Light or visible light is electromagnetic radiation that can be perceived by the human eye. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres, corresponding to frequencies of 750–420 terahertz, between the infrared and the ultraviolet. In physics, the term "light" may refer more broadly to electromagnetic radiation of any wavelength, whether visible or not. In this sense, gamma rays, X-rays, microwaves and radio waves are also light. The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization. Its speed in a vacuum, 299 792 458 metres a second, is one of the fundamental constants of nature. Like all types of electromagnetic radiation, visible light propagates by massless elementary particles called photons that represents the quanta of electromagnetic field, and can be analyzed as both waves and particles.

Read more in the app

Astronomers discover potential habitable exoplanet only 31 light-years from Earth

Squid skin inspires novel “liquid windows” for greater energy savings. Bio-inspired system optimizes wavelength, intensity, dispersion of light reaching interiors.

Light therapy: Not just for seasonal depression? - Harvard Health. Bright light therapy can help ease SAD, major depression, and perinatal depression.

Astronomers Find What May Be a Habitable World 31 Light-Years Away

Theoretical Physicists Devise New Path toward High-Energy ‘Quantum Light’

Wormholes could magnify light by a factor of 100,000

Researchers devise a new path toward 'quantum light'

515-Million-Year-Old Fossils Shed Light on Evolution of Annelid Worms

Analysis of Cellular “Vehicles” Sheds New Light on Alzheimer’s, Parkinson’s, and ALS

Light Pollution Is Dimming Our View of the Sky, and It's Getting Worse

Recreating the natural light-harvesting nanorings in photosynthetic bacteria

Incredible Footage Shows Planets Circling a Star Light-Years Away

Solid material that 'upconverts' visible light photons to UV light photons could change how we utilize sunlight

A fairy-like robot flies by the power of wind and light

Nuclear Popcorn: New Research Sheds Light on the Enigmatic Strong Nuclear Force

Researchers Create Dandelion-Inspired Robot Controlled by Power of Light and Wind

New Study Sheds Light on the Genetic Origins of Cleft Lip and Palate

A “Missing Link” – Researchers Shed Light on the Origin of Complex Life Forms

Challenging Past Assumptions: Light From Outside Our Galaxy Much Brighter Than Expected

It’s Already Hard Enough to Block a Single Star’s Light to See its Planets. But Binary Stars? Yikes