The speed of light is 299,792,458 meters per second and that constant tells us much about cause and effect in the universe.

When we measure the speed of light, it's always in two directions. Measuring it in one direction may be impossible.

Lidar is an acronym that stands for "light detection and ranging." It's basically like a tape measure—except that it uses the speed of light to measure distance, instead of a physical object.

Light is faster than anything else in the known universe, though its speed can change depending on what it's passing through.

The mind-bending concept of time dilation results from a seemingly harmless assumption—that the speed of light is the same for all observers.