Black Box

"You don't really know how powerstones work. You've created a whole city that relies on an energy source you do not understand. 'Magic!' you say. 'It's magic!' Oh, how clever. And then when the magic fails, you simply say, 'It must have been more magic!'"

— Yawgmoth, The Thran

In engineering terminology, a "black box" is a device with one or more inputs (cake ingredients, an excerpt of text in Mandarin, iron ore), one or more outputs (cake, the same text translated into Frisian, a battle golem), and an internal process that is either:

1. irrelevant and/or needlessly complicated.
2. unknown and/or unknowable.

In narrative terms, this is a device that produces near magical results but the comprehension of the device is at best a guess by the characters, meaning if it breaks, a replacement is not easy. The original creator is unavailable (either dead, an alien or from a long-gone civilization or otherwise can't be reached), but said technology is really convenient. Such technology falls into the hands of some organization, usually the military or a commercial business. The organization's analysts went over the thing, and while most of it makes sense, there are these elements, either program or device, that they cannot comprehend at all. Removing them causes the entire thing to simply not function (or triggers a more active response). The organization may be able to reverse-engineer copies, or lesser versions, but they don't understand how it actually works.

So, since the financial bottom line or military advantage is so important, they go along with it anyways.

... Yes, of course, the technology has a bizarre effect that nobody could have predicted — you really need to keep track of those inputs and outputs! Usually, it's in the form of acquiring sentience or a bizarre weapon, or only being able to be used by people of the show's target demographic. (It's common in Humongous Mecha series.)

This is surprisingly common in Real Life, with many different scientific fields having their own viewpoint on the issue. This is particularly known in programming, where the programmer is the only one who really understands how what they've built works (and sometimes, not even them^note Even a "simple" (no graphics, purely command-line and input file driven and with the only output being more text files) scientific application that does anything actually useful can easily exceed ten thousand lines of code in a high-level language and is probably the result of the work of multiple people, none of whom knows every detail of the parts they didn't write. And even if a single dedicated programmer wrote the whole thing personally, it's virtually certain that at least some of it uses infrastructure in the form of library routines or system calls that were not written by the same programmer.). It is something of a Running Gag in tech start-up culture that being the first to design the infrastructure of a new system is ultimate job security, as it would take years for another programmer to understand the coding to the same degree. This is especially evident in high-level languages, where the programmer can for example tell the computer to replace all occurrences of "cake" with "apple" in a text, and doesn't have to worry about how the system does it — they get a changed text back and that's that. This also happens in pharmacology, where it might be discovered that a drug has a positive effect on people with a certain illness but when it's first used doctors and scientists don't understand why.

In a Scavenger World, most complex technology is like a Black Box, because generations that grew up After the End don't know how Precursor technology works. And with so few to reverse engineer junk, when just surviving is a daily challenge, much of it becomes Lost Technology.

Sister Trope to Disposable Superhero Maker. Compare Missing Steps Plan, Unobtanium and In Working Order. See also Right for the Wrong Reasons.

Not to be confused with "Black box" flight recorders, the kind of theatre, the Italian house music group, the method of c██████████ information, the former video game developer who used to make the Skate series and various Need for Speed games, or a black-colored Censor Box.

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Examples:

Anime & Manga

• In Eureka Seven AO, all IFOs are equipped with a "Third Engine" based on technology found in the Nirvash. They know it can use trapar as fuel, giving the IFO theoretically limitless flight time, and the Nirvash has increased speed and maneuverability while using it, but they have no idea how to turn it on or how it does these things. Elena and Fleur do eventually manage to get theirs working, but it only lasts as long as it needs to for them to rescue Ao, then shuts off almost immediately once he's free. Elena credits The Power of Love, which, given the previous series, is most likely the exact reason it worked. It activates a second time for Fleur in the finale, but nothing comes of that.
• GaoGaiGar: In one flashback, characters actually discuss a strange interface on Galeon, an alien mecha lion, and refer to it as a Black Box. Once they figure out how to activate it, it contains designs for half the Applied Phlebotinum in the show.
• The Kabizashi blades in Knights of Sidonia, which are the only weapons that can kill Gauna. No one knows for sure how they work, and no one knows how to make more of them. They were recovered from inside a mysterious Big Dumb Object floating in space, and their properties discovered by complete accident. Production is later established. Understanding? Not so much.
• The GN drives in Mobile Suit Gundam 00. GN Drive technology can be mass produced in months (reversed engineered by The Federation from the GN-X drive model), but true GN Drives, the ones which emit green "pure" particles used by Celestial Being's Gundams, are equipped with a "Topological Defect" Blanket, which can only be manufactured around Jupiter with a total production time of six years. Somehow harnessing the power of topological defects (a mathematical solution involving differential equations) allows the drive to funnel energy back into itself, allowing for unlimited operation time. Additionally, Celestial Being's true GN Drives have a literal black box which no-one could figure out, which turns out to contain the data for the Gundams' Trans-Am Function and the Twin-Drive System.
• In Nausicaä of the Valley of the Wind, nobody has the technology to build new airship engines anymore, so when an airship is downed, there's a scramble to salvage the irreplaceable engines.
• The development of the Evangelions in Neon Genesis Evangelion is very much along the lines of this trope, with Misato even namedropping it in Episode 20. The Reveal is that they were constructed using Angel DNA, but due to their Eldritch Abomination nature, they're unpredictable and dangerous to even use. The S2 engine (recovered from an Angel corpse) is a particularly fitting example. American attempts to reverse engineer the device and implant it in an Eva result in a massive disaster — the test engine and Eva Unit-04 vanishes, along with the entire research facility and all other objects in a 50-mile radius.
• Outlaw Star:
  • The eponymous Cool Ship and Melfina are revealed to have been created based on the unknown data (the black box) that Gwen Khan could not translate from an advanced ancient civilization which is implied to have created all of the ancient ruins of the galaxy. Only Melfina can open the door to the Galatic Leyline itself, and grant the people that go there their ultimate desire.
  • For a while, the Caster Gun employed by main character Gene Starwind was a black box of lost knowledge. Caster guns are essentially antique pistols that fire unique shells with a wide variety of effects that can even counteract the magical attacks of Tao Masters. Nobody knows whether they are lost technology or, as later confirmed, magic that has been encapsulated within the shells.
• The flying machines in Simoun have two black boxes: the "Helical motor" (according to the sub) and the "Simoun Gem". Trying to find out how these things work apparently drives you mad for a little while.
• The sentinel stations in Sound of the Sky. Felicia points out that they're just checking to see if they still work and there's nothing that can be done if they're broken. Noël even calls them a black box.
• In Tora Kiss – A School Odyssey, we have Academy Island and the Monument. Structures of unknown origins carrying huge amounts of information, some of it on science and technology that are light years ahead of anything on Earth. People can access that information to some extent, but have no idea how the database holding it works or where it comes from.
• The plants in Trigun can do pretty much anything depending on how you power them, but nobody's really sure how they run anymore. (The manga actually calls them "humanity's ultimate black box".)
• In the American release of Voltron (which combined the separate series GoLion and Dairugger XV), it's established that the Vehicle Voltron was built as an imitation of the original Lion Voltron built by the late King Alfor of Arus. Since the original Voltron is semi-mystical in nature and the magic was not copyable, the duplicate can only stay unified in giant robot form for five minutes at a time.
• A scientist in Yozakura Quartet equates the workings of Youkai and supernatural powers to Black Box technology. He makes the comparison that just as we don't understand how magic works, most people don't understand how a computer turns on apart from pushing the "on" button.

Comic Books

• Atomic Robo's heart was constructed by Nikola Tesla using means that not even Robo can even take a guess at, and by the 2010s, the world's leading nuclear physicist couldn't even come close to recreating it even with access to the most advanced lab and unlimited funding. He could make a theoretical copy, but it would only operate half as effectively as the original, would be significantly larger, and would be constructed mostly out of material that doesn't exist. The eventual replacement is also a black box, which is constructed by delegating the task to one of the world's most advanced AI's, which at that point is in a dead-but-dreaming kind of state, which takes the manufacturing task on board, does something and spits out a new heart that works slightly better than the original but is just as baffling.
• Captain America's shield is essentially a Black Box in design; made of an unknown alloy of Vibranium, other metals and a mysterious bonding agent — which the creator doesn't know about, having fallen asleep during its production — which results in a shield that has properties unlike anything else in existence. Some say that agent was American Rightousness (as opposed to American self-righteousness), explaining why it seems to act as almost an Empathic Weapon to Cap.
• Eega Beeva of the Mickey Mouse Comic Universe is a man from the future with hyper-advanced technology like bottomless pockets. In one issue, desperate scientists hoping to secure their funding ask him for one of his gadgets to study. He pulls out a literal black box, claiming it can replicate anything known in his time but, to their disappointment, as far as their instruments can study it's just a solid block of inert molecules, putting them back at square one.
• Star-Lord has his Element Gun, given to him by the Master of the Sun, er... his father when he was just a teenager. Quill's carried it all the way up through to the modern day, but in Guardians of the Galaxy (2020), he notes he's modified it, changed its appearance, and even managed to build a spare... and he still has no idea how it actually works.
• In Suicide Squad, Shade, the Changing Man admits that he does not understand any of the principles under which the M-Vest — which grants him his powers — works, as the vest was constructed by Meta's greatest scientist and he was the equivalent of a beat cop. While he understands how to operate the basic functions, he needs the Squad's resources to try and figure out how to get it to return him to his home dimension.
• The first three T.H.U.N.D.E.R. Agents were all recipients of black boxes. As their origin shows, their devices were found amid the rubble of the lab of a famous inventor, who had been killed by minions of the Warlord. The Warlord's mooks had looted the place, but missed a few items. Several early stories were about the agents discovering drawbacks to their new powers.

Films — Animated

• This is a main plot point in Robotech: The Shadow Chronicles. The Haydonites provide humans with shadow technology which greatly aids them in fighting Invid, but the technological information supplied by Haydonites is incomplete, so even though the shadow devices were built by humans themselves, they still have flaws which Haydonites exploit when they attack humans.

