Have you ever wondered what it would be like to scream in outer space? Would your voice be heard? Or would it simply vanish into the emptiness of the cosmos?
While it sounds like somethiing straight out of a sci-fi movie, the answer is actually very scientific: in space, no one can hear you scream. Why? Because there’s no air out there.
Sound is a mechanical wave, which means it needs a medium like air, water, or solid matter to travel through. On Earth, sound moves by vibrating molecules in the air until it reaches our ears.
But in the vacuum of space, there are almost no molecules. It’s essentially empty. That means sound has no way to travel from one place to another. So, even if you screamed at the top of your lungs, no one would hear it not even you.
According to neuroscientist Allison Coffin from Washington State University, all sound requires some kind of physical medium. Without molecules to carry the vibrations, there’s simply no sound.
Interestingly, scientists have managed to detect sound waves in places like gas clouds far beyond Earth’s atmosphere. But these sounds are incredibly low in frequency so low that human ears can’t detect them. Coffin describes them as “mega bass” frequencies that are beyond our hearing range.
Even though sound can’t travel in space, astronauts are still able to talk to each other using radio communication. Radios don’t rely on air because they transmit signals using electromagnetic waves, which can move through a vacuum.
These devices convert voices into electronic signals, send them out as waves and then translate them back into sound on the receiving end.
Films like Gravity and 2001: A Space Odyssey portray outer space as silent during explosions or collisions and that’s scientifically accurate. In contrast, many action movies add dramatic sound effects, even though in reality, a huge explosion in space would occur in complete silence.