light

Also known as lights, near-visible light, near-visible spectrum, near-visible electromagnetic radiation, light wave

thumb|upright=1.3|A triangular dispersive prism|prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (green-blue) are separated.

OverviewAI-generated

Light is an electromagnetic wave and optical radiation that is the opposite of darkness. It has a speed of 299792458 and is composed of photons. The subject possesses a spectrum and is studied by optics. It is distinct from the visible spectrum.

Light has uses in the visual system, photosynthesis, art, and video art. It is referenced by 2,312 other encyclopedia articles. The topic appears on the Wikipedia:List of articles all languages should have and Wikipedia:Vital articles/Level/4. It is described by sources including the Brockhaus and Efron Encyclopedic Dictionary, Encyclopædia Britannica 11th edition, Oxford English Dictionary, and Monash University.

Synthesized by Vinony from 17 facts across 3 sources: Wikidata, PubMed, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.

Research

1,257,782 papers

[Artificial light at night].ReviewUgeskrift for laeger · 2026Jensen CN, Madsen HØ, Martiny K et al.DOI: 10.61409/V06250466
What is light? The visible spectrum and beyond.ReviewEye (London, England) · 2016Sliney DHDOI: 10.1038/eye.2015.252
Seeing the Light: Perception and Discrimination of Illumination Color.ReviewAnnual review of vision science · 2025Hurlbert A, Yu CDOI: 10.1146/annurev-vision-121423-013755
Dark matters: effects of light at night on metabolism.ReviewThe Proceedings of the Nutrition Society · 2018Nelson RJ, Chbeir SDOI: 10.1017/S0029665118000198
Light behind bars: how light impacts mental health in prisons.ReviewInternational journal of prison health · 2025Urrutia-Moldes ADOI: 10.1108/IJOPH-11-2024-0074
Effects of outdoor artificial light at night on human health and behavior: A literature review.ReviewEnvironmental pollution (Barking, Essex : 1987) · 2023Wang T, Kaida N, Kaida KDOI: 10.1016/j.envpol.2023.121321
Light wavelength and pulsing frequency affect avoidance responses of Canada geese.PeerJ · 2023Lunn R, Baumhardt PE, Blackwell BF et al.DOI: 10.7717/peerj.16379
Light-emitting diodes (LED) for domestic lighting: any risks for the eye?ReviewProgress in retinal and eye research · 2011Behar-Cohen F, Martinsons C, Viénot F et al.DOI: 10.1016/j.preteyeres.2011.04.002

via PubMed

~33 min read

Encyclopedic overview

21 sections

Contents

Electromagnetic spectrum and visible light
Speed of light
Optics
Surface scattering
Refraction
Measurement
Light pressure
Historical theories about light, in chronological order
Classical Greece and Hellenism
Classical India
Descartes
Particle theory
Wave theory
Electromagnetic theory
Quantum theory
Quantum optics
Use for light on Earth
See also
Notes
References
External links

thumb|upright=1.3|A triangular dispersive prism|prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (green-blue) are separated.

Light, visible light, or visible radiation is electromagnetic radiation that can be perceived by the human eye. Visible light spans the visible spectrum and is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz. The visible band sits adjacent to the infrared (with longer wavelengths and lower frequencies) and the ultraviolet (with shorter wavelengths and higher frequencies), called collectively optical radiation.

Excerpted from Wikipedia’s “light” article, available under the CC BY-SA 4.0 licence.