SO(3)
From Mathematics wiki
Representations
The Lie algebra of
is
. Representations of the group are labeled according to the representations of the algebra, which are characterized by their spin
.
Topology
is homomorphic to the 3-sphere
. The map
is a surjective homomorphism of Lie groups with kernel
.
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
where we are left with one rotation about each possible direction (unit vectors that terminate on the 2-sphere).

