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->"''I consider the Laws of Thermodynamics a loose guideline at best!''"
-->-- '''Vaarsuvius''', ''Webcomic/TheOrderOfTheStick: On the Origin of [=PCs=]''

Most of us with a basic knowledge of physics know that [[EquivalentExchange Mass-Energy in equals Mass-Energy out]]. Whenever work is done on an object, energy has to come from somewhere. When you lift your fingers to type, energy from a chemical reaction is used to do it. Which raises the question, when [[AWizardDidIt a wizard does it]], where does that energy come from?

In SpeculativeFiction, the Law of Conservation of Energy is disregarded more often than it is honoured. Whether it's magic or psychic powers, people can perform superhuman feats while the question of where the energy comes from to do them is never answered. Things can be set on fire, lifted with the power of the mind, crushed, or altered without an apparent energy source.

Sometimes it is explained by having a character get all that energy from being a BigEater and/or HeavySleeper. Which in itself can be an example of ArtisticLicenseBiology.

This can also work in reverse with energy apparently being destroyed. Actions that should release a huge amount of energy, particularly energy in the form of heat, don't.

The Law of Conservation of Mass is similarly ignored, particularly when involving powers that create something from apparently nothing or where shapeshifting is involved.

This can lead to weird results when you start JustForFun/AbusingTheKardashevScaleForFunAndProfit.

It is generally more common in {{Fantasy}} settings, especially with ArtisticLicensePhysics, although some authors will try to explain where the power for magic comes from anyway. Some authors try to maintain conservation by invoking a law of EquivalentExchange.

[[TropesAreTools Of course, it could be argued that any use of energy which is unequivocally already supernatural to begin with,]] [[JustifiedTrope just by definition doesn't necessarily have to follow physical laws anyway.]]

Minor sidebar for Science Fiction authors who ''want'' to violate conservation of energy: You'll want to look up [[http://en.wikipedia.org/wiki/Noether%27s_theorem Noether's Theorem]], which says that for every differentiable symmetry of the action of a physical theory there is a corresponding conserved quantity. This basically means that if energy is not conserved, then the laws of physics must be changing over time. See also Wikipedia's further coverage as this applies to conservation of energy [[http://en.wikipedia.org/wiki/Conservation_of_energy#Noether.27s_theorem here]].

PerpetualMotionMachine is a subtrope of this. See also ShapeshifterBaggage, ElementalBaggage, ArtMajorPhysics. This trope is often implied among certain RequiredSecondaryPowers. It is seldom recognized that TimeTravel involves the violation of conservation of mass and energy, in that matter disappears at one time and reappears ([[TimeTravelTenseTrouble loosely speaking]]) at another time.



[[folder:Anime and Manga]]
* Titans produce a large amount of body heat in ''Manga/AttackOnTitan'', yet they will only eat humans, who haven't been available to eat in large numbers for nearly 100 years. It's implied that because of their lack of digestive systems, they eat humans just because they're tasty. If the observations about them slowing down when they're deprived of light is any indication, their bodies act like solar panels to absorb and use energy.
** [[spoiler:It's unexplained where the mass/energy comes from to generate a Titan body by the Shifters. For what it's worth the body mass does seem to release a high amount of heat as energy when the human leaves it and it begins to disintegrate.]]
* ''Anime/DragonBallZ'':
** These people can destroy PLANETS. They can casually shoot beams from their hands that level mountains. Aside from a somewhat [[BigEater large appetite]] (and only in the case of the Saiyans), this is never explained.
** Beerus in ''Dragonball Super'' goes one further: he has the ability to "nullify" energy, completely erasing it from existence. Good thing too: [[spoiler:that energy burst he and Goku created during their battle was potentially powerful enough to annihilate multiple stars whether or not Goku had managed to block it (which he didn't).]] Of course, Beerus ''is'' the God of Destruction, and he has that title for a reason.
* In ''Anime/TengenToppaGurrenLagann'', it's a key plot point that Spiral Power does not conserve matter or energy. [[spoiler:Overuse of Spiral Power is projected to eventually cause the creation of the "Spiral Nemesis", a supermassive black hole large enough to destroy the entire universe.]]
* ''Manga/{{Naruto}}'': About the same reasons as ''Dragonball'', including the "Chakra system" that basically increases as a shinobi trains and matures. Subverted with the titular character, because most of his techniques are impossible for the characters WITHOUT demons nesting inside of their souls.
* Averted in ''Manga/FullmetalAlchemist'', where EquivalentExchange is the central dogma of alchemy, and where that extra bit of energy needed to [[MatterReplicator reassemble matter]] is always [[MinovskyPhysics fully explained]]. You'll get a different answer depending on whether it's alchemy from Amestris or alkahestry from Xing, but basically the power comes from geothermal energy and tectonic activity. However, Father had created a barrier of souls underneath Central, which allowed him to suppress alchemy within his lair.
** In the [[Anime/FullmetalAlchemist 2003 anime version]], because [[OvertookTheManga alchemy's origins hadn't yet been explained in the manga when it was made]], the power instead comes from an extra-dimensional energy source consisting of [[spoiler:''[[LifeEnergy the souls of the dead]]'', more specifically, the dead of ''our'' world; recent advances in medicine, agriculture and ''warfare'' have provided enough deaths for Amestris to develop alchemy]]. Alchemists are normally bound by Newton's laws, but they can start AbusingTheKardashevScaleForFunAndProfit if they [[spoiler:provide souls from their own world; as in ''commit a few genocides to create Philosopher's Stones'', like those convenient '''[[FantasyCounterpartCulture Ishballans]]''' [[TheWarOnTerror on the eastern border]]..]].
* In ''Manga/ZettaiKarenChildren'', the PsychicPowers are explicitly stated to violate the conservation of energy and not bound by normal physics therefore allow the protagonists to ScrewDestiny.
* ''Manga/OnePiece'' has examples of disregarding this law (Zoan-type and Logia-type Devil's Fruit Users) and flimsy explanations (Big Eaters to gain all the energy they need).
** And also in the One Piece world exist some magical shells called Dials, one of them, the Reject Dial not only has the property of absorbing kinetic energy and then release it, but also release ten times the kinetic energy that was absorbed.
* Touma from ''LightNovel/ACertainMagicalIndex'' presents an interesting case in that his right hand is stated to have the power of [[AntiMagic nullifying magic and esper powers]]. However, he can effortlessly block the punch from a golem made of solid rock that stands a good thirty feet tall, which would entail nullifying the inertia of several tons of rock moving at high speed. Then again, given that something thirty feet tall and made of solid rock shouldn't be able to move under its own power in the first place, it could be argued that he's actually ''[[InvertedTrope enforcing]]'' the laws of physics by getting rid of kinetic energy that should never have existed in the first place.
** Completely played straight by Accelerator's powers, which somehow allow him to not only redirect force vectors, but also manipulate them in such a way that they can be instantly reversed and magnified. It also somehow allows him to create a ball of plasma using nothing but wind.
** Then there's the matter of teleportation abilities, shared by at least two [=ESPers=] in the series. The way in which inertia is treated is somewhat inconsistent, with the teleportation effect either eliminating it entirely or somehow redirecting its vector after repositioning.
** A minor case may occur with Uiharu's ability to stabilize the temperature of one object against its environment, although its actual level of effectiveness (if it could completely eliminate any changes in temperature) is not clarified.
** One bank robber had a power called "Equal Speed", which essentially allows him to make moving objects retain their inertia, even when smashing through a storefront barrier. Logically speaking, the destruction of said barrier should have involved a transfer of kinetic force from the moving object into the barrier.
* ''Anime/CodeGeass'' has their own version of a nuke known as the F.L.E.I.J.A (pronounced [[Myth/NorseMythology "Freya"]] [[JapaneseRanguage because the Japanese can get away with that sort of thing]]). Instead of releasing a fast amount of energy, the Freya creates an [[SphereOfDestruction expanding energy field]], which after a few seconds implodes and leaves only a void. It has never been explained what happened to all the matter that suddenly disappeared into thin air.
* ''Manga/RanmaOneHalf'', being a SupernaturalMartialArts {{Shonen}} series, is [[{{Pun}} naturally]] rife with this, but a very special mention goes to the final enemy in the series, ThePhoenix King Saffron:
** He can throw blasts of flame so powerful they not only singe ''rock'', they cause superheated air to rush outwards with enough force to ''punch down walls'' of said rock in an instant. One sweep of [[WingedHumanoid his wings]] created a pillar of flame powerful enough to destroy the entire top half of a hollowed-out mountain. Try to collapse a cave using a flamethrower, we'll wait.
** He can [[HealingFactor regenerate any injury]], [[GoodThingYouCanHeal no matter how serious]], due to being a phoenix that creates its own flame. Where the mass comes from, or how he creates that regenerating flame in the first place, is a mystery.
** His mere BattleAura is hot enough to ''melt rock into lava'' and form a SphereOfPower of blinding white light around him.
** He can release heat beams several dozen meters wide strong enough to ''vaporize'' entire ''rows'' of mountains. ''Vaporize''. And do this with zero preparation (except to [[CallingYourAttacks strike a pose and call out the attack]].) And then do it AGAIN immediately afterwards, pausing only to realize the first blast didn't take, with ''no'' recovery time.
** And last but not least: the incarnation of Saffron that Ranma et al encountered in the series is merely an immature brat who was in a very bad mood. The immortal Phoenix King's ''true'' role is to simply [[OrcusOnHisThrone sit tight on his perch]] and [[MundaneUtility provide endless ambient heat and light for all his subjects so they're comfortable]]. He's not even once shown to have a big appetite or something. He just generates infinite amounts of heat because he ''does''.
* In ''Anime/PuellaMagiMadokaMagica'', the WeaselMascot specifically mentions that magic defies the laws of thermodynamics. [[spoiler: This is very important to him, as he's harvesting the magic power generated by Magical Girls mutating into reality-warping {{Eldritch Abomination}}s in order to stave off the heat death of the universe, even though he does not understand why this energy can violate thermodynamics in the first place.]]