Films — Live-Action

• The Machine in Contact is Imported Alien Phlebotinum. Humans are given plans for a Machine, but not an explanation of what it's supposed to do or how it does it. When it's activated, the chair for the occupant drops straight through in a matter of seconds, while 18 hours passes for the occupant, causing onlookers to think that it didn't work. One scientist remarks that the video recording from the chair consists of 18 hours of static, which he is unable to explain.
• Godzilla vs. Kong: For all of Apex Cybernetics' boastings about human superiority over the Titans, their secret project is actually extremely reliant on seizing outside resources which are eldritch in nature as key materials to make the thing work at all; and Apex intend to use both resources with only a surface understanding of their capabilities and no true understanding of their inner workings. Apex have converted Ghidorah's skull into a Wetware CPU for Mechagodzilla based on their discovery that Ghidorah's remains retain a telepathic connection to each-other, and Apex are planning to use the Mineral MacGuffin in the Hollow Earth as a power source for their superweapon based on their remote satellite discovery that it has high energy readings. Mixing these two things into a Humongous Mecha without an in-depth understanding of either of them ultimately leads to Ghidorah's subconsciousness from the skull taking control of a fully-charged, super-destructive Mechagodzilla for itself. "Monkey see monkey do" indeed.
• Marvel Cinematic Universe:
  • In Captain America: The First Avenger, when the Red Skull finds the glowing blue Tesseract (a version of the all-powerful cosmic cube of marvel comics) he uses it as an energy source for his tanks and weapons. Until his supposed death when the cube sustained damage from Captain America's shield and began to warp reality itself, he only saw it as an unlimited power source. Ditto for the scientists on the American side, who attempted to harvest the minuscule yet overwhelming bits of energy powering the guns (blasting a hole in one of the research facilities when they tried to discover its properties).
  • Avengers: Age of Ultron has the Staff, which HYDRA uses to conduct experiments in giving folk superpowers and developing artificial intelligence... somehow. The implication is they were just throwing stuff at the wall to see what stuck, since they only come out the other end with a lot of non-functioning robots and only two traumatized teens with superpowers. Later on, it's implied the Staff, which is alive in some form, is what brings Ultron to full sentience.
  • It's already implied in The Avengers (2012) that there's more to the Tesseract than Red Skull's experiments, but both the Tesseract and the Staff are later revealed to be Infinity Stones, representing a fundamental aspect of the Universe itself, and become the core plot of Avengers: Infinity War.
  • Tony Stark's superscience had many demonstrations throughout the franchise, so Spider-Man: Far From Home and Spider-Man: No Way Home have what amount to Stark Industries black boxes, in the former a device in Tony's jet that Peter uses to create an advanced Spidey suit, and in the latter a machine in one of Tony's old bunkers that develops whatever could fix the conditions of the universe-hopping villains (and in a demonstration of "no easy replacements", once the Green Goblin destroys the thing it takes three Spider-Men to finish the research).
• The guidance system abroad the Russian communication satellite in Space Cowboys is a downplayed example — it's not an artifact of a lost civilization, it's just so archaic that no-one except the original creator understands it.
  "It's pre-microprocessor! It's pre-EVERYTHING!"
• The Algorithm that is the MacGuffin of Tenet is specifically referred to as this.
  Neil: It's a formula, rendered into physical form so it can't be copied or communicated. It's a black box with one function. Inversion, but not objects or peoples. The world around us.
• In Zack Snyder's Justice League, the eponymous League doesn't have much of an idea how the Mother Boxes work beyond using one to resurrect Superman with a big electrical impulse. Steppenwolf, meanwhile, uses them to teleport himself via Boom Tubes.

Literature

• In Animorphs, the kids are given the power to morph by touching the Blue Box by the alien Elfangor right before he is eaten alive by Visser Three. Later, David shows up with the same blue box and it is used to give him morphing power even though no one present has any idea how the technology works. This happens later again when the Auxiliary Animorphs are created, and yet again when the Yeerks steal the blue box and use the morphing power to create their own soldiers with the morphing ability.
• In Atlas Shrugged, the remains of John Galt's motor were found in an abandoned motor factory. Dagny Taggart's new purpose in life (for the next few chapters at least) is to find a scientist to reverse engineer the motor and put it to use on her railroad. It's a particularly interesting case, as Galt realized that the unbelievable stupidity of Starnes heirs were the symptoms of a cultural decline. He could thus safely walk off and leave the prototype and the plans right there in the lab without fear that they would be stolen, as no mind capable of understanding how valuable they were, let alone making use of them, would ever work there again. A notable subversion of Low Culture, High Tech.
• The O/BEC processors in Blind Lake. Created by accident due to the use of self-rewriting code, not even the scientists who operate them are quite certain how they do what they do. There are only two in existence; all attempts to make a third by replicating the conditions that led to the first two have failed.
• In Competitors, the alien technology aboard the Platform is so far beyond human understanding that it took the people sent there years to figure out certain basic things. Unfortunately, most people who end up there lack any technical background, so any engineer who finds his or her way to the Platform is paid handsomely to try to figure out how to even work the systems, much less reverse-engineer them. The engineers also have a fairly high fatality rate due to the fact that they have really no idea what they're doing. Sure, the ships left by the mysterious aliens have fairly basic analog controls (dumbed down for an average human), but it took at least a year to figure out that there are toilets aboard. It took about as long to figure out how to flush one without depressurizing the whole ship. The aliens are giving bits and pieces of their tech to their human contacts on Earth, allowing their contacts to get filthy rich off the patents.
• In Death or Glory, anything produced by the Swarm is so far beyond what the rest of The Alliance can do that they can't even grasp the principle behind the functionality. On the other hand, they have managed to at least learn to produce exact copies of some of the devices. The same applies to any piece of Departed tech that's discovered.
• In the Russian Death Zone Shared Universe, the mechanical artifacts found in the Five Zones usually fit this trope. While people understand that they're a product of Mechanical Evolution from runaway terraforming nanites called skorgs (it turns out that releasing them on Earth instead of Mars was a bad idea), affected by the mysterious Zones, it's almost impossible to reproduce the devices without, basically, copying what the skorgs are doing. This doesn't stop many people, groups, and outside corporations from studying them. Stalkers have also figured out how to use some of the equipment in their daily lives, but they still have no idea how it works.
• The Belt of Deltora from Deltora Quest is technically a Black Box, with the belt part itself the box and the gems the internal mechanisms. It can be assumed that no one knows exactly how it works; indeed, how it works is irrelevant. All anyone knows is that the Belt is "greater than the sum of its parts" and removing one of the pieces (i.e., one of the gems) would stop it functioning.
• Discworld:
  • The Devices discovered by dwarfs are ancient Black Boxes with assorted functions, including power sources and recording devices, and often cube-shaped to boot. Part of the reason why nobody knows how they work is that they're also totally indestructible — it's hard to study the insides of something you can't open.
  • The magical supercomputer Hex is also a Black Box; it's added so many peripheral devices to itself that even its original designer, Ponder Stibbons, is no longer sure exactly how it works. (He's also Organic Technology; he uses ants instead of electrons.)
• In Friday, there is the Shipstone; a battery that comes in sizes from a lifetime miniature system for a flashlight, to a large battery that can power a house, to a possibly colossal one that powers spaceships. The black box-ness of it comes because the inventor never patented it, since that would require that he publish the schematics. He just started a company and started manufacturing them under lots of secrecy. Attempts at dismantling and reverse engineering a shipstone usually resulted in a big kaboom.
• Full Metal Panic! has a bunch of 'Black Technology', created by the mysterious 'Whispered'. Many are simply extrapolations of existing technologies, which are mass-produced and change the world drastically — Whispered are explicitly not useless. Others, however, are perfect examples of the trope — Foremost among them is the 'Lambda Driver', a true Black Box which enables users to warp the laws of physics through sheer willpower.
• In Dave Barnett's Gideon Smith novels, the British eventually control the mechanical brass dragon, Apep. Apep, despite being made in ancient Egypt during Akneheten's reign, is beyond the ability of a late 19th century Steampunk Britain. The British would dearly love to copy Apep but can't because of all the Magitek used in its construction. British scientists have tested Apep and the mechanical doll bound to it, so they know that Apep can fly at 100 miles per hour (and possibly faster than that) and it has an unlimited supply of fireballs that are 1949 Celsius in temperature and these never lose any intensity of heat until they hit a target. However their studies show that the clockwork mechanisms making up Apep, should not have been able to work and they have no idea where Apep's fireballs come from. The only thing they know is that it takes a number of magical artifacts to use Apep.
• The titular Deathly Hallows of Harry Potter and the Deathly Hallows: a wand more powerful (and less "loyal") than any other, an invisibility cloak that never stops working (as invisibility cloaks in that universe are wont to do), and a stone that can summon the shades of the dead from the afterlife. Legend has it that they were created by the Grim Reaper himself and gifted to three brothers. Dumbledore speculates that it's more likely that said brothers were just prodigiously talented magical craftsmen. Whatever the case, no one has been able to replicate their three masterworks.
• In Heavy Object, the targeting system of Objects requires regular calibrations incorporating the expertise of three separate engineering disciplines and the intuition of the Elite. Because of the odd interaction between such differing methods and the unique human factor of the Elite, nobody is entirely certain how the system works, only that it does.
• This exact phrase is used to describe the Highway in William Gibson's short story "Hinterlands". Astronauts go in and come out, sometimes bringing back pieces of alien civilization with them. The "jump" only happens when the astronaut is alone and they all, invariably, come back either dead or catatonic. Sometimes the jump doesn't happen at all...
• In His Dark Materials, the subtle knife is an ancient weapon that can cut through anything, including the fabric between dimensions. However, it has the unfortunate effect of creating a soul-eating monster every time it is used, and eventually weakening the equilibrium of the universe.
• The Hitchhiker's Guide to the Galaxy Trilogy:
  • The starship Heart of Gold features the infinite improbability drive that enables improbability manipulation up to a point where the ship exists everywhere at once and can drop out anywhere instantly—universe wide teleportation. The hitch is that nobody knows how the improbability drive really works, some smartass junior scientist just figured out one day that all he needed to know was how improbable it was for that drive to come into existence and voila, instant Black Box. Then he got lynched by his fellow scientists for being a smartarse.
  • The starship Bistromath works on a similar principle. In restaurants math works differently than anywhere else in the universe. This is why you can never correctly guess what the bill will be, what a proper tip is, how much each person at the table should owe, etc. Nobody knows why this is, or how it works (the attempt to understand it led to a generation of brilliant mathematicians dying of obesity and heart disease), but that doesn't stop them from building a spaceship modeled on a small Italian Bistro to take advantage of this fact and break several laws of physics.
• Into the Looking Glass has a device about the size of a pack of cards that does "interesting" things with spacetime. It was given to them by the friendly aliens at the end of the first book, who had found it on some other planet and had no idea what it was for. Although they did warn that one should not apply a "significant voltage" to it. Hooking up a double-A battery leaves a 10-mile crater. A car battery destroys the (deliberately uninhabited and unimportant) planet. Three-phase current erases the solar system. They eventually figure out how to turn it into a warp drive and use it to power the ASS Vorpal Blade. Turns out hooking it up to a car battery was using it wrong.
• In The League of Peoples 'Verse, the Technocracy has pretty much no idea about how most of its own technology works, as the majority of it was just handed to humanity by Sufficiently Advanced Aliens.
• The Legacy of the Aldenata series features the alien Posleen (or "people of the ships" in their language), who are similar to the Covenant in Halo in that they use technology they understand poorly if at all. One of their commanders stares in confusion at a computer helpfully informing him "Incoming ballistic projectiles. Impact in 10 seconds. Five.... etc" The views of their society in the initial books of the series are vague for the most part but imply that they only really use the systems that kill things or are almost entirely automated. A literal black box used by the humans in the same series appears in the form of the AID which is a black memory plastic box about the size of a pack of cigarettes with an extremely potent AI embedded in it. They act as a Universal Translator as well, but are provided by another species and the humans haven't a clue how they really work or how to make them. This turns out to be a serious problem for a number of reasons.
• Willis Linsay's stepper boxes in The Long Earth, which enable people to step from one world to another in an endless chain of parallel universes. They are cheap, easy to build using basic electronic components and powered by a potato. And nobody can figure out how they work. Linsay's daughter is a natural stepper, but since nobody knows how that works either, it's not clear how it helped him invent the box.
• In A Lord from Planet Earth, many Seeder artifacts are found, replicated, and used, but the principle of their function remains unknown. This is intentional, as the Seeders are, in fact, 22nd-century humans, using Time Travel to seed the galaxy with humanoid life in order to create an instant (from their viewpoint) army in a war. The artifacts were left behind intentionally to help guide their development.
• The Machine of Death is a device that takes a person's blood sample and predicts how that person will die. It's cheap to use and possible to duplicate, but no one knows how it works.
• In Rainbows End, pretty much all engineering is done by putting together modular black boxes whose contents are unknown, except to the companies that manufacture them. This is done to protect copyrights and trade secrets. Plus, it's supposed to make things simpler. At one point, Robert Gu gets frustrated, and tries to open a black box under the hood of a car, using a cutting laser. The result is an explosion.
• Redshirts has the Box, a microwave-shaped device that if given a sample of any xenobiological problem, will go 'ding' and provide the solution when dramatically appropriate. Truly unusual due to the fact that even the writer for the show doesn't know where it came from, since it never appears in any scene that is filmed. It just appears out of nowhere so that all the miraculous cures needed in the show are possible.
• In the Revelation Space Series novels, everyone uses a certain kind of stardrive, but only the makers know how they work, and fiddling leads to an enormous explosion. The most powerful weapons are barely understood gifts from Sufficiently Advanced Aliens or future humans who will send the blueprints back in time. Judging by one character's vague discription of the internal conditions in a stardrive in "Weather", the Conjoiners kept the stardrive technology Black Box so that the 'retarded' (everyone else) wouldn't try and weaponise it. And also because of the whole disembodied-brain thing...
• In the spy thriller Running Blind by Desmond Bagley, the MacGuffin is a piece of technology couriered by the protagonist who is being chased by Soviet agents. At one point he gets a tech-savvy friend to examine it, who's ends up completely baffled as to what it does. At the end of the novel he discovers that the Soviets were supposed to capture it and waste time and money trying to figure out what it does, which is absolutely nothing.
• In the Spiral Arm series, much of the technology humanity uses is no longer understood, and in fact believed to be so far beyond human understanding that it could only have been crafted by Gods. A distinction is explicitly drawn between "science" and "engineering". "Science", the understanding of how technologies work, is considered religiously mystical and beyond human understanding; the most that men can aspire to is "engineering", creating working reproductions of existing technology.
• In The Stars Are Cold Toys, the rat-like Alari outfit a human Buran shuttle with plasma engines for the mission. When the protagonist asks the shuttle's commander if it's possible to study and replicate this tech on Earth, the commander grimly replies that it is... in about a hundred years. Despite this, even this addition is a strict violation of the Conclave's rule prohibiting Weaker races from sharing technology.
• In The Sun Eater, even if the Solan Empire wanted to recreate the reality-warping Star Killing weapons of the ancient Mericanii A.I., they can't and these have since become Lost Technology owned by the immortal Fallen Hero Kharn Sagara. That's because when these weapons were made, the Mericanii A.I. had upgraded themselves into being Mechanical Abomination intelligences and were on the cusp of ascending into becoming Cosmic Entities until they were destroyed by the God-Emperor. Even the brightest genetically-engineered humans can't fully understand them.
• In Super Minion, Tofu relies heavily on a program called human.exe which basically allows him to be as smart as a human. However, he has no idea how the program works, it shuts down if he tries to check its source code, and he doesn't even know where he downloaded it from.
• In The Thran, the whole Thran Empire relies on powerstones as their source of energy, but even the engineers who work on them don't exactly know how they work.
• The Three Worlds Cycle: In the Well of Echoes quartet, the clankers draw energy from nodes. No one knows why it works, but there are some illegal books that speculate on these topics. This becomes a major problem when nodes start to fail, because the humans depend upon clankers to fend off the lyrinx that have been killing the human race.
• Troy Rising: Gravplates are cheap, ubiquiutous, and pivotal to most space travel. Everyone in the galaxy knows how to make them — but the only way to make them requires using gravplates, and nobody knows who the heck made the first one, or how.
• In the Uplift series, all of the alien species in Galactic civilization are happy to use technology they don't understand and can't repair, so long as it comes with the blessing of the Great Library passed down by their revered ancestors and somebody, somewhere, knows how to repair or replace it. The exception is Humanity, who know darn well that relying on such tech will make them economically dependent on other species. They try to use their own (comparatively very primitive) tech while struggling to learn how alien devices work. Occasionally, Humans even benefit from Rock Beats Laser. However, even Earthclan has to rely on Black Box technology for certain things — i.e., reality shields, psi shields, hyperspace, and the Library itself.
• Variable Star has a living black box in the form of Relativists. These are men and women who can coax a ship's engines to accelerate to relativistic speed apparently by Contemplating Their Navels. The Relativists think up a number of poetic descriptions of what they do all day to keep the engines going, but in the end, they admit that even they aren't really sure how they're doing it.
• In The Wheel of Time, there are the ter'angreal (magical items), the secret of whose making has been lost for three thousand years. The Aes Sedai keep plenty of ter'angreal around for use as black boxes without understanding how they work, and many more items where they don't even know what they do.
• In You (2013), all of Black Arts's games are based on the WAFFLE engine, but no one at the company really understands how it works. The narration directly refers to it as a "black box" at one point.

