So you are someone who wants more power? Well, If one is good, two must be better, right? Not necessarily. You see, some forms of Applied Phlebotinum are incompatible and attempts to mix the two will yield dangerous results. There may be several reasons for this:
- The types of phlebotinum used are polar opposites: Generally speaking, using two polarized sources of power together like that will be impossible. Light and darkness will try to engulf each other and mixing fire with either ice or water will get you water or steam, respectively. Contrast with Yin-Yang Bomb.
- They both have a failsafe to prevent this. If the phlebotina are made by the same person/group or people related to that person/group, then they would be compatible enough to work together. Thus if the combined forces are capable of The End of the World as We Know It, then chances are that they implement systems to prevent them from working properly together or just make it impossible for them to work together at all. (This is more common with technological phlebotinum.) Of course, if Failsafe Failures come into play, then watch out.
- It would be Awesome, but Impractical: The use of both phlebotina would actually make it harder to use either one to its full potential. Simple as that.
Of course, there can be other reasons why it would be a bad idea to mix two different sources of great power.
A very common version in more science-based works is drug interactions.
Compare Unstoppable Force Meets Immovable Object. When the heroes are warned of this and have to do it anyway because they've hit the Godzilla Threshold, that's Forbidden Chekhov's Gun. Contrast Phlebotinum-Handling Equipment, where one piece of phlebotinum is used to contain the other. Sometimes this is invoked to make an Obvious Rule Patch less obvious.
- In One Piece, what is currently established about Devil Fruits is that, among other things, you do not eat another fruit if you've already eaten one because you'll die — it's believed to be because the "devils" inside the fruit will fight each other, causing the eater to implode. Blackbeard proves himself an exception, as he already an user of Dark-Dark Fruit and manages to get Whitebeard's Rumble-Rumble Fruit power and even more later on. Though the process of which is still unknown, but seems to have something to do with his body being abnormal.
- Kenichi: The Mightiest Disciple has Roar-As-One. It's a technique that combines Sei and Dou Ki. While it does give the character immense power for a while, the end result will normally cripple or outright kill the user. Using the technique in short bursts helps, but using it too often in a short period of time is still not recommended.
- The Joker's trademark Joker venom is sometimes portrayed (most notably in "The Laughing Fish") as a combination of two otherwise-harmless chemicals that produces instant, smiling death. Very useful for targeted assassinations.
- And the Giant Awoke: The first element of Olenna Tyrells poison is put into Littlefingers soaps, and the second one, which makes it deadly, is in candle wisps in his room. Then an excellent medicine was used against the poison and prolonged the agony.
- Incompatible System: Human technology is based heavily on the use of WIMP (Weakly Interacting Massive Particle) fields, which give them artificial gravity, FTL, and more. However, exposure to WIMP fields causes eezo to destabilize so violently that a few kilograms can glass entire continents.
- In The Incredible Hulk, Blonsky makes Sterns infuse him with Bruce Banner's blood so he can gain the Hulk's power. Due to his own Super Soldier Serum reacting with it he undergoes a one way transformation to the stronger (and uglier) Abomination.
- Exploited in Star Trek Into Darkness where John Harrison's agent destroys the Section 31 weapons lab by dropping a ring he's wearing into a glass of what at least looks like water, causing a tremendous explosion.
- Batman (1989) takes the aforementioned Joker Venom ("Smylex") up a notch. It's a binary compound with the components seeded among dozens of different personal-care product brands. This means, effectively, that brushing your teeth after using a certain conditioner could make you die laughing. Fortunately, Batman's trusty computer helps him to figure out which combinations of products will do what, which when leaked to the media foils Joker's plan.
- Reign of Fire explains dragon fire by establishing early on that dragons have glands in their mouths that produce "opposite chemicals". The dragons work kind of like a spitting cobra, spraying the chemicals at a target, and when the chemicals come into contact with each other they react and ignite.
- In the Ringworld universe, Known Space has the life-extension drug boosterspice. The inhabitants of the Ringworld have their own life-extension drug, but you can't take both: boosterspice is poisonous to someone who's used the Ringworld drug.
- In The Dresden Files, this is why mixing potions is not a good idea. According to Harry, potions are basically drugs (magic aside), and mixing drugs is dangerous.
