Abstract

The selective synthesis and manipulation of chiral molecules is a major part of stereochemistry. Interactions involving components with “handedness” also occur in nuclear and particle physics. Both fields employ phenomenologies based on group theoretical classifications and symmetry constraints such as the conservation or violation of parity. Smale's discovery of a sphere eversion—homotopic to a central inversion—evades the parity dichotomy by allowing states of opposite chirality to be connected by smooth maps. This transformation demonstrates that parity changes can, in principle, result from the action of sufficiently complex processes, and do not necessarily have to be interpreted as violations of a symmetry.