Mohs Scale of Science Fiction Hardness/Sandbox

== The following examples are from the text of Mohs Scale of Science Fiction Hardness circa June 3, 2011. As per the Trope Repair Shop discussion, the page has been substantially revised. New examples should be added where indicated on the main pages, not here. ==

""The fun, and the material for this article, lies in treating the whole thing as a game. I've been playing the game since I was a child, so the rules must be quite simple. They are: for the reader of a science-fiction story, they consist of finding as many as possible of the author's statements or implications which conflict with the fact as science currently understands them. For the author, the rule is to make as few such slips as he possibly can.""

- Hal Clement, Whirligig World

Speculative Fiction fanatics are always raving about how "hard" the science is in various stories -- but it's not like you can rub a story with a piece of quartz and see if it leaves a scratch on the plot. So what is "hardness" in SF? Why do people want it? And how do we put a number to it?

Beginning with the first question: "Hard" Science Fiction is firmly grounded in reality, with few fantastic flights of fancy not justified by Science. "Soft" Sci Fi is more flexible on the rules. Even the fantastical aspects of the story will show a divide -- in hard SF, they operate through strict, preferably mathematical, laws, where in soft SF they just work however the author feels like. What this leads to for hard SF -- and this is part of the attraction for many people -- is a raised bar for the amount of work the writer must put into the story, and usually this is shown quite clearly.

Example: A character is shown a machine for traveling into the past and asks, "How does it work?"


 * In really soft SF: "Plot device."


 * In soft SF: "You sit in this seat, set the date you want, and pull that lever."


 * In hard SF: "A good question with an interesting answer. Please have a seat while I bring you up to speed on the latest ideas in quantum theory, after which I will spend a chapter detailing an elaborate, yet plausible-sounding connection between quantum states, the unified field theory, and the means by which the brain stores memory, all tied into theories from both Albert Einstein and Stephen Hawking."


 * In really hard SF: "It doesn't. Time travel to the past is impossible."

Unfortunately for analytical purposes, this pattern is not universal - hard SF stories can skip over the details as long as the basic explanation is correct given what's been established so far. Therefore, regardless of the typical stylistic flourishes of hard SF, the only way to define it is self-consistency and scientific accuracy.

Which leads us to the Scale.

0. Softest: The MST3K Mantra is your Survival Mantra. Expect some elements of Fantasy thrown in. At best, expect things to run on nonsensoleum.

1. Imported Alien Phlebotinum: There are technologies that break the laws of physics, but we don't have any real idea how they work, or they are dependent on a resource that apparently appeases some higher power.

2. Minovsky Physics: The laws of physics are broken in a specifically declared way. Expect hundred-page dissertations on fictional physics and consistent internal rules.

3. FTL Travel: The only intentional departure from the laws of reality is that we've finally outsmarted Einstein, or just made him look the other way while we slip by -- at the very least to send messages. Everything else will be justifiable under known scientific principles. Generally, the full ramifications of FTL communication/travel are ignored.

4. No FTL: Mostly justifiable under known scientific principles, including any (necessarily sub-lightspeed) space travel, limited mostly to Interplanetary Voyages, with anything greater being a massive undertaking-- Casual Interstellar Travel is an impossibility. Even if some aspects are slightly softer than in a story with FTL, the physicists will forgive it in exchange for appeasing their Einstein-worship. (Ken Burnside has a particularly scathing rant to that effect.) Home of the Generation Ship.

5. Unobtainium: Contains only theoretical yet plausible elements. NO FTL in any way, shape or form.

6. I Want My Jetpack: Real Life plus Space Travel. The only objective way to grade these is by their age: newer generally means harder. Zeerust hits hard here - one can always tell when Science and/or Tech Marches On.

7. Next Sunday AD: Exactly What It Says on the Tin. Just like now, but some interesting technologies are more effective and/or more accessible. This may or may not be a good thing.

8. Hardest: Real Life.

Bear in mind, of course, that no simple single-dimensional scale can encompass the full nuances of the idea of "hardness" in Science Fiction. (Just look at the arguments on the discussion page!) Other scales might be made - for example the Kheper scale. Consider also the Mundane Manifesto -- an attempt to define a set of rules for writing a hard SF story or series by deliberately forbidding many of the traditional tropes of media Sci-Fi.

Please recall, though, that harder is not always a good thing. Some authors try so hard to make a story realistic they forget plot and characterization, or end up justifying their occasional break from reality with layers of Techno Babble (never mind that the most famous example of that is on the soft end). Textbooks cannot replace storytelling - at least while you're telling stories. No degree of hardness is intrinsically better than any other, and any given person's preferences will depend on their personal tastes and the strength of their Willing Suspension of Disbelief. Sturgeon's Law trumps the laws of physics 90% of the time.

Also remember that there are many, many times when what the imagination makes up is just more interesting than what was researched. A work of soft sci-fi is by no means inferior to a work of hard sci-fi; it all depends on how engaging and well-realized the world is. Not every sci-fi story or setting needs to justify itself, and there are many cases in which an unnecessary justification would break the suspension of disbelief or alienate the audience. This does not mean the story is incomplete or missing anything, just that the creative powers that be felt that that was the best way to tell it. Remember, less is more.

Beware, beware, of stuff that looks hard, but isn't. There are elements, unrelated to actual scientific plausibility, that tend to differ between soft and hard SF. (E.g., shiny spaceships vs. grubby spaceships; elite heroes vs. working class heroes.) As a result, something that has "spinoff" hard tropes is often mistaken for hard SF, even when the actual science is nonsense. E.g., Stephen Donaldson's Gap Cycle has working class heroes in grubby spaceships dealing with the machinations of Starfish Aliens, and has been called a hard SF epic. However, the explanations for the high technology (superluminal acceleration, matter cannons) are more telelogical than technological.

The name comes from the Mohs scale of mineral hardness. Compare Sliding Scale of Realistic Versus Fantastic and Sliding Scale of Like Reality Unless Noted.

''Please note: This list of examples is ranked. That means Soft stuff goes on top, and Hard stuff goes on the bottom. Softer items are closer to the top, while Harder items are further away towards the bottom. So, if you know about a really, really hard work of sci-fi, don't place it under "Hardest"; instead, place it at the very bottom of the list, right above "Hardest".''

''Please also note: Science Fiction only, please -- no Fantasy. If discussing works with both sci-fi and fantasy elements (e.g. Warhammer 40000 or F.E.A.R.) evaluate all elements as SF for purposes of classification. For fantasy works that follow self-consistent rules, see Magic A Is Magic A.''

Softest
The MST3K Mantra is your Survival Mantra. Expect some elements of Fantasy thrown in. At best, expect things to run on nonsensoleum.


 * Dragon Ball: A good example when it comes to Science Fantasy. Supernatural Martial Arts, results in Person of Mass Destruction that can destroy a planet with only their energy. Balls that summons a Benevolent Genie that grants you any wish you want (which includes having a character Back From the Dead. The afterlife exists complete with a Celestial Bureaucracy. Time Travel was used as a plot device in one Story Arc, in that very same arc we are also introduced to Artificial Humans (some of which borders on Ridiculously-Human Robots) and Cyborgs. Artificial Gravity also exists, and was used as a method of training. The methods of travelling space is probably FTL spaceship, though it was never really explained. Myriad of unexplained technologies from capsules that reduce things put inside of it to "scouters" which detect Power Levels. Wars aren't fought with conventional weapons as we know it but instead with Ki Attacks. If it wasn't for all the aliens (who happens to speak English) and space travel in Z (and GT), it probably definitely would've been considered pure fantasy.


 * Barbarella: Other than the very airiest of explanations, expect nothing at all but bizarre fetishy goings-on in bizarre fetishy Space Clothes. Never mind "creative" violation of special relativity and Heisenberg uncertainty, some technologies featured violate basic physics.


 * Bionicle. The story begins with a Patchwork Map island in the middle of a Single Biome Planet, inhabited by Cyborg Hobbits who live like primitive humans. They are joined by a Six Man Band of cyborgs with superpowered masks and Elemental Powers. Although many of the initial mysteries have been resolved, and the series went through a drastic shift from mystical to semi-sci-fi, there is almost no explanation of how anything actually works. Also, creator Greg Farshtey has the MST3K Mantra in his sig on the fansite BZ Power.


 * Super Mario Galaxy and Super Mario Galaxy 2: Even softer than Mystery Science Theater 3000. Not only does stuff happen and things run on nonsensoleum but the depicted reality contradicts what we are familiar with in everyday life. Planetary systems and galaxies twirl around one another, and everything has a near-Earth gravity. The protomatter of stars help you launch from place to place and ludicrous speed travel between the loosely defined galaxies are a must. Shiggy believes in putting fun before everything else, including basic logic. Also, Mario can breathe in space.


 * Asterix and the Falling Sky: In what is usually a mundane/fantasy-ish classical antiquity setting, we have a science fiction-esque plot. There are two alien races shown, one of them have tin-can rats as soldiers while the other have Superman clones. Both have spaceships (one had a rocket while the other had a flying saucer) and came from places light-years away from Earth, only coming to the Gaulish village to fight over the iconic magical super potion that said village have.


