• mkwt@lemmy.world
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    12 days ago

    It’s pretty well settled mathematics that infinities are “the same size” if you can draw any kind of 1-to-1 mapping function between the two sets. If it’s 1-to-1, then every member of set A is paired off with a member of B, and there are no elements left over on either side.

    In the example with even integers y versus all integers x, you can define the relation x <–> y = 2*x. So the two sets “have the same size”.

    But the real numbers are provably larger than any of the integer sets. Meaning every possible mapping function leaves some reals leftover.

    • Steve Dice@sh.itjust.works
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      11 days ago

      Weeeell… not really. It’s pretty well settled mathematics that “cardinality” and “amount” happen to coinciden when it comes to finite sets and we use it interchangeably but that’s because we know they’re not the same thing. When speaking with the regular folk, saying “some infinities are bigger than others” is kinda misleading. Would be like saying “Did you know squares are circles?” and then constructing a metric space with the taxi metric. Sure it’s “true” but it’s still bullshit.