- One of the Mesan assassination weapons in the Honor Harrington series is the binary neurotoxin. Neither of the two chemicals used is itself dangerous (the Mesans smuggled them past a poison detector disguised as exotic perfumes), but when they're mixed they become an incredibly lethal nerve gas.
- In X-Wing: Rogue Squadron, after Imperial Intelligence Agent Kirtan Loor captures Corran Horn's friend Gil Bastra, he discovers that Bastra has been taking a drug that reacts with one used in Loor's preferred torture method to cause anything from amnesia to death. Loor attempts an alternate method, but Bastra suffers a fatal allergic reaction to the bacta Loor uses to heal him up between sessions and dies. It's later stated that Bastra had previously been exposed to a sabotaged batch of bacta which caused this reaction, though it's unclear exactly how: Loor thinks it was accidental, but the series' Big Bad, Imperial Intelligence Director Ysanne Isard, thinks it was deliberate (she calls Bastra's death a suicide).
- Nanny Oggs Cookbook, a supplementary Discworld Book, contains Lord Vetinaris recipe for bread and water mostly a detailed explanation of how to detect possible poisons. For example, even if you think that bread and water passed their separate tests, you should remember about a case where the poison became lethal only if you ate the bread and then drank the water.
- Age of Fire: Similarly to Reign of Fire above, dragons are explained to spit chemicals from glands in their mouths which, when mixed and exposed to air, ignite into flames.
- Codex Alera: This turns out to be part of the reason behind the human-Icemen war. The humans use firecrafting to stay warm in the arctic regions the Icemen inhabit, while the Icemen communicate using watercrafting-based telempathy. These two magics interfere with each other, causing irritation and discomfort on both sides and turning already tense first-contact scenarios into a series of fiascos.
- In one episode of Dark Angel, out of desperation, Max used a brain implant designed to boost normal humans to superhuman levels of performance, although the physical strain dramatically shortens their lives. With her genetically-enhanced physiology, she became unstoppable, although it would have killed her in hours if the implant hadn't been disabled soon after.
- Stargate SG-1:
- The early episode "Singularity" shows that in addition to the main way naquadah is explosive, it reacts explosively with an alloy of iron and potassium (we're talking two microscopic amounts of each obliterating a whole room, including the camera on the other side of it), a fact used by Nirrti to turn a girl into a walking weapon of mass destruction.
- In "Summit" the Tok'ra unveil a binary chemical agent that is incredibly toxic to Goa'uld symbiotes: an amount small enough to fit in one's pocket can reportedly produce enough Deadly Gas to kill every Tok'ra in their current base.
- Parodied with the page quote, where the actual names of the ingredients for an experiment are blurred out to keep from giving the audience ideas.
- When examining the Hindenburg disaster, they tested the flammable properties of both the hydrogen gas and the zeppelin's metallic paint, and decided that a combination of the two was probably responsible.
- When they were testing a Breaking Bad method of Disposing of a Body, they accelerated sulfuric acid with some "special sauce" to make something monstrously corrosive.
- In the Firefly episode "Ariel" an undercover Simon Tam saves a patient from cardiac arrest, then tears the patient's doctor a new one for causing it. The doctor had made the mistake of giving his patient a painkiller that, when combined with a standard prep drug used for the patient's procedure, reacts to form a vasoconstrictor (a chemical that makes blood vessels contract).
- In the Burn Notice episode "Bad Breaks" one of Michael's customary voiceovers narrates his efforts to foil a gang of bank robbers.
"Mixing medications is always a bad idea, especially when one's an upper and one's a downer. Anxiety and allergy meds together are a scary combination, and that's before you add the caffeine of an energy drink."
- Invoked by Londo Mollari in an episode of Babylon 5, when he gives Lord Refa part of a deadly poison. It's a binary poison, meaning the two components are harmless by themselves, but if they're brought together, they are very lethal. He warns Refa that the Centauri's war of conquest needs to stop, or he'll introduce Refa to the other half of the poison.
Londo: To your health, Lord Refa.
- The Late Show with Stephen Colbert had a story about a guy who mixed cough syrup with LSD, drove his car through several fences, then hallucinated that a house was on fire and broke in to rescue the family dog.
