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The interesting thing here is that it's much harder to put this problem properly into mathematical terms than it is to solve it. The whole insight here is that
by xyzzyz 13y ago
The interesting thing here is that it's much harder to put this problem properly into mathematical terms than it is to solve it. The whole insight here is that you a "description" of number is just some finite sequence of symbols from a finite alphabet. Now, if you understand why cardinality of continuum is greater than aleph null, it's totally straightforward to show that there are only countably many descriptions, but continuum many reals, it's the kind of problem you give freshmen students on their first encounter with cardinalities. Thus, the big achievement of this guy is to actually come up with idea of indescribable numbers by himself and interpreting this question mathematically. In other words, the questions are usually more important than answers.
There's one minor, but nevertheless important mistake made by the author. Author says :
>The infinity just a step bigger than [aleph null] is Aleph one, the infinity of real numbers: The infinity of an impossibly dense line of numbers
While cardinality of reals is certainly larger than cardinality of integers, it is not true that it's just one step larger. Funny thing is that it's not false either: it was proved by Cantor and Cohen that it's impossible to prove or disprove that aleph one is cardinality of continuum. This is the famous continuum hypothesis.
- danbruc 13y agoI will just assume the continuum hypothesis is true until someone shows me a set with cardinality between Aleph 0 and Beth 1...oh, wait...
- cousin_it 13y agoInterestingly, for any method of describing real numbers (i.e. mapping from finite strings to real numbers), the diagonal argument gives an explicit description of a single number that's undescribable by that method. Just out of reach, so to speak.
- gjm11 13y ago> it was proved by Cantor and Cohen Goedel and Cohen. Goedel proved it might be (constructible universe); Cohen proved it might not be (forcing). I think Cohen's on record as saying he suspects that with the "right" axioms, mathematicians might come to think that CH is obviously false.
- xyzzyz 13y agoAh, of course, I don't know why I have written Cantor. It's too late to edit now.