 * Cloudy with a Chance of Meatballs: Even if you accept the premise of water molecules turning into food molecules via atom rearrangement - this movie will challenge your Willing Suspension of Disbelief by throwing anything resembling logic out of the window to replace it by Rule of Fun. See the main entry for more details. The original book (and its sequel) did this too.


 * Mystery Science Theater 3000: Stuff happens. Don't think too much how. Characters breathe in space on at least two occasions. Artificially intelligent robots built entirely out of random spare parts. A VW Microbus converted into a spaceship. As the theme song says: "It's just a show. You really should relax."


 * Futurama: Chock full of every single popular science fiction trope, often with intentionally silly Reverse the Polarity style answers to justify them. Only "harder" than Mystery Science Theater 3000 because there's no MST3K Mantra in the opening and the occasional legitimate maths and science appears as a Genius Bonus. Just for startes, there's a ship that once made the entire universe move around it, while the ship itself lay still, making the ship work at triple capacity.


 * The Hitchhiker's Guide to the Galaxy: Packed full of all kinds of bizarre nonsense (one example -- the fastest mode of travel through the universe is by bistro. Yes. Bistro. As in "place you eat in" or "second most overworked word in food marketing after new "(Or more appropriately, the creative mathematics used to calculate bills in such establishments), and the second fastest mode is a drive runs on the power of improbability and how unlikely it is for said event to happen), but the stories are fully aware of how absurd it is, and the reader is encouraged to think about it. It Runs on Nonsensoleum was clearly a favorite, if not the favorite, trope of creator Douglas Adams.


 * The Lexx universe runs on a combination of horror and sexy. There are a few allusions to traditional science-fictiony concepts like von Neumann probes, but the show is more a horror/sex farce than anything to do with sci-fi.


 * Megas XLR runs on Rule of Cool and nothing else. Where else can Philly Cheese Steaks replace oil?


 * Tengen Toppa Gurren Lagann: The universe is not run not by the laws of physics, but by the Rule of Cool. While the show remains relatively non-screwing with physics in the first arcs, the latter one more than makes up for it.


 * Star Driver: Trying to apply any sort of logic or physics to this show's sci-fi elements is like trying to force a square peg into a round hole. Then again, its main character's title is "Galactic Pretty Boy" and the show's Humongous Mecha are powered by "libido", so I think that it's safe to just call Rule of Cool and Rule of Funny.


 * Getter Robo: being Gurren Lagann's Spiritual Grandaddy, it's pretty much just as unscientifically ludicrous and run by Rule of Cool (hell, Spiral Energy's a giant Expy of Getter Rays). The only reason why it's "harder" is we have yet to see Ryoma kill a giant robot using a pair of sunglasses. Only break dinosaurs with his bare hands.


 * Digimon: Kids traveling with data-based lifeforms from a parallel universe founded Earth's Communications network. If the explanation didn't involve technology, most seasons would be considered pure fantasy. Digimon Tamers is slightly harder, but not by much.


 * The original 1978 Battlestar Galactica had a very bad case of Sci-Fi Writers Have No Sense of Scale. Although they never explicitly say they're exceeding the speed of light -- the closest one episode came was having the Galactica accelerate to the speed of light -- they still cross interstellar and even intergalactic distances in a matter of weeks or days. Spacecraft maneuver like airplanes, unless they're big, in which case they maneuver like ocean ships. Laser cannons fire bright red or blue pulses that the eye can easily follow. Since this series was essentially cashing in on the popularity of Star Wars, which had just made its debut the previous year, it's not surprising that realism takes a backseat to the Rule of Cool.


 * Star Trek: Voyager: Ship went so fast that it was everywhere in the universe at once and then the crew "evolved" into salamanders? Yow! (Specifically the episode "Threshold", recapped here.) The episode has since been disregarded by the writing staff. Other, slightly less bunk episodes have not.


 * The DC and Marvel universes, which in some ways resemble sci-fi versions of the Fantasy Kitchen Sink, will occasionally make weak, palsied gestures in the direction of verisimilitude and then follow that with a two-page spread that violates every rule of physics yet discovered, except the most important one.


 * Earthbound: Psychic Powers, zombies, a living tent, mind-controlled sentient animals, a dog possessed by a member of the dev team, a cult that worships the color blue, an idol that makes people greedy and an Azathoth clone as a Big Bad. And the sequel is even weirder.

The first game was full of this as well. You get attacked by household items in the very beginning of the game! A cactus sings to you! All There Is to Know About "The Crying Game" is that you defeat the final boss with The Power of Love! (And they also had Psychic Powers and zombies here, too.) It's no wonder that this and the second game are the former Trope Namer for Magicant.


 * Air Gear: Where to start? Start by forgetting everything you've heard about inertia, gravity, and especially aerodynamics. Wielding motorized Rollerblades the right way will allow you to fire hurricanes at people. Hundred-foot drop? No problem, your A-Ts will absorb the impact. The awesome part is that all of it is explained in the manga. While air gear starts off semi-realistically, it's as if the author just keeps making up laws of physics on the go, purely to to justify increasingly unrealistic attacks.


 * Pokémon: Takes place in an Alternate Universe where the only major difference is that evolution took a completely different route. Some of the creatures have rather fantastic powers, though most of the more outrageous ones are given at least some justification (Slowking is superintelligent because toxins reacted with its brain chemistry, burns from Houndoom's fire never heal because enzymes in the flames prevent skin from regrowing, etc.). There are also several technologies which are unrealistic, such as teleportation and the ability to convert creatures and various items from your backpack into Pure Energy for storage and reconstruct it later, the (limited) exchange of creatures through time and (in the video games) a device that newly records habits of a creature within minutes of first encountering it. Don't even try to figure out the digital teaching of special moves with what looks like a CD.


 * Kingdom Hearts: Extremely condensed universe, yet each planet is somehow represented as a distant star. Faster than light travel, deflector shields, tiny Single Biome Planets, Asteroid Thickets, a Space Whale, do-anything computers (including an Inside a Computer System sequence), and the softest of mad science.


 * Command and Conquer Red Alert series: It starts off with Einstein traveling back in time to assassinate Hitler. By the time we're finished, we have dolphin commandos, psychically-controlled giant squid, electricity-draining UFOs, psychic soldiers that set people on fire with their minds, cloning machines, teleporting commandos who erase their targets from space-time, and bear paratroopers.


 * Transformers: Okay, so there are these impossibly ancient space robots, right? And they come to Earth in search of energy, right? And to disguise themselves, they turn into cars and trucks and guns and stuff, right? And the cars have realistic engines and passenger compartments and tires and everything, even though it's actually a giant outer space robot. Oh, and some of them can shrink down from giant space robot size to tape deck sized. And some of them are entire living cities and planets and stuff.


 * Warhammer 40000: Chainsaw swords, psychic spacemen, elves in space, orcs in space, undead robots, planet-eating bugs, three-hundred-metre-tall millennia-old walking battle cathedrals, soul-eating space stations and vehicles that travel faster because they're painted red (justified). The primary means of FTL is flying through Hell. In 40k, Rule of Cool is physics. As is Rule of Scary.


 * Power Rangers: It varies from season to season, but within a fairly narrow range. It sets its own rules and follows them surprisingly well; its just that none of those rules make any sense whatsoever. Even if you accept morphing as an explanation for a lot of things, it doesn't explain enough to place it higher on the list.


 * Neon Genesis Evangelion: A lot of the Applied Phlebotinum in this series involves branches of biology and engineering that neither exist in real life nor are ever likely to exist. "Metaphysical biology," for example -- Doctor Kozo Fuyutsuki's specialty -- is kind of like genetics, only it involves human souls instead of genes.


 * The Lensman novels: A classic pulp SF series, which originated the trope of Space Police armed with incredibly powerful and flexible weapons, and arguably, the whole Space Opera genre. Lensmen had intertialess drives, habitable gas giants (with surfaces you could land on)... it was pretty soft even when the first stories were published (in the 1930s), and since then, the Science Marches Onmarch of science has made hash out of most of its assumptions. However, it is remarkably self-consistent, and it did pay respect to basic scientific principles - the FTL drive only suspended inertia, which returned when the drive was turned off. Space combat takes place in 3D. Rayguns didn't cause objects (or people) to magically vanish, but simply delivered enough energy to melt or boil them.


 * Star Trek (the 2009 film): One of the squishiest incarnations of the franchise yet. Just a small sample of how soft it is: it contains (1) Time Travel (2) by flying through a black hole. They're extremely dense objects in space with an immensely strong gravitational field, not some sort of actual hole you can go through, with lightning storms. Had they used wormholes -- as other Trek series occasionally have, clearly distinguishing them from black holes -- they might have had a stronger justification, but they very explicitly made it a black hole. Which was just a hole. In space. And then they came out the other end, in an alternate past. Oh, and they can also be created from a spark of "red matter". And at least one ship is clearly shown half-in-half-out of a (flat) black hole.


