By Jack Sharkey, October 25, 2016
You know how space movies all pretty much sound the same...creepy, dark ambient-mashups that make you feel like something bad is going to happen at any moment? Well, that's pretty much fake, except it turns out it's based on reality (of sorts).
Sound cannot be heard in space because soundwaves rely on matter to transmit their energy. Assuming you're in your office right now, stand up and scream and wildly clap your hands. The people in the cubes next to you will hear you and their suspicions about you will be confirmed, unless you immediately follow-up your sudden outburst with the phrase "it's okay, I'm doing this for science!" The reason your cubic neighbors heard you was because the vibrations of your voice and your clapping hands traveled through the matter that makes up the air between you and them (before arriving at their ears where the vibrations were translated by the tympanic membrane and the cochlea into electrical impulses that their brains processed as recognizable sounds). Matter down here on Earth is tightly packed together so sound waves find lots of particles of matter to bump up against. In space, matter is few and far between, and I mean really few and far between, so sound waves simply dissipate before they find any matter to vibrate against.
Inside your space helmet you'll hear sounds, outside not so much.Radio waves can travel through space because they are electromagnetic (EM). I would explain electromagnetism in detail but I would have to use phrases like luminferous ether, covariant formulation of classical electromagnetism, and Galilean invariance, and it's far too close to the weekend to get involved in that. Suffice to say, electromagnetic waves are themselves matter so they can travel through the near-vacuum that is space. Luckily, humans can't hear electromagnetic waves (think about all the electromagnetc waves from cell phones and LANs and the like floating around your head right now).
This brings us to Voyager, the NASA probe that left Earth in 1977 and has recently left interstellar space (our Solar System) for points beyond. Whilst traveling about the cosmos, Voyager used things like magnetometers, Infrared Interferometer Spectrometers, Triaxial Fluxgate Megnetometers and other complicated-sounding devices necessary for things like exploring the planets to capture radio waves being emitted by the planets and their moons. NASA took those EM waves and put out an album called Symphony of the Planets which was released in 1992 (never a huge seller, it's no longer in print). Before releasing the album, NASA engineers downshifted the EM waves (typically by a factor of 44) to bring the waves into the human audio spectrum. The sounds were then edited in such a way that they became somewhat musical in nature. The video below is the manipulated sound recordings of the downshifted EM energy, and not surprisingly, it sounds just like we all thought space would sound:
But, if you think that's pretty cool, you should check out a direct link from NASA's JPL that contains short sound clips from the planets in their unedited state, along with explanations of what you're listening to: https://www.jpl.nasa.gov/multimedia/sounds2/index-nasa.html. Some of the sounds are downshifted, and others are not, so this site is a particularly cool visit.
During my Internet travels to bring you this amazing and peculiar piece, I also came across Dr. Fiorella Terenzi, an astro-physicist and musician from Italy who captures interstellar radio waves, downshifts the waves to the audible range and composes music with them. I'm no physicist, but I found this somewhat odd, and cheesy, and fascinating. Plus, I always find anything with Timothy Leary explaining how my brain works to be interesting, to say the least.
The universe is full of waves of energy, we just have to know how and where to listen.