Live-Action TV

• Babylon 5 has a variety of Black Boxes, mostly leftover First One technology:
  • Nobody knows who built the first jumpgates or what principle they operate on, and every spacefaring race in the universe simply produces replicas thereof without understanding how they work.
  • Shadow devices that allow for remote control of ships. Like Sheridan says, the younger races don't understand them and can't build them, but are sure willing to use them.
• In Battlestar Galactica (2003), it's eventually revealed after the destruction of the Resurrection Hub that the "Significant Seven" Cylons don't understand how the resurrection process they use actually works, and so they can't reconstruct it after it's gone. Only the Final Five have the knowledge necessary to recreate the technology, since they designed it in the first place.
• Caprica has New Cap City. In effect, it is a virtual reality MMORPG located on their version of the Dark Net. It is an enormous city that doesn't seem to end, and nearly everything is trying to kill you. Most people use it like GTA, while teenagers use it to engage in orgies and drug use without harm, although a few are devoted to unlocking its mysteries. The one rule to play is that you only get one life, and are immediately and permanently locked out if you die. Its origins, and the reasons for its existence, are a complete mystery to everyone. Even the creator of the V-World technology has no idea who built it or why. The hardcore gamers all insist that there must be some reason or point to it, and are obsessed with the idea of "beating" the game, even though it doesn't seem to work that way. Eventually the point is rendered moot when the protagonist reshapes the whole world into a forest fantasy kingdom full of dragons. Really.
• Doctor Who: In "Turn Left", the TARDIS serves this role. The episode is set in a crapsack timeline where the Doctor died for real because he never met Donna Noble. Later on, after the world has gone to hell and The Stars Are Going Out, a universe-hopping Rose Tyler and UNIT use the recovered TARDIS to power a makeshift time machine to send Donna back to change the past and Set Right What Once Went Wrong. Rose admits to Donna that they don't have any idea how the TARDIS actually works, but she gets Donna to when in the past she needs to be — but not where, almost ruining the whole operation.
• Invoked in Person of Interest. When Harold Finch and his partner Nathan Ingram created the Machine, they made sure its workings were inaccessible to the government, claiming that this was Loophole Abuse — the Machine takes in raw electronic surveillance data and spits out a person's social security number to lead the user to a threat, but as long as the government doesn't see the data, then no one's constitutional rights are being violated. No one believes that this will hold water should the Machine be exposed, however, and the actual reason why is the Machine is too powerful for any person to have access, and so Finch encrypts it so heavily that even he will never be able to access it again.
• Power Rangers: A literal black box is used as a plot point in the season finale of Turbo, and in the third episode of In Space; nothing is mentioned about the technology inside of it (possibly to avoid Technobabble or add some mystery to it), but it is stated that it contains codes to allow the Astro Megaship to transform into the Astro Megazord.
• Stargate-verse:
  • The titular Stargate itself is a black box. It was built by the Ancients. They have figured out how to hook computers and power up to it and send signals to it. However, the Stargate itself is way beyond Earth human tech (though not beyond Tollan's tech, who do manage to manufacture their own), though that might have been because they had the help of the Asgard, who knew the Ancients and know the gate system as well as anyone bar the Ancients themselves. When summing up the Tollan just before they go to their new planet, Daniel says, "They're smarter than us." and then, after seeing the new gate, ruefully mutters, "Much, much smarter than us."
  • Stargate SG-1 often adapts lesser versions of the technology the crew encounters from other planets. "It doesn't quite work like the original" is commonly stated. However, they're far more aware than most Black Box users of the potential for unexpected side effects.In fact, nearly every piece of technology they pick up is mentioned to be sent off to Area 51, either in the episode where it's introduced, or when they decide to use it again. This leads to situations that look like Forgotten Phlebotinum, until two or three years down the line where the device pops up again. Except for anything that comes with a trigger (Zat guns, anyone?) which is usually put into active service immediately. Which should come as a surprise to nobody, since military usage (including stuff that makes an Earth-Shattering Kaboom) is usually the first application mankind can think off for any given tech. Naquadria bombs, anyone? Which makes sense in a way, as acquiring weapons to defend Earth is the SGC's first mission.
  • In Stargate Atlantis and Stargate Universe, the protagonists uncover treasure troves of Ancient and alien technology. Though they know how to operate the Ancient technology they find (most of the time), they don't know their exact inner workings. The Goa'uld, on the other hand, make very little effort to study the Ancient technology they use. They've based their empire on things like the Stargates and ring transporters, but they really have no idea how any of it works.
    • There are, however, exceptions to the rule. The biggest of them is Ba'al, a System Lord who knows more than any other Goa'uld (or human) how the gates work (with the possible exception of Anubis). When one human scientist figures out how to infect a gate with a virus that locks it down, Ba'al quickly reverse-engineers the virus and modifies it to infect the entire gate network. Later on, they require Ba'al's help to help with some gate coding, and he's able to use portable human computers just fine (it helps that he has spent some time on Earth as a corporate CEO).
  • At one point, the Tollan offer Earth one of their ion cannons that can one-shot a Goa'uld Ha'tak mothership. However, after studying the schematics, Carter explains that there's no way Earth's science can build the cannons in at least decades (possibly centuries). There's also the fact that Tollan tech lacks any mechanical parts, wires, or anything else a human scientist or engineer might recognize. They habitually use phasing tech to walk through walls, whereas only one Ancient scientist was able to make something similar (and kept it a secret). The Tau'ri are better at reverse-engineering actual alien technology than technology of fellow humans.
• In Star Trek: The Next Generation, Data's positronic brain that makes him a Ridiculously Human Robot is a bit of an unknown factor. While Starfleet has a pretty good idea of how it is supposed to work, along with the rest of his body functions, how he is sentient is a complete mystery to them, especially since the genius inventor who built him is dead. While Data can be dismantled in general pieces, they are reluctant to really dive into the fine mechanics of his brain and his memory centers — after a particularly overzealous researcher takes the issue to court in "The Measure of a Man", Data gains the legal right to refuse such a dismantling anyway. His own attempt to replicate the technology seems to succeed when he builds a "daughter", Lal, in "The Offspring", but he ends up proving the problem as her mental capacities increase exponentially until the system collapses. Also, the risk of creating another Lore (Data's dangerously violent older brother) highlights the risks of succeeding at building a stable brain.
  • In Star Trek: Picard, we learn that Bruce Maddox (who's been communicating with Data in order to figure out how to make more androids) was forced by Starfleet to develop the A500 series of androids. They were inferior to Data but were able to perform manual labor at the Utopia Planitia shipyards. Then they suddenly turned on their masters and destroyed the shipyards. The attack left tens of thousands dead and ignited the Martian atmosphere. Subsequently, a ban on synths was instituted. Maddox and Altan Inigo Soong, Data's creator's biological son, formed a small colony on Coppelius and began to use a radical new method to extrapolate Data's mind left in B4 into his "children." Some shared Data's gold complexion, while newer models were designed to pass for humans and even fool scans. After the events of season 1, the synth ban was lifted, and Coppelians were offered Federation membership. At the same time, Soong was also working on a special synth that could be used to transfer his consciousness into in order to cheat death. Agnes Jurati helped him perfect the synth and the mind transfer procedure. However, they ended up having to use the synth to save Picard, whose biological body was dying. Afterwards, Soong spent the rest of his (short) life working at a Section 31 facility on a new android that would combine Data, Lore, B4, and Lal.