[[folder:Comic Books]]
* This is so standard for super powers it almost goes unnoticed. Nearly every SuperHero and SuperVillain with powers produces far more energy than their body contains. Occasionally you'll see a HandWave like ComicBook/{{Cyclops}}' or Franchise/{{Superman}}'s "solar power" or Havok of the Comicbook/XMen's "powered by cosmic rays", although if you do the math on their demonstrated energy usage, it doesn't really add up. It also means that with so much potential energy stored in their bodies, every time they get their powers [[PowerNullifier neutralized]], they should explode like atomic bombs.
** In ''ComicBook/UltimateFantasticFour'', Ellis ''tries'' to avoid this; he still has Reed "eating" air. Invisible Woman's explanation consists of a LampshadeHanging, and Ben's power goes unmentioned. The Human Torch's bio-fusion is highly implausible but at least gives a HollywoodScience HandWave to his energy source. Every other book in ComicBook/UltimateMarvel, well, decidedly less so.
** Several novels and AlternateContinuity series (and occasional {{canon}} theories) have proposed that many or most supers draw energy from AnotherDimension. As with most canon elements these days, whether or not this is given any weight varies DependingOnTheWriter.
** Some fans have theorized that Superman's gut is actually a thermonuclear reactor, or even a matter-to-energy converter, that squeezes every last megaton of available energy out of the food he eats. (This would explain why he [[NobodyPoops never goes to the bathroom]]...)
* In ''Comicbook/IronMan'', the arc reactor in Tony Stark's suit is generating a surplus of energy. In earlier stories, the energy powering the suit is being amplified by transistors. Transistors are not that impressive, as far as electrical components go, unless Stark designed ''super'' transistors.
* Several mass-changing characters actually need to absorb mass from outside themselves; Stronghold of Creator/ValiantComics, a ''WesternAnimation/StaticShock'' villain, etc. Most just "get heavier".
* Of the [[Franchise/JusticeLeagueOfAmerica Justice League's]] "Big Seven", only Franchise/{{Superman}} and ComicBook/MartianManhunter still run afoul of this trope. Franchise/WonderWoman, Franchise/TheFlash, and Franchise/GreenLantern are all explicitly powered by Phlebotinum or magic. Comicbook/{{Aquaman}} is pushing it with his ability to swim at 100 miles per hour.
* Done in ''ComicBook/SteelgripStarkeyAndTheAllPurposePowerTool''. The tool is driven by "technalchemy", which allows it to run with no visible power source, synthesize new components and materials out of thin air, and is apparently indestructible. [[spoiler:Justified as it's implied that technalchemy is a form of magic.]]
* Averted in ''ComicBook/RisingStars''. The Specials have a finite energy source, which means that as they use their powers, they gradually get weaker as this energy is used up. Furthermore, when a Special dies, his/her energy doesn't disappear, but is instead transferred to the surviving Specials, making their powers stronger. The relevant laws of physics are mentioned by name and used to explain this.

[[folder: Fan Works]]
* Magic and {{ps|ychicPowers}}ionics in ''Fanfic/WithStringsAttached'' are said to be powered by the universe's Field of magic, which the user taps into and shapes. Although one unversed in magic will not feel the Field around them, Paul discovers after he learns to cast spells that he is now aware of the ebb and flow of raw magic around him.
** Jeft implies that magic and energy are related when he mentions that to keep Paul's strength from overwhelming him, much of it is transformed into raw magic and returned to the Field before it leaves his skin.

