I Higher Dimensional Spheres viz. Cubes

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The discussion focuses on the properties of higher-dimensional spheres and cubes in Euclidean geometry, particularly their volumes as the number of dimensions increases. It highlights that while the volume of a unit sphere approaches zero, this is due to the unit cube expanding infinitely, as its diagonal grows without bound while the sphere's diameter remains constant. When comparing spheres and cubes of equal volume, it is noted that the diagonal of the cube is approximately 2.066 times larger than the sphere's diameter. Additionally, a unit cube of dimension n/4 or less can be completely enclosed by an n-dimensional unit volume sphere. The intersection volume of a unit volume n-ball and n-cube, when centered together, diminishes at a rate of roughly 1/sqrt(n), indicating that both shapes grow at the same rate but diverge in their dimensional expansion.
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This is about Euclidian geometry in n dimensions. On this subject it is often noted that the volume of the unit sphere goes to zero as n increases. However this has more to do with the unit cube getting larger than the sphere growing smaller. As n increases the diagonal of the unit cube grows without bound while the diameter of the unit sphere remains constant, so the result is no surprise.

How about comparing what happens with spheres and cubes both with volume one? Then the sphere can also grow. Things cancel out nicely so using Stirling's approximation we get that with large n

(diagonal of cube)/(diameter of sphere) = (pi*e/2)^1/2 = approx. 2.066.

That is, the "diameter" of the cube is a bit more than twice that of the sphere of the same volume.
Taking it a step further, we can show that for large n a unit cube of dimension n/4 (rounded down) or less can be entirely enclosed by an n dimensional unit volume sphere.
 
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Suppose we have a unit volume n-ball and n-cube that share the same center. How large is their intersection?

The volume of their intersection goes to zero at a rate of roughly 1/sqrt(n). Both figures grow at the same rate but in different directions.
 
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