Edit made on June 11, 2016 by ColinWright at 19:51:54
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WW WM
HEADERS_END
Here's an interesting paradox.
We know that the rational numbers are countably infinite.
That means we can list them in order: EQN:r_1,{\quad}r_2,{\quad}r_3,
* EQN:r_1,\;r_2,\;r_3, /etc./
So cover
* the first rational with an umbrella of size 1/2,
* the second rational with an umbrella of size 1/4,
* the third rational with an umbrella of size 1/8,
* the fourth rational with an umbrella of size 1/16,
and so on ...
The umbrellas are open.
Clearly all the rationals are covered.
Even more, consider some rational. Its umbrella is of
rational size, so we can look at the rationals under
its edges. Clearly they are rational, so they're covered with
umbrellas, and these umbrellas overlap.
This shows that all the real numbers must be covered and kept dry.
Or not.
The umbrellas are, in total, of length 1. They overlap,
so the amount of numberline ~number-line covered is strictly less
than 1.
So the number line ~number-line is, in fact, entirely wet.
How does that work ~work ??!!