* In the remake of ''Film/TheDayTheEarthStoodStill2008'', the heat energy from the spacecraft rapidly decelerating should have turned the UN and the surrounding landscape to molten slag.
* Between the mothership, the ship reactors, and...well, everything... [[BellisariosMaxim don't think about]] where all the energy comes from or goes in ''Film/IndependenceDay''.
* Parodied in ''Film/GalaxyQuest'', when the crew has to land on a hostile planet to retrieve a "Beryllium Sphere", because it supposedly powers the ship, for reasons completely unexplained and unknown, except that it happened on the TV show. This is a direct parody of the Dilithium Crystal that somehow makes warp drive possible in ''Franchise/StarTrek''. It is there to "mediate" the matter-{{antimatter}} reaction and create a pair of tuned plasma streamers. This is only explained that way in official material ''outside'' of the show, which makes this AllThereInTheManual.
* In the 2009 ''Film/StarTrek'' movie, Spock uses a drop of "red matter" to collapse a supernova into a NegativeSpaceWedgie via some sort of chemical reaction. The wedgie seems to work like a [[UnrealisticBlackHole Hollywood black hole]], sucking up the entire supernova--and Spock's ship--with a lot of mass that appeared out of nowhere. [[WildMassGuessing Even if this isn't technically how it works]], there's no obvious way to explain how a tiny blob of goo reversed the momentum of an ''exploding star''. These little goo-blobs are also capable of making entire planets collapse in on themselves into Wedgies which seem to have much more mass than the planet did. And it's not just that the blobs are extremely dense; Spock has about a million times the supernova-erasing dose in his ship, and he can easily carry a canister of the stuff by hand.
* In ''Film/HoneyIShrunkTheKids,'' the principle behind the shrink ray is explained thus: atoms and molecules are made up largely of empty space between the subatomic particles.[[note]]This is true; the distance from the nucleus of an atom to its electron cloud is on par with the distance from the Sun to Pluto, relative to its size[[/note]] The ray shrinks an object by reducing this empty space. However, this should mean that a shrunk object retains its mass. Ergo, the shrunk children should be just as heavy and ''just as strong'' as they were at full-size. There should be no plot, because there's no way they could get swept up in the garbage by accident, and they should have the strength to jump up and activate the machine themselves - assuming their incredible density didn't make them fall straight through the floor.
* In ''Film/CaptainAmericaTheFirstAvenger'' a 95 pound Steve Rogers is injected with 6 vials of Erskine's serum and a few minutes later emerges from the Vita-Ray infusion device as the 230 pound Captain America. Everyone who handles one of the serum vials acts like they only weigh a pound or so, so where did the other 130 pounds that Steve so rapidly put on come from?

