When Serial Experiments: Lain wasn't terrifying you with its warped vision of the internet (called "the Wired"), it was dropping in little Easter eggs for technophiles: if you look closely, you'll notice that Lain writes code using Lisp, and that one screenshot of her computer shows Conway's Game of Life, a zero-player game that models the division of cells. Clearly, the creators did their homework on real-life tech.
But then they go deeper — they start referencing memex, and Xanadu, and the Eight-Circuit Model of Consciousness, and John C. Lilly's research on telepathic communication with dolphins, and how you can use the Earth's Schumann resonances to create a global communication system that links everyone's mind without any devices, and suddenly you're thinking "Wait, is this real? Is the Wired possible?"
And that's the magic of jargon: even if you don't fully understand what all the words mean, it makes just enough sense to bridge the gap between the science and the fiction. Sci-fi anime mastered this art decades ago: Neon Genesis Evangelion, Ghost in the Shell, Ergo Proxy, all of them ride the line between real-life science and plausible-sounding technobabble. So how do they do it?
THE AGE OF ENTANGLEMENT
First, it's helpful to realize that "jargon" covers pretty much anything that isn't common knowledge, and there's a lot that the average adult doesn't understand: for example, a good portion of adults still don't understand what nanotechnology is, or how lasers work.
This may not be a problem of ignorance or bad education—according to commentators like Danny Hillis, we've entered the "age of entanglement," in which "we're building systems that can't be grasped in their totality or held in the mind of a single person." Whether it's artificial intelligence or autonomous cars, even the people who work on these pieces of tech usually understand only a portion of what they're building. This leads us to Arthur C. Clarke's old adage: "Any sufficiently advanced technology is indistinguishable from magic."
So sci-fi has a problem: how do you make incredibly complex pieces of science (which are essential to your story) understandable to normal people without having their eyes glaze over from boredom? Even tougher, how do you introduce people to the fictional stuff, which follows its own rules?
This is where jargon comes in. In real life, jargon is what keeps most people from understanding how science works, but in sci-fi, it can be used as a bridge to connect the layperson's understanding to the show's worldbuilding, as well as smooth the transition between what's real and fake.
An ongoing question for sci-fi creators is whether to take a real-life science concept and extrapolate a new, sci-fi concept from it directly (we call this hard sci-fi), or just fiat some new scientific phenomenon into existence (or soft sci-fi). Either way, the new concepts need some new jargon to help ground them.
One technique is to carefully re-define some familiar terms. A good example of this are the eponymous "ghosts" and "shells" in the Ghost in the Shell series. To help the audience slide into the cyberpunk mindset, the show uses new words to replace "soul" (which has a sacred, religious connotation) and "body" (which has a connotation of flesh and blood). Calling a body a "shell" makes it less jarring when people start swapping bodies, and the same goes for using a computer program to re-write or erase a person's "ghost."
"…Spatial Alternation Dynamics [is] based on the theory that our universe phases in and out of existence every 1/48 second, blinking on and off like a strobe light. While our universe is "off," it is temporarily replaced by a more compact universe called Phase Difference Space, which is 1/240th the size of our universe."
Fun fact: there is no "spatial alternation dynamics," or anything remotely close to it in real science, but that sure sounds like some kind of weird quantum mechanics phenomenon, right?
This kind of method is risky, because it relies solely on spouting nonsense that mimics the logic and character of modern science, which shifts over time: Newtonian physics was usually simple, elegant, and reasonable, but in the quantum age, weird, counter-intuitive, and seemingly impossible cosmological phenomena (like multiverse theory) became par for the course. Hence, Spatial Alternation Dynamics doesn't sound so crazy in the year 2018.
DOING IT RIGHT
So let's talk about something everyone understands: giant robots. The first time Shinji Ikari gets into Eva Unit 01 (a giant mecha) in Neon Genesis Evangelion, there's a bunch of shots of a control room going through a pre-flight checklist, like a NASA launch: they talk about detaching the restraints, enabling power, filling the cockpit with LCL, adjusting the thought-controlled interface to Japanese, and so on.
Did you notice the transition there? The checklist starts out with mundane stuff, then seamlessly moves into the fictional stuff. For both the latter two points, we also have a visual to go with the words: as they introduce LCL, Shinji's cockpit is flooded with an orange liquid, and as they announce the mind-synching, the cockpit's walls shift to different patterns and colors.
From a story perspective, the people in the control room essentially have two jobs: commentate on what's happening with the robot fights, and contextualize the new concepts the show's trying to introduce. They are the bridge between the science and sci-fi in the show. But here's the thing: even though they're there to help the audience make sense out of what's happening, the use of jargon is carefully tuned to keep things just blurry enough to let the showrunners do what they want.
For example, when Shinji fights the angel Leliel, we're told it has an "inverted AT field," which allows it to trap Shinji inside its shadow-like body. Now, up to this point in the show, AT-fields have been presented as something like a force-field—something that keeps enemies and attacks out. This Angel's AT-field, however, sucks enemies in. The rules of AT fields are deliberately kept blurry to allow the showrunners to play around with their properties, as well as keep their true nature a secret.
The Angel's weird, 2-D body is also described as a Dirac Sea, which is a real-life physics concept with almost zero relevance to the situation—despite a quick scene explaining it with a chalkboard, it's straight-up technobabble. Here's what makes it work, though: the jargon is kept short and compact.
This is the careful balance jargon needs to work: if you're describing something that doesn't exist (ie, AT-fields), demonstrate it visually so the audience can intuitively understand it, but keep the theoretical aspects vague. When you're adapting something real to a fictional situation (ie, the Dirac Sea), keep it self-contained and its effects simple. In the end, you'll get a sentence like this: "Shinji was sucked into an Angel whose body resembles a Dirac Sea, but we can get him back out by counter-acting the Angel's negative AT field."
And just like that, you've got an excellent string of jargon.