 * Haruhi Suzumiya. The series has already enough problems with Science Fantasy. Vaguely defined Applied Phlebotinum doesn't help! At least the Time Travel is clearly elaborated. Haruhi is entirely consistent; it's just that its "one big lie" is bigger than most.


 * F-Zero: Futuristic racing with vehicles that go over 1000 km/hour on a regular basis. The vehicles have shields that protected them from completely crashing while said shields can also be used as boost-power to make your car faster. The racetracks also have many different tricks such as boosters, jumpers, shield rechargers, and many others. In the setting as a whole, we have a somewhat galactic civilization with many planets (most shown are Single Biome Planet) and aliens but it was never really explained. Rule of Cool has the final say regarding the races in the franchise while the rest of the setting as a whole seems to be Excuse Plot.


 * Freelancer: Space Is an Ocean in its top splendor. The space battles look like World War II air battles, only without the limitation of gravity. And on top of that, the in-game scale is warped enough to have entire planets with a 200 meters atmosphere, and no more than 2 km of diameter. These "softnesses" can be considered Acceptable Breaks From Reality, though, because they actually make the game more playable.


 * Farscape: Generally let the needs of the plot come first while known science could take a flying leap for all it cared. Sort of Lampshaded in "I Shrink Therefore I Am" when Sikozu starts pointing out all of the reasons being shrunk to one one-hundredth your normal size shouldn't work and Rygel tells her to shut up, because it was happening whether she liked it or not.. John says "We throw Einstein's theory of Relativity out the window every time we go out for groceries."

The science of Farscape is an invention that doesn't attempt much concordance with Real Life science. Sometimes this series can be very soft, and other-times it can have hard elements. Many things get no explanation: "any sufficiently advanced technology is comparable to magic."


 * Star Wars: Magic is present, though it is not called magic, and according to the prequels has some genetic basis but is still sufficiently advanced genes. Jedi telekinesis still violates Newton's First and Third Laws. The Death Star runs on Applied Phlebotinum and the Rule of Cool. Lightsabers. Dramatic Sound in Space, Old School Dogfighting, etc.
 * The Star Wars Expanded Universe ranges up and down the Scale Depending on the Writer. Relatively Casual Interstellar Travel, the existence of the Force, and many and varied alien species are all constants, but otherwise it's largely up to the writer. Some books actually try to explain away some of the soft elements from the movies. And then there's the matter of Onderon, a planet with moon that gets so close that their atmosphere's actually touch, never mind that gravity should be doing horrible things to both bodies.


 * Ratchet and Clank: Almost every entry in the series has an item which can turn enemies (including entirely non-organic robots) into a chicken/sheep/duck/pig/cow/penguin/monkey in seconds. Definitely Rule of Funny. The most powerful weapon in the galaxy universe also has a built in audio player. That only plays the finale for the 1812 Overture!


 * The two Bill and Ted movies, both of which involve time travel using a phone booth in order to make sure that the unlikely events which created the society of the future (where it's said that everything's clean, including the dirt) actually happened; the second movie also features a pair of intelligent robots built from parts bought in a 20th-century DIY store.


 * Doctor Who: FTL, several uses of death rays, humanoid lizards as a dominant species in Earth's distant past, creatures of living plastic, a time machine that disappears in one place and reappears in the next (also works as an FTL ship with a capacity to tow planets), methods of stealing planets into a place "one second out of sync with the universe", parallel and bubble universes, cyborgs consisting of brains and nervous systems in metal armour, easily-cloned flesh, at least one cloned race, "statues" that eat the potential lifeforce of whatever they touch, beings that use mind control and voodoo through science and the Trope Namer for the Timey-Wimey Ball.


 * Red Dwarf: Hard to place because, as a comedy, it naturally has many absurd elements, but the Absent Aliens, the fact that it takes time to go places, the way robots are treated and (in earlier series) soft light holograms make it seem a lot harder than most. The novels are harder.


 * Star Trek: Deep Space Nine: Although taking place in the same era as Voyager and The Next Generation, there was much less technobabble and fantastic plots, with instead a greater focus on diplomacy and personal interaction. The honking great war that dominated the last few seasons probably helped harden things up too.


 * Star Trek: The Original Series: Debatable though, many aspects of the show were pretty hard sci-fi when it was created, and only seem strange now after decades of science. Though the setting is stranger than other Star Trek shows, the ships and the technology are much more grounded. Some traits of the show (Rubber Forehead Aliens, All Planets Are Earthlike, Aliens Speaking English) can be explained by the technical limitations of the show when it was made (the 1960s). Others (Time Travel, Disintegrator Ray for example) cannot.


 * Metroid: 8-bit video game logic is the foundation of this franchise. Enemies die and turn into health and ammo pickups, and respawn when you leave the room, and your weapons are defined by their gameplay function, not their grounding in reality. Eventually it's revealed that the setting has everything from Organic Technology to full blown Magitek, but the it never bothers to try to justify how it works. Of course, the Metroid Universe is so well realized and full of mystique that it doesn't really become problematic or require an explanation to become a convincing or engaging setting. It never introduces anything to contradict itself, and only requires that you accept the fact that it takes place on an alien planet (or many).


 * Maximum Ride: It runs thoroughly and completely on nonsesoleum, to the point where there isn't even any Techno Babble to even try to pretend to explain splicing avian DNA into humans, or cloning either, for that matter.


 * The Giver: We never get any scientific justification whatsoever for...well, anything, really. Not the psychic transmission of memories, not the total control kept over every aspect of the Community, right down to its climate and The focus is more on human nature.


 * Robert A. Heinlein's latest fiction more or less goes right here. He went wild with speculation and his works can be called fantasias or phantasmagorias just as easily as sci fi.

Imported Alien Phlebotinum
There are technologies that break the laws of physics, but we don't have any real idea how they work, or they are dependent on a resource that apparently appeases some higher power.


 * The Stargate Verse: Considering the entire premise of the show is that ancient Earth religions were based off of alien snakes that take over your body or little grey men, that Atlantis is really a flying city in another galaxy, and that if you die, you can pop back again good as new after ascending/sleeping in a sarcophagus/being rebuilt by nanobots... it's surprising how hard they can get if they put their minds to it. StargateSG-1 got softer as it progressed, letting mystical concepts like Life Energy, Ascention, Evolutionary Levels and the power of belief take center stage. It also loses points for having each show's Omnidisciplinary Scientist actually figure out how to mass produce much of the Phlebotinum. Just in Time for the SGC to Save The Day. Over and over again.


 * Animorphs: Translator Microbes, technological shapeshifting, shrinking rays, hyperdrives, time machines, artificial gravity, telepathy, etc. Mostly shrugged off as being alien technology, but their resident alien does try to explain some of it.


 * Andromeda: Tries to be harder than Star Trek. Set farther in the future, and teleporters, interstellar radio (they use couriers to deliver mail), and holodecks (they use virtual reality instead) are all still impossible. Rather than hand phasers, they use small tracking bullets, or if they're desparate, plasma bursts, though they can only fire a few shots of those. Also, their main weapons are small missiles traveling near the speed of light that hit with their kinetic energy. Trouble is, a lot less stuff is actually explained, meaning you usually have to take their word for it or make something up yourself whenever they use technology.


 * Command and Conquer Tiberium series: Uses only one form of real Applied Phlebotinum, in the form of the titular Tiberium, but Tiberium itself has all manner of weird properties. By the third installment, though, the Sufficiently Advanced Aliens arrive with all manner of odd and physics-bending technology.


 * H.P. Lovecraft, by his own admission, preferred to "supplement reality rather than contradict it." His fiction takes a serious look at humanity's true place in the universe, and is full of Extradimensional beings, Starfish Aliens, and scarily plausible explanations; there's no use of Aliens Speaking English or Rubber Forehead Aliens unless they're played for horror (since neither trope should naturally occur). Lovecraft stories also provide scientific-ish sounding rationales for merfolk, time travel, and the effects of witchcraft (it's really ).


 * The Half-Life series, while having well-researched speculative human technology, all the lifeforms from the Xen borderworld and beyond, which include psychic aliens that use their lifeforce to revive a comrade who is near-death, 28 Days Later-esque "fast" zombies and at least semi-organic gunships sharply soften it.


 * The Uplift series, by David Brin: Hard science mixed with a lot of Imported Alien Phlebotinum to make one of the 'hardest' of the Space Operas, a sub-genre that is usually very 'soft'. Although, in fairness, there are really two Uplift series. The first trilogy is vastly harder than the second, which degenerates into pure magic alien squishiness by the end -- including aliens wishing their enemies out of existence through reality warping.


 * Halo; some of the technology used by the UNSC is upgraded real-world tech or technology based off predicted future developments, like railguns and AIs. The primary form of FTL are extremely dangerous and unpredictable "Slipspace" drives. Things get a lot weirder with time-and-space-bending Forerunner technology, which is made worse by the comparative weirdness of their tech and flatly refusing to explain how anything works.
 * The UNSC's technology level can vary wildly. On one hand, they have giant coilguns on their ships that shoot 600 ton slugs at 40% the speed of light... and on the other hand they're still using plain ol' chemically-propelled personal firearms for their troops.


