I think questions like this A mirror flips left and right, but not up and down (which is pure geometry) should be moved to Mathematics.

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    $\begingroup$ Darn Anixx, after discrediting fundamental physics questions by saying they are metaphysics did not pan out, you are not going after physics questions that naturally involve mathematical concepts to move them away, or are you? The one you cite in this question is a perfectly good physics question. $\endgroup$ – Dilaton Sep 5 '12 at 14:56
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    $\begingroup$ The community here has not previously shown much interest in drawing this line very strongly. $\endgroup$ – dmckee --- ex-moderator kitten Sep 5 '12 at 15:49
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    $\begingroup$ I find the mirror question to be an odd example, since the logic could disqualify the entire optics field. $\endgroup$ – Alan Rominger Sep 5 '12 at 16:14
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    $\begingroup$ @AlanSE For that matter I find the mirror question odd as an example of a math question because the "paradox" revolves around the perception of the image as a "person" possessed of a point of view and entitled to evaluate "left" and "right" in its own frame. If you stopping attributing person-ness to the image then it becomes clear that the mirror flips in/out but not any transverse direction. $\endgroup$ – dmckee --- ex-moderator kitten Sep 5 '12 at 16:18
  • $\begingroup$ @dmckee left and right in the person's basis is a pure geometry. $\endgroup$ – Anixx Sep 5 '12 at 17:11
  • $\begingroup$ @Dilaton if you do not see destinction between physics, mathematics and philosophy, it is your problem. This does not mean the destinction does not exist. $\endgroup$ – Anixx Sep 5 '12 at 17:13
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    $\begingroup$ The question is stated physically, it involves real objects --- a mirror and a human, not some abstract mathematical concepts. $\endgroup$ – Yrogirg Sep 6 '12 at 4:47
  • $\begingroup$ @Yrogirg Well if you ask how to make a gold ball with the same volume as a given gold cube, will this question be mathematical or physical? $\endgroup$ – Anixx Sep 6 '12 at 6:54
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    $\begingroup$ Physical of course --- you just melt a cube into a ball. $\endgroup$ – Yrogirg Sep 6 '12 at 7:02
  • $\begingroup$ @Yrogirg no, you are asked to create a second object, not to destroy former. Also to make a ball you have to know a radius. $\endgroup$ – Anixx Sep 6 '12 at 7:25
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    $\begingroup$ As long as enough people think it is appropriate here, then it need not be moved. $\endgroup$ – MBN Sep 6 '12 at 10:22
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    $\begingroup$ How is this not physics? $\endgroup$ – Abhimanyu Pallavi Sudhir Jun 23 '13 at 14:05

The reason this is not a good idea is because there is a lot of mathematical thinking which is done outside the mathematical community, because it has not acquired the proper rigorous embedding into standard axiomatic systems. Fluctuating quantum field theory is an example, but so is statistical theory of fields (like turbulence), mathematical topological models (like the topological field theories, which are easier to make mathematics because they have a smaller Hilbert space, but the embedding to mathematics is still not complete), and various cases where the best mathematical solution is not the most useful physical solution, for example, the flow of a fluid in a square duct.

The physics approach to mathematical problems is to make whatever approximations work best given the physical context, so an exact solution, like the exact solution of the quadratic equation, is often inferior to a linearized solution. The mathematics site looks to the answer which gives the most insight into the formal structure of the problem, not the answer which gives the most insight to the physical structure of the problem.

So I would even tolerate pure math questions where physicists and mathematicians disagree on the best answers, because the disagreements reflect a different point of view regarding what are the important aspects of a well posed mathematical problem.

  • $\begingroup$ Okay but what about the proposed example? The question is just elementary geometry. $\endgroup$ – Anixx Sep 10 '12 at 19:43
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    $\begingroup$ @Anixx: I'm not a fan of it, but I'd rather err on the side of inclusion. You can't exclude all "golly-gosh that's cute" questions, and that one dates back to long before I was here. Just tolerate it, it isn't doing much harm. It does give those people who don't want to do more serious science something to do, and that's a good thing, it gives a sense of contribution to get people at any level to say "hey, I know this one!". $\endgroup$ – Ron Maimon Sep 12 '12 at 6:50

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