Light

Photobiology is the scientific study of the interactions of light (technically, non-ionizing radiation) and living organisms.

Tired light is a class of hypothetical redshift mechanisms that was proposed as an alternative explanation for the redshift-distance relationship.

Sunset or sundown, is the daily disappearance of the Sun below the western horizon as a result of Earth's rotation.

Photo-degradation is the alteration of materials by light.

Sunrise or sun up is the instant at which the upper edge of the Sun appears over the eastern horizon in the morning.

Sāyaṇa (Kannada; with honorific Sāyaṇācārya; died 1387) was an important commentator on the Vedas.

Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum.

In photometry, luminous intensity is a measure of the wavelength-weighted power emitted by a light source in a particular direction per unit solid angle, based on the luminosity function, a standardized model of the sensitivity of the human eye.

A Slower Speed of Light is a freeware video game developed by MIT Game Lab that demonstrates the effects of special relativity by gradually slowing down the speed of light to a walking pace.

The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics.

Right to light is a form of easement in English law that gives a long-standing owner of a building with windows a right to maintain the level of illumination.

A standard illuminant is a theoretical source of visible light with a profile (its spectral power distribution) which is published.