Physical Meaning of Quantum Space-Time Symmetries

A definition is given and the physical meaning of quantum transformations of a non-commutative configuration space (quantum group coactions) is discussed. It is shown that non-commutative coordinates which are transformed by quantum groups are the natural generalization of the notion of a tensor operator for usual groups and that the quantum group coactions induce semigroups of transformations of states of a system. Two examples of non-commutative transformations and the corresponding semigroups are considered.