You know it if even just subconsciously - the oscillating sound that implies "Outer Space". It's most associated with science fiction of years past but it's been rehashed in so many things, especially for children, that it's basically an audio queue at this point.
But...where did it originally come from, exactly? And why that sound, given that with space being a vacuum there isn't any audio sound, and extraterrestrial radio signals converted to sound are more like a dull roar or screeches.
It's not even like Sputnik's iconic telemetry sound, nor is it really like radar or sonar. So where did this sound effect come from?
Louis and Bebe Barron's soundtrack for the 1956 film Forbidden Planet.
Well, maybe not the exact sound effect you linked to in your YouTube clip, OP. But the Barron's work was enormously influential in determining the soundscape for outer space when it came to the movies.
Leitmotifs, a passage of music which was associated with/evoked a certain character, place, or idea, was a technique first developed in opera (particularly by Wagner) which carried over into film scoring. Often times in early film, an encounter with a stranger or other would be accompanied by a leitmotif stereotypically associated with that character's culture.
When sci-movies came into vogue in the early 50s, film composers were faced with the challenge of creating leitmotifs for aliens. Electronic music became the convention for creating a suitably otherworldly effect. The earliest go-to was the theremin, which had been invented in the 1920s and first appeared in Hollywood film scores in the 40s; in particular it was used to cue a character going into a dissociative state in the Hitchcock thriller Spellbound, which won best original score at the Academy Awards that year. Several early 1950s sci-fi movies employed the theremin to create eerie leitmotifs for alien encounters (Rocketship X-M was this first; Bernard Hermann's The Day the Earth Stood Still has stood the test of time a lot better). Theramin is still strongly associated with sci-fi scores.
But it’s with Forbidden Planet that musical scores for extraterrestrial movies really broke the mold and went from “eerie but recognizably orchestral” to bleeps, bloops screeches and oscillations. And that’s down to the Barrons. The couple were pioneering electronic musicians who set up a small studio in Greenwich Village in the early 50s, working with avant-gard artists like the composer John Cage and the writer Anais Nin. The Barrons created all their own instruments, sending electricity through oscillators, vacuum tubes and circuits, and ring modulators to create unique sounds.
Unfortunately, working with cutting edge artist types in the Village didn't pay so well, so the couple decided to try and break into movies. They talked their way into a job creating sonic effects for the film, and producers were so impressed with their creations that they were eventually handed the entire score.
The film did pretty well at the box office upon release (though a turf fight with the film musician’s union left the Barrons ineligible for an Oscar). But its set design and score were enormously influential on subsequent works in the genre. In particular, the oscillating effect you’re interested in can be heard all over the Forbidden Planet soundtrack; I’d say it shows up most prominently in “Love at the Swimming Hole”.
Sources:
James Wierzbicki (2002) Weird Vibrations: How the Theremin Have Musical Voice to Hollywood's Extraterrestrial "Others," Journal of Popular Film and Television, 30:3; 125-135
Trevor Pinch. Space is the Place: The Electronic Sounds of Inner and Outer Space. Journal of Sonic Studies. https://www.researchcatalogue.net/view/108499/108500
Ryan Lambie. 2019. The Influence of Forbidden Planet on Star Trek and Star Wars. https://www.denofgeek.com/movies/the-influence-of-forbidden-planet-on-star-trek-and-star-wars/