 * Macross: Plenty of Humongous Mecha, No Sense Of Scale and ships that pack more than their own weight in missiles. On the other hand, space combat scenes are not particularly fanciful and there are realistic depictions of zero gravity environments, decompression and the like.


 * Starcraft: While most of the terran technology, sans FTL, is believable, or at least has a basis in real technology, it has several softer sides, particularly in regards to psychic powers and terraforming. Things get quite a bit weirder with the protoss, though at least their warp in technologies has the explanation of being an extension of FTL travel. Minus the Crystals And Spires aesthetics of the protoss, most of their non-magic technology is reasonably believable, and their rather odd biology seems to be a Shout-Out to Starship Troopers, which was fairly hard for its time. Things get weird once again with the zerg, though besides the Lego Genetics, nothing is too far out of place. All of this is drawn from the fluff and cutscenes rather than gameplay, which has Gameplay Story Segregation in full force. Like many other series, Starcraft has its ups and downs Depending On The Writers.


 * Peter F. Hamilton's Void Trilogy: Some of the technology (gaiamotes) is explicitly Imported Alien Phlebotinum, teleportation is possible, as is manipulation of the actual quantum structure of the universe. The funny thing is that it takes place in the same universe as the Commonwealth Saga (see below under Minovsky Physics), albeit 1500 years later, but feels significantly softer.
 * Though this is partly an effect of Clarke's Third Law, since we're reading about a society 1500 years more advanced than the last time we read about it (when it was pretty advanced already).


 * Prehistoric Park, a Speculative Documentary spinoff of Walking with Dinosaurs. The only true departure from reality as we know it is the Time Travel by Nigel Marven to the prehistoric times. Of course, the time travel device was never elaborated on how it works or how it even came to being. Instead, we have Nigel Marven trying to create a prehistoric safari filled with various creatures that were long extinct by bringing them back from the past. The prehistoric animals as a whole were depicted as realistically as it is possible.


 * The softest Robert A. Heinlein's juveniles got was here. He tried to restrict himself to less than FTL and I Want My Jetpack, but occasionally, on the very rare instances that he allowed for aliens, allowed alien phlebotinum.

Minovsky Physics
The laws of physics are broken in a specifically declared way. Expect hundred-page dissertations on fictional physics and consistent internal rules.


 * Babylon 5: Has its ups and downs, but just edges into hardness 2.
 * On the "hard" side: No Space Friction, Starfuries are a plausible spacefighter design, Artificial gravity is rare and advanced alien technology. Human ships use centrifugal gravity sections. Objects destroyed in space leave debris. Alien biology often treated as properly alien, requiring unusual atmospheres, etc. No Translator Microbes, and biochemical barriers do exist so alien hybrids can't naturally occur and alien plagues won't affect other species.
 * On the "soft" side: Aliens spacefighters are very 'fighter in space'. Artificial gravity, FTL drives, visible beams, Rubber Forehead Aliens (who often come from a Planet of Hats), Sufficiently Advanced Aliens and Psychic Powers do exist with effects that don't have to worry too much about thermodynamics. JMS wouldn't know about scales if you hit him on the head with a lightyear long yardstick, and everyone uses Explosive Instrumentation . Some of this may be Executive Meddling, though.
 * On the issue of Space Is Noisy. Word of God specifically says the sound is expressed from the standpoint of being inside said craft, where there is still an atmosphere to carry sound. As far as Sense of Scale goes, though, JMS specific quote is "Ships move at the speed of plot."


 * Traveller : FTL travel at a normal rate of one week per parsec. No messages FTL unless actually carried on a starship. Space Is an Ocean. Believable economic and political systems. Well worked sociology though sometimes a little hatty. Technology explained in lavish detail.


 * The Matrix: Fairly hard for a story about a man who discovers the earth is really a burnt out husk ruled by flying robot squids who force the last of mankind to play MMORPGs to leech off their body heat. And The Chosen One has the cheat codes to the universe. The sequels and spinoffs help clear up some of the confusion.
 * Allegedly in the original script the machines were using humans as Wetware CPU s, but they thought the audience wouldn't understand that so they made up some bullcrap about using them for energy.


 * Anne McCaffrey's Talent series is, for the most part, a rather hard Sci-Fi. She supplies understandable ways in which psi powers might manifest and how they work. Since psi powers are primarily limited by how much energy a human being can create, being able to gestalt with an electrical generator to supplement one's psi makes sense. Also, screw using any sort of advanced technology for FTL travel or communications; psychic powers expressly bypass the speed of light, so we can transport stuff using them! The series does begin to head a bit more towards the "softer" side with the more aliens contacted (a grand total of two species), but she also does a fairly good job with them as well. One is insectoid, one is...vaguely humanoid, and both have very alien thought processes. The energy requirements also tend to go out the window as each generation gets more powerful and has less and less reliance on generators.


 * Sid Meier's Alpha Centauri: The Tech Tree expands based on our current understanding of science, the quotes from the in-game characters always make sense, nonsensical Techno Babble is almost nonexistent, and a lot of in-game scientific and technological advancements have already been predicted by several writers and scientists. Would be smack in the middle of "Unobtainium" if the Psychic Powers didn't look a bit too much like magic.


 * Mobile Suit Gundam: UC only; the later ones tended to add more fantastic flights of fancy, but the original only had Psychic Powers, Minovsky Particles, and the basic unlikeliness of Humongous Mecha (which it goes to great length to justify).
 * Which series/universe is more "real" than others has lead to a massive number of flame wars. For instance, Gundam Wing doesn't go as far to justify the use of Humongous Mecha (largely using Unobtanium instead of Minovsky Physics), but has no Psychic Powers and unmanned mobile suits.
 * On the other hand, GN Particles from Gundam 00, you know, the ones that regenerate limbs, produced for near-limitless energy, allow telepathy, SEEM to be incredibly ridiculous, it's specifically stated to be the solution for the quantum entanglement problem, which in Real Life is paradoxical and unsolved. Soft Sci-Fi or an eventual case of Science Marches On?
 * Quantum entanglement isn't a paradox anymore (see Bell's inequality)- it's the popular misunderstanding of how it works that is a paradox (the paradox is a myth). Playing off a popular myth (such as 'we only use 10% of our brains') is excellent for willing suspension of disbelief (since people already buy the myth anyway), but is not legitimate science (i.e. does not qualify for hardening the scifi level, but rather softens it considerably by contradicting real science).


 * Infinite Ryvius: While its Space Is an Ocean (quite literally, in fact), complete with Space Whales, and contains Phlebotinum-based gravity-manipulating Humongous Mecha fights, the series also features relatively realistic Artificial Gravity and remembers to avert such things as Infinite Supplies and Sci-Fi Writers Have No Sense of Scale.


 * Alastair Reynolds' Revelation Space series: Has no FTL travel but does contain several superscience technologies, e.g. the Conjoiner near-lightspeed drive, space/time manipulating weaponry, messages from the future to the past (also the basis for FTL messaging). There is a form of FTL travel present, but it tends to
 * Although


 * The works of H. Beam Piper: Uller Uprising opens with an essay explaining the silicon-based Ullerans. There are no death rays, just bullets. Nuclear power is used. There's no full-on explanation of FTL, but when he gives a detail (such as gadolinium being key, or it including time dilation), he doesn't contradict it. (The Paratime series, on the other hand, is quite soft, right down to giving reincarnation a free pass in one story; granted, that was a case of Writer on Board).


 * A Miracle of Science: Everything that's used is explained via modern theory, with the exception of a few staples such as FTL and Deflector Shields -- which is only used by a sect of Sufficiently Advanced humans. Fairly impressive for a series based around mad scientists running amok.
 * Well, look at the rants. The authors are really into this stuff.


 * Jerry Pournelle's CoDominium Shared Universe: Military Science Fiction hard enough to chip teeth. It has a Portal Network and a Force Field designed by Dan Alderson, a Real Life celebrated scientist at JPL. Two books co-authored with Larry Niven introduce a species of distinctly non-Human Aliens, but they are sublimely well-constructed and everything else -- everything, is real, proven or entirely plausible near-term technology. Pournelle even counted on Science Marching On, justifying it with Medieval Stasis enforced by the namesake Obstructive Bureaucracy.


 * Both the Night's Dawn and Commonwealth Saga books by Peter F. Hamilton. FTL is done by the use of ZTT (Zero Temporal Transit) drives, which work by a well-explained principle based on wormholes, and stasis technology based on the same effect takes the place of Human Popsicles. In every other respect, very, very hard indeed, subverting the vast majority of the Space Does Not Work That Way tropes and just plain avoiding the rest; no dogfights in space, explosive decompression is only occasionally dealt with, and is done so with great accuracy, and space is far more like...well, space, than it is like an ocean.


