Tech Questions? Get the Answers: 4/12/2023

Q: Why is there no sound in space?

A: The short answer is that there is no air in space. Sound travels by air molecules bumping into each other in a domino-like fashion. Without air, there is nothing for the sound energy to bump into, so it could not travel. Unlike sound waves, light waves can travel through a vacuum. Light travels as both waves and particles, or photons, and is part of the electromagnetic spectrum. Photons travel at the speed of light, or roughly 156,000 miles per second or 300 million meters per second. Because photons travel on their own and do not need other particles to bump into, they can move through space or air or water, or anything else that is transparent.

Light is the fastest thing in the universe, so that makes sound very slow in comparison. This can be observed when watching a fireworks show. At just 761 MPH at sea level, the sound from an exploding firework reaches your ears long after the light from the same firework reaches your eyes. When watching a jet approach, you might be able to hear the engines as it comes toward you. If that same jet were traveling faster than the speed of sound, you would not hear anything as it approaches because the jet is faster than the sound it makes. However, as the jet passes, there would be a deafening sonic boom. This is created when the air can not move out of the way of the jet fast enough and it creates a shock wave. This is a high-pressure wave that is produced by the front of the jet, much like a wave created from the front of a boat. As that wave expands, it eventually reaches your ears resulting in a loud sound. This shock wave is capable of shattering windows and even causing hearing loss. Fortunately, it is not legal for jets to fly faster than the speed of sound over nearly all of the United States.

As deafening rockets blast off into space, their sound eventually disappears as they climb higher and escape the atmosphere. While it may be disappointing to realize that space is not filled with iconic sound effects from science fiction movies, it is important to understand the scientific principles that govern our universe.

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