What do sound waves and infrared waves have in common

Explanation:

Sound waves (mechanical waves) and infrared waves (electromagnetic waves), both can transfer energy through matter. However, there is a huge diference between them:

Mechanical waves only propagate through matter and can not propagate in vacuum. This means, they necessarily need a medium to propagate.

On the other hand, electromagnetic waves can propagate  through matter and in vacuum, too. This means their propagation does not depend on the existence of a medium.

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