 * The Honor Harrington book series: Space Is an Ocean, but the series demonstrates admirable internal consistency, relies on essentially only one piece of "new" technology (gravity control methods), mostly merely extending other pieces of current technology (medical science, nuclear fusion containment, lasers). Additionally, space combat is very three-dimensional and ship-to-ship engagements are often fought at fractional light-second distances (contrast the traditional Star Trek Starship Standoff).


 * And speaking of David Weber, let's not forget the Starfire wargame series (which Weber and Steve White used as the setting for 4 novels). Starfire had naturally-occurring Warp Points as the only means of faster-than-light travel. Star systems without Warp Points are simply never visited. The starships use a technology called the "drive field" which protects them from direct impacts, so missiles have to detonate a short distance away from their targets; this puts beam weapons on par with nuclear warheads in space battles. The drive field also acts as a variety of inertialess drive, allowing starships to accelerate from a dead stop to 10% of the speed of light instantly, but requiring a moving starship to change direction in long slow curves; thus, space ships move like ocean ships.


 * Mass Effect: Mobile Suit Gundam was the Trope Namer for the Minovsky Physics, but Mass Effect gave us the Trope Codifier with Element Zero, a form of exquisitely researched Unobtainium that defines every use of sci-fi technology. Quite realistically, something as important as eezo and the mass effect fields it generates fundamentally influences every aspect of society, meaning Kinetic Weapons Are Just Better even with man-portable Deflector Shields, and people born with the stuff in their systems can manipulate gravity. The programmers definitely have a great Sense Of Scale, as you traverse the galaxy via the Portal Network even with your mass effect drive. All the aliens speak English because of ubiquitous computers and translation software. The Rubber Forehead Aliens are in fact the most alien, with truly Bizarre Alien Biology. Other things in the setting tend to more or less reflect realistic science, like non-element zero physics, astronomy, alien biology, and military tactics and strategy. Behold, Sir Isaac Newton: The Deadliest Son of a Bitch in Space! Think of it as Planetes with an eezo center, like a Everlasting Gobstopper.


 * Vernor Vinge's The Peace War, The Ungoverned and Marooned in Realtime: Mostly explore the consequences of a single fictional technology:


 * Larry Niven's Known Space stories: No Human Aliens here! Er... with one exception, and the humans tend to simply do very unlikely things. A variety of "interesting" planets are explained by way of a subtle bug in the first generation of colony seedships: Instead of seeking a habitable planet, they settled for a habitable point (and didn't examine that too thoroughly). Thus, one colony is on a plateau of habitable land in the upper atmosphere, above a Venusian miasma, while another is swept by hurricane-force winds for most of its year (the probe arrived in the calm season). The FTL, Artificial Gravity, Psychic Powers, stasis fields and other Wondertech keep this from being rock-hard scifi, but the astronomy is very solid, and much of the supertech is purchased from Sufficiently Advanced Aliens. Niven gets uber bonus points for having obsessively Shown His Work, and occasionally retconning fan-discovered errors. ("The Ringworld is unstable!")
 * It is worth noteing that Known Space starts out harder but softens as in universe and Real Life Science Marches On (when it started there was no FTL and pisonics was semi-credible).


 * Schlock Mercenary is almost entirely plausible scientifically, although little of the theory appears in the work. Its placement is primarily due to limiting its Applied Phlebotinum to gravity manipulation(but not generation -- ships are built around spheres of neutronium as sources of gravity to manipulate), taking it for granted that the process is as well developed as electronics, and playing the result to its natural conclusions; ubiquitous Flight, Deflector Shields, traversable wormholes(one example which justifies a Time Travel storyline), and quantum teleportation. Some find the easy nanotechnology a bit of a stretch.


 * The Pentagon War tries to be as hard as possible when describing spacecraft technology, space battles, etc., even going so far as to apologetically throw in a magic alien-designed force field to explain something as mundane as controlled nuclear fusion of ordinary hydrogen. Then it throws the baby out with the bath water by introducing "hyper bombs" that can create infinite-speed corridors between star systems, and a device that provides an end-run around the most basic premise of Einsteinian relativity.


 * Eve Online: FTL speeds are possible, but only applicable within a single solar system. As far as players are concerned, bridging the massive space that separates solar systems requires advanced stargate technology or highly costly specialized equipment that costs even more to use because of fuel limitations. The latter method requires a ship or particular structure already be in the system, while the stargate network was built by absolutely massive ships traveling between systems at roughly .3c. Weapons are fairly realistic, employing relatively justifiable laser technology, magnetic railcannons, particle weapons, missiles, drones and even good old fashioned bang-you're-dead projectile weaponry. The universe is ridiculously huge, much like actual space, with over 7000 unique solar systems, though it falls short of the following category because, as New Eden's space is based on fluid physics and has the viscosity of firm gelatin, ships have a "Top speed" and decelerate once the engines turn off. The fluff states that this is an effect of the warp drive and that a ship without one would travel through space realistically, but be limited to sublight speeds within a system.


 * Battlestar Galactica: The 2003 series, despite taking place in another solar system, had mostly real-world technology as far as the humans were concerned with the exception of FTL technology. However, Cylon Resurrection technology involved downloading a Cylon's memories upon their death and frequently beaming them across vast distances of space. The process was usually handled pretty consistently but was never explained in detail as to how it is possible.
 * Fair enough, since.
 * But why a normal (i.e. not Cylon) virus can infect a Cylon ship though the resurrection link is never satisfactorily explained.
 * Also, the inclusion of RCS on fighters suggests that (at least when it comes to style) there is no Space Friction.


 * Yokohama Kaidashi Kikou: Very difficult to categorize, because it essentially includes magic. However, it is subtle, quiet, and is not there to drive the plot, but to add to the atmosphere of the work, and provide a dualism with the receding human civilization. In some cases attempts are made to analyze the magic scientifically (mostly out of pure curiosity), but these turn out to be inconclusive. At any rate, the actual technology shown is all fairly realistic. The Ridiculously-Human Robots are perhaps a bit implausible, but not impossible, and make sense within the setting. The overall feel is Twenty Minutes Into the Future, and most of the Applied Phlebotinum we see is accordingly grounded.


 * The more ambitious works of fiction by Stanislaw Lem tend to fall into this category, erudite as he was in scientific theories of his times. The best example of it is to be found in his Fiasco, where it takes him no less than a whole separate part of the book to explain the physics of inter stellar travel. However, if one of the characters is called Ijon Tichy or professor Tarantoga, the reader should instead get prepared for a fair amount of nonsensoleum.


 * Xenogears would have been in the Applied Alien Phlebotinum category entirely if not for its massive in-game walls of text coupled with its voluminous Perfect Works companion. This may apply to Xenosaga as well. Basically, virtually all unscientific principles are ultimately attributable in some explained way to a select handful of sentient entities that have been present since the beginning of the universe (and in the case of Xenosaga ). In Xenogears, this is primarily . In Xenosaga, these are featured, but there are also, and it very decidedly strays even further into Applied Alien Phlebotinum territory with the Gnosis.


 * Alan Dean Foster's Humanx Commonwealth series operates on a great deal of Phlebotinum mixed with just enough hard sci fi elements to keep things sounding plausible. For example, FTL Travel is performed by means of Artificial Gravity generators that violate conservation of energy, but the rules for employing them are very strict, and most other technologies are based on things resembling known physics, or are logical extensions of the use of Artificial Gravity. However, once the Precursors start to show up with their Lost Technology, things get really fanciful really fast. Examples: constructed artificial planetoids that can traverse the galaxy in a week and fire star system-destroying bursts of energy across intergalactic space, entire planets that warp through alternate dimensions, etc.


 * Back to The Future: The (initial) setting is real life 1980s except an obscure scientist managed to figure out how to Time Travel. There was a fair amount of technobable in the first movie about how the time traveling works and how it was done. The full ramification of it was also discussed throughout the series (It was the former Trope Namer of Timeline-Altering MacGuffin Gray's Sports Almanac after all).

FTL Travel
The only intentional departure from the laws of reality is that we've finally outsmarted Einstein, or just made him look the other way while we slip by -- at the very least to send messages. Everything else will be justifiable under known scientific principles.


 * Starship Operators has FTL travel (called warp drive, no less) and but is otherwise very hard.


 * Altered Carbon: Humanity has FTL communications (discovered from studying Martian ruins) but not FTL travel. By and large most technologies not dealing with space travel (e.g. AI, cloning, cortical stacks, etc) seem to be both plausible and purely human developments.


 * Voices of a Distant Star. FTL travel is possible only for starships. News about the battle at a distant star system takes years to arrive to Earth, same for cell phone signal. And when the battleship blows up, there is a big bright flash, no flame, but there's still sound.


 * Most of CJ Cherryh sci-fi novels. FTL is only possible for starships, with no FTL communications or sensors. If communications is taking place across distances measured in light-minutes then the round-trip time delay is taken into account, plus if starships are traveling at a significant fraction of light speed the change in delay over time is taken into account. In space weight is provided via rotation (centrifugal force) rather than artificial gravity. The "Alliance Union" series is made slightly softer by the fact that the FTL drive can, in addition to letting ships travel through hyperspace, allow for instantaneous changes in velocity while in normal space.

