How can I expand the definition and some specifics of pyrokinesis?

I'm writing a sci-fi world where, if you put it in simple words, a small percentage of population can manipulate the matter. I'm not going to dive into specifics, because I'm still working on WHY and HOW it started or was discovered.

One of the main characters was born with pyrokinesis. I want to develop this ability from a scientific point of view. Said character can't just magically create fire out of nowhere because DUH MAGIC, but has the ability to manipulate the speed of particles - speed them up to create heat or fire, slow them down to get rid of it. Does it sound scientifically valid, or am I missing something?

Said character also has no high heat tolerance, because the ability to manipulate the thermal energy doesn't make them impervious to it. They can take it only to the point a normal human without any superhuman abilities can. As a result they had to train for years to learn how to use their powers without hurting their own body with created high temperatures and burns, and even after that they can only use said powers wearing special armor that protects their body from all the heat when using pyrokinesis on a large scale.

How can I expand the definition and specifics of pyrokinesis ability in that setting? Any ideas and advice would be highly appreciated. I want to explore the phenomenon of pyrokinesis in my world more, make it as interesting and realistic as possible.

Welcome to worldbuilding SE! here are some thoughts on how it could be explained:

• electricity(most probable)
• magnetism(furthest of a stretch)
• actual heat(stupid)

I'll go into it further. For the electricity option you could have it be something to do directly with nerve cells(which produce electricity) would create a electric field at the persons command which would create heat sort of like how lightning gets extremely hot with electricity. Moving on to magnetism which is a real stretch. The person could use strong magnetic fields (which can heat) to cause fire, the main problem being im not sure if it works on nonmetals and having stuff fly at you wouldn't be the best. Moving on to actual heat which is just a bad idea. you could have the user have the ability to emit intense heat out of their skin chances are they'd end up burning away with this one.

Overall going with electricity is the most realistic solution I can see if you want it to be as for getting rid of it, magnetism would be the most logical to hold them in place aka cool them but have no fear electromagnetism saves the day. You could use it to freeze the atoms in place(please not that reality doesn't work like that and if you really want it to be realistic than there would be no way to stop the fire if its real fire) but you could have the fire be the electricity and only look like fire and go away when the person no longer wants it to be there but side fires would have to remain(unless they were able to take o2 away from the fire somehow). you could also have it so if they got tired then the fire would disappear. Overall I would use the electricity option because it seems the most realistic.

A lot of heat is stored as vibrational energy in atoms and molecules. If you were able to manipulate the quantum field, you could change the vibrational state of atoms and thus create or remove heat from a system. Since quantum physics is all about probabilities, Matter Manipulators (MMs) would have to be masters of probabilities in order to operate. They would have to get good at:

• Perceiving the quantum field,
• Changing it and perceiving the consequences of those changes,
• Anticipating those consequences and being able to prevent the unwanted ones like side effects or cascading changes,
• Being able to create the precise conditions to increase the chances of a desired outcome.

Since PKs act upon only the simplest / crudest property of matter, they would be seen as the lowliest of the MMs, unable to do precise chemistry or matter forging. Blunt instruments - think fire mages vs. enchanters. They would have their place in society because of the free energy they can generate (especially if they can create sustainable heat generation) but would be looked down upon, maybe even coerced to work.

On the other hand, they could wreck total havok as probably the most powerful MMs and one day use this power to their advantage.

if you're asking of what to do with this power then let me tell you, controlling the movements of particles, in the right hands, is far more deadlier that an arsenal of WMDs.

Heat is an increase in the speed of the particles, but if you can also control Direction then it's a whole different beast. From the top of my head the things i can do:

• sudden increase in temperature (like making all the water inside a person turn into vapor in the same second, nasty stuff)
• stop particle movement (absolute zero, a.k.a.: thing stop being thing and disappears into dust. bonus point if you do it with a finger snap)
• reality slash (if you command particles to move away from a line you're basically cutting it at atomic levels)
• concentrate particles in a specific location (from handheld vacuum to black hole)
• concentrate specific kinds of particles (from air to tritium and then into H3 reactor, or hydrogen bomb when lazy)
• matter out of thin air (in the end everything is made of protons, electrons and neutrons, just a little accommodation and we can have petrol or uranium at demand)

even when going big things stay deadly:

• if you have no upper limit to the speed you can give to stuff then E=MC² is your friend (neat example by xkcd)
• even if you have limits bullets are slow enough to emulate, just with bigger payloads.