* In the ''Literature/HarryPotter'' universe, the answer to the riddle about where vanished objects go is that they merge with the rest of the universe. This implies that they don't create matter when they conjure items, either. Wizards just steal matter from their surroundings, reorganize it into the shape they want, then return it when they are done.
** Played straight with broomsticks, however. They fly as high as you like, but they never seem to need fuel, except maybe [[AWizardDidIt the wizard's magic]]?
*** Since the wizarding community doesn't believe anybody can reach the moon (not only did they not do it first, they think space travel is impossible), and they've got spells to handle the environmental problems, there probably ''is'' a limiting factor. Or some ambient planetary field all magic is powered by.
*** There is some limiting factor: it's mentioned in passing in Quidditch Through the Ages that some models of brooms became difficult to control or otherwise erratic at high altitudes.
*** Actually, I don't think they do have spells to handle the environmental problems. The Bubble-Head Charm may act more like a filter/compressor/gill than an oxygen tank, extracting oxygen from the environment rather than generating it. If there's no oxygen, it won't work. And there's no evidence Shield Charms prevent gas transfer, meaning you couldn't go into vacuum.
** Also played straight with Freezing Charms.
* Averted in Creator/AnneMcCaffrey's Talent 'verse (''Literature/ToRidePegasus'' trilogy and ''Literature/TowerAndTheHive'' series), which explains that the power necessary for the telekinetics to hurl spaceships around like toys comes from ''massive'' generators. Psychic activity (with or without a generator gestalt) also burns ''a lot'' of calories, meaning that, while a telekinetic with no generator handy can get the job done quicker, he's still doing the same amount of work as someone doing it by hand. Many of the telekinetics are shown eating some pretty high-calorie meals and snacks throughout the day to keep their strength up, and get extremely fatigued after teleporting very large objects (even with the generators helping). Also, it's stated that energy must be '''absorbed''' when negative work is done (for instance, teleporting an object from orbit down to ground level), although simply being the conduit for such large amounts of energy can still place enormous stress on physical systems.
* Averted in ''Literature/TheShipWhoWon''. A brainship finds a world where magic actually works, complete with all the standard no conservation of energy tropes. Then they discover that [[spoiler:there's actually a huge generator complex powering all this, which the magicians have completely wrecked by using it for stupid things like fireballs and levitation]].
* Averted in Robert Asprin's ''Literature/MythAdventures'' book series: magic is fueled by {{ley line}}s crisscrossing the worlds, and you have to be tapped into those forces to be an effectively powerful wizard.
* It's often hard to reconcile stories that involve {{shapeshifting}} with the related law of conservation of mass. In one of his ''Literature/FafhrdAndTheGrayMouser'' books Creator/FritzLeiber makes an exception by having a character who's shrunk needing to find a few zillion spare atoms if he wants to get back to normal size. [[spoiler:In the end he gets them from a fat girl, who suddenly finds herself skinny. Eww.]]
* Creator/IsaacAsimov's ''Literature/TheGodsThemselves''. The trope is subverted because the law of conservation of energy is upheld when a device which appears to obtain energy out of nothing actually gains it by taking advantage in the differences in physical laws between two universes (at the loss of 20 electrons in our universe and the gain of 20 electrons in the other universe, as well as positron radiation). The obvious thermodynamic implications apply -- [[spoiler:the energy transfer between the two universes is bringing their physical laws into equilibrium, which will eventually destroy all life in both of them. The aliens are aware of this and want to exploit it only until our sun explodes so they have free energy for generations]].
* Subverted in Literature/LarryNiven's ''Literature/TheMagicGoesAway'' fiction. All magic is fueled by mana, a natural non-renewable resource. The setting is a '[[TheTimeOfMyths lost age]]' of high magic on the decline, as the last of the world's magic is expended, leaving behind the mundane world we live in.
* {{Hand wave}}d in David Eddings's ''Literature/TheBelgariad'' series. Belgarath explains that nothing can truly be destroyed (it just changes energy forms), and trying to 'unmake' something will end up with some [[YourHeadAsplode unfortunate consequences]].
** Also played totally straight in that they seem to be able to create whatever they want, with no requirement to take energy/mass from anywhere for it.
** In the books, it is explained that creating things works off your own creative energies, which is why it's much more exhausting to make a door than to blow it to pieces. Also, the inability to destroy things doesn't come from the conservation of energy, but from the universe itself - which is, apparently, alive and says "No you don't!" to attempts at unmaking, something it doesn't even allow the gods to do. Long story short: It's magic, it plain doesn't ''work'' by the laws of physics (and the books certainly don't try to pretend that it does).
*** On the other hand, it does. Turning a stone around takes less effort and energy if you simply get it rolling by pushing at the top than it does if you lift it up, turn it around and then drop it upside down, which leaves you both incredibly tired and ''pushed down into the ground by the opposite reaction of its weight'' if you don't brace yourself. Moving air gradually takes less energy than moving it all into a storm-strong wind in an instant and even then it's taxing enough to leave the very experienced person who does it passed out from exhaustion. Creating something new usually involves taking something that's similar in some way (like the type of matter or the right shape) and changing that (and still takes a great deal of effort) and unless you've got about several thousand years of practice or a handy near inexhaustible supply of power in the form of an orb most things are very taxing. Though the Malloreon tends more towards this trope.
* The ''Literature/{{Animorphs}}'' books [[HandWave address]] this - when they shrink down to cockroach size, their extra mass is shifted into Z-Space, the same dimension that FTL starships travel in. Likewise, when they morph into something larger than themselves, the extra mass comes from the same place. What merits complaining about there is stuff like 'How are portals into Z-space opened,' 'Where does ''that'' energy come from,' etc.
* Creator/TerryPratchett's ''Literature/{{Discworld}}'' novels try to at least give this a nod. Teleportation's pretty risky too, especially with the knowledge that even if you're sitting on a chair you're still really moving somehow.
-->'''Ponder:''' Er -- It's not as simple as that.
-->'''Ridcully:''' Why not? Bring him back by magic. We sent him there, we can bring him back.
-->'''Ponder:''' Er... it'd take months to set it up properly, if you want to get him back right here. If we get it wrong he'll end up arriving in a circle fifty feet wide.
-->'''Ridcully:''' That's not a problem is it? If we keep out he can land anywhere.
-->'''Ponder:''' I don't think you understand, sir. The signal to noise ratio of any thaumic transfer over an uncertain distance, coupled with the Disc's own spin, will almost certainly result in a practical averaging of the arriving subject over an area of a couple of thousand square feet at least, sir.
-->'''Ridcully:''' Say again.
-->'''Ponder:''' I mean he'll end up arriving '''as''' a circle. Fifty feet wide.
** Salacia, a vampire in ''Discworld/{{Thud}}'', has issues with this when she turns into a bat. She has to settle for turning into many bats. Which are a pain to get back together...
** ''Literature/{{Discworld}}'' magic also obeys the conservation of momentum (except for {{flying broomstick}}s). If a wizard wants to hurl himself from the ground to the top of a tower, he has to cause a stone with an identical weight to his to fall from the top of the tower and magically link his ascent to the stone's descent.
*** Magic carpets are also exempt, although this may be because they use magic in a different way (in 'Weird Sisters' Magrat's broomstick is shown to lose its capacity to fly if it loses too much magic, and in Equal Rites, Granny's broomstick doesn't work in sunlight, although this is later solved).
** Telekinesis also gets a brief mention when it is pointed out that when you try and lever an object using your own mind as a fulcrum, the most likely outcome is that your brain gets forced out of your ears. Much training in the psychic equivalent of a gym is required.
** While the Discworld novels are reasonably respectful of conservation of energy (as much as one can be while satisfying the demands of [[TheoryOfNarrativeCausality Narrative Causality]] and RuleOfFunny) they often play fast and loose with ''entropy''. A lot of [[Discworld/IShallWearMidnight Tiffany Aching's]] practical magic, in particular, involves moving heat from one place to another. It's never really clear whether the net heat of the system increases, as it must in real-life refrigeration.
* ''Literature/WildCards'' shapeshifters often have a HandWave of "virtual particles", basically acting in ways that in no way resemble the virtual particles of real-world physics.
* Creator/AlastairReynolds ''Literature/{{Revelation Space|Series}}'' novels feature two examples - the Conjoiner engines, space drives with a more-or-less unlimited energy source used by lighthuggers to get around, and Cryo-Arithmetic computers used to siphon heat out of the universe. The former is subverted in ''Redemption Ark'' when it is revealed that [[spoiler:the engines are powered by a miniature wormhole that opens into the Big Bang, as, even though trying FTL travel is a CosmicHorror in its own right, ''time travel'' is just practical enough to work]].
** [[spoiler:Relativity allows for all sorts of crazy things to exist, including wormholes that join different regions in time and space (FTL travel implies time travel). Having stuff travel into the future seems positively safe compared to inertialess FTL drive system, seeing as it doesn't even cause any paradoxes.]]
* In ''Literature/TheDragonAndTheGeorge'', the trope is either slightly inverted or subverted. Speaking on the subject of the power available to mages, the wizard Carolinus irritatedly says (paraphrased), "Just because a number's infinite doesn't mean you can use it to get something for nothing." (This may be true in this universe, as he's apparently referring to Cantor's hierarchy of infinities, and spells may require infinite expenditures.) As with the ''Literature/YoungWizards'' series above, later books note in the background the development of ways to tap new sources of power, some of which probably provide infinite energy, but which still avert the trope.
* Creator/DanBrown's ''Literature/AngelsAndDemons'' is based around the female protagonist/her dead father pumping vast quantities of energy into the LHC to form {{antimatter}}, which they can then annihilate with normal matter to provide 'clean, sustainable energy for all' (instead of the bomb it inevitably becomes). It somehow never occurs to either of these highly trained scientists that they would have to put more in energy to create the antimatter than they could ever get out (though note that even in-universe, characters seem awed by the quantities they made; it might be safe to assume they found a way past or around this problem).
* Lampshaded in ''Literature/{{Firestarter}}''. After a government experiment in which Charlie [=McGee=] vaporizes a cinderblock wall with her pyrokinetic powers, the next chapter is an Interdepartmental Memo in which one of the evil government scientists points out to the head evil government scientist that, despite producing 30,000 degrees of spot heat, the nine-year-old girl in question burned about as many calories as if she were reading a good book--leading the seriously weirded-out scientist to wonder just where the hell the energy is coming from (and to start thinking about stuff like black holes and things we breathe a sigh of relief that we can only observe from millions of light-years away and pretty much wondering if this little girl is some kind of rift in the very fabric of the Universe).
* ''Literature/{{Carrie}}'' at least mentions energy. When Carrie is exercising her telekinetic abilities, it is stated that her body is burning a ''lot'' of energy, which seems to be going nowhere.
* Creator/AlanDeanFoster[='=]s ''Literature/HumanxCommonwealth'' series has a brain-bending use of this trope in its mechanism for FTLTravel, which involves generating a small black hole in front of your ship and letting it "pull" you along until it evaporates, at which point you generate a new black hole, and so on. The first novel in which it's introduced even {{lampshade|Hanging}}s it by having the viewpoint character struggle with the concept.
* Moorcock's series ''The Dancers At The End Of Time'' averts it: one million years in the future the advanced technology of mankind has turned the remaining members of our species into undying {{Reality Warp|er}}ing {{Physical God}}s. Except that this technology cost so much energy that the Degenerate Era (an era that should occur 100 ''trillion'' years from now) has already began: in other words, by achieving godhood, mankind has divided by ''one hundred million'' the lifetime of the universe. [[spoiler:of course, since it happens in Moorcock's Multiverse, one man eventually realizes that with an infinity of universes, there is an endless pool of energy to draw from, which allows the dancers to flip one off at Thermodynamics by the end of the story.]]
* Averted in regards to conservation of mass in the ''{{Literature/Deverry}}'' novels. The mazrakir (shapeshifters) all change into an animal form the same size as their normal form. Nevyn pokes fun at the old 'sorcerers turning people into frogs' story by pointing out the stories never mention that the frogs would have to be big enough to ride.
** ''Any'' kind of dweomer working leaves the 'sorcerer' hungry. The bigger the working, the more ravenous the worker.
* Averted in Eric Nylund's ''A Signal Shattered'' where an alien merchant sells the people of Earth a teleportation device which works by borrowing a negligible amount of the Earth's rotation. Needless to say, widespread use of this "free" technology results in Earth's destruction. [[spoiler:Which was all part of the alien's plan, of course.]]
* Starships in the ''Literature/HonorHarrington'' universe use the Impeller Drive, which create gravity waves that the ship can "surf" on at over 500 G's acceleration. A starship requires far less energy from its fusion reactors to run its Impellers than the amount of kinetic energy it gains from that acceleration.
* Averted in ''Literature/TheDresdenFiles'', where magic "still has to do business with physics" so that energy can't come from nowhere. Generally energy is drawn from latent magical energy in the world, which is produced by life and emotions, though there are plenty of other sources, such as large leylines of raw energy (which should not be messed with unless one is a skilled wizard) {{Hellfire}} (from downbelow) [[WhiteMagic Soulfire]] (drawn from one's [[OurSoulsAreDifferent soul]]) or even from existing energy, like latent heat. The latter has been used multiple times by Harry Dresden to freeze things by ripping latent heat from his surroundings, like pulling the heat from a lake's water to freeze it, or pulling the heat from around a vampire to freeze it (and then throw that heat at another vampire to burn it to ashes). Even the {{Physical God}}s Mother Summer and Mother Winter state that conservation of energy must occur[[note]]They call Einstein a sage for realizing this[[/note]]. Not even they could obliterate a culmination of energy, like a Knight's mantle. This is key in the fourth book when a missing mantle was stolen and then [[spoiler:made inert by putting into a human who was TakenForGranite]]. It seemed like it was gone but wasn't truly.
* The titular character of ''Literature/TheChroniclesOfProfessorJackBaling'' wonders about this one, both as it applies to the perpetual motion machine created by his student and his own disintegrator ray. Using the latter in quick succession does end up blowing a fuse, but the amount of energy involved in powering the thing in the first place is staggering. He shouldn’t be able to get that much juice at once in the first place.
* Averted in the ''Literature/InheritanceCycle''. Doing something with magic takes the same amount of energy as doing it without magic, and characters get progressively more tired the more magic they cast. Apparently the character's physical (or mental, or magical) condition factors into how much magic s/he can cast before collapsing.
** Even in this case, there's a CriticalResearchFailure. When preparing to enter the Hadarac, Eragon, as an experiment, attempts to convert a small quantity of sand to water. In this universe, a spell cannot be aborted once started unless specifically phrased to allow that. The calculations based upon the packing fraction curve and determined that the energy required to turn 30 grams of sand (determined by the mention of a "thimblefull" of water as the final product) into water would require more than 300 times the daily intake of energy in a 3000-calorie diet (2000 per day is typical - it's increased here because of Eragon's strenuous lifestyle at the time). Even Saphira couldn't have provided that much energy. He should have died then and there.
* Similarly averted with some kinds of magic in Literature/{{The Kingkiller Chronicle}}s. Sympathy, a voodoo-like magic system, is completely about turning one kind of energy into another. There's inefficiency associated with poor links and distance. When introduced to that inefficiency, one character notes that the energy has to go or come from somewhere, and it turns out that's ''the Sympathist himself''. Played straight with Naming, more traditional magic, as well as the Fae.
* Averted in ''Literature/TheStormlightArchive'', but very little attention is drawn to it. When [[AlchemyIsMagic Soulcasters transmute something]], matter is conserved, even though differing densities can make it look like a lot more is being produced. Transmuting a cart-sized boulder to smoke results in enough smoke to fill a very large chamber, for example. In the second book (''Literature/WordsOfRadiance''), Adolin witnesses some of his father's Soulcasters creating a stone wall from thin air, and wonders why the air rushes ''towards'' the stone rather than away. This is because they are literally transmuting the air into stone, which obviously needs a lot of air.
* Averted in ''Literature/HereticsOfDune'': when Miles Teg unlocks the ability to move faster than the human eye can follow and think at super-human speeds (even by Mentat standards), he can only keep it up for a couple of minutes, and afterwards is ''starving''. He's shown eating multiple full-course meals after such stunts to replenish his strength, to the amazement of onlookers.