In her Hell Burner books (within the Alliance Union series), the peculiar nature of near-light-speed combat is very seriously considered, as are the dangers of space, the nature of large-scale construction projects, and the proper procedures for pressure suit maintenance.
 * Freefall: Tends to limit itself to 'theoretically possible but difficult' technologies, such as genetically enhanced sapient animals, terraforming, AI and cryogenics. Even artificial gravity is absent (as the name suggests), and though the Dangerous and Very Expensive(D.A.V.E.) Drive enables interstellar voyages measured in days, it is explicitly not Casual -- Planet Jean was colonized by slower-than-light ships carrying Human Popsicles.


 * Contact by Carl Sagan: Scientists spend the first third of the book struggling to raise money for the SETI program amid sponsoral skepticism. Once they finally find an alien transmission, they spend the second third deciphering the transmission, considering all the possibilities involved, and thoroughly applying the scientific method, all the while showing the social impact of knowing that we're not alone. It would rank even lower in the list if the last third was not about building borderline Imported Alien Phlebotinum, but it could be softer, because the setting and the clearly established rules actually make the alien device look rather hard.


 * Alien and its sequel. Spaceships have slow FTL travel, during which the crew lie in cryogenic sleep for months or even years. The many discovered planets go by numbers, but almost none of them are naturally inhabitable. Technology is otherwise quite plausible. The titular Alien's physiology stretches credibility a little, with its rapid growth an ability to infect seemingly any species.
 * Other films diverge from the first two in various ways, and become somewhat less hard as a result. Things like the chestbursters taking on features of their host, super-rapid growth into adult aliens, stealth warships, etc etc require disbelief to be suspended somewhat higher. Novels and comics set in the Aliens/Predator extended universe inevitably follow the Rule of Cool and the authors do not always understand the consequences of their ideas.


 * Three Worlds Collide has the physics associated with the "Alderson starlines" edging it up the scale, but is otherwise fairly realistic in the physics department.


 * Blue Planet: The "Mass Effect" of Tabletop Games. Some insist that Fish People have certain thermodynamic issues, but the footnote where they are stated to have hemocyanin for blood instead of human hemoglobin is fairly obscure. The biotechnology takes a hit due to the existence of "Longevity Matrix Ore" aka "Long John", but rolls with it as it is not the Spice of Life most in the setting consider it to be, but . Would be thus be rock-solid Unobtainium if not for the traversable Masters-Vishenko Wormhole.


 * Robert L. Forward's Timemaster: probably one of the few hard science fiction stories you'll ever encounter that has Time Travel at the core of the plot. The only iffy element is a substance with a negative rest mass: although such a material has never been observed, several mainstream theories of physics predict its existence.


 * Avatar: (The James Cameron film). Another mix of hard and soft, but somewhat more crunchy than the Hollywood norm.
 * Common misdemeanours like Artificial Gravity and FTL Travel are Averted... the Venture Star is a fairly realistic slower than light starship, and even has huge radiators, averting Space Is Cold. The awful economy of interstellar trade is balanced by Unobtanium's value, and much manufacturing is done on Pandora without imports. Even the mech-like AMP suits aren't too improbable, being used for physical work as well as combat making the most of their human-like control systems for ease of use and travel.
 * On the soft side, The Na'vi, a race of Humanoid Aliens, look and act like a mesh of Native American stereotypes painted blue. Their genetic equivalent is mixed with human DNA to create the Avatars, although in the Pandorapedia apparently this was a lengthy and complex research project. The Pandorapedia also implies the existence of a Subspace Ansible, though this does not impact the film.


 * Ursula K. Le Guin's Hainish Cycle novels: There is no FTL travel, although there is FTL communication using the ansible (which also made an appearance in Ender's Game as a Shout-Out to Le Guin). Travel between stars involves nearly-as-fast-as-light ships, and comes with "realistic" time dilation effects. Very little super-technology is discussed beyond this, except for some hints about genetically engineered species. Nearly -- human aliens appear, but a major plot point On the other hand, the novels tend to focus on people and societies, so relatively little space is dedicated to describing how technology actually works. Telepathy also makes an occasional appearance, though it is discarded in later novels (Le Guin wrote that essentially, she did away with it because Science Marches On -- telepathy seemed more plausible when she was writing the earlier works).


 * Ender's Game is most likely also in this category. The ansible, as mentioned above, does factor significantly into the story. However, the first book in particular can be surprisingly hard -- things such as gravity generators are not ignored, and the world seems to be (relatively) politically and scientifically reasonable for not-so-far-in-the-future. Perhaps the most interesting sci-fi invention in this book is the internet (called something like the Nets). Remember that the first book was written in 1985. However, the series gets stranger and somewhat softer as it continues (admittedly, many of the books jump 2000 years in the future), with genetic mutations that strain credibility and much, much weirder FTL travel.
 * Actually, most of the space travel in the Ender's Series (up until the very end of Xenocide, as well as parts of Children of the Mind) is based on General Relativity. The faster you go in space, the slower time travels for you is actually a real phenomenon, even to the extent that Ender (ab)used it in the series. The Park Shift (how they get to relativistic velocities)), on the other hand, is merely described as something that was accidentally discovered one day and that nobody quite knows why it works so well.


 * Orion's Arm: Traversable wormholes are a major part of life but both causality and relativity strictly curtail their use. The laws of physics are never actually broken but the powerful AI Gods certainly bend them. The most scientifically questionable parts of the setting are usually mentioned as being semi-mythical and possibly nothing more than memes created by powerful transapients or confused terragens.


 * Primer. Here because of the similarity in Minkowski space of FTL and time travel, the mechanisms of time travel are, shall we say, meticulously explored.

No FTL
Mostly justifiable under known scientific principles, including any (necessarily sub-lightspeed) space travel, limited mostly to Interplanetary Voyages, with anything greater being a massive undertaking-- Casual Interstellar Travel is an impossibility. Even if some aspects are slightly softer than in a story with FTL, the physicists will forgive it in exchange for appeasing their Einstein-worship. (Ken Burnside has a particularly scathing rant to that effect.) Home of the Generation Ship.


 * Firefly: No sound in space (except for inside the ion cloud in The Movie, where the sound has a medium to travel through) and no aliens, and a few other things that seem like the writers actually did do the research (such as how nasty stomach wounds are), but there are some things, such as terraforming, temporary cryonics, Artificial Gravity and space ships that may or may not be viable 500 years from now -- though all of them seem to have problems. Terraformed worlds all have "quirks" such as unique diseases that crop up or "black rock" failures, cryonics can cause a bit of a shock if you come out of it too quickly, spaceships break down easily, spacecraft crews don't notice other spacecraft until they're practically on top of them, etc. The most improbable feature of the world is probably River's apparent telepathy, and even the characters aren't sure they believe it. The ships also move at the speed of plot, with Whedon waffling back and forth as to whether or not they can travel faster than the speed of light -- it's eventually revealed that it's all in one (fairly large) solar system, so given that ships travel between planets in a timeframe of days or weeks, travel is definitely subluminal, if still fairly fast. The ships that left Earth took a "generation" at least to get to the system, but that was presumably generations before the story takes place.
 * It was. Extra materials note that even just the completion of terraforming on most of the non-Core worlds was completed in 2435 (the series/movie is set in 2517 and 2518), and before that was the arrival of humans at the system and colonisation of major Core worlds such as Sihnon, Londinium and Osiris, with those worlds being overpopulated by 2435.
 * It's also worth noting that the tech base in Series/Firefly is very...off, yet surprisingly advanced for the Space Western aesthetic. Most of the particularly advanced technology is in the background, i.e. the terraforming and Artificial Gravity, and is, at best, only discussed in terms of effects and not the actual technology behind it. It's also pretty well established that most of the cutting edge stuff is out of reach of most of the population, for instance hand held energy weapons exist but the demands of their manufacture and maintenance cause them to tend be both prohibitively expensive and downright flaky in most cases, hence almost everyone just gets by with good old slug throwers only some of which are all that more advanced than what we have today.


 * Dollhouse. The core speculation is that people are purged of their identities and imprinted with others - the rules are pretty consistent, and space travel doesn't enter into it at any point, but the internal science is still covered with loads of Techno Babble.


 * Cowboy Bebop: Has no Space Friction (except during dog fights), Artificial Gravity, travel outside this solar systems, and no FTL Travel. The least realistic thing is the Portal Network, which was only included to keep travel time between planets down -- but is explicitly not faster than light. It takes place in an Alternate History where we had a Space Age instead of a Cold War, and developed efficient spaceplanes and Terraforming by the 2070s (and those things on Mars that look like Deflector Shields? Air curtains.). Much like Series/Firefly above, a more improbable element is that they could terraform most planets and moons of a solar system to habitability.


