Why we can not hear sound in Space?
Sound waves are machanical waves. Sound is produced in the form of a pressure wave. When an object vibrates, it causes the surrounding air molecules to vibrate, initiating a chain reaction of sound wave vibrations throughout the medium. So, in order for sound to travel, there has to be something with molecules for it to travel through. On Earth, sound waves travels to your ears by vibrating air molecules but in deep space, the large empty areas between stars and planets, there are no molecules to vibrate. So, there is no sound there.