Now, if you're asking for a scientific reason to be able to manipulate particles and their speed you could potentially explain it with an anomaly that allow your character to form a quantum entanglement with random stuff, allowing it to control things like their vibration speed

Expanding on Topcode's answer a bit:

Electricity by itself is hard to use in the ways it is often shown being used (control must extend quite a distance to get lightning to behave). On the other hand, there is a concept that lies neatly between fire and electricity, and is manipulable via electromagnetism to boot: Plasma.

What you'd basically need is to ionize materials into a plasma state, then carefully control the shape of the plasma. If you require the aesthetic be as fiery as possible, rather than having a straightforward path to glowy fantastic "energy" things, you can make it difficult to accomplish and control without a flammable substance to wield. The uncertainty here is the amount of energy involved: if you can mess with these enough to get something resembling pyrokinesis, what type of plasma could one create with that out of, say, air? It isn't as though plasma screens just keep a wad of plasma in there doing nothing while they're turned off; unbound plasma surrounded by normal matter will quickly interact with that matter and find a more stable state, so the ability to generate and manipulate can't be too disparate. The utility of the resulting plasma, however, can, if the sort one could pull out of atmospheric gas would be glowy-but-useless.

Alternatively, focus on Oxygen

Most fire that people experience on a daily basis is exothermic oxidation. Manipulating oxygen specifically might be helpful, though sciencing the mechanism is harder than working out the chemistry once the ability is defined. This probably wouldn't differ too much from Full Metal Alchemist's Colonel Mustang's flame generation and manipulation, although where the energy comes from and how it gets into the air is harder to handwave than personal electric field generation.

Personally, I'd lean toward electricity, and the more scientifically accurate you want it to be, the more you'd want to research plasma and ionization energies.

One More Thing...

Some people irl claim they can manipulate flames. Weirdly, the last time I checked Wikipedia, this was dismissed out of hand with almost no discussion (but that was several years ago). Every case I've heard has been small-scale "make the flame dance / rise) type tricks, which could probably be accomplished with careful directing of one's breath (it's telling that the two unrelated anecdotes I've heard both involved meditation with breathing exercises). One of these was doing similar tricks to one of those fake martial artists from the 80s (was it Count Dante?), spinning a needle with "ki" (the famous example being revealed as doing it by directing his breath). In a world with a single handwave to amplify this sort of trick, it isn't necessarily implausible that one could go from parlor tricks to something with practical application.

Comparing with the electricity and oxygen options, this seems the simplest, but also the least exciting. I still lean toward electrokinesis as the more balanced option, since all the magic has to do is one simple thing that we can already do with technology and bioelectrogenic animals. It would, however, come with several non-flame applications.

To Summarize:

• Breath / airflow / weak aerokinesis: has real-world precedent, so is easy to explain but hard to scale up or expand upon. Easy but restricted.
• Electricity, probably generated and directed by the person's body or some substance they're always in contact with. There is some real-world physics to draw upon, but it is somewhat complex, dependent on a number of factors such as materials, temperature, etc, and has the potential for expansion into a variety of applications other than manipulating fire and generic plasma.
• Oxykinesis: most directly applicable to both generation and control of flame, with a few scary secondary options like strangling people by seizing control of their oxygen supply. While there is room for hard science in terms of the chemistry and energy involved, the mechanism is a bigger handwave than the others, and the applications comparatively narrow, if more powerful.

I haven't mentioned the way my most prominent pyro character does it, partly because it's softer than what you seem to be going for, but mostly because it involves a handwavium substance whose properties and implications I'm still struggling to pin down. The result looks like a mix of the weak aerokine and electrokine scenarios, with the handwavium being mostly invisible when it isn't in very high concentrations, and being able to replicate in an almost life-like manner in the presence of the right chemicals and electric currents. So the cheap way to throw a fireball is to just have a stupid amount of the stuff, get enough electricity flowing to ignite it with a spark, then fling the burning droplets like incendiaries. And the more skilled version cultivates the supply and carefully directs currents to create shapes and strands of handwavium that can be manipulated as above for a variety of effects.

