Science Puzzle
Could You Hear an Explosion in Space?
In films, spaceships explode with a deafening boom and laser blasts crackle across the void. It looks and sounds thrilling.
If a real spaceship blew up right in front of your window in deep space, would you hear a thing?
The Answer
Not a sound. Sound is not a thing that travels on its own; it is a wave of squeezing and stretching that passes through a material, usually the air. Bump the air near your mouth and that bump passes molecule to molecule until it jostles your eardrum.
Deep space is very nearly empty. With almost no molecules to pass the bump along, the wave has nothing to travel through, so it never starts. The explosion would be blindingly bright and utterly silent. The films add the boom because silence feels wrong to us, but the science is on the side of silence.
The same rule explains why the old classroom demonstration works: ring a bell inside a jar, pump the air out, and the bell falls silent even though you can still see it swinging.
The principle: Sound is a mechanical wave. It needs a medium, a solid, liquid or gas, to travel through. In a vacuum there is no medium, so no sound.