 * Max Headroom: Strongly related to its Twenty Minutes Into the Future premise, though still spiced with the occasional TV commercial that makes people's brains explode. Which may be a comedic exaggeration of a Reverse Funny Aneurysm; certain TV shows have been known to trigger grand mal seizures.


 * The works of Greg Egan: Tend to include in-depth discussions of physics, maths, computer science and biochemistry in a non-Techno Babble way, and many start from the assumption that, given time, modern science will go the way of Newtonian Physics. He gets bonus points by never using this as a cheap excuse for FTL travel.


 * Charles Stross's Accelerando series: An Einsteinian universe without FTL but with wormholes whose endpoints can be positioned by STL means. Matter transport is done using rapid assembly and disassembly and normal communication channels. There's a fair amount of uploading and computronium to facilitate STL travel in a sensible fashion. The characters speculate about distant aliens performing a timing channel attack on the computational ultrastructure of space-time itself, and the eventually-weakly-godlike-robot-cat claims to have a Halting Oracle, but that might be intimidation.


 * The works set early in the timeline of Larry Niven's Known Space universe fall into this category, including Protector (which featured Bussard Ramscoops but no faster-than-light travel). The later in the timeline of Known Space you go, though, the farther the scale slides toward the soft side, with FTL, reactionless drives, inertialess drives, indestructible transparent hull material, and finally psychic luck all entering the fray.


 * Poul Anderson's Tau Zero. Features a flight to the stars in a near-light-speed Bussard Ramscoop. At the time it was written, the only technological handwaves were the scoop field that could draw in interstellar hydrogen without ionizing it, and the gravity nullifier that only worked at relativistic speeds. (And those funny molecular-interpenetration boat anchors at the beginning, but those weren't essential to the plot. )

Unobtainium
Contains only theoretical yet plausible elements. NO FTL in any way, shape or form.


 * The Core. Unobtanium, a material that strengthens with pressure, is essentially the only thing theoretical in the movie, besides what it is really like deep inside the earth.
 * Which of course is the entire point of the movie.
 * Oh, and you can restart the earth's core with a nuclear bomb.


 * Gears of War: All the weapons and equipments of the humans seems to be mostly plausible from the basic infantry weapons to the superweapons. Even the locusts seems to avoid some of the standard Bug War tropes with them being mostly humanoid only underground. Of course, their Bizarre Sexual Dimorphism seems to stretch the credibility a bit, not to mention the various Big Creepy-Crawlies that the Delta Squad encountered. There is a reason why it was put at the very top of this section. The Unobtainium element is the Emulsion, which seems to be the main fuel source in the planet and had a hand in the creation of the lambent locusts.


 * Transmetropolitan: Basically a melting pot for every Cyberpunk and demented transhumanist's fantasies into a single series. Most of the concepts are scientifically possible without violating known rules of physics, but that's about the degree to which the series is willing to be realistic.
 * The Foglets are pretty iffy, though; how could a cloud of nanomachines move with any reasonable speed, and not be scattered by wind, let alone be capable of converting air molecules into solid objects on the fly? Likewise, the Grey aliens.
 * Greys are just weird. Foglets, however, are just plain fucking awesome.


 * Stellvia of the Universe never clearly contradicts anything we know to be science fact, and goes out of its way to show such elements as journeys between Foundations within and around the solar system taking several months. The Starfish Aliens being able to  does kind of hiccup the Starfishness of the Aliens, the amount of energy the lasers can fire is astronomical, and the   is based on a somewhat questionable physical model, but the writers nonetheless have a pattern of Showing Their Work.


 * Robert L. Forward's Rocheworld setting was quite hard (it should be, he's a physicist). The only major implausibilities in the first book are alien life and a life-prolonging drug. Points are lost to Sequelitis; In the third and later books, the science softens to mush, including finding native coffee beans on the moon of a gas giant circling a red dwarf.


 * Ben Bova's Grand Tour novels: Perfectly credible spaceflight-within-the-Solar-System stories. The only Phlebotinum is nanotechnology, which is at least theoretically possible. Some extraterrestrial life features, but it is plausibly primitive.


 * Allen Steele's Near Space series. Spaceflight-within-the-Solar-System stories with no Phlebotinum at all, except in the farthest-future setting, A King of Infinite Space, which features reversible cryosuspension and a class of humans genetically engineered to function in space.


 * Century City: The science tried to be hard. The plots, on the other hand...


 * Gattaca: Set in a very near future that introduces no really new technology but speculates on the advance of subtle human genetic manipulation and fetal selection and the ethical and social implications of a society that quickly relegates the non-engineered to second class status. The gamete selection technology portrayed in the movie is a reasonable extrapolation from technology that already exists; indeed, the furthest-out thing in the film is a manned expedition to Titan (and given an entire world population of geniuses, it's not much of a stretch except for the fact they don't wear spacesuits or seatbelts). Hard, well acted, and highly entertaining. In a marketplace where this movie tanks and Transformers 2 makes half a billion dollars, Hollywood will probably never make a better hard sf movie.
 * Tailored suits are the only proper wear for beautiful, athletic, smart people to travel in space via silver space hotrods. Their headquarters was built by Frank Lloyd Wright, after all.


 * Vernor Vinge's Rainbows End: Set Twenty Minutes Into the Future. The most speculative parts concern the existence of certain vulnerabilities in the human brain against information-based attacks.


 * Strange Days: A film with one innovation ("playback" of memories via portable superconducting quantum interference devices) and the consequences thereof.


 * Patlabor: What giant, humanoid robots would be like in the real world. All units are awkward to pilot and their abilities are extremely limited. Police-issue labors can brawl with rogue worker mecha but will get utterly trashed by conventional weaponry meant for any vehicle of similar size. Military labors are few and far between, and common anti-tank weapons are quite effective against them. Pilots need months of training and software assistance to perform well, and so on.


 * The works of the dearly departed Michael Crichton. He frequently showed his work about plausible technology as it becomes workable and just before It Got Worse; usually because arrogant humans insist on Tempting Fate. Once he acquired a degree of Protection From Editors, he took advantage of that to move into more controversial territory.
 * Timeline, however, falls squarely in Minovsky Physics territory. While internally consistent and explained in some detail in the novel, in reality the "multiverse theory" is largely a product of fiction and outright speculation. It doesn't actually even qualify as a theory.
 * Um, no. The Many-worlds interpretation is a logical extrapolation of quantum physics proposed by the physicist Hugh Everett and is adhered by many modern scientists. The unrealistic part of Chrichtons book are travels between the universes, which MWI doesn't permit.
 * The films even less so, primarily due to Executive Meddling.


 * The works of Thomas Pynchon. Mr Pynchon studied engineering physics in the '50s, and studied WWII in the '60s, and it shows.
 * There is, however, an unexplained oddity that calls Causality Itself at the core of Gravity's Rainbow.


 * GURPS Transhuman Space: So far possibly the hardest SF RPG released, no FTL whatsoever. Biotech is harder than Blue Planet, but still somewhat soft in places. The AI (and especially "uploading") are speculative at best.

"Masamune Shirow: It's easy to shrug off psychic phenomena as being "unscientific", but assuming the person experiencing them isn't totally faking it, it's probably more scientific to consider such experiences in psychological or neuro-physiological terms. They could, for example, be considered the result of "naturally-occurring magnetic or electrical phenomena that affect the brain," or they could be analyzes as a type of "mass hypnosis," etc. It's unscientific to laugh off poorly understood phenomena instead of trying to analyze them."
 * The Ghost in the Shell franchise -- particularly the first manga. Shirow Masamune goes to great lengths to make his Technology Porn look as realistic as possible. (For example, Project 2501 is .) Most problems with it are due to Science Marches On, or (more frequently) political changes unrelated to the technology. The author is apparently a retired science teacher.
 * Man-Machine Interface adds Psychic Powers to Shirow's Post Cyber Punk universe. His opinion is that Science will March On, validating theories previously discarded.


 * Neal Stephenson's Cryptonomicon and The Baroque Cycle. They'd be straight-up historical fiction if not for the Solomonic Gold.


 * Robert J. Sawyer's Calculating God is grounded firmly in reality, for a given measure of reality. The importance of the scientific method is emphasized throughout the novel; characters highlight inaccurate science in Star Trek; the aliens have suitably unusual physiology; a few alien civilizations have space travel, but humans do not (and most of the novel takes place on Earth anyway). In short, it's a rare example of Aliens Speaking English being the only impossible trope rather than one of multiple impossible tropes.


 * Ingrid's space colony in Starstuff is portrayed very realistically, and the show tries hard and generally succeeds in being genuinely educational. The weird natural fluke that allows Chris and Ingrid's computers to communicate over a distance of thirty years, however, is pure Negative Space Wedgie.


 * Otherland mostly belongs here, as most of it is based in plausible theoretical developments. The origin of the Other's psychic powers and the elements, however, are somewhat implausible.

I Want My Jetpack
Real Life plus Space Travel. The only objective way to grade these is by their age: newer generally means harder. Zeerust hits hard here - one can always tell when Science and/or Tech Marches On. Arguments as to why we do not have space travel do not belong on this wiki, but EVERYONE agrees that its lack is part of the reason We Suck.


