چکیده (انگلیسی):

To propose that “darktom” is the basic unit of darkness. Major databases including National Library of Medicine, PubMedand Cochrane Library were used in the literature search conducted in English. Light and darkness are two extremes in luminous world. Darkness appears to be contained in every sealed hollow object, a default that requires no energy unlike visible light which is a fraction of the electromagnetic spectrum. The luminous world with two competing phenomena: darkness and light, is at mutually exclusive equilibrium in which the presence of one elicits the absence of the other.