The Speed of Light

Light flies. If you don’t believe me, go outside tonight, crank up the family car, and try to race the beam streaming from the headlights to the end of the driveway. Light is fast—really fast—traveling at 186,000 miles per second. How fast is that? In the time it takes you to snap your fingers just once, a ray of light can circle the globe seven times. Like I said, light is quick. 

Light has to be fast because the universe is so big. The warmth you feel on your face when you walk outside on a sunny afternoon is light that…