[[folder:Live-Action TV]]
* In ''Franchise/StarTrek'', while not involving FunctionalMagic or PsychicPowers in this case, whenever phasers vaporize people, rather than create explosions from that much matter losing cohesion, they just disappear. The in-canon explanation is that they ''don't'' vaporize, phasers convert matter into [[MinovskyPhysics undiscovered particles]] that dissipate into {{subspace|OrHyperspace}}.
** And there are the various shape shifting aliens that can go from something the size of a mouse, to a human and back. While this could be explained as simply increasing density rather than reducing mass, Dr. Bashir even notes Odo's ability to change mass in one episode of ''[[Series/StarTrekDeepSpaceNine Deep Space Nine]]'' (without even giving a theory as to how). Odo at one point had to ''reinforce his floor'' because some of his forms were too heavy for it to support.
*** {{Hand wave}}d at one point; Changelings like Odo are a kind of partial {{Energy Being|s}} whose form overlaps with normal space and subspace, allowing them to draw their mass into or out of normal space. They can also become FIRE and other energy forms with practice.
** Photon torpedoes have antimatter warheads and yet they seem to function more like big glowing cannon balls than anything else. In real life, matter/antimatter annihilation would result in a blinding flash of light along with a burst of gamma radiation and high-energy subatomic particles.
* {{Hand wave}}d at once on ''Series/BuffyTheVampireSlayer''. Most of the time, magic works like this. But once, Willow said something about rearranging elemental forces. Making a fire caused a rainstorm. Having said that, the jury is still out on whether said rainstorm was Willow goofing up, or Dracula.
* Zatguns on ''Series/StargateSG1'' had similar issues to ''Franchise/StarTrek'' phasers, until writers decided that was stupid and [[RetCon stopped using that feature]].
** Another prime offender in Stargate is Naquadah and its various sub-forms which can somehow turn a normal nuclear bomb into a continent buster among other insanity. [[{{Fanon}} Calculations by fans]] indicate it must have an energy density greater then antimatter, which is not physically possible.
*** The wormholes created by the titular Stargates are also impossible, but they're [[RuleOfCool cool enough]] that most people don't care.
---> '''Spellman, to Carter:''' It defies the laws of physics and you know it!
** Averted by [=ZPMs=] in ''SG-1'' and ''Series/StargateAtlantis'', as they draw energy from subspace, and so don't need to follow the conservation of energy law. And yet, this is the one form of AppliedPhlebotinum on the show for which running out of energy (after performing some truly amazing feat) ''is'' often portrayed as an issue.
* ''Series/{{Space 1999}}'':
** During its second season one of the main characters (Maya) constantly changed shape, size and mass without even a nod given to where the energy/mass had to come from/go to for this to work.
** Never mind the Moon itself getting ''thrown out of orbit'' by a 'mere' nuclear explosion too small to noticeably damage it in the first place and then somehow being able to conveniently move [[TravelingAtTheSpeedOfPlot at the speed of plot]] afterwards without having so much as a propulsion system to serve as an excuse.
* Almost averted in ''Series/{{Eureka}}'' when a decelerating spacecraft needed a high-energy "cushion" to slow it down. While the energy from the spacecraft was absorbed by the field, there's no mention of what the field did with the energy.
* In ''Series/AgentsOfSHIELD'' several scientists preform an experiment that creates matter by using a mystical book. Another scientist, with no knowledge of the book, starts going over the numbers and points out they somehow got out more energy (and matter) than they put in.

