Chirality (mathematics)
In geometry, a figure is
chiral if it is not identical to its mirror image, or, more precisely, if it cannot be mapped to its mirror image by rotations and translations alone. For example, a right shoe is different from a left shoe, and clockwise is different from counterclockwise. A chiral object and its mirror image are said to be
enantiomorphs. The word
chirality is derived from the Greek χείρ, the hand, the most familiar chiral object; the word
enantiomorph stems from the Greek ἐναντίος 'opposite' + μορφή 'form'. A non-chiral figure is called
achiral or
amphichiral. The helix and Möbius strip are chiral two-dimensional objects in three-dimensional ambient space. The J, L, S and Z-shaped
tetrominoes of the popular video game Tetris also exhibit chirality, but only in a two-dimensional space. Many other familiar objects exhibit the same chiral symmetry of the human body, such as gloves and shoes. A similar notion of chirality is considered in knot theory, as explained below. Some chiral three-dimensional objects, such as the helix, can be assigned a right or left handedness, according to the right-hand rule.