Tabletop Games

• A fair bit of Lost Technology in BattleTech is considered black-box level of complexity, usable by the Inner Sphere but completely beyond their understanding in regards to how it worked due to 300 years of total war destroying means of production and conspiracies to assassinate scientists. This includes things like Drop Ship and Jumpship construction technology (described as fully automated and unable to be built), human myomer implantation (with horrific results if it fails for reasons unknown), and faster-than-light 'secret transmission' technology, which sends faxes across the stars. One of the most famed in-universe black boxes was the New Avalon Valkyrie factory, a fully-automated facility that kept producing brand new, function Battlemechs for centuries after it was turned on: raw materials went in one end, Valkyries came out the other. The New Avalon Institute of Science wanted to try taking the factory apart to see if they could replicate it or switch it over to produce a more powerful Battlemech, but fears that they wouldn't be able to put it back together afterword kept them from doing so. As the timeline has progressed, however, there have been some gains in the understanding of such technology.
• Quoth the Bliss Stage: Ignition Stage rulebook: "In the center of every ANIMa creche lies a scavenged piece of an alien's brain. It's possible that this is the only thing that an ANIMa requires to function, and that the rest of the machine is there to inspire more confidence on the part of the pilots."
• Justified in CthulhuTech. Since the Dimensional Engine runs on non-Euclidean mathematics, attempting to find out what goes on inside one will cause weak minds to break.
• Mad Science in Deadlands: A Mad Scientist may create fantastic devices that surpass anything "regular" science is able to produce, but it's impossible to mass-produce Mad Science gizmoes — they just don't work. Throughout the centuries, Mad Science gains or loses popularity, depending on the shifting popular opinion. Mad Science is partly magical, the ideas for it coming from Manitous, malevolent spirits serving the setting's Big Bads. It is part of a master plot to (eventually) bring about Ghost Rock bombs, nuclear weapons capable of warping or killing spirits of living things, and to transform the entire Earth into a terror-filled wasteland.
• The Dungeons & Dragons campaign setting Eberron has two:
  • Black box magic was used to develop the warforged through schemas, which are essentially magical blueprints conveniently left behind by an ancient giant civilization. It turns out (in the Secrets of Xen'drik supplement) that it was an attempt by an ancient extradimensional race to escape to our world from the realm of dreams by creating artificial bodies, though this doesn't explain why modern warforged are fully sentient and appear to have souls (it does explain why the bodies can easily contain souls, but considering the aforementioned extradimensional race is active on another continent and using specially bred mostly-humans for on-demand possession exactly where their souls are coming from is another question...).
  • In a sort of meta-example, divine magic (the sort of magic used by Cleric spells) in Eberron works on a "clap your hands if you believe" basis. Unlike in other settings, even high-level Clerics cannot communicate directly with their gods; when they try to do so, at best they get an entity that claims to be a high-level servant of the god rather than the god itself. The setting is extremely coy with respect to whether or not any gods actually exist, and if so, which ones. Even the beings reached with, say, a commune spell will, if pressed, hang a lampshade on this, saying of course they haven't personally seen or talked to the gods, but they must exist, because praying to them works, doesn't it? Divine magic works even for the Clerics of one particular cult who know for a fact that their god does not exist (yet), because they're working on building it.
• In Dungeons & Dragons itself (regardless of campaign setting), artifacts are typically this. Regular magic items can typically be made by spellcasters fairly reliably, depending on the power of the item. Artifacts, on the other hand, generally greatly exceed the power of other magic items and are not something that modern wizards and clerics (especially those who are player characters) can build anymore. Typically, they were crafted by or at least with the aid of a god or some other being of phenomenal power, or a highly advanced precursor civilization (which may have been human or dwarven or elven, or it might have been from some weird species of sapient frogs or dragons or whatever that's no longer around anymore) that had much more advanced knowledge of how magic worked than anyone living does. The Suel Empire and Netherill Empire are both known for the powerful artifacts that modern spellcasters might figure out how to use the basic functions of if they study them long enough, but can't come close to reproducing them and generally have no idea of their true capabilities.
• Subverted in Exalted. Many of the great and wondrous artifacts can be understood... it's just that most of the great designers would have been among the Solar Exalted, who were murdered and had their Exaltations sealed away so they couldn't reincarnate. It doesn't help that the Solars specifically designed many artifacts to only function for Solars... because they never imagined there would be a time when they weren't around. In theory, any Celestial Exalt (or Terrestrial of sufficient age and experience) could bring themselves to understand the complex workings of Solar artifice. The problem is that reaching that level of excellence is much harder for non-Solars, they can't achieve nearly the same level of speed, and besides they've been a bit distracted since then.
• Wonders in Genius: The Transgression work in a similar way to Deadlands: Geniuses can build devices that delicately bend the laws of physics, usually with a crackpot theory given legitimacy by the light of Inspiration. For many years, various Geniuses have tried to find out the secrets behind Inspiration, with little success.
• The titular Numenera are devices that for a number of reasons got enough Ragnarök Proofing to function thousands or even millions of years after having been created and the civilizations that made them fell... but not only are they so advanced that the setting treats them like magic, but they also didn't have enough Ragnarök Proofing to survive being used more than once after being unearthed—and because of said civilizations falling so long ago, the full knowledge of what they can do (let alone how to repair them) just doesn't exist anymore.
• Space 1889: There are plenty of such phenomena where you know the input and the output but how no idea how it is achieved. It is not only the fictional Martian left-over technology from long ago but plenty of things we now know how it works that were a mystery to historical Victorians. For instance the sun seems to send out a lot of energy from nowhere, much more than any known type of fuel could possibly sustain for more very long — leading some people to believe the solar system cannot be more than a few thousands year old. You seem to inherit traits from your parents, but having no idea of DNA, the mechanism for this is a mystery to Victorians who sometimes think it is somehow literally "in the blood" or "with the mother's milk," but that makes it hard to explain how plants can inherit traits.
• Inspired Science from Trinity Universe (White Wolf) is developed through means that humans can't replicate. Anyone can use it, but making more requires the inventor to be present (unless it's noetic biotech), and any attempt to explain the science of how it works to an un-Inspired mind comes across as complete nonsense.
• Warhammer 40,000:
  • The modern Imperium of Man is a borderline Scavenger World that has lost a great deal of technological knowledge over the millennia, and as a result many of the devices lovingly maintained by the rituals of the Adeptus Mechanicus are irreplaceable ancient relics. One example would be the Gauntlets of Ultramar, a paired set of power fists with integrated boltguns that is a treasured relic of the Ultramarines chapter of Space Marines. The Adeptus Mechanicus would love to study the Gauntlets, but since that would mean disassembling and possibly forgetting how to reassemble the weapons, the Ultramarines have "declined" the Mechanicus' requests to examine them, emphatically and repeatedly.
  • The "gene-seed" that transforms a normal human into a Space Marine is derived from the genetic material of the twenty Primarchs, who were created by the Emperor of Mankind to lead his Great Crusade to reconquer the galaxy. Since the Emperor is currently a skeletal husk sustained by the Golden Throne, and the Primarchs are all either dead, lost, fallen to Chaos, or otherwise in no condition to contribute, it's impossible to create "fresh" gene-seed. Instead, each Space Marine sports a pair of "progenoid" organs that can grow germ forms of all the other implants, which are cultivated by a chapter's Apothecaries to use in the next generation of recruits. This means one of an Apothecary's most important duties is securing the corpses of fallen battle-brothers and extracting those progenoid glands before they are lost to the enemy, and Space Marine chapters who run low on gene-seed, through battlefield losses or mutation, are in danger of dying out entirely.
  • A nonhuman example would be the Blackstone Fortresses of the Gothic Sector, a sextet of ancient space structures that were appropriated by the Imperium. The AdMech were able to patch into the stations' power systems and hook up their own weapons and life-support, but nobody was sure of the things' function... until Abaddon the Despoiler showed up with some artifacts of his own and fully activated the Blackstone Fortresses, deploying guns that tore holes in space-time and could make suns go nova. Turns out they were created by the Eldar's forge gods as a means to harness Warp energy to destroy the C'tan.

