“Sound cannot travel through a vacuum”

Many people commonly believe that sound cannot travel through a vacuum, a notion often reinforced by science fiction films depicting silent explosions in space. This misconception arises from a fundamental misunderstanding of how sound propagates and what a vacuum truly is. The idea of space being completely silent is largely correct, but the underlying scientific reasons are key to understanding why this myth is confirmed in most practical scenarios.

Sound is a mechanical wave, meaning it requires a medium—a substance composed of particles—to transmit its energy. Imagine a line of dominoes; for the wave to travel, each domino must knock into the next. Similarly, sound waves are created by vibrations that cause particles in a medium, like air, water, or a solid, to bump into adjacent particles, passing the vibration along. These pressure waves are what our ears interpret as sound.

In the vast emptiness of space, which is largely a vacuum, there are virtually no particles to facilitate this transfer of vibrational energy. Without a medium, sound simply has nothing to travel through. This principle was famously demonstrated by Robert Boyle in the 17th century, who showed that a ringing bell became inaudible when the air was pumped out of its container, creating a vacuum. While recent scientific research has explored highly specific conditions under which sound-like energy can "tunnel" across extremely small vacuum gaps between piezoelectric materials, these are highly specialized circumstances and do not negate the general rule for everyday sound in the vastness of space.