Posters for the classic sci-fi film Alien famously read, "In space no one can hear you scream," but so many other sci-fi films, explosions in space sound really loud. So which is more accurate? It depends exactly where in space you are.
Of course, sound is a mechanical wave of energy emanating from a vibration and transferred via solid, liquid or gas molecules that's ultimately detected by your eardrum deep inside your ear. There are three tiny bones - the malleus, incus, and stapes -- that transfer these vibrating waves into a nerve signal that your brain perceives as sound.
Since space is essentially a vacuum, there is medium to transfer these sound waves to your eardrum. Technically, space isn't a true vacuum: NASA says there's about one atom per cubic centimeter (or one atom per 0.06 cubic inches), but that's not nearly dense enough to pass along a sound wave.
So even if you're blowing up something even as massive as, say, a small moon (like the Death Star), it would be completely silent (that's one point for Ridley Scott and 0 points for George Lucas). And spaceships, unless they're flying within a planet's atmosphere, would also be silent. You would, however, hear sounds if you were within the confines of the pressurized cabin of a spaceship, so astronauts on the ISS, for example, can hear each other just fine.
However, there IS another way to pull sound directly from space, not in an atmosphere, or in a spacesuit... take a guess what you think it could be in the comments section. If this video gets 7,000 likes, the DNews team will release a follow-up video with the answer/ So get Googling, amateur astronauts (or at least hit "like" if you give up!
What is a vacuum? Is it matter? (via Jefferson Lab)
"A vacuum, to us, is a space with no matter in it. As a practical matter though, it's really a space with very little matter in it."
Matter in Space (via NASA)
"There is matter spread all through the Universe, it is just spread very, very, very, very thin."
Why you might sound like a Smurf on Venus (via New Scientist)
"Ever wondered what natural sounds you would hear on another planet?"
How Bone-conducting Headphones Work (via How Stuff Works)
"To understand how bone conduction works, you first have to understand how we hear sounds."
Can humans hear in space? (via How Stuff Works)
"Before we begin to talk about space, we should probably define it."
How Voyager 1 recorded noises when there's no sound in interstellar space (via NBC News)
"Beyond the border of interstellar space, the distant Voyager 1 spacecraft called back to Earth earlier this year with noises from its new environment."
Can you hear sound in space? (via Cornell University)
"I'm afraid that your friends are right. In empty space, there is no air, and what we call 'sound' is actually vibrations in the air."
Chris Hadfield shares the everyday sounds of space on SoundCloud (via Wired)
How Sci-fi Doesn't Work: Sound in Space (via How Stuff Works)
Comet Will Barely Miss Mars
Is Our Universe a Hologram?
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