We say that a medium is a requisite for the propagation of a wave. So how does light travel in a vacuum where sound cannot travel?

Question

We say that a medium is a requisite for the propagation of a wave. So how does light travel in a vacuum where sound cannot travel?

Accepted Answer

Of course, a medium is necessary for the propagation of a wave. However, it does not mean that the materials medium is necessary for all waves for their propagation. In a vacuum, Scientists believe that there exists a hypothetical medium called ether medium which is highly rigid and tenuous and the light travels through the ether medium. When light travels through the ether medium, the ether particles vibrate about their mean positions, and the disturbance is propagated from one region to another region in the space. However, the sound waves are mechanical waves that need materials medium for their propagation. Since the ether is a nonmaterial medium, the sound waves cannot travel through it.

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