Home > Encyclopedia of Science > Light

• Historical concepts
• Words to Know
• The mysterious ether
• Return of the corpuscular theory
• Duality of light and matter
• Čerenkov Effect
• Making light stand still

Light is generally defined as that portion of the electromagnetic spectrum with wavelengths between 400 and 700 nanometers (billionths of a meter). Like all forms of electromagnetic radiation, light travels with a speed of 186,282 miles (299,728 kilometers) per second in a vacuum. It is perhaps the swiftest and most delicate form of energy found in nature.

Historical concepts

Considering how important light is in our daily lives, it...