Darkness

Darkness is a condition in which light is absent or insufficient for the eye to distinguish colours and shapes clearly. It is also called the absence of light or the absence of visibility. Darkness is not an independent physical entity, but a term describing the scarcity of light (the visible radiation that the eye can perceive).

The degree of darkness varies. There is complete darkness, where no single ray of light enters, as in a deep cave or a sealed room, and partial darkness where some light is present, as on a moonlit night or in a room with dim lighting.

Causes of darkness

Darkness arises from two main conditions: first, the absence or depletion of a light source; second, the presence of light but its path is blocked by something that light cannot pass through. Shadow is an example of the second type. Earth's night results from the planet's rotation: the side facing away from the sun is in its shadow.

The eye and the perception of darkness

The human eye has the ability to adapt to low light, a process known as dark adaptation. When moving from a brightly lit place to a dark one, vision is initially weak but improves within minutes. In darkness, colours are perceived with difficulty, because the light-sensitive cells responsible for colour vision require more light.

Metaphorical use

In many languages, including Somali, darkness is used in a figurative sense. It refers to ignorance, an unclear condition, or a difficult time. In sayings and poetry, light and darkness are often contrasted as symbols of knowledge and ignorance.