What is Light?
- the Institute
- 6 days ago
- 1 min read
Light is electromagnetic radiation that travels in waves at approximately 300,000 kilometers per second in a vacuum. It exists across a broad spectrum of wavelengths, though we typically use "light" to refer specifically to the visible portion that human eyes can detect—roughly wavelengths from 380 to 700 nanometers.
The Dual Nature of Light
Light has a fascinating dual nature: it behaves both as a wave and as particles called photons. As a wave, it exhibits properties like interference and diffraction. As particles, photons carry discrete packets of energy that can interact with matter in specific ways.
The Electromagnetic Spectrum
The visible spectrum ranges from violet (shortest wavelength, highest energy) through blue, green, yellow, orange, to red (longest wavelength, lowest energy). Beyond visible light, the electromagnetic spectrum includes radio waves, microwaves, infrared, ultraviolet, X-rays, and gamma rays.
How Light is Produced
Light is produced when electrons in atoms or molecules transition between energy levels, releasing photons. This happens in various ways:
Nuclear fusion in stars
Electrical excitation in LED bulbs
Chemical reactions in bioluminescent organisms like fireflies
Light's Fundamental Role
What makes light particularly remarkable is its fundamental role in physics: it represents the speed limit of the universe, its behavior helped reveal quantum mechanics, and Einstein's insights about light led to special relativity. It's also essential for life on Earth, driving photosynthesis and enabling vision.
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