[[folder:Tabletop RPG]]
* ''TabletopGame/DungeonsAndDragons''. In the AD&D 1E Dungeon Master's Guide, Gary Gygax explained that the power of wizardly magic came from other dimensions, and the power of divine magic came from deities.
** In 3.5 it's explicitly stated that while you do need to follow conservation of energy, you can pull any extra heat you need, for example, from the elemental plane of fire. Which is infinitely large and all of it is fire. So the only real limits are how skilled you are at moving things around. Once you get into the plane of shadow, or the positive and negative energy planes, it gets weirder.
* Explicitly averted in ''TabletopGame/{{GURPS}}'''s default magic systems as of 4e. Mages use ambient mana to power spells (if there's not much mana they can seriously hurt themselves). Clerics channel power directly from a deity. Ironically psi powers, which are treated as more scientific, give no explanation for how they operate without outside energy.
* ''TabletopGame/TheFantasyTrip'' has magic being powered from the wizard's physical energy reserves. Effectively, casting spells tires out the wizard, similar to the way magic works in the Literature/InheritanceCycle.
* One of the example technologies available for [[SufficientlyAdvancedAlien T+ 4]] ships in ''Diaspora'' is the ability to dump heat into another dimension. This is important, as the game remembers that hard vacuum is an insulator.
* Averted in both ''TabletopGame/{{Warhammer 40000}}'' and WarhammerFantasy. In the former psykers harvest energy by summoning miniature gateways to the high-energy chaotic realm of the [[HyperspaceIsAScaryPlace Warp]] with attached risks of drawing [[EldritchAbomination daemons]] through with the power they use, in the latter wizards are able to draw upon the ambient Winds of Magic (which have chaotic and irregular power levels, no less) to fling spells.
* ''TabletopGame/{{BattleTech}}'' is rather guilty of this on closer examination. 'Mech and vehicle fusion engines are [[ArtisticLicenseNuclearPhysics basically magic]] in their ability to provide power for any number of energy weapons all day long with only lip service being paid to any refuelling needs (the limiting factor is always waste heat, never power or fuel reserves), and strategic fuel use for larger spacecraft throws conservation of energy out of the window altogether, allowing even two-million-ton battleships to cruise along at a steady acceleration of 1G at the cost of just under forty tons of hydrogen fuel for their in-system fusion torch drive ''per day''.

