I'm currently trying to refine my magic system which is able to manipulate the elements using the body's natural energy.
As examples:
I can create water out of the air by coalescing available moisture in the air and/or combine the elements of oxygen and hydrogen to increase the volume created.
I can split and combine elements from compounds like carbon from charcoal and infuse it into iron to make steel.
I can manipulate the elements and compound to create shapes (mould a steel ingot into a gun barrel).
I can do anything that manipulates the elements as long as I have the necessary element or compound nearby, I cannot create it from nothing.

The difficulty is trying to understand how difficult these tasks should be. Assume for the moment that 1 joule of energy from the body can manipulate 20 joules of magical energy (Value for example purposes and not set in stone). We of course do not have an infinite amount of energy, assuming a level fit for a human and using it up would be like finishing a marathon at maximum effort.

How many joules (in bodily energy) would it require to manipulate the elements? From creating water or causing a breeze in the air to splitting/infusing elemental compounds. For example, would splitting carbon from steel take the same level of energy for infusion carbon into iron to make steel? Is there any reading material someone can point me to to give me a better idea? I'm no chemist so would need something not overly technical.

Lots of questions sorry but at the moment I'm trying to figure out how difficult it would be for my protag to craft a semi-modern gun in a period that's set somewhere similar to the middle ages. Please ignore other issues about gun manufacturing for now though, I've already got another post from a few days ago that went into that and other specific issues about this I think I'll ask in a new and separate post.

Edit: Had a lot of questions, narrowed down now I think? If not I'm really not sure how to narrow it further without missing important points.

  • $\begingroup$ Others may comment on the question format and narrowing it down, bu what I want to know is, can the energy from say - oxidizing something (burning) be re-directed to heating something else up or reducing something, it could help solve the exhausted-wizard issue? $\endgroup$ Commented Jan 17, 2021 at 15:55
  • $\begingroup$ Please narrow this post down to 1 worldbuilding question with a limited scope $\endgroup$
    – L.Dutch
    Commented Jan 17, 2021 at 15:59
  • $\begingroup$ I can try but not sure how I can without leaving important stuff out. Regarding energy re-directing I'd say no for now. I could possibly change if it makes it easier for myself to write though. :p $\endgroup$
    – GMHLee
    Commented Jan 17, 2021 at 16:05
  • $\begingroup$ my advise to you don't re-invent the wheel, in physics energy comes in discrete form and follows a set of rules but that doesn't mean you should force magic to use the same rules ;D $\endgroup$
    – user6760
    Commented Jan 17, 2021 at 16:11
  • $\begingroup$ If the magic is supposed to feel magical, then don't use physics and chemistry as a model. $\endgroup$
    – NomadMaker
    Commented Jan 17, 2021 at 16:12

1 Answer 1


You have laid out enough rules to make your story work. Now lean into the magic.

It is technically possible to figure out the energy to remove carbon from steel, or break a nitrogen-hydrogen bond, or melt and reform a piece of metal. It is not the same calculation for each thing you want to do and at the end of the day you have spent hours figuring out enthalpies for a story about magic.

You have laid good ground rules.

  • No something from nothing.
  • Energy must come from body of spellcaster
  • Magic requires effort.

Now make your own rules in service of the story. For example - maybe pulling water from the air is easy as compared to pulling it from the earth or from living things even though there is more water in those things. Why? "The water doesn't want to be in the air. It likes to get out and come to me." Adding carbon to steel is harder than removing it. Why? "The carbon really hates to be with the steel. It is disgusted. I think it wants to be in a plant again; celluose, you know. I promised we would make that happen."

Physical chemistry is great, but you can do better for a magic themed fiction and it will be pretty original. Give elements (and I mean the elements of the periodic table) and physical processes their own wants and needs as though they were demons or minor dieties. That will determine the energies needed by your spellcasters.

I like the idea of a spellcaster that discovers it is actually very easy to magically dissociate the two nitrogens in N2 gas, even though the enthalpy for that reaction is high. Why? "It's so exciting when they get back together! But you have to let them get back together or they get upset."

  • $\begingroup$ thanks for the unique way of looking at it, though perhaps just a bit too 'magical' for the theme of my novel. :P $\endgroup$
    – GMHLee
    Commented Jan 17, 2021 at 16:18
  • 3
    $\begingroup$ @GMHLee - the idea was from my own experience of organic chemistry. Nitrogen wants to be with nitrogen. A single oxygen atom is lonely, and needs company. You do not need to have them literally be demons but that is a shorthand your elemental manipulators use which lends itself to story telling better than enthalpy numbers. Also to learning organic chemistry. $\endgroup$
    – Willk
    Commented Jan 17, 2021 at 16:42

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