There are vibrations in space, but there is no medium to transmit them; there is no air, just a vacuum. So, no matter how many vibrations there are, if there is no medium to transmit them, there can be no sound; so there is no sound in space.
There is a very interesting experiment. We can, for instance, introduce an alarm into a vacuum bell. We will not be able to remove absolutely all the air, but we will observe how, as we remove it, the sound of the alarm fades away. If we suddenly introduce the air again, we will hear it again. This clearly shows how, by removing the medium that transmits the vibrations from the source of the sound to the receiver, we eliminate that sound.
In science fiction films, the battles going on in space would not be heard. Conversely, there is sound inside a spaceship, because it is transmitted through the structure of the ship itself and through the air inside.
Answered by Chantal Ferrer, director of the Department of Applied Physics and Electromagnetism of the University of Valencia.
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