Question

Why are light waves able to travel in the vacuum not sound waves ?

Answer 1

This is because light is an electromagnetic wave and sound is a longitudinal and mechanical wave. In vacuum nothing is present. Sound needs either solid, liquid or gas to propagate and hence it is called a mechanical wave. Sound is a form of energy which is transferred by vibrating air molecules if motion of propagation is air. Air molecules themselves are not energy. But light is composed of photons and photons are energy themselves.

Photons can travel in any medium. Light is produced if there is any change in electric and magnetic field but sound is produced by vibrating body.

In short light itself travels from one point to another and hence do not need any medium but sound is transferred by vibrating bodies and hence need a medium to travel.