SO(3)

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Representations

The Lie algebra of SO(3)\, is \mathfrak{su}(2)\,. Representations of the group are labeled according to the representations of the algebra, which are characterized by their spin (j_1, j_2)\,.

Topology

SO(3)\, is homomorphic to the 3-sphere S^3\,. The map S^3 \to SO(3)\, is a surjective homomorphism of Lie groups with kernel \{\pm 1\}\,.

Since rotations of the same angle are in the same conjugacy class, and since rotations about the same axis form a subgroup isomorphic to SO(2), roughly, the quotient group SO(3)/SO(2) = S^2\, where we are left with one rotation about each possible direction (unit vectors that terminate on the 2-sphere).

See also

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