Video Games

• .hack: CC Corp's The World, the MMORPG that serves as the setting of the series, is basically Black Box: The Game. The World is actually an updated version of Fragment, a game that CC Corp did not develop but simply acquired from a German programmer called Harald Hoerwick who sold it to the company for absolutely nothing. Hoerwick based the game on the epic poem Epitaph of Twilight by Emma Wielant. After Emma's tragic death in a car accident, Hoerwick became obsessed with immortalizing her work as well as his love for her through Fragment. The general public knows nothing about this, and even among CC Corp, very little is know about how the game actually functions. To top it all, only a handful of programmers of the company are aware of the existence of a black box inside Fragment and how any attempt to decipher it ended in failure. When Fragment was updated to the retail version of The World, the Black Box remained in the game's code. It was later discovered that the Black Box was actually a womb for a new breed of Artificial Intelligence, and was designed to create an "Ultimate A.I." based on the personality data of the players of The World. Along with this, Hoerwick created a program called Morganna that would act like a caretaker and oversee the birth of the Ultimate A.I. Problems arise when Morganna realized that once the A.I was born, she would have no purpose left. Unable to process this, she attempted to stall the growth of the A.I indefinitely, resulting in many of the events in the series.
• Afterimage: Among the three artifacts stored in the Grand Archives of the Holy Grounds, the Primeval Orb is considered the strongest (allowing humans to see a projection of the Sea of Souls), but it is also the "most mysterious", not even the Mastermage Levine can understand its material composition. One In-Universe speculation from the mastermages claim that it might be an instrument made by God.
• Devil May Cry 5: Cavaliere is one. Nico's report mentions that she can't figure out how it works, and even Dante has no idea how he put it together.
• In Dishonored, whale oil is an incredibly efficient source of fuel, but no one really knows why this is the case. When Emily was asked how whale oil works during her lessons, she responded that it's a trick question, since nobody knows the answer. The Heart claims that the whales are actually supernatural beings.
• Duke Nukem 3D: When 3D Realms sought to make a sequel to their Duke Nukem sidescrolling games, they shopped around for someone who could make a convincing pseudo-3D engine. Teenaged Ken Silverman sent in his hobby demo, which would later become the infamous BUILD engine, and got the job. He sent 3D Realms the executable file and a bevy of documentation to explain how to make levels with it, and let them build the actual game and its assets without knowing how it works internally. Turns out 3D Realms didn't know how good they had it: the code was eventually open sourced, and internet code analyst/Google software wizard Fabien Sanglard dove into it, only to find it one of the most dense, most obtuse, most esoteric pieces of code ever committed to computer memory. It was very obviously not meant to be intelligible to anyone whose name isn't Ken Silverman. Read all the gory details here (tellingly, Sanglard had to have Ken Silverman proofread/explain parts of the article).
• Dwarf Fortress:
  • Not only is Toady One very protective of the source code behind his masterwork, but his software development skills are almost entirely self-taught. The handful of people who have been entrusted with backup copies of it have attested that the code is almost impenetrable to mere mortals.
  • Really, this can apply to just about anything a player creates in the game. Fortresses can get so elaborate that critical functions are simply forgotten or change completely as they are built upon; this especially applies to Succession Games, since players tend to not use the in-game labelling function. Many a fortress has run into fun because the guy running it forgets which lever opens the door to the mess hall and which one activates the fortress' lava-based self-destruct. A truly stand-out example has to be where one Let's Play ended up creating a fortress so convoluted that one room ended up becoming its own Pocket Dimension. (Not literally — but for some reason, no player was ever able to locate that room unless they zoomed in on a dwarf who was already inside it.)
• The Elder Scrolls V: Skyrim: Dwarven technology is almost always a Black Box of some kind whenever anyone in the game has to use it to accomplish a task. The most common example is "Dwarven metal", which is a unique alloy that resembles bronze but never dulls or corrodes. Nobody by the time the game takes place knows how to create it since the Dwemer have vanished, so smelting it essentially involves recycling pieces of their scrap metal.
• Final Fantasy:
  • In Dirge of Cerberus: Final Fantasy VII, no one knows how the power source of the airships works.
  • For a society almost solely based off of using technology, it turns out the Al Bhed of Final Fantasy X don't actually know how machina work. Averted by the end of X-2, as the Machine Faction's quest is to innovate rather than rebuild.
• Galactic Civilizations:
  • Random events might result in your gaining a Precursor ship or two, which tend to be far stronger than anything you have for much of the game. You can't reverse-engineer the tech, but, by the end-game, you can build ships that are better.
  • According to the manual, the Arceans intended humans to fall into this trap when making First Contact via a sublight probe. They transmitted the plans for building a hyperspace gate, deliberately modified by them to prevent humans from shutting the gate off, allowing the Arceans to invade Earth. Subverted, in that the humans said "hell no" and started trying to reverse-engineer the thing and figure out a way to make it better. They succeed by virtue of having developed fusion power and being able to minimize a "gate" into a portable hyperdrive. Then some idiot decides to send the plans to everyone else.
• In Halo, much of Forerunner technology is still considered this by the galaxy's current races, despite their best efforts to reverse-engineer it:
  • Not only is almost all of Covenant's technology reverse-engineered from Forerunner relics, but a good percentage of their equipment is directly constructed by prehistoric Forerunner machinery, and some high-end Covenant ships even have Forerunner components directly installed. However, due to the Covenant worshipping the Forerunners as gods, even just trying to better understand Forerunner technology runs the risk of being seen as heresy. For this reason, the Covenant do not use even their own knock-off technology very efficiently, much less the Forerunner originals.
  • Proper Forerunner technology is still largely a mystery to humans, despite the occasional reverse-engineering success. For example, humanity's post-war flagship Infinity has several Forerunner components installed, including its slipspace drive. However, not even the ship's chief scientist quite understands how said components actually work.
  • In Spartan Ops, one frustrated human scientist describes the current state of his species' research on Forerunner technology as such:
    "We're turning on dormant technology we don't know the first thing about! We're like monkeys, hammering on a nuclear bomb because we like the sound it makes!"
• Hellsinker: Deadliar's previous nickname was Blackbox in true spirit of this this trope since no one had any idea how he operated and produced the results he did.
• Homeworld plays around with this trope.
  • The Historical and Technical Briefing describes the discovery of a large amount of Lost Technology in the wreck of an ancient spacecraft, including something eventually identified as "a solid-state hyperspace induction module." It's implied that much of their limited understanding of how it actually works was gained from building a couple of scaled-down copies and fitting them to small spacecraft, pressing the "on" button and watching to see what happened.
  • Then it turned out that said module is actually a 10,000-year old Progenitor; only three of them exist in the whole galaxy. One of these are in the posession of the Bentusi and it's the basis of all hyperdrives in the galaxy, save the Kushan ones. It is also said that no matter how much they study them, they can't figure out why the reverse-engineered versions are much slower than the originals even though they know how to make other ships tag along by "riding the quantum wavefront." In fact, combining the three Far Jumpers will break the laws of physics (black holes disable hyperdrives yet the Trinity still works flawlessly).
  • The semi-canonical Expansion Pack Cataclysm has a fourth hyperspace core, whose capabilities are on par with the Progenitor Far Jumpers (except it was built a million years ago), except that it came from another galaxy on an experimental exploration ship called the Naggarok. Besides the extremely-advanced hyperdrive, the ship also has inertialess sublight drives (allowing the massive craft to zip around the battlefield faster than any fighter), extremely-precise long-range ion cannons (able to swat fighters like gnats), and a powerful Phase Disassembler Array that can convert even a dreadnought into energy in a matter of seconds (said energy can then be used to build cruise missiles). While the ship is destroyed in the Final Battle of the game, the tech inside it likely fits this trope.
  • In the Homeworld: Deserts of Kharak prequel, we learn that the nomadic Gaalsien were able to reverse-engineer some of the tech from ships that crashed in the Kharakian desert (thanks to interference thrown up by the Far Jumper on the planet). This allows their vehicles to hover, whereas the Northern Coalition utilizes traditional treads and wheels for locomotion.
• Mass Effect:
  • The Citadel and mass relays are thought to be built by the Protheans. Humans and other races use them, though their inner workings and construction are poorly understood, and any attempt to understand them is regarded as an exercise in futility. It turns out that a race of Abusive Precursors, the Reapers, were the real builders of these wonders, and the Protheans were just barely figuring out the technology themselves when they were wiped out.
  • Matriarch Aethyta very much dislikes the black box nature of the relays and once proposed trying to study relays more intimately, maybe even building one. As she puts it, the other Matriarchs "laughed the blue off my ass."
  • The design of their conventional Faster-Than-Light Travel system is much the same, being almost entirely reverse-engineered from the Protheans. This means that they have no idea how to disengage certain safety protocols that prevent ships from being flown into planets or other vessels at relativistic velocities. While this is generally a good thing, it prevents the military from using this tactic against the Reapers.
  • The third game kicks this up with the Crucible, a light flung into the future so many times that barely anyone who tried to build it understood what it was or what it did. Not even the Protheans were sure how it even operated, and they nearly finished the damn thing before the Reapers completed their invasion. It's hammered home numerous times through the game that it could do damn near anything because while there are easily understandable blueprints for it, there's no data on how to use it or what it does. At one point Commander Shepard likens the situation to a child playing with his father's gun. It turns out to be little more than a giant power source used to brute-force hack the Citadel and Relay network to either destroy or control all Reapers. It can alternatively forcibly convert all organic and machine life into cyborgs if certain conditions are met, but this was apparently not an intentional part of the design.
