different sizes, and the size of an infinity needs to be taken into account when working with them.

        Rama subtracted one infinity that is twice the size of another from it, so he subtracted twice as many numbers as his equation implies.

        • jana@leminal.space
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          1 year ago

          Infinities do have different sizes, yes. But not on that scale. Both of these are countably infinite sets.

          Think about this: there are infinitely many primes. Obviously, not every number is prime. But you can still map primes 1:1 with the natural numbers. They’re both the same size of infinity.

          • Tavarin@lemmy.ca
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            1 year ago

            Not when you’re adding them together.

            c - 4c = -3 - 6 - 9 - 12…

            In order to make c the same as the divergent series you have to subtract the series:

            f = 0 + 4 + 0 + 8 …

            Which is not the same series as 4c.

              • Tavarin@lemmy.ca
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                1 year ago

                It makes the series equal length. You’ll notice this is discussed in the wikipedia article, and a bunch of bullshit handwaving has to be done to try and correct for it.

                c - 4c = -3 - 6 - 9 - 12…

                Simple as that, not some crap divergent series. Rama was a troll.

                • jana@leminal.space
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                  1 year ago

                  You’re adding a bunch of zeroes. Zero is the additive identity. It doesn’t change the value.

                  • Tavarin@lemmy.ca
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                    1 year ago

                    To clarify you cannot add zeros to a non-convergent series, which the series c is.

                    In regular summation you are only allowed to add one zero to the start of a convergent series without changing it’s value, since you know a convergent series has a specific answer.

                    But for non-convergent series you cannot do this mathematically in normal summation.

                    The value of a series is calculated by summing to n digits, and extrapolating. So c to 4 digits is 10, and to 5 digits is 15. 4c to 4 digits is 40, and to 5 digits is 60. But the series 4c with added zeroes at 4 digits is 12, and at 5 digits is still 12.

                    So 4c and 4c plus zeroes are not the same series. The only way to make 4c work in the posted equation is to use “super summation” which is a load of bull. Someone else posted a good video showing why this is the case.

                  • Tavarin@lemmy.ca
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                    1 year ago

                    But it does change the length of the infinity.

                    once again:

                    c - 4c = -3 - 6 - 9 - 12…

                    That’s it, that’s the answer. Anything else is clearly false.