Fire, in this case, is two parts. The first is that fire is generated from an exothermic reaction, usually involving oxygen. The second is that what we perceive as heat is just faster moving molecules at least in general.

In addition to this, reactions this fun and exciting are generally not spontaneous unless one or more of the materials is highly reactive. A chunk of soduim/potassium in water is a fairly tame example and a good chemistry class introduction. Chlorine trifloride (yes, flourine is THAT good at what it does) is very nasty in is ability to burn things.

So where to go from there?

Said character can't just magically create fire out of nowhere because DUH MAGIC, but has the ability to manipulate the speed of particles - speed them up to create heat or fire, slow them down to get rid of it.

What you are missing is that this technically isn't fire -- it's "just" kinetic energy. You can make things catch on fire if you heat it enough, but on its own, you aren't actually setting things on fire in a conventional layman's sense of the word.

Now it is entirely plausible that you can heat something up enough to catch on fire. Paper to roughly 233 Celsius comes to mind first thanks to Mr. Bradbury, but even something like hydrogen gas or wood burns if hot enough. Creating a line of heated fuel to react to burn is plausible. Where the energy comes to add heat from might be your plothole. And you will need to address that lest somebody go "Well why can't they just heat it to X degrees for Y effect?"

Probably the easier extension is to add a bit of heat to a large area to get that sort of heat haze effect that can be seen on really hot days. It might not have an everyday use, but it is something that isn't fire that can be done.

Another extension is that by manipulating the speed of matter directly, you can also remove speed from it, cooling it down. This will lead to the inverse, cryokinesis. Unlike with adding heat, your character's issue will be where the energy removed from the system goes.

Your major problem is that, unless this is a thing, why the correct way to kill people is liekly to burn them from within ... probably painfully. Making an inferno to trap them in while visually cool looking, would likely be highly inefficient for killing. Good for a delay though.

Your character's lack of immunity also make sense. You are concerned with a single break in reality without actually having the required secondary powers to handle things like this safely. The energy will want to escape the system and return to equilibirum.

From the lens of science, gasses are bound (roughly) by the Ideal Gas Law -- PV = nRT. So if you are increasing the temperature with your powers, then the pressure and/or the volume will rise to compensate. That is something that to consider when deciding limits -- when your control from an area is cut, then that hot air will do something to reach equilibrium with its surroundings. If one constrains a set volume of hot air, then only the pressure rises -- big boom once released all at once perhaps?

Another condieration: If you can manipulate individual atoms instead of molecules, then you could do something like move part of a water molecule so fast it splits into hydrogen and oxygen. Now split, it is susceptable to burning by again maniuplating the speed of them to incite combustion. This would work with methane and other hydrocarbons (Alcohol fire breath?). Doing this to table salt might be a bit nasty because the sodium in it will burn, and chlorine can do nasty things on its own. If this is possible then you have a plentiful source of fuel in water and the air around you. And by controlling where you pull molecules apart, one should be able to at least partially control where the fire goes.

You are changing the activation energy requirements of chemical reactions.

To create a chemical reaction, you need a certain combination of activation energy and compression. Things that burn are chemical reactions that are exothermic that release enough energy to create more exothermic reactions in the surrounding medium. Now that said there are tons of exothermic reactions in this world that release heat, but generally don't involve material densities or enough ambient heat to "burn".

The most exciting of these reactions to a pyromancer would be the formation of Dinitrogen Tetroxide from Nitrogen and Oxygen.

N2 + 2(O2) -> N2O4


Nitrogen and Oxygen are the basic building blocks of our atmosphere, and their reaction is exothermic! Don't panic though because our atmosphere is way to cold and thin for these elements to just go around catching fire, but if a pyromancer were to create an bubble in space were the activation energy requirement of the reaction we to be temporarily sublimated, he could conjure up a fireball out of thin air.

That said, as impressive as pyromancers would be for their on-demand fire starting skills, where they would really shine would be in their ability to prevent fires. If a pyromancer were to project his ability over a battlefield, he could make gunpowder require too much activation energy to burn there by rendering all guns useless. If a pyromancer where extraordinarily skilled, he could even manipulate the metabolic processes in a person's body causing them to die in one of so many different natural looking ways that no one would even suspect pyromancy.