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Beginning in Genesis and going through Revelation, light is mentioned in the Bible more than one hundred times. “Let there be light” (Genesis 1:3), “Light of the world” (Matthew 5:14), and “I [Jesus] am the light of the world” (John 8:12, 9:5) are all from familiar verses of the Bible. In the Word of God, light is used to illustrate important points such as wisdom, illumination, and good vs. evil. But what is “light” from a scientist’s perspective?

From the ancient Greeks and Egyptians to Newton to Einstein to modern-day engineers, the quest to understand light and use it is rich with history. While this history is worthy of study in and of itself, this article will briefly touch on the fascinating science of light and color and describe a few inexpensive hands-on experiments that you can try at home.

What Is Light?

Like all other topics in science, knowledge builds upon knowledge. The ancient Greeks and Egyptians thought that light was something that emanated from our eyes. Today we know that light is a form of electromagnetic energy. Some light we can see; some we cannot. The light that we can see is called visible light. It is a small portion of the broad spectrum of electromagnetic radiation.

Light is unique in that it exhibits the properties of both a wave and a particle. If two people were holding a jump rope, and one of them snapped her wrist, the rope would move in “waves.” This motion gives us a good illustration of the way light travels in waves. That action adds energy to the rope in the form of a wave that travels along the length of the jump rope to the other person. Each time the jump rope holder snaps her wrist, another wave is generated.

The distance between one peak of the wave to the next peak is referred to as the wavelength. The wavelengths in the visible spectrum are measured in nanometers and range approximately from 380 to 740 nanometers. A nanometer is one-billionth of a meter. (A human hair is about 100,000 nanometers wide.)