  • Mass Effect: Andromeda has a similar situation with the Remnant Vaults. The Andromeda Initiative finds out pretty quickly that the Vaults are able to terraform entire planets, which is very good because the planets they had intended to settle had been environmentally ruined by the Scourge. But nobody has a clue how any of the Remnant technology actually works, and the dangers of relying on it are pointed out.
• Mega Man:
  • The titular robot of Mega Man X was the last and greatest creation of Dr. Light, who then had X put through 30 years of ethical testing to ensure that he wouldn't misuse his "limitless" power. When Dr. Cain discovered X and studied the robot, he admitted that some of X's systems were "black boxes" he couldn't understand, but did his best to reproduce X's design. The result was the Reploids, a generation of robots more advanced than anything previous, but the fact that they were all imperfect copies of Light's design led to the Maverick uprisings. It wouldn't be until the time of Mega Man Zero that a fully successful replication of X's systems would be completed by Ciel; unfortunately for everyone, Copy X didn't get the "30 years of ethical testing" and turned into a powerful Knight Templar that only Zero had a chance of defeating. Even then, Zero is convinced that the original was still more powerful than Copy X. Dr. Light's design was so far ahead of his time that even centuries later no one managed to fully match it.
  • Later games reveal that Zero, likewise the last and greatest creation of Dr. Wily, has similar black boxes, possibly stolen or copied. Notably, one of Zero's discussions with Dr. Light when obtaining an Armor Part for X in X5 has Light's Virtual Ghost regrettably inform Zero that he can't enhance Zero's performance in the same way because he knows nothing about Zero's body structure and presumably cannot analyze it. This makes either Dr. Cain or the X-Hunters (most likely Serges) rebuilding Zero in X2 and Isoc's heavily implied hand in restoring Zero between X5 and X6 (as well as his intricate knowledge of Zero's internal systems) all the more impressive, since it should have been impossible to fully repair Zero, let alone improve upon his original design. Then again, the games hint Serges and Isoc's familiarity with Zero stem from the fact that they are Wily.
• Metroid:
  • Samus Aran's Power Suit has a ton of hidden properties the Chozo didn't have time to teach her about, but fortunately the suit is smart enough to make use of them anyway. Not only that, but the suit is actually capable of adapting non-Chozo technology to upgrade itself when Samus acquires some, which gets really strange when she picks up Luminoth, Space Pirate and human technology.
  • The Metroid Prime Trilogy subseries involves the use of Phazon, a blue gooey substance that turns its users nigh-invulnerable and greatly amplifies their weapon strength, at the risk of corruption. By Metroid Prime 3: Corruption, the Federation is able to develop a PED Suit that contains a "black box" that allows its wearer to safely utilize Phazon to improve their combat capabilities, but unfortunately Samus' variant gets damaged early in the game.
• The superweapons of the Naval Ops series, especially in Warship Gunner 2, are considered to be Black Boxes by the people fighting against them. In WG 2, they run off a Black Box "Engine" strapped into oversized conventional ships (for a given value of conventional). The equipment you can unlock for customizing your own ship is explicitly labeled in game as "Black Box Technology" in the equipment screen, with individual pieces labeled Enigmatech (Enigmatech Bridge, Enigmatech Sensors, etc.).
• The Demon Summoning Program in the Shin Megami Tensei series is a monstruously powerful piece of software capable of bringing forth demons into the physical world. However, when analyzed in Shin Megami Tensei: Strange Journey, the technicians are baffled by the dozens of Black Boxes in its code, and its use is only authorized in the eve of extreme duress. Across the series, a handful of people have been seen to develop some variation upon Akemi Nakajima's original program, but it bears mentioning that aside from Nakajima himself and Stephen, most of these are inhuman entities using and distributing it for their own purposes. Even those two eventually Ascend to a Higher Plane of Existence, Nakajima as Izanagi and Stephen as The Dragon for the Goddess of Tokyo.
• No one in the world of SIGNALIS really knows how does the Bioresonance work and what is its origin. Despite that, it's widely used for terraforming planets, achieving artifical gravity and creating Replikas. As one document in the game even states, constant reliance on Bioresonance has led to the stagnation of all conventional tech by almost a century.
• In Sins of a Solar Empire, the Advent field Phase Inhibitors stolen from the TEC, who use Phase Inhibitors captured from the Vasari... who also don't know how Phase Inhibitors work, and simply field copies of ones that they found.
• Most ship and weapon tech in Starsector has been lost due to the fact the blueprints had copy protection on them. After the Collapse, the entire sector was isolated from the companies that could manufacture these copy-protected blueprints, so the only source of new ones is through scavenging. Similarly, fighter LPCs (Limited Production Chips) work by containing the information for a carrier's nanoforges to manufacture fighters without allowing for the copying of the design.
• Stellaris generally averts this, and you can scan battle wreckage of even Precursor ships to reverse-engineer their components, but until you have end-game science buildings it's going to take a looong time to complete those research projects. Or you can play this trope straight by taking the "Enigmatic Engineering" Ascension Perk, which makes your technological designs sufficiently esoteric that your rivals can't study them — a good way to keep the unique technology derived from defeating one of the Leviathan enemies limited to your forces.
• The Trails Series has artifacts, ancient devices that predate the Great Collapse, a disaster of unknown origins 1200 years ago that devastated the world and led to the collapse of society. The Septian Church, the primary religion of the setting, has a policy where they must confiscate an artifact if it is still functioning. They don't apply this to artifacts that have lost their power. The church's justification for this is that because no one knows how these artifacts work, it's too dangerous to allow an active artifact out in the open. And to be fair, there have been incidents involving artifacts that justify this logic — for example, pretty much everything after the prologue in Sky The 3rd is the result of an artifact turning itself on while the people trying to take it to a secure facility don't know what it is or how to turn it back off.
• X: Played with through the gates. While operation is terribly easy — push a spaceship in one gate, and it'll pop out the other gate in the pair a few seconds later, no matter how far away — no one in the central interstellar trade system understands anything but the lies-to-children version of how they work. While there are a few scientists capable of repairing damaged gates, no one even thinks about trying replication or reconfiguration, and the irregular outages or changes in the system caused by meddling precursors is treated like mystery or even legend where it's not just a natural risk of the gates. The species that actually made the system in the first place not only consider it outside of the range of understanding of the normal races, they think it's impossible for a species to understand without getting a few points higher on the Kardashev scale. Then the Terran humans get involved, and not only get the theory down and create a new gate on their own, but also create a Jumpdrive that's a separate Black Box to everyone else in the setting; when the test ship (the Xperimental Shuttle) gets dumped in the X-Universe by a Blind Jump in X: Beyond the Frontier, nobody can repair it; not even the pilot after he establishes a MegaCorp solely to repair it to get back home. The ship can be re-acquired thirty years later in X3: Terran Conflict, where it's still unknowable and impossible to reverse engineer; presumably, the now reconnected Earth State isn't helping the player to reproduce it.
• Xenoblade Chronicles 2: Poppi is an Artificial Blade who is the product of three generations of brilliant Nopon engineers (Soosoo, Tatazo, and Tora) having created and refined the process, with Tora having actually taken the years of research into the concept plus the experimental and so-far unreproducible ether furnace of his grampypon's design into the process of constructing her. As a result, she has many features that not even her designers fully understand, not helped by Tora being such a recluse he added many extra features, and she has the capacity to upgrade even further.
• Xenogears has Gears, the Humongous Mecha of the game. While the setting's current powers are capable of making their own, the best Gears are relics from previous wars between precursor civilizations, leading to an Archaeological Arms Race between the nations of Aveh and Kislev to recover weapons they don't fully understand. Protagonist Fei's Gear, Weltall, is comprised almost entirely of black boxes, something the Yggdrasil's Gear mechanic will comment on. Naturally it's the strongest Gear in the game, and new abilities will come online at seemingly random intervals, culminating in Weltall transforming into the titular Xenogears, a 100% Organic Technology Black Box. According to the Perfect Works book, most of the black boxes are either Ether amplifiers, or components used in its transformation between Weltall and Weltal-Id-.
• Xenosaga:
  • KOS-MOS is an android built by Kevin Winnicot, but when she goes berserk and murders him she has to be rebuilt. Unfortunately, the only way Kevin's successors are capable of creating another KOS-MOS is to simply repair and (attempt to) reprogram the same prototype unit that killed him because he took the plans for her to his grave. As a result, the current KOS-MOS is treated like a faulty hand grenade which her development team is loath to admit they have zero control over if push comes to shove. She's laden with black box parts and programs, each with unknown functions, which come online at seemingly random intervals (like her Gnosis-obliterating X-Buster ability), often to shocking effect. Series protagonist (and KOS-MOS co-creator) Shion is only able to figure most of them out enough to rebuild KOS-MOS a second time after gaining access to Kevin's original plans via a time paradox.
  • A great deal of the series' technology is the product of one man, Joachim Mizrahi. After he died on Militia during the Federation's invasion, a great amount of effort has been poured into piecing his prototypes back together, as well as reassembling his codex of knowledge: the Y-Data. Efforts to recreate his work from scratch by his rival Dr. Sellers amount to impressive, but fatally flawed knock-offs.