 * The movie Destination Moon; written by Robert A. Heinlein with assistance from that worthy's many, many friends in the United States Armed Forces.
 * The Moon Is a Harsh Mistress: Minus Mike itself, pretty much everything is already around, or could easily be put together in the next half-century (the book is set in 2075-2076). The only fly in jam here is that we had a moonbase for a minimum of thousands by the 90s.
 * Most of Heinlein's work could fit here, at least among his juveniles. His rocket ships tended to be chemically powered and fly in realistic trajectories. His later work tended to be more speculative.


 * The Tintin stories Recap and Explorers On The Moon. The print medium enables Hergé to better display the colossal engineering needed to develop interplanetary spaceflight. Though science has marched on considerably since it was written, at the time it was practically a student's primer on both nuclear energy and spaceflight.


 * 2001: A Space Odyssey: Unusually among films and TV series with space travel, the vacuum of space is actually silent. Oddly enough, this is one of the few cases where the book is softer than the movie, due to going further into the details. The iconic monolith is ill-defined, but never really breaks any physical laws. Unscientific elements tend to be part of a Mind Screw.
 * One difference between the film and novel is that the novel explicitly contains an instance of, while the equivalent point in the movie is kept vague. The events shown could instead be interpreted as a metaphorical, psychological journey, for instance - nothing is shown or stated to make it clear one way or the other. Since the book and film were created at the same time and differ on a number of other points, the book's more explicit explanation need not take priority. Clarke's later sequels to the 2001 novel also eventually ret conned the   away.
 * In the sequel novel (2010: Odyssey Two) and movie (Two Thousand Ten the Year We Make Contact), Jupiter . When one of the characters starts to complain about the scientific problems with this, another one tells them to shut up; obviously it can happen because it is happening, and the scientists will have plenty of time to think up an explanation for it later.


 * Star Cops: Very hard in its late '80s way.


 * Space Odyssey: Voyage to The Planets: Set an indeterminate number of decades in the future, this docufiction tells the story of a manned mission to Venus, Mars, Jupiter, Saturn and Pluto. Contains some (relatively mild) examples of Space Does Not Work That Way, though. Will most likely be highly vulnerable to Science Marches On in the near future.


 * Moon: Minus the Space Is Noisy and  it was so spot on, NASA personnel who screen tested the film just to see how close they got it were pretty impressed. The best explanation is when one of them asked the Director, "Why does the base look like a bunker?", he replied that he figured that it would just be easier (and cheaper) to transpose stuff that already existed onto the moon -- and then another in the group stated that she's in fact working on just that.


 * Planetes: Commercial spaceflight less than a century in the future and almost completely limited to the Earth Sphere itself. Detailed orbital mechanics, realistic effects of space on health, dependency theory, diapers under spacesuits, and invisible laser beams. Even the gratuitous In Space Everyone Can See Your Face is justified as mere thematic close-ups on the characters' faces -- with their faceplates down. Its premise -- the collection of space garbage to prevent multimillion-dollar spacecraft from being scrapped by screws -- is a Real Life problem but economically unfeasible(nowadays we Just Ignore It - military satellites are fitted with maneuvering thrusters to dodge but nobody cleans it up), but this is actually a major plot point -- though the job is essential to actual commercial space travel, the fact that nobody can find a way to make money off it means they ignored it right up until the accident that killed Yuri's wife. Then the Debris Sections were formed in response to public outcry -- and staffed by underpaid office drones with gear older than they are.
 * Even the Tandem Mirror drive is named after/based on a real magnetic confinement fusion technique, which has been noted to be uniquely suited to application as a space drive.


 * Orbiter is essentially Planetes meets Microsoft Flight Simulator. It's awesome, though not without a steep learning curve. Its creators have really Shown Their Work, most Tropes in Space clichés are averted and the science and spaceflight principles involved are as hard as humanly possible for a layman-accesible spaceflight sim. GameMods taking place in an established fictional setting (e.g. Star Trek) are generally a bit softer than the rest of the scenarios, but they still remain very realistic (often even more than their source material).
 * The creator, Martin Schweiger, is a physics professor who originally started building it to let his Orbital Mechanics students get more hands-on with the concepts, so it's no surprise that the science is solid.
 * The only real implausibility in the sim is the absurdly high energy density of several of the crafts' fuel (the signature Delta Glider in particular). But given that the learning curve required to pilot the realistically modeled Space Shuttle is challenging even for otherwise experienced Orbiter pilots, this is readily excused for the sake of making the game accessible.


 * Moonlight Mile: Planetes with raunchy sex. Twenty Minutes Into the Future, Helium 3 fusion has become viable; the Space Race has begun anew. What Do You Mean It's Not Political??
 * Slight clarification for anyone looking this up on Netflix: It's the Anime, not the romantic drama with the same name that stars Susan Sarandon.


 * Rocket Girls: Moonlight Mile without raunchy sex, fusion or power politics. Present Day; the first private company to conduct satellite maintenance has hit a snag - their only viably stable rocket design is underpowered and their only astronaut has freaked out as he was ordered to get to around 90 pounds. Solution? Find new astronauts... lighter astronauts... The only improbable thing is getting high school girls to be astronauts. And fully functional skintight spacesuits, though these ones will shortly replace those big bulky spacesuits from nowadays.


 * The Diamond Age by Neal Stephenson is pretty hard... though nanotech is commonplace, it does not magically bypass the laws of thermodynamics and as AI appears to be impossible, does not trigger The Singularity. It could be argued that this belongs in Next Sunday AD, depending on your views on nanotech... and its depiction in this novel is particularly 'hard', outlining the need for a supply of many refined raw materials and power in order to function.

Next Sunday AD
Exactly What It Says on the Tin. Just like now, but some interesting techologies are more effective and/or more accessible. This may or may not be a good thing.
 * Metal Gear generally hangs around the soft end of this area. No space exploration beyond what was actually done in real life, some flawed genetic experimentation, walking robots with rigidly-defined physical properties, Powered Armor, VR training and registered weapons. The supernatural elements soften it a lot, though (even though psychic powers supposedly work on a physical basis and mindreading can be blocked by 'surgical implants', that doesn't explain why one of the bosses is a ghost), and then there's the absolute not-even-trying factor of the way Nanomachines are handled in Metal Gear Solid 4. There's also a few references to aliens, although only on an Easter Egg level (Otacon believes in alien visitations to Earth; Colonel Campbell, Major Zero and Gary McGolden have all had alien abduction episodes.
 * However, as noted, there are several elements that are never explained by any sort of technology, and many people within the fanbase will freely admit that they make no sense. Such examples include: a man with the inexplicable ability to manipulate and create massive amounts (10 million volts to be exact) electricity within his body, a man who can photosynthesize, a man who can telepathically control bees (or is it hornets?), two genuine psychics, and a medium capable of manipulating and interacting with the spirits of the dead (while himself having been dead for several years). Oddly, in the second and fourth game, a man who can walk on water, and due to healing abilities, is seemingly immortal, and enjoys drinking blood is treated as an absolute absurdity, despite being the only instance of superhuman powers that is not genuine.
 * This is because Vamp is a dick, and no-one wants him to be as awesome as he should be.


 * First Encounter Assault Recon: Despite the supernatural elements, most of the actual sci-fi technology is plausible tech that may be developed in a few decades (i.e, Mini-Mecha powered armor, lasers, semi-intelligent robotic drones, particle beams, optical camouflage, etc) though it does involve some tech that is a little softer.


 * GI Joe: The Rise Of Cobra: Powered Armor, active camouflage, Nanomachines with rigidly defined capabilities... not half bad for a Merchandise-Driven movie by the director of The Mummy Trilogy.


 * Dennou Coil: Cyberspace via Goggles That Do Something Unusual. As with 2001, the more unscientific elements are part of a Mind Screw.


 * Snow Crash: Real life with a few cooler technologies, some of which have come into existence since it was written (Second Life and Google Earth were first conceived in Snow Crash). Introduced The Metaverse, the most realistic treatment of Cyberspace at the time. Though treatment of memetics and neuroprogramming is a bit far fetched.


 * The Boys From Brazil: An in depth and thought provoking mediation on the ethics of cloning... Hitler. Averts the more absurd Cloning Tropes.


 * Heavy Rain: The entire setting of the game is actually not much different to Real life with the exception of FBI Agent Norman Jayden's ARI, which is best described as a virtual reality sunglasses. It is used for various things from games to detective work.


 * Eleventh Hour: Regenesis with an Omnidisciplinary Scientist. Thus making it a touch softer.


 * Regenesis: Set in the present, showcases bleeding edge biotechnology for its science fiction aspects (most of the technology featured are real or in the "possible but impractical/expensive/unethical development stage)". Sometimes it's less science-fictiony than CSI.

Hardest

 * Real Life: A Shared Universe which spawned its own genre, known as "Nonfiction". Real Life has spawned much imitation, and comes close to the hardest end of the scale, but Reality Is Unrealistic.