Stephen: But his cough is gone now!
- Dungeons & Dragons
- First Edition had the Potion Miscibility Table, which had a variety of results when someone drank two magic potions. The bad results ranged from mild poison to lethal poison to an explosion inside the victim.
- Putting a portable hole into a Bag of Holding causes very bad things to happen, although precisely what effect results depends on which is put into which. Putting the bag into the hole sucks both into the Astral Plane and renders both items lost forever. Putting the hole into the bag opens a dimensional breach into the Astral Plane, destroying both hole and bag and sucking anything in a ten foot radius into space.
- In Spider-Man: Shattered Dimensions, Juggernaut gets his hands on a fragment of the MacGuffin tablet which increases his already insane physical strength, but it cancels out his own invulnerability, meaning Spidey can take him down.
- Exploited in Evil Genius. Turns out that pesky Super Agent Dirk Masters is hopped up on tons of illegal steroids. Giving him a dip in your Bio-Tanks causes a series of delightfully nasty mutations, turning your former foe into a Freak under your command.
- Innumerable examples in chemistry.
- Basic laboratory safety techniques include diluting acids by adding the concentrated acid to water, not water to acid. Dissolving acids in water (especially stronger acids like sulfuric acid) causes a release of heat (technically known as "enthalpy of dissolution" or just "heat of solution"). If you have a small amount of water and a large amount of acid, the heat given off can be enough to raise that small amount of water to boiling, splattering concentrated acid in the process.
- Another example of two things that react violently is any strong acid/strong base combination, as the heat of formation can be quite high. For example, mixing potassium hydroxide with hydrochloric acid yields potassium chloride, which has an enthalpy of formation of on the order of four hundred thousand joules per mole. This is about a third higher than the molar enthalpy of formation of nitroglycerine.
- Adding pure alkali metals (such as lithium and sodium) to water produces a hydroxide of that metal, highly inflammable hydrogen gas, and a lot of heat... enough heat to cause the water to boil (spraying scalding-hot water with a caustic base dissolved in it) and the hydrogen to combust (causing sparks that can start fires). In other words, Don't Try This at Home for a number of reasons.
- In the CRC Handbook Of Chemistry And Physics, a real life Big Book Of Everything for scientific data, one section lists chemicals which react dangerously with each other. Of special note is the entry for elemental fluorine, which simply reads "everything".
- A number of early chemists working with fluorine literally blew up their laboratories. The first guy who tried reacting fluorine with carbon was one of them. He then tried using reacting it with hydrocarbons instead of carbon itself, and got another explosion.
- As seen in the Firefly example above, some medicines can interact in ways that are harmful to the body, depending on the chemical substrates of the medicine.
- Bleach and ammonia. Both are excellent cleaning agents, but if mixed, they react and produce poisonous chloramine gas.
- Binary chemical weapons exploit this trope. Two chemicals are relatively innocuous by themselves, but when combined they produce something far deadlier.
- Binary agents in general. For a relatively low-key example, mix baking soda (base) with vinegar (acid). You get a big bubbly foamy reaction which ultimately just produces a bunch of CO2 and water, and a little bit of sodium acetate. For a much more energetic example observe hypergolic fuels, like the two-part fuel used in the Me-163 Komet interceptors of World War II, which spontaneously ignite when mixed. This is amazingly useful when designing a rocket motor, because it enables you to dispense with the extra weight and complexity of spark-gap or pyrotechnic igniters and can start and stop your motor as often as you need to by simply opening a valve, but it creates some formidable extra safety issues.
- ANFO is a well-known industrial explosive whose name stands for its two ingredients: ammonium nitrate (a common ingredient in chemical fertilizer) and fuel oil. Commercially available ANFO is purer, made of ammonium nitrate pellets and #2 fuel oil, but lower-grade ANFO can made relatively easily by terrorists with chemical fertilizer and diesel or kerosene, which has led some governments to outlaw ammonium nitrates and related compounds altogether.
- This is why mixing medications without proper medical advice isn't a good idea. For both legitimate and illicit drugs, a particularly dangerous combination is taking stimulants and depressants at the same time. This was the immediate cause of death for John Belushi, as he had taken a mixture of cocaine (stimulant) and heroin (depressant).