[[folder:Video Games]]
* Semi-averted in ''VideoGame/InFamous''. Cole's special powers use up stored electricity, which can only be recharged by absorbing more from some electrical source. On the other hand, his basic lightning attack doesn't use up any stored electricity. Also, the amount of electricity gained can be a little strange. For instance, you gain a surprisingly large amount of electricity by draining a person.
** Made worse when you consider that his basic lightning attack can be used so that it actually "generates" electricity! Though you do actually have to hit something that would give electricity if drained, so it may just be transferring that to you. It still begs the question of why Cole can't just use the energy to recharge his power meter.
** This is actually a plot point: [[spoiler:the Ray Sphere gathers all of the electrical energy from the people in the destroyed city blocks to concentrate it on Cole, and presumably that wouldn't have worked with standard electricity sources]].
** After being seriously harmed at the start of the second game, many of his powers are lost or altered. The most noticeable effect is that Cole's basic lightning bolt required electricity to use at all times, drawing from the same energy pool as his other powers.
* Averted in ''VideoGame/{{Geneforge}}''. To make creations, you have to keep up your essence, and to get essence, you have to drink from essence pools, which are filled by whoever is tasked with making essence in a long, highly dangerous process.
* ''Franchise/{{Pokemon}}'' is a pretty big offender, with ElementalBaggage and Poké Balls changing in size between, roughly, a golf ball to a softball in [[Anime/{{Pokemon}} the anime]].
** Also evolution. At level 20, Magikarp, weighing a measly 22 pounds, suddenly explodes into Gyarados, who weighs ''518.1 pounds''. Where does all of that extra mass come from?
** All the details of Pokémon biology that come with each Pokédex entry might as well just not exist. Anyone with half a brain should know that Pokémon shouldn't continuously exhale water as if they're attached to a hose or a pipeline. How does Squirtle store all that water into its tiny body? Flapping your wings can realistically create a gust of wind, but it would also send the offender flying backwards.
*** Considering that the ''Pokémon'' universe (and, presumably, laws of physics) was created by a Pokémon, this might be a case of ScrewTheRulesIMakeThem
* In ''VideoGame/EVEOnline'', the energy conservation rule doesn't exist at all. The main example would be the logistics ships, that can use (since they have energy usage bonuses on certain modules) a module giving 324 GJ to an ally for the cost of only 108 GJ energy usage. There are probably more examples.
** It gets even worse with the above example. Two logistics ships can transfer 324 GJ of energy every few seconds to each other while only using 108 GJ each to do it. This results in each ship gaining 216 GJ of energy every 5 seconds that literally comes from nowhere.
*** Another example would be the "Thermodynamics" skill description: "Also gives you the ability to frown in annoyance whenever you hear someone mention a perpetual motion unit."
* The ''VideoGame/{{Portal}}'' games play merry hob with physics. Consider the things you could accomplish with a zero-energy link between two discrete surfaces in spacetime -- setting up a perpetual motion generator would be trivial, not to mention [[FTLTravel violating relativistic causality]] at a whim. ''VideoGame/{{Portal 2}}'' introduces materials that are just as bizarre, including gels that have greater than 100% elasticity and a negative coefficient of friction, all gleefully {{Hand Wave}}d by Aperture Laboratories' [[MadScience reckless approach to research]].
* Averted in ''Franchise/DragonAge'', mages are lucid dreamers with the ability to draw some element of the Fade into the real world to make it respond to their will. And in most cases they still have to use [[GreenRocks lyrium]] as a power source.
* In ''VideoGame/DwarfFortress'' smelting, forging metal items, and other things that require great heat can get the heat from magma rather than by burning fuel. But since in the game magma remains at the same fixed temperature regardless of how much heat has been extracted from it, a small bit of magma isolated from the planet's core can supply an endless amount of heat energy.
** There is also the [[http://dwarffortresswiki.org/index.php/DF2012:Water_wheel#Dwarven_Water_Reactor Dwarven Water Reactor]], which is a power-producing perpetual motion machine that relies on using a pump to raise water to power multiple waterwheels (which are hooked up to the pump and whatever else needs power)
** Creatures with a fixed body heat (like magma men and fire men) are endless wells or sinks of heat coming from and going to nowhere.
** Wooden items, if set on fire, will keep on burning until they are completely incinerated. [[MadeofIndestructium Artifacts cannot be destroyed]]. The logical conclusion is to create eternally flaming artifact wooden weapons or coal statues.
* Surprisingly, Franchise/SuperMarioBros somewhat averts this. Some of the characters are described as drawing power from stars inside them, which would provide more than enough energy for the things they do. There's still no explanation for how this works; and it's still played straight otherwise.
* The conflict between Red and White boils down to this in ''VideoGame/DuelSaviorDestiny''. Red is magic and creates stuff out of nothing while White is science and says you can't create something where you didn't already have materials and energy before. Red, for some reason, finds this position equally bizarre, though it's not clear how since magitek exists.
* The ''Franchise/ResidentEvil'' series pretty much stopped caring about conservation of mass when it comes to extreme transformation since ''VideoGame/ResidentEvil4'', what with the Las Plagas, Urouboros and C-Virus. The latter two especially, where the former even when it takes in a couple of body piles manages to grow into a a towering tentacle monster that required a satellite laser to kill it, and the latter, where it is entirely possible for [[spoiler: Simmons to transform into a grotesque T-Rex as well as a creature that has a natural railgun that shoot bone fragments (said fragments are replaced through regeneration)]]
* The ''Franchise/MetalGear'' series is a major offender of this, with several instances throughout (despite the [[ShownTheirWork scientific accuracy regarding nuclear power, weapons, and decay]]). Expect [[VideoGame/MetalGearSolid psychics controlling people]], [[VideoGame/MetalGearSolid3SnakeEater people generating an electrical current]], and [[VideoGame/MetalGearRisingRevengeance cyborgs blocking 300 tonne tanks]].

[[folder:Web Comics]]
* Averted precisely once in ''Webcomic/TheAdventuresOfDrMcNinja'', [[http://drmcninja.com/archives/comic/17p82 here]].
* ''Webcomic/ElGoonishShive'' initially averted this with Grace, your average teenage everyday shapeshifter, who initially had a constant mass (and presumably variable density), no matter what form (even a squirrel?). Then, once the TF gun is used on her, she's surprised to discover that her mass now does change with her form. This is apparently possible because both the TF gun and her shapeshifting powers use a type of energy that can be classified as magic. In addition, the magic users burn up Ki energy, which they constantly recharge, and can burn caloric energy instead, or use the Ki energy as a boost for things that normally use caloric energy. Still a little odd, especially considering where the Ki energy comes from, how immortals fit in, etc., but [[MagicAIsMagicA explained well enough for this trope to be largely averted]]-- especially for comics, who get a free pass for some things like this.
* ''Webcomic/TheOrderOfTheStick'', is an RPGMechanicsVerse and magic is a big part of the comic, so conservation is ignored if it's better for the story. It is still {{lampshade|Hanging}}d (especially as everyone has MediumAwareness), as are other laws of physics.
* ''Webcomic/TheInexplicableAdventuresOfBob'' acknowledges this, even if it is handled in a very toony fashion. Snookums started as a giant {{Kaiju}} and got compressed to the size of a basketball; he's shown to still be enormously heavy, but still not nearly as heavy as his original size would indicate.
* Averted in ''Webcomic/{{Oglaf}}'', after [[http://www.oglaf.com/weepingwoods/1/ an unintentionally helpful suggestion.]]
* ''Webcomic/BobAndGeorge'' operates on RuleOfFunny, so this is played with back and forth. One character claims that they've violated every law of physics, but somehow George manages to exploit the law on energy conservation. George claims that his lightning based powers is powered by the sheer amount of ice cream he eats, but then [[UnreliableNarrator admits that he was just making an excuse for his love of ice cream]]. George later somehow exploits the conservation of energy by forcing too much energy through [[spoiler: the Helmeted Author]]'s magical shrinking box, even stating the law outright.

