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Since

SU(2)/Γ ≅ SO(3)/A5

the Poincaré homology sphere is the space of all geometrically distinguishable positions of an icosahedron with fixed center and size in 3.

Since we can think of SU(2) as the unit sphere in 2, we have

SU(2)/Γ ⊂ 2

2/Γ is the space of all geometrically distinguishable positions of an icosahedron with fixed center and arbitrary (possibly vanishing) size in 3.

The singularity happens when the icosahedron shrinks to zero size!










For more, read the Wikipedia article homology sphere and especially this article: