Science fiction has been defined as a genre where the "incredible" elements are "recognizable as not-true, but also as not-unlike-true, not-flatly- (and in the current state of knowledge) impossible" (According to Darko Suvin, from Wikipedia link).

This is often compared against fantasy, where magic has no pretense of being scientifically possible.

Yet, sometimes an author doesn't want to get into lengthy explanations for every technology that appears in a novel. This may be for a variety of reasons, brevity being one of them, keeping an air of mystery another.

Let's suppose there is this technology X. X works following some even remotely possible scientific concept. The author knows the concept, but never explains it. X gets a lot of space in the novel: the reader can see the technology in use, understand what it does, and even what it requires to work. Maybe it's a machine needing fuel and electricity. Maybe it's a weapon emitting huge ray bursts.

In short, X's effects are clear, but the details of X's inner working are never laid out.

How can the author maintain a pretense of "scientific plausibility" without giving a reasonable explanation? After all, X is never explained out loud; the scientific principles that it operates on are left entirely on speculation.

Probably related:

  • Do you really want mystery on this question? – a CVn May 6 at 13:43
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    Thanks for giving us a great question that fits the tags of the week! I agree with @aCVn though, mystery isn't really the right tag. I fixed some typos for ya but left your tags alone. – Cyn May 6 at 14:20
  • Maybe you're right. I've seen it used on a similar queston, but it's maybe unrelated here. I'm editing it out. – Liquid May 6 at 14:29
  • I think it would be appropriate in your SF question if there was a plot line about the mystery of how X worked. Vs just "the author never explains it." – Cyn May 6 at 14:39
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    In my opinion, science fiction is NOT just scientifically plausible fantasy. I read a wonderful article about the role of science fiction which I unfortunately can't find just now, but a paraphrase from it is, "Science fiction is the herald of possibility; it is a plea that someone work on the future; it is the dream that precedes the day when a scientist awakens and goes to his workbench saying, 'I wonder if I could make that dream come true in the world of reality.'" – Wildcard May 7 at 19:01

10 Answers 10


I think you may be thinking a little too hard about things as the writer. Instead look at things from your characters' perspectives. Unless you're writing an engineer or someone actually building X, they probably won't actually know how it works. Heck, even an engineer building X would only know about the tiny portion they actually work on. The rest is probably done by other teams or even other computers.

Remember that to the layman, things just work.

Let's imagine that X is actually a car in today's world. If you were to ask some John Doe on the street, he'd explain to you that the car works by turning the keys and pressing the right pedals. He probably understands what it's good for and how it interacts with the world (ie: what can go wrong if you collide with something). He knows that when the little needle gets close to the 'E' he needs to put more Magic Fluid in it from one of the Magic Fluid depots around the city. But that's about it.

Focus on the things your characters care about. Those are the things that will affect them

Does John Doe know how the car burns the gas to cause propulsion? Or how the brakes work? Or even why it's so easy to turn a wheel and change the direction of two tons of metal? I'd guess not. And guess what--this lack of knowledge doesn't even affect him!

What John Doe does care about is how the price of Magic Fluid has been going up lately. He cares about how cool the new models of cars look compared to his old one or what (to someone from 70 years ago) minor features were added.

You're not writing an encyclopedia or manual--you're writing a story!

If knowing or not knowing a fact doesn't affect your characters, then guess what--it doesn't affect your story! And if it doesn't affect your story, then it has no place in the pages you're writing.

Remember that all of this technology is just a pile of tools that work to build an image for the reader of what your world is like and propel your story. At the end of the day, all that really matters for the story is probably exactly what you've written: it's "see[ing] the technology in use, understand[ing] what it does, and even what it requires to work."

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    This is the answer I was going to post. To most people, stuff just works, so approach it like your characters; unless they are brand new, hover-trains would be totally normal (and boring) to the daily commuters riding them. Exceptions apply, of course, if the science or tech is central to the character or the story - the first astronauts going through a wormhole are going to care very much about all the fussy details about what exactly happens to them and why. – BradC May 6 at 20:31
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    And all this science / I don't understand / It's just my job / Five days a week / Rocket man / Rocket man – Monty Harder May 6 at 22:45
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    This answer made me realize what bugs me about the (few) hard-science books I've read - the protagonists invariably know literally everything about each object they interact with, down to equations level. As a scientist myself, I can only chuckle if the astrophysicist starts explaining microbiology because the author needed an outlet for an infodump. – xLeitix May 7 at 14:31
  • @xLeitix, not only scientists; it's common to see in such books (and esp. in sci-fi movies) that ordinary people engage in technical conversations about things that are supposed to be ordinary for them. For the benefit of the reader, of course... – Zeus May 8 at 0:27
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    @xLeitix - I feel like appendices are severely underrated things. – Obie 2.0 May 8 at 3:55

"Scientific plausibility" can be tempered by exoticism, time, and distance. It can also be flatly ignored because it's just a plot convenience, or substituted as a metaphor for the real story you are telling.

"This technology is so exotic that we barely understand it ourselves!"

The technology's narrative role is that it pushes credibility, or is difficult to grasp for the characters. Used as a positive it conveys a sense of wonder. Science is always on the edge of new discoveries that will transform our lives.

Used negatively, the exoticism implies a threat. Scientists are playing god. Technology is going too fast and humans should slow down. This is ultimately a conservative message, a fearful message. Man should not attempt to jump the line, or the unseen hand of cosmic justice will slap them down.

"In the final decade of the 21st century, men and women in rocket ships landed on the moon."

The quote above is from Forbidden Planet (1956). The first actual moon landing would be only 13 years later, not 140 years – maybe it's the "and women" part that sounds too far fetched so they had to set it further in the future. Too many innovations in a short amount of time will jeopardize suspension of disbelief (having too many "buys" in the story). 1956 audiences could not accept both rockets and women on the moon in just 13 years.

Add another century and… well, maybe.

By 1966, Americans could accept that body swapping technology exists in the 23rd century, but not female Starfleet captains. No technology is too outlandish given enough time, another century, another millennium (so long as the people with lady-parts are kept away from the things that go boom).

"...the end of the universe? Or do you see this as the beginning…?"

The above quote is from another Star Trek episode where they accidentally travel so far away that the laws of physics are different. Matter and thought become blurred in metaphysical soup. Strangeness increases with distance.

By extrapolation, objects from far away bring their exotic properties with them, hence signals from a distant galaxy, artifacts recovered from a distant planet, even the traveling strangers themselves can show up on our door bringing a sophisticated technology that requires no research or development phase. The general public can have sudden (unearned) access before it is fully understood.

In Altered Carbon the cortical stacks come from technology discovered on an alien planet (you'd think the discovery of aliens would factor into the story somehow, but nope, just a pretext for instant technology).

I'll separate the last two because they are strictly narrative, and ignore any worldbuilding pretext.

It's perfectly valid to leave it unexplained. If it doesn't serve the narrative, don't waste time on it. We have a very unflattering word for this: infodump. If the climax is ultimately about shooting a gun at the thing, or rescuing a princess, or doing a distraction dance, no amount of technobabble "filler" is required to explain it.

The final narrative function is that it's a metaphor. The "mystery" is only explained through subtext and theme, but not directly through facts and science. That impenetrable barrier at the edge of space is really a metaphor for the limits of human understanding. When it mostly makes sense within the context of the storyworld, or if it mirrors a character's internal state, it's probably more symbolism than metaphor (the frozen Oort Cloud of the soul). Metaphor is something completely outside the storyworld. The psychic planet Solaris is a metaphor for depression (isolation, guilt, mental health), since the story doesn't feel the need to explain it in a literal sense the author is free to explore the metaphor more completely.

Horror can be considered a metaphor since the story logic will follow the theme (haunted house in spaaaace) even while characters comment on events that are unnatural or unexplainable.

  • A suggestion for handling the infodump is to write an appendix that explains such things for those who want to read them, but leave it out of the main flow of the story other than a footnote upon the first use of the technology referencing the appendix. . – Monty Harder May 6 at 22:44
  • Fair, but don't you think that this might depend on the audience a work is trying to reach? If a work is going for the Star Wars audience, it can say that the "technology" is created by exotic crystals from the Big Bang, and the viewers or readers will accept that it can do anything. If the work is going for the The Martian audience, it could give the equations of motion and the audience might still complain. – Obie 2.0 May 7 at 0:32
  • @Obie2.0, your comment falls under time. The first man on Mars is maybe a few decades away.... Star Wars isn't relatable to our time at all – aside from being a fairy tale with anachronistic elements, the "technology" is (maybe) thousands of years off (if not tens of thousands). – wetcircuit May 7 at 2:01
  • I'm not sure what you're saying. Some of the technology in Star Wars is thousands of years off, some is decades off, some is impossible. Although the series is actually set in the past. But I wasn't talking about that: I was saying that perhaps there are actually differences between audiences in how much deviation from the established principles of science they're willing to accept. I could have mentioned the MCU (extremely loose "science" set in the present) vs. Ancillary Justice (more solid science set in the far future) to illustrate the point about different audience expectations. – Obie 2.0 May 7 at 2:16
  • LOL! Do you believe MCU fans would reject the franchise and stage a boycott if those scripts made an attempt to be more than magic people chasing magic candy crystals? No one considers those movies "sci-fi", anymore than Scooby-Doo is "sci-fi" for having a talking dog. Harry Potter is closer to sci-fi than the MCU. – wetcircuit May 7 at 11:38

The easiest way to show your technology fits science fiction is to have it break, and then get it fixed by an engineer with a spare part or something.

More generally speaking, in the reader's mind it will be "technology" if it is treated like "technology". In particular, show it can break and needs to get fixed by some guy with a screwdriver. In that scene the tech gets treated as we would treat a misbehaving iPhone, as an irritating inconvenience. We don't really know how an iPhone works either, but we don't treat it like its magic.

You will see this trick used in Star Wars, repeatedly, the drives and machines malfunction. R2D2 may beep, and we can't understand that, but the actors all treat the beeping as a language they know, and respond in English (usually in a way that lets us know what R2D2 said).

You will see the same trick used in Star Trek, Scotty was always there to remind Kirk (and the audience) that the warp drives weren't magic (but apparently Scotty was magic, always doing the impossible.)

Treat it like a fallible machine, and it will be seen as one. As a general rule, magic contains some mechanism of action that is not scientifically explainable. That is true even in detailed magic systems.

Technology will not, the characters all think of it as a machine, even if they have no exact knowledge of how the machine works; they know that machines depend on parts, the parts can wear out or break, and the machine will stop working.

Treat it like technology, and you don't have to really explain how it works, your readers will see it through the eyes of your characters, as a machine.

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    +1 for the idea, and also for "apparently Scotty was magic," – Basya May 8 at 9:04

How technology works is sometimes in a novel or movie or other work (some authors give you every last detail, like Andy Weir) and sometimes it's just there as a given.

While avoiding explanations in visual media is more common than in printed ones, the fact that it happens at all is telling. Take something like the TV series (and movies) of Star Trek. Warp speed is part of every episode and is vital to the functioning of the plot. In fact, several episodes show them in danger because the warp drives are malfunctioning.

We usually get no explanation; they're just a given in the universe. When there is an explanation, it's gobbity-gook. Sometimes it's internally consistent and other times it's not.

Some folks say that any story with faster-than-light travel isn't realistic, no matter how far in the future. Yet, you'd never call Star Trek, or any other story with FTL travel "fantasy" because of it.

The important part isn't if the author explains the technology to the reader but if the characters believe it. There are plenty of technologies in the real world I don't understand on a technical level, where I couldn't explain how or why they work. But I still believe they're real. I know they're not magic.

To call your story science fiction, the tech merely has to be scientific. It's not important that the reader understand the scientific principles behind technology in your story.


Scientific plausibility is maintained by not doing anything that breaks it. That is all there is to it. Details get bit more complex.

Unless you somehow signal otherwise the default assumption any reader will and should make is that your world works the same as the world they are familiar with. The issue comes with how to not signal more than you intend. When you introduce a new element the reader will try to fit it to some model they are familiar with. You need to control what that model will be. A task complicated by different readers being familiar with different things. Assumptions safe with one audience will utterly fail with another.

And the context has major impact. I am specifically talking about genre. If your story reads like fantasy or space opera or has gothic horror vampires you should not waste much time trying to look scientifically plausible. It won't work.

When you introduce an element that is beyond the known science but wish to to maintain plausibility anyway there are two parts to it.

First is still not saying anything that breaks the plausibility outright. If you say or imply it is "magic" you will lose. Do not use fantasy conventions. Do not imply it is magical. Do not imply it is sufficiently advanced to be considered magic.

Second is simply signalling to the reader that it should be considered plausible. That it is science. All that means is that somebody understands how it works, and somebody built it with normal engineering without any magical rituals. Or could have done so even if they did actually use ritual incantations due to superstition. That somebody discovered the science behind it, and understands it. That it fits in the overall framework of science and scientific method.

Sadly, very sadly, the established practice to convey that is technobabble. Try to keep it minimal. All you need is enough that the reader gets your intent.

For example for an FTL drive you could mention that it is a [a] drive based on the [b] effect discovered by [c] in [d]. That this particular one was built by [e] in [f] and is special because it can [g] and has [h]. But that unfortunately it has issues with [i] and needs regular [j] which increases upkeep or limits its use in some way.

Just speak about it in recognizably the same manner and same kind of language that is used to discuss things that are common place, not at all magical, and obviously entirely plausible. For a space drive look how enthusiasts talk about car engines or jet engines. For a weapon look how gun enthusiasts talk about guns. Then either have such a character be enthusiastic 'on camera' or have some other character or the narrator give a toned down version.

It is annoying but you do not need to spend lots of time on it, you just need to do it every time you first introduce a new element. Preferably without it sounding ridiculously forced and unnatural. Technogeek characters that are constantly babbling things nobody wants to hear can be convenient.

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    Except Clarke and "indistinguishable from magic". FTL for a prime example - we know the energy required exceeds E=mc^2 for the entire universe, by many orders of magnitude. And in the opposite direction, magic must have laws and limits, otherwise the story will always just be "and then the wizard waved his wand and it was all fixed". The challenge for both is simply to decide what physical laws you're going to break, and then stay consistent. – Graham May 6 at 21:09
  • @Graham No, we do not know how much energy FTL would take. None of the models we have allows FTL in the first place, so if FTL is possible anyway none of our models can be used to predict its energy costs or anything else. This is a sadly common form of circular logic. "If we assume that something mutually exclusive with A is true, then A causes contradiction, therefore A must be false." I think the reason it is so common is because it works well as a sanity test for how plausible something is. – Ville Niemi May 6 at 21:40
  • @Graham The best you can actually do is to build a model that would allow FTL and then test that model against actual data. Sanity checks against existing models would be useful when making the "FTL model" but they are useless in proving or disproving it. – Ville Niemi May 6 at 21:42

The most important thing I recommend is to hold to Sanderson's First Law of Magics:

An author’s ability to solve conflict with magic is DIRECTLY PROPORTIONAL to how well the reader understands said magic.

While you draw the line between magic and science fiction, this rule is essential on both sides of the line. It's important because much of what makes science fiction fun dabbles along the edge. You have to be able to obey the laws of magic while you're teetering over on the magic side.

It also points directly at the key to your question. Your reader must understand the magic. If they understand the magic, they will give more leeway in the scientific plausibility. One pattern I have seen many times is to establish a character with scientific credibility, and then rely on them to give credibility to whatever you are writing.

Probably the most important thing to remember that's unique to science fiction is the flow of science. Science does not give any credibility to predictions outside of the status quo without experiments showing something different. People are trained to be skeptical of these things. If you have to violate a "currently known law of physics," you are going to want to make sure they can believe whatever experiments were done to move science in that direction. Thus, if you need FTL, pay attention to how the new rules might have been discovered. If you need to break the law of conservation of energy, make sure you do so gracefully. And, if possible, introduce these changes in a way that does not solve conflict. That way, at worst, readers can respond through Sanderson's Law.

And remember:

We often think of scientific discovery with shouts of "Eureka! Eureka! I have found it!" and the subsequent public indecency as one streaks through Syracuse naked. Real scientific discovery rarely sounds like that. Far more often, it sounds like "Hmm. That's kind of funny."

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    In engineering, it's often "hmm, it's never done that before...". Same basic idea. – a CVn May 9 at 15:36
  • @aCVn I've learned to silence that voice. For some reason, saying that makes management disinclined to fund you further =D – Cort Ammon May 9 at 15:37

The question you seem to be dancing around is, will your audience revolt if you do not explain the workings of X? The answer essentially depends on what X is. Some X's naturally lend themselves to one interpretation over another.

For example, let's say you have some futuristic Sci-Fi story. In that story, a number of people are said to be able to communicate telepathically, sending messages, sensory experiences, and so forth. Now, is that magic or is that science? Given no other information, the audience will likely assume that this is magic, because that is usually how telepathy works in stories.

But if your telepathy is done through some kind of brain implant that broadcasts what people want others to hear over the Internet or whatever, there are many ways of communicating that this is technological without talking about brain implants. All you need is something that makes it clear to the reader that technology is involved. Someone saying that they're recording thoughts onto a medium (or the cloud) for someone else to pick up later would be enough to switch the audience from "magic" to "science".

Now, such presentation needs to happen early on, so that you're giving people the right impression from the start. But it need not be a description of brain implants or whatever.

In general, if there is a physical device involved, especially if it requires electricity, then the reader is far more likely to accept it as "science" than as "magic." But this needs to be tempered with the fact that the more magical the effect appears, the more it will trigger "magic-in-science's-clothing" than "science". That was the point of the telepathy example: you need something to let people know that people are producing a magical-seeming effect through technological means.

That having been said, some people are pickier than others. For example, some people will reject even the above telepathic example unless you come out and and directly state at least the basic mechanism behind it. For them, the single phrase "telepathic brain implant" would probably be enough to get them on board.

So basically, your question boils down to how important it is to you whether you keep the pickiest of Sci-Fi readers happy. And that's a question you can only answer yourself.


Do you need to convey plausibility?

Other answers have already mentioned this. Depending on your intended audience, and what you personally want in your art, you might not need to convey scientific plausibility at all. If your audience is Twilight fans, the number of chromosomes vampires, werewolves, and vampire-human children have is relatively ancillary; even if they get an explanation, they probably wouldn't have complained if they hadn't. If your audience is Star Wars fans, they'll expect more trappings of technology, and more "explanations," but plenty of things can still go unexplained. They can still accept the Force without midichlorians. On the other hand, if your audience is fans of The Martian, they might be expecting something rigorously plausible, and if you put in some totally new technology without reassurance, they might not like it.

That said, if want to make the scientific plausibility explicit without providing a lengthy explanation, here are two ideas.


If you want to save space or not directly explain how some technology works, but still have something recognizably scientifically plausible to a knowledgeable individual, use a description, not a specification sheet.

Imagine a nuclear fusion bomb. You could certainly explain how it works, how the explosives increase the density of the nuclear material, how the high kinetic energy leads to a cascade of collisions, how hydrogen atoms fuse and release the mass difference as energy: in short, the science. Or you could describe the appearance and effects of the bomb instead. How much does it weigh? What kind of explosion does it produce (shape, light)? Does it poison people afterward? Or if someone takes the material out....

Or what if you want to use some fictional but still plausible technology. You can make it clear that the box that talks is a quantum computer by mentioning its temperature (quantum computers often operate at very low temperatures), and that it reacts poorly to a static shock.

By seeding these sorts of hints, you certainly maintain brevity, and even suspense for most readers, while nonetheless writing something that is obviously scientific and not magic or simply a plot device. Readers who are familiar with the principles behind the device will feel affirmed, whereas those who aren't won't miss anything.

Supplemental material

Works set in a historical setting, or a setting based on a historical setting, or even a real-world setting likely to be unfamiliar to the reader for whatever reason, often will have an appendix or prologue laying out the real-world background behind the story. Despite the fact that most readers won't be able to distinguish between actual Ancient Egypt, which existed, and Atlantis, which probably didn't, a story might nonetheless explain the history of ancient Egypt in the appendix.

This strategy could work for you; you can provide the scientific details in a supplemental section for those readers who are interested in such things. I've even seen a few particularly dedicated authors who wrote up a treatment of their work's physics or technology and posted it online. Any of the previous strategies will let you save space, or not spoil the story, while still providing the information for those who might want it.

This works best in a printed work; if you are writing a screenplay the additional filming costs may be prohibitive, or people might just not want to watch an additional video or listen to additional radio time.


One approach you might look at is the "5-space theory" in Lois McMaster Bujold's "Vorkosigan" saga, particularly in "Komarr". The protagonist has to solve a plot in which a 5-space device plays a crucial role, so there has to be enough theory to drive the plot forwards while giving the reader a sense that there is some real science going on, but within an entirely fictional branch of physics.

Bujold does this by mixing two things:

  1. Some honest magic: 5-space forces are manipulated by "Neklin rods". Apart from the fact that these are big and extremely precisely manufactured we never learn anything about their principles of operation.

  2. References and resonances with real science. Einsteinian relativity is a 4-space phenomenon (3 dimensions plus time), so 5-space could be an extension of his theory. There is a reference to the idea that "wormholes" (exploited by 5-space drives) do not impinge on normal 3-space; their forces act at 90 degrees to our normal 3 dimensions, so we can't detect them.

So you can create a technology by setting down some ground rules with double-talk based on current science, extended with whatever magic you want. Make your future tech consistent and with rigid rules that the characters cannot break.


For my money my two questions aren't related to this in the least, they're about things that can't be explained within the universe and whether such elements have a role in Hard Science Fiction. You appear to be asking "how much does one need to explain the science in their science fiction?" there isn't a one size fits all answer to this question but I would put it like this "invoke enough established science to give the reader a basis for suspension of disbelief" what does that mean? It means give your audience some basic principles that underlie the technology and let them fill in the blanks with whatever speculation they like, or none at all.

Example: sample FTL Drive exploits the energy of other universes, assisted by phenomena it's inventors would be scared stiff to contemplate, to break the uncertainty principle just enough to let it be somewhere other than where it was. The in-universe explanation, (and what is initially presented to readers), is that it uses a trick of quantum gravity to exploit the interaction between absolute zero and the uncertainty principle to transport ships point-to-point across vast distances. It's based in the one-big-lie principle, in this case the lie is that you can get anything back from that absolute zero state apart from a scattering of individual atoms, or atoms worth of exotic energy, spread across the whole volume of space involved.

You give the reader some of the science on which the technology is based, thus proving that it is techno-science not magic but you never really need to explain in detail how it really works, unless you want to for dramatic purposes.

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