[[folder:Web Original]]
* The Literature/WhateleyUniverse makes a few attempts to HandWave this, comic book style. For example, magic users need a suitable power source (Fey draws upon ley lines for this purpose and has trouble when those get disrupted badly enough) or else have to cast their spells from their limited personal supply of 'essence'. Energizers tend to be {{big eater}}s, although it's implied that the real source of their power may be outside themselves -- Earth's magnetic field has been brought up at least once. Tennyo's body apparently produces antimatter naturally (inasmuch as the term applies to what seems to have evolved into some form of highly advanced android body by now), which sort of explains where she gets the power for her destructive blasts and energy sword from. As with most comic book examples, though, it's still best not to poke ''too'' hard at the finer points of the 'science' behind it all.
* Averted in ''Literature/ShadowUnit''. Betas and gammas, humans with paranormal powers, burn twice as many calories as normal humans even when they ''aren't'' using their powers, and burn even more when they are using them. A [[PlayingWithFire pyrokinetic]] died of starvation over the course of burning a single person to death, her own body cannibalized by her powers to fuel the fire.
* From the ''Wiki/SCPFoundation'', items labelled with the "[[http://www.scp-wiki.net/system:page-tags/tag/ectoentropic ectoentropic]]" tag specifically involve this trope as it means the object can generate matter and/or energy in manner that violates the laws of thermodynamics.

[[folder:Western Animation]]
* In ''WesternAnimation/AvatarTheLastAirbender'', benders can create or manipulate their given element. This is {{hand wave}}d as chi manipulation, but benders don't seem to be using nearly enough energy to do what they do, even assuming the human body contained enough energy for some of the Avatar-level bending, though it's never really stated how much energy the chi itself actually contains. This is especially obvious with waterbenders, who can change the state of large amounts of water from solid to liquid to gas and back again.
** Avatar-level bending may be justified (or at least plausibly hand-waved); in the Avatar-state, energy is apparently being drawn from elsewhere (presumably skimming from the entire planet).
* ''WesternAnimation/BatmanTheBraveAndTheBold'', of course, usually plays this dead straight. Still, there was a notable aversion in "OMAC Attacks!": Batman wonders how the villain keeps regrowing his weapons without losing mass elsewhere; it turns out he was absorbing the kinetic force of the DumbMuscle's attacks against him. An attempted aversion, anyway, since the DumbMuscle would have to convert his ''own'' mass into energy to hit with that kind of force. Otherwise he's literally punching energy out of nothing, which is, admittedly, pretty badass. Not to mention the amount of energy that is. In order to regrow a gram of mass, he'd have to punch with an amount of energy comparable to a nuclear bomb. If he was punching anything that wasn't hyper-efficiently absorbing it, the energy would most likely be released with pretty much the same effect. He's also violating a few conservation laws by creating matter without creating antimatter. Admittedly, he could make the electrons by making an equal number of anti-neutrinos, which would largely go unnoticed, and baryon (proton and neutron) conservation is most likely more of a guideline. There might be one or two more he can't get around, though.
* In ''WesternAnimation/{{Futurama}}'', Professor Farnsworth describes his ship's afterburner having 200% efficiency. Another character comments that this is "''especially'' impossible."
* Small aversion in ''WesternAnimation/{{Gargoyles}}''. WordOfGod states the Gargoyles strength is fueled by solar energy absorbed by their bodies while they sleep during the day. However, Gargoyles DOES avert this trope nicely with its mention of how magic works, that energy is energy, etc...
* In ''WesternAnimation/JusticeLeague'' Batman invokes the law of conservation of energy (well, he exchanges 'energy' with 'mass', but otherwise...) as an indication that [[spoiler:a DisintegratorRay believed to have vaporized Superman]] didn't work the way its creator intended -- there were no scorch marks, leftover atoms or increased ambient energy on the site, which it should have been had it worked as intended.
* Lots of theories abound about where all of Generation 1 Megatron's mass wanders off to when he transforms in ...well, ''WesternAnimation/TheTransformers''.
** Handwaved in the early IDW comics, as changing to gun form A) required a special high-energy form of energon, and B) was incredibly dangerous to anyone in the immediate vicinity. This was forgotten within three issues.
** Not to mention Soundwave, Blaster, Optimus Prime's trailer... and then there's [[http://tfwiki.net/wiki/Image:MakeHoistHuffer.jpg this]]...
* In the episode of ''WesternAnimation/TheSimpsons'' where the teachers go on strike, Lisa eventually snaps and builds a perpetual motion machine in a failed attempt to cope, which prompts this quote:
-->'''Homer:''' "In this house we obey the Laws of Thermodynamics!"

[[folder:Real Life]]
* While violations of conservation of energy do not occur in classic physics, it is worth noting that there are ways around various other laws regarding energy usage, and getting as close to 100% energy efficiency as physically possible is a long-standing engineering goal:
** Chemistry - Catalysis alters the series of structural changes a chemical has to go through in a reaction, usually with the end effect of the reaction occurring at a lower temperature and, due to the nature of heat loss in most chemical equipment, requiring less heat input from the equipment.
** Power generation - The general engineering limit on power generation, known as the Carnot efficiency, is averted by the use of generators that don't rely on heat reservoirs, such as photovoltaic cells.
** Various perpetual motion devices based on magnets appear on first inspection to violate conservation of energy, to the point that people have attempted to patent them. In actual fact such devices extract energy from the domain ordering of the magnets and are no such thing.
*** There are similar devices that work off of gravity, differences in air pressure, and other forces that allow the machine to run "perpetually", without any apparent input.
** Thermoelectric cells and reactive braking allow many modern vehicles to get energy "for free" from what otherwise would be waste energy. A number of advertisements have specifically played off of the perpetual motion idea.
** The energy of empty space is technically non-zero. Though in physics this "zero-point energy" is by definition not extractable, its existence has resulted in great loads of pseudoscience from people that need to brush up on their math. Has to some extent displaced quantum entanglement as the handwave justification for new-age mysticism in recent years.
** Technically, conservation of energy is a long-term phenomenon. Macroscopically, it always holds, but brief violations at the subatomic level happen on a regular basis, and radioactivity would be impossible without them. Any energy that appears from nowhere must vanish whence it came before it can be observed (if you tried to observe it, you would necessarily supply the borrowed energy with your measuring device).
** The [[https://en.wikipedia.org/wiki/Zero-energy_universe Zero-energy Universe theory]] suggests the energy of the Universe contained in matter is canceled by the energy present in the form of gravitation. Such an Universe could have been born from a quantum fluctuation in the middle of [[https://en.wikipedia.org/wiki/Ex_nihilo#Modern_physics nothingness]] and requires the Universe to be flat[[note]]With no measurable space curvature[[/note]], in line with current observations.