Schematic illustration of light rays passing through the prism.

Infinite Mirrors

Does Light Go On Forever?

 

Materials

  • one pocket mirror and one wall mirror

Try This

  1. Stand in front of a wall mirror.
  2. Hold the pocket mirror up near your eyes, facing away from you, so that it is pointed at the other mirror. How many mirrors do you count?

What's Going On?

Light reflects off one mirror into another mirror, which reflects this light back again, and so on. In theory, the light causing these reflections goes on forever. We know this because light in space, without anything blocking it, travels enormous distances. Telescopes have observed light from a galaxy 13 billion light-years away from Earth. In other words, this light has traveled for 13 billion years without stopping!

Schematic illustration of a girl standing in front of the mirror.