In the spirit of

Can we finally kill 0.999=1?,

Can we finally "kill" (read: "lock") "Do complex numbers really exist?" ?

  • $\begingroup$ Actually, my wife asked me a variant of this question - saying that she can't relate to complex numbers since she can't "see" them. The thread has helped me, particularly I haven't thought about the idea of denoting it as a pair with arithmetic defined on it, and later identifying (0,1) with i. Simple, but effective. $\endgroup$
    – KalEl
    Commented Aug 24, 2010 at 11:17
  • 2
    $\begingroup$ I think if you change the title it's actually a good question. (The title is very silly though, and it is a shame that it is named so badly) $\endgroup$
    – anon
    Commented Aug 24, 2010 at 13:12
  • $\begingroup$ See Can we finally kill 0.999...=1? for the reasons to kill and the effective handling (by Katie Banks) of a question such as this that has very likely received all of the useful answers it possibly could - but is still worth keeping around. $\endgroup$ Commented Aug 24, 2010 at 13:45
  • $\begingroup$ To what extent would you be satisfied filtering out questions tagged [philosophical]? $\endgroup$
    – Larry Wang
    Commented Aug 25, 2010 at 0:00
  • $\begingroup$ @Kaestur: Thank you for the filtering suggestion. I am satisfied with the outcome of the conversation thus far - I really just wanted to ask the community and enough have chimed in (or remained silent) in support of leaving this question untouched at this point. $\endgroup$ Commented Aug 25, 2010 at 2:15
  • $\begingroup$ My choice of language apparently had some unforeseen backlash :/ $\endgroup$
    – BBischof
    Commented Aug 25, 2010 at 4:28
  • $\begingroup$ Related question: math.stackexchange.com/questions/199676/… $\endgroup$
    – Nick Alger
    Commented Dec 7, 2012 at 15:20

3 Answers 3


Why? Some folks (including I) spent significant time to give thoughtful replies.

  • 3
    $\begingroup$ So just lock it, i.e. no one can change and bump it anymore $\endgroup$ Commented Aug 24, 2010 at 7:11
  • $\begingroup$ Of course, and their efforts (and yours) are extremely useful. The action taken on 0.999=1? was intended to preserve the replies but lock it to keep it from collecting more responses - as it is unlikely that more responses will add anything useful at this point. $\endgroup$ Commented Aug 24, 2010 at 13:43
  • 5
    $\begingroup$ Why do you think that future replies are unlikely to add anything useful? I think future members might have much of interest to say. I don't think the thread should be closed, locked, or restricted in any way. $\endgroup$ Commented Aug 24, 2010 at 21:00

It could be protected, to put a 10 reputation threshold for the new answerers. But I disagree that it needs to be locked or closed, for the moment.


Kill it because it's poorly conceived. In what sense do real numbers "exist" anyway? Do ordinary people even understand what is meant by cauchy-completeness? The ordinary examples of real nonrational numbers are still zeroes of polynomials with coefficients in Q (algebraic). In what sense does the quantity $\pi$ "exist"?

The idea that the real numbers are a totally concrete concept is really just a misunderstanding of the facts. In the same way that $pi$ is defined to be a solution to the pair of simultaneous equations cos(x)=-1, sin(x)=0 up to integral multiplication, $i$ is defined to be a solution to the equation $x^2+1=0$.

  • $\begingroup$ why downvote? I upvoted back. Sometimes such questions about mathematical meaning of something is just vague, and I agree those that holds mathematics is no more than a manipulation of rules. $\endgroup$ Commented Dec 23, 2016 at 4:58

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .