complementarity science definition

The concept that the underlying properties of entities (especially subatomic particles) may manifest themselves in contradictory forms at different times, depending on the conditions of observation; thus, any physical model of an entity exclusively in terms of one form or the other will be necessarily incomplete. For example, although a unified quantum mechanical understanding of such phenomena as light has been developed, light sometimes exhibits properties of waves and sometimes properties of particles (an example of wave-particle duality). See also uncertainty principle.