Webcomics

• Drive (Dave Kellett): The human Empire's Ring Drive. Only members of "la Familia" who rule the Empire are even allowed to see the inner workings, and they don't know how it works, just how to maintain or duplicate it, because their ancestor reverse-engineered it from a crashed alien ship.
• In a flashback arc of Gnoph, a scientist criticizes the military for creating a breed of Super-Soldier pretty much by accident and then using them despite not really understanding how or why they work. Sure enough, things soon Go Horribly Wrong.
  Dr. Westman: Gotta love that military mentality: "Ah don' know why ut works, but they sure do kill!" Idiots.
• An early Goats storyline involves such a machine — you put kittens in, and pop tarts come out; nobody knows what happens to the kittens. Later it's revealed that the machine is a stolen alien spaceship engine, which is powered by the good feelings created when the kitten is placed in a loving home. But it's still a Black Box, because even the aliens don't know where the pop tarts come from.
• Sydney's Orbs in Grrl Power. Sydney found them while SCUBA diving and they bonded to her, allowing her to use their powers. One allows her to fly as well as open wormholes, one allows her to create a nigh-indestructible forcefield, one allows her to create a pseudopod made of pure energy, and one allows her incredibly powerful True Sight, as well as telepresence and the ability to teleport to her telepresence projection. At the start of the series, there are two orbs whose functions are a complete mystery one of those orbs is eventually revealed to create breathable air, at the very least. Finally, the orbs seem to have the ability to "level up" (seemingly) after Sydney defeats powerful opponents, and even the upgrade system is a Black Box, as the upgrade nodes are unlabeled, and Sydney has to spend her upgrades blindly, hoping for something useful. It's unclear if the nature of the orbs is technological, magical, or some combination of both. It's also repeatedly suggested that Sydney is only tapping into a fraction of their true power. The wormholes that she can open are referred to as "Aetheric Causeways," and usually require massive power sources (such as those found on city-sized spaceships) in order to open them. Krona, a sorcerer with a unique "programming" style of magic takes a look at the orbs and informs Sydney that, with the information contained within the orbs, her magic would be capable of completely altering fundamental forces of reality, such as gravity.
• Gunnerkrigg Court:
  • Anja and Donlan created a computer that runs on magic, which even they don't fully understand the workings of. They're the only ones who use it — the rest of the Court distrusts it precisely because it's a Black Box.
  • Diego's Super Prototype robots (which also appear to run on a combination of magic and technology) are also black boxes. They have no visible power source, nor means of moving their limbs. They are golems made by a master mechanician who wrote their "OS" in what under a magnifying glass turns out to be a small book worth of runes. Modern robots are black boxes even while self-documenting. When asked to print their operating code, one produced a 3D image of some complex structure made of runes, with density requiring a microscope to read, without any sort of map legend, and neither derived from nor designed to be compatible with, any human languages, natural or programming (they are robot-built).
• Nobody Scores! has an arc where the main characters end up getting their hands on a literal black box — things went in, and other things came out. It was when it started producing multiple copies of the severed head of Shia LaBoeuf (who was still alive) that they started trying to get rid of it...
• AI in Questionable Content. AI don't know what makes them sentient. Even the inventor/"God" of AI, John Ellicott, doesn't understand how artificial sentience evolved, just that "A certain combination of software and hardware led to artificial intelligence, and once we figured that out, we could mass-produce them."
• In Spacetrawler, it's implied that the eponymous spacetrawlers (which the entire galaxy relies on to enable faster-than-light travel and matter synthesis from space debris) are so complicated that only the Technopath Eebs can understand and construct them. It's eventually revealed that their construction is less complicated than implied, but the details are so horrific that it's no surprise that the builders insist on keeping them secret.
• In Westward, Escherspace — a form of Faster-Than-Light Travel — appears to be a Black Box. Publicly, the government claims that "only a few scientists" know how it works; in reality, it's strongly hinted that only the mysterious alien Phobos may be capable of understanding it, and he must personally work the controls when the webcomic's eponymous Cool Starship makes an interstellar jump.

Web Original

• Most of the super-advanced technology in the Orion's Arm universe is at least partly powered by transapientech. This is by definition designed by beings orders of magnitude smarter than ordinary folks. This is something of a subversion in that the inner workings are completely known, and probably published somewhere on the net, but the people using them can't understand them, since their brains aren't complex enough. It's sort of like trying to teach a small child nuclear physics in depth.
• SCP Foundation:
  • The Foundation classifies objects into three broad categories: Safe, Euclid, and Keter. Safe objects' properties are researched enough that the foundation knows what the object does, even if it's not completely understood why it works. Most "black boxes" would fall into this category, since the input and output are stable. Note that here, "Safe" means "understood" and "easy to contain", not "non-dangerous".^note SCP-2501, for instance, is an inanimate, wearable claw that can crush any object in its user's field of view through a pinching motion. Up to and including astronomical objects. Easy to contain? yes. Understood? Yes. Potentially world-ending? Also yes.
  • SCP-914 is a more literal Black Box than most; it's an incredibly complex mechanical machine into which you put an object, and it comes out "refined" from the other end.
• In Starsnatcher, the effects of technologies created by vastly superhumanly intelligent A.I.s like Fountainhead are clear enough (e.g. wormholes allow interstellar travel, singularity stones uplift people, etc.). However, the characters have no hope of modifying or replicating them, even though the resources to create at least some of them are there.
• In Worm, Tinker-tech suffers heavily from this as the Tinkers themselves don't fully understand why their technology actually works. The result is a number of built-in flaws that quickly render their creations inoperable without constant maintenance from the Tinker themselves. Eventually explained as limits placed by the Entities to encourage creativity and discourage research into fields such as space travel and nanotechnology.

Western Animation

• Ben 10's Omnitrix. Not from Earth, seemingly simple to use on the surface... but it has secrets, hidden abilities, glitches, and occasionally, a mind of its own. Eventually they meet its creator, who doesn't seem to understand what he's built either. He fully understands its inner workings, it's just that he's very reluctant about revealing them to other people.
• Hazbin Hotel: As Charlie learns in episode 6, no one in Heaven actually knows what makes a soul worthy of going to Heaven or Hell, not even the High Seraphim. Sera simply accepts not knowing out of fear that questioning things will make her a Fallen Angel, while Emily protests how unfair it is that sinners are denied the opportunity to redeem themselves simply because no one knows if it's even possible.
• The train in Infinity Train is an Eldritch Location running on incomprehensibly advanced technology, but Tulip and Amelia as the fake Conductor are able to control it to some extent by analyzing its observable mechanisms (particularly the orbs every objects and creature seem to be tied to). Tulip even compares it to programming a game.
• Wakfu: The Eliacube, a powerful MacGuffin and Amplifier Artifact belonging to the Eliatrope race, is this for most people of the World of Twelve. The Xelor Nox had been in possession of it for over 200 years and suffering for it, and he freely admits he still doesn't understand a fraction of what it is truly capable of, despite using it as the centerpiece of his plan to power a Reset Button. Yugo, as an actual Eliatrope, is able to tap into its power in minutes what took Nox years or even decades to do the same, and he and his dragon brother Adamai still don't really know how to use it aside from pouring their energy into it and hoping for the best. The only person who knows how to use the Eliacube to its full potential is the Eliatrope Qilby, its original creator.

