White objects look white because they reflect nearly all wavelengths of visible light equally.

The longer version

A white surface sends back nearly every wavelength it receives rather than favoring one part of the spectrum. Microscopically the material scatters light many times over, and because no wavelength is preferentially absorbed, whatever illuminates it comes back to the eye in roughly its original proportions.

That is why white cloth glows faintly blue under fluorescent light and orange under candlelight: the object has no color of its own, only the color of the illumination. Snow and paper look white for a related reason, scattering light from countless tiny surfaces. Adding a dye introduces absorption and removes the effect.

Where this entry sits

These facts explore how light behaves and how human eyes turn it into the colors we see. Along the way you meet rainbows, prisms, mirrors, shadows, lasers, and optical tricks that fool our vision every day. The full list sits on the Color and Light page, where every entry is listed in order.

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More From Color and Light

Eight more entries

Black surfaces look dark because they absorb most of the visible light that falls on them.

Sunlight contains all the colors of the visible spectrum blended together into white light.

Violet light has the shortest wavelength visible to humans, while red has the longest.

The sky looks blue because air molecules scatter short blue wavelengths more than long red ones.

Sunsets often look red because sunlight travels through more air, which scatters away the blue light.

Laser light differs from ordinary light because its waves are aligned and share a single wavelength.

The traditional spectrum is often listed as seven colors, including red, orange, yellow, green, blue, indigo, and violet.

Most people cannot distinguish indigo from blue or violet in an ordinary rainbow.

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