Which medium does light travel fastest through

Liquids are not packed as tightly as solids. And gases are very loosely packed. The spacing of the molecules enables sound to travel much faster through a solid than agas. Sound travels about four times faster and farther in water than it does in air.

The fastest thing in the whole universe is the speed of light in a vacuum (like outer space!), clocking in at a great 2.99 x 108 m/s. Light travels in waves, and we call thistraveling propagation. Propagation of waves has both a speed and a direction, called the velocity.