Real Life

• The Jargon File and its dead-tree twin, The New Hacker's Dictionary, is rife with terms describing programming Black Boxes, most notably Black Magic, where a switch is found with its two positions labeled "Magic" and "More Magic". The only wire soldered to the switch goes directly to the case of a server—specifically, to a ground pin. There is electrically no way it can affect anything on the server (except for EXTREMELY bizarre capacitance effects), and yet switching to "Magic" causes the server to crash.
• Genetic algorithms (computer programs that emulate neo-Darwinian synthesis) can produce hardware that no human could design. For example, an array of logic gates that sets its output high when it hears "go" and low when it hears "stop". Inside the circuit, 5 of the 37 gates are not even connected to the rest, yet the device stops working when their power is disconnected! An order of magnitude weirder than the magic switch. Other examples include a research team accidentally reinventing the radio receiver while trying to evolve an oscillator, and very unusually shaped antennas that can be held in the palm of the hand and transmit signals from satellites to the surface of the earth. More about the magical stop go circuit here.
  • This actually has a parallel in biology, with non-coding DNA, sometimes called "junk DNA". Like computer code that doesn't produce any output, genome sequencing has revealed chunks of DNA in numerous species that have no apparent function, but mutations, errors, or omissions within these chunks still cause problems.
  • Genetic algorithms have a variant called Evolutionary programming. Basically, it's when you solve a programming task by having the computer generate an initial population of randomly-generated programs, then apply natural selection mechanism to mix-and-match them until you get a program which solves the task satisfactorily... but its code may be completely incomprehensible to a human. To make this an even stronger example, genetic algorithms just make random changes and go with what's best. They don't understand it either. It's a black box even to the designer.
• Black Box programming is a very important concept in real life. For example, all APIs (which allow developers to connect to things like Facebook or Google Maps) are black boxes; generally, the only details developers have are usage instructions and a description of what it does, since someone writing, say, a GPS application doesn't need to know anything about how Google Maps works.
  • In this case, this is actually considered a good thing: abstraction means compatibility. If your software is designed without using any knowledge of how the black box part works, it will (at least in theory) be possible to swap that library out for an updated or improved version later on. So long as somebody knows how it works, it's just a matter of trusting one's fellow engineers. In contrast, the moment you have to know how each variant of something really works instead of just one set of common operations, a task that should be trivial turns into a nightmare. Remember those DOS games and their sound setup programs?
  • In object-oriented programming, objects are supposed to be black boxes, often having public and private groups of variables and functions. The "client" only need to know what the functions do and what should be put in the variables, and not anything about the inner workings. Similarly, template libraries and built-in functions in many programming languages (like C++'s STL) are Black Boxes. The documentation on C++'s sort() function, for example, doesn't tell you what kind of sorting algorithm is used, because it doesn't really matter (although one can deduce that it's probably a quicksort implementation from what they say about its running time).
    • And if someone else wants the class to do something else, the chances are they'll write another class that extends and/or calls the old one, rather than trying to rewrite the existing source code.
    • This practice of extending and calling old classes, especially when other programmers in turn extend and call those extensions and calls, can lead to extremely tangled dependency charts, in which a single eleven-line package, deleted in a fit of pique by a programmer you've never heard of, can break the entire repository your code depends on.
• Older electronic (and most especially military) technologies may well have been designed by people who are dead, coded in languages which no-one ever hears of nowadays, use electronic standards long since obsoleted and built by companies that dissolved or got eaten by other companies some time ago. Black Boxhood arrives quite naturally for such devices, which could conceivably include missile guidance systems or nuclear warhead triggers which are still quite useable today.
  • FOGBANK
  • One notable example is the Patriot Missile, whose software was originally written in a proprietary software language developed specifically for the project back in the seventies and never used again, making the source code incomprehensible to anyone who isn't an engineer who worked on the Patriot program at some point. This caused problems as various generations of the missile are expected to be in use into the 2040s, and replacing engineers means teaching them a new language. In the 2010s they gave up and started an effort to port all the software to a standardized programming language in order to make the code maintainable.
• COBOL used to be a very common language for developing business software in. Though superseded by modern languages like Java or Visual Basic, old working software was not replaced. The pool of skilled COBOL engineers is rapidly dwindling simply because they are retiring and in due course upgrade and maintenance engineers will simply not exist anymore.
  • Some colleges have tried to avert this by offering courses in COBOL.
• It seems that the original programming of Microsoft Excel might be a black box, since after the principal programmer quit, the project virtually stopped. Luckily he came back.
• Many psychiatric drugs work via mechanisms that are either unknown or only loosely understood. The laborious (sometimes decades long) process of searching for side effects and other quirks irons out many of the Black Box problems that plague fiction.
• Real Life is rife with stories of a programmer being fired for whatever reason, only for his ex-boss to realize nobody knows how to maintain the server.
• Older Than Radio: During the early 18th century, Antonio Stradivari hand-crafted several wooden violins that, compared to other violins before or since, produce the highest-quality sound. Many violin manufacturers have, for centuries, attempted to not only replicate the sound of the Stradivarius, but have even labeled violins as "Stradivarius" as a marketing ploy. Unfortunately, when Stradivari died, the technology and skill required to produce a violin of such caliber died with him. Scientists continually do research on the Stradivarius sound and technologies to replicate that sound, and original Stradivarius violins remain the most valuable musical instruments in the world.
  • The "Stradivarius" label on violin is not there for marketing reasons. It's actually a model of violin — Antonio Stradivari's instruments had very specific proportions (also being slightly larger than ones made by competing crafters). If you see a violin labeled "Stradivari", it means that its proportions and size match those of an original Stradivari instrument.
  • It has been speculated that the sound quality is due to the wood available at the time. He built them around the little ice age, and wood at that time was particularly thin and brittle due to the odd weather patterns, making them irreproduceable. On the other hand, other violin makers of the time were unable to reproduce it either.
  • Blind listening tests between Strads and top-of-the-line modern instruments tend to be inconclusive, as the listeners tend to be top-rated violinists who can not only distinguish the sound of a Strad from a modern instrument, but can often tell you which particular Strad is being played. And sometimes who is playing it.
  • While some new evidence proves that Stradivari violins aren't that great compared to modern violins, they could be still considered technical marvels back in the day and most of their inflated prices comes from being collection pieces.
• Damascus steel. The precise technique through which blacksmiths of medieval Damascus produced their wares has been lost and no one since around 1750 has been able to duplicate the original exactly, although many have claimed to have done so.
• The philosophy of instrumentalism boils down to "the only important thing about any theory is whether it's usable, i.e., predicts a result of given experiment". Hunting for explanations is but a pointless infinite regression. This means that "light is truly made of particles" and "light is truly made of waves" are fancy statements that delusionally bind real events to imaginary constructs, while "wave model correctly and in convenient form predicts diffraction/interference effects" or "particle model correctly and in convenient form predicts absorption/emission effects" states everything that really matters in this issue. From this point of view anything is a Black Box, the only difference is that we already know how to dismantle some blackboxes to several smaller blackboxes and what buttons to push.
• Arguably the universe itself is a black box since we don't (yet) have a complete physical theory of the universe. Also, while we do have two theories that work fine in their respective arenas (General Relativity: big and heavy stuff, Quantum Mechanics: small and light stuff), they are contradictory and become completely incomprehensible when used together.
  • There's also an older theory called classical Newtonian mechanics, which works for medium-size and medium-mass stuff. It was specifically created to avert this trope and describe a Universe governed by simple, understandable laws; it failed at that. However, it works nicely for 90% of the stuff we encounter in our lives, and that's why it, and not GR or quantum, is taught first at schools.
• Nikola Tesla, thanks to a heady mixture of personal eccentricities, outlandish claims, and industrial FUD both during and after his time, has a reputation for this sort of thing rivaled only by fiction. All his well-documented inventions work from explicable, if clever, principles of engineering — but poorly documented claims abound of death rays, earthquake generators, and yet stranger things unreproducible by modern science.
  • The fact his documented ideas tended to get stolen (most infamously by Thomas Edison) might have something to do with it.
• The human body itself is quite the black box. With the exception of your occasional doctor or biologist, everyone uses theirs without the slightest hint of how the lot of it works. The brain in particular is quite the mystery, for if it was simple enough that we could easily understand it, we would be unable to use it to do exactly that.
• There was a fad for "miracle cure" machines at the beginning of the twentieth century that were actually called Black Box machines. You just set a few controls, turned it on, and whatever quack therapy that model was based on would cure the illness. The reason they were intentionally kept as black boxes was the controls did nothing to its function, and most in fact had no working parts, or the method of using the device was subject to considerable interpretation not based in any standard practice. One good example is the E-meter.
• This situation tends to happen whenever a nation receives exported military equipment from another nation's military (planes, tanks, ships etc.) and something sours political relations between them. A sudden change in government, or an embargo due to some unsavory incident, can effectively turn a chunk of a nation's military into a black box. No longer getting the support in terms of maintenance to keep them in service or upgrades to keep them relevant, the material in question rapidly becomes warehoused for fear of damaging it beyond repair or obsolete. Solutions are varied, ranging from reverse-engineering, putting in locally-made upgrades, producing their own replacements or getting a replacement from another friendly nation. Examples include the F-14's Iran received before the Shah was overthrown and various helicopter models China received just before the Tiananmen Square incident.
• For a very common (and far more mundane) example, many, if not most, things that people use day-to-day are effectively black boxes. There is an oft-quoted analogy about how the ability to drive a car does not equate to an ability to design and build a car, or even to fix one.
  • Once you give up, go here.
• In biology, the occasional black box arises in the form of a living organism. For example, of the twenty or so species of beaked whale known to science, about three are well documented. The rest are very poorly understood, some of which we haven't even seen living specimens of yet. Where they live, how they breed, what they eat, how deep they dive, none of these are known. We know that they exist because we have dead bodies (for a while, one species was known only by a jawbone), but how they exist is largely a mystery.
• For much of the Cold War, nuclear weapons were black boxes, either entirely or to the people working with them. All nukes were designed by multiple people, but sometimes these teams worked loosely with each other in isolation, the effect being that no one person knew how a particular nuclear weapon worked. This method of security eventually fell out of favor as some of the bombs produced by these teams were abject failures, to the extent that at one point in US history, nearly all the warheads carried by US submarines were duds due to their faulty safety systems. In the other case of nuclear black boxes, teams designing ICBMs and bomb cases were given the bare minimum of information needed to design a delivery system.
  • A remarkable example of this effect is describing how, exactly, thermonuclear bombs work: Only the engineers and scientists who have designed them actually know. Even though the technology is over a half-a-century old and possessed by at least half-a-dozen countries, details of the mechanism have remained strictly classified. The public "Teller-Ulam" design which is the de facto standard for all thermonuclear weapons has been pieced together mainly through inference and assumption, and is quite free of details.
• Several of the computer rankings that make up the Bowl Championship Series formula in college football are proprietary. Accordingly, no one exactly knows why they would rank the teams in the way they do, and major bowl bids (and millions of dollars) can hinge on the result. The BCS system was replaced in 2014 by a selection committee that decides how teams are ranked, with the top four teams playing for a national championship at the end of the season.
• The Mechanical Turk was a machine built in the eighteenth century that supposedly was able to play a strong game of chess against a human opponent. Though the cabinet could be opened to reveal a complex gear mechanism, nobody who saw it in action could figure out how it worked. Of course, the reason was because The Turk wasn't an automaton at all, but was concealing a human player, and the reason no one could determine exactly what was going on for almost a century was the human player was very well-hidden. That said, several people over that span came close to figuring it out, but their hypotheses were always flawed in some way.
• Hex in Discworld (above) was based on one of Sir Terry Pratchett's own computers, a ZX Spectrum he tinkered with and added hardware to until it did what he wanted. Eventually he lost track of it all, and there were components which he couldn't remember or deduce the purpose of, but it you took them out then everything stopped working.
• Black boxes, often by that name, are used as an important learning tool in signal processing. The idea is that you give a student a way to produce a variety of inputs (oscillators, noise generators), a suite of measuring tools (oscilloscopes, spectrum analyzers), and a black box. By applying different inputs, taking measurements, and applying the signal processing principles they've been taught, they try to infer exactly what's inside the black box. With enough constraints on the parameters (e.g., "This will only contain amplifiers and attenuators, because we haven't learned about filters yet.") the black box can become simply a logic puzzle.
• In topology diagrams used by computer network admins, a part of the network whose internal structure is unknown or irrelevant is represented by a cloud. A site to site WAN linking two corporate sites, such as an internet VPN tunnel or private WAN are good examples. The admin doesn't have to worry about what technologies are used internally within the cloud; they just care that it gets packets from one side to the other. This is where the term "cloud computing" comes from.
• A significant part of The Dark Ages after the fall of the Roman Empire turned a lot of the Empire's technological developments into this. Highly effective concrete, the ability to build aqueducts, their methods of producing weapons and armor, and more were all lost when the Empire collapsed, and it took hundreds of years for society to recover to the point where they could reach and surpass it. In the East this is still happening with the Byzantine recipe for Greek Fire. When the Empire fell, the recipe was lost, and to this day no one knows what was in it in order to make it be able to burn so intensely, even on water.
• A variant of this trope: in ancient times, doctors would recommend that people suffering from depression and the like drink mineral water from springs. While it worked, they had no idea why. It turns out to be because water from springs tends to contain a lot of lithium, which has an anti-depressant effect and is still used for that purpose.
• In archive science, the "black box" method (devised at the University of Michigan in the 1980s) refers to a schema for making appraisal decisions. The goal was to create a series of questions that archivists could ask to evaluate documents, granting a level of transparency to decisions that may not otherwise be clearly motivated — in other words, to avoid the black box.
• Swedish band Wintergatan's claim to fame is the Marble Machine. However as their YouTube channel shows, even they don't know exactly how it works. Martin Molin's videos show him trying to troubleshoot one problem with the rebuild or trying to solve another known problem only to find even more issues with it. At one point he was trying to solve just one marble's tracks issue with losing marbles, and found over seven different problems that he wasn't even aware of. None of which had anything to do with the initial issue he was working on.
• Much of economics can be described as working this way.
  • To start with, one of the reasons that command economies are impractical is that much of the information needed to fully plan the economy is locked inside people's heads, where it may be secret, private, or often not even consciously known. Hence, essentially all economic theory revolves around people and firms acting as black boxes, taking in price signals and outputting production and consumption decisions.
  • Secondly, even though in principle the internals of a firm may be examined, most firms are, in practice, very limited in how outsiders are permitted to access their information. While you can physically walk into their offices and rifle through their internal files, if you don't have a court order or similar, that's a good way to get arrested for corporate espionage. Likewise, most corporations counsel their employees not to talk to journalists, so you only see the inner workings when something seriously untoward is happening. So most people treat them as black boxes. Although, like signal processing black boxes, you can learn something about the inner workings from the official accounts, particularly in the case of ponzi schemes, which often grow too fast to be anything else.
  • Thirdly, the phenomenon of black boxes that suddenly stop working is a feature in many economic crises.

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