This exhibit shows that sound waves don’t travel in a vacuum.
When the clapper hits the bell, the metal begins vibrating. These vibrations travel through the air. Without the presence of air, no air molecules can be pushed to and fro and thus no sound waves can travel. Light, on the other hand, consists of electromagnetic waves, i.e. electric and magnetic fields arranged in such a fashion as to propagate over large distances. These fields do not need a carrier like sound waves. They can still travel in pure vacuum.