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mrsuspicious
2012-09-11, 12:24 AM
I've been working, for some time now, on a campaign setting to be used with d&d 3.5 and pathfinder. The setting is characteristically gritty and very 'low magic'- that is to say there are no magic items, dragons are just big lizards- that kind of world.

Anyway- what I came here for is advice. I have yet to finalize out the actual mechanics of the magic system I've been creating. What I really need now is help from someone with an advanced understanding of chemistry to help me streamline the basic rules for my magic system so that it follows the law of conservation of mass correctly.

So- the magic, referred to as 'Primathurgy', is used by people known as Shapers (the single spell casting class in my setting)
A Shaper draws his power from an dimension known as 'The Aether' a realm of infinite energy and matter accessed through a Shaper's mind.
A Shaper is able to send matter and energy from the physical world into the aether in exchange for the exact same quantity of matter and energy in different forms or compounds. For example- a Shaper could send a lump of coal and some breathable air into the aether to produce sugar (which is made of Carbon, Hydrogen, and Oxygen).

This all starts to get very difficult when I bring energy into the mix. Essentially, what I need to figure out is where the energy goes. Assuming the Shaper can ignore the need to complete chemical reactions and is able to piece together compounds manually, how can I make it work?

The most important thing is that the amount of matter and energy in the physical world always remains the same.

devlingreye
2012-09-11, 02:11 AM
The simplest way I can think of to produce the energy is to use your own life force to send into the aether and pull out the energy you need. Also i believe Dark Sun uses a system that you might be able to adapt to your campaign setting.

Defilers
who draw their power quickly, killing plant life around them, and significantly sterilizing the soil those plants were in, rendering it impossible to grow new plants there for centuries. This defiling of the land is why the once healthy planet is mostly a desert. Very powerful Defilers are able to draw power from creatures as well. Powerful Defilers can kill people in this manner.

Preservers
who draw their power more carefully, enabling them to cast their spells without destroying plant life, but sacrificing spellcasting power. Very powerful Preservers are able to draw power from creatures as well. Powerful Preservers have this ability, but they will not seek to kill with it.

Those might work by saying to are pulling to energy around you in natural through the aether and then pulling it out for your use. Just a thought.

NichG
2012-09-11, 02:29 AM
So there are a few obvious uses that are entirely separate from the chemistry angle.

Do you care if the entropy remains the same? If not, one good use for this kind of magic would be the ability to freeze stuff (pull thermal energy from something in exchange for making an energy-rich compond) or burn stuff cleanly (take any energy-rich substance and convert it at 100% efficiency to raw elemental matter and a lot of energy).

How about sending an enemy's head into the Aether in exchange for a lump of coal? Or part of a wall that's in your way?

Another application: changing the shape of objects. Even if you map stone to stone, being able to change the shape of stuff is a big deal.

In principle these types of uses are much simpler than something like coal+air -> sugar, since they don't actually change much. Then something like coal+air -> sugar would be the low-middle complexity (you're just making a lot of one thing), producing bigger biological compounds (medicines, raw protein, etc) would be middle complexity, and producing big multi-component things (a duck) would be high complexity.

Energy-wise, you just have to figure out what payment is available:
- Thermal energy. The product is really cold, or you need something hotter than the environment to power this (if you care about entropy).
- Binding energy. The source components were all separated out, and the stuff you make is tightly bonded. Something like going from a cloud of water vapor to a globe of water can produce some available energy via surface tension, for example.
- Trade some reactions for others. Take a handful of sugar and turn it into 50% coal and 50% TNT, or whatever the appropriate ratios would be.
- Gravitational. Take something whose mass is distributed evenly through the transported volume, and get something whose mass is all clustered towards the bottom. This isn't going to give you much kick, so you could only do this for balancing minor changes in energy.

mrsuspicious
2012-09-11, 08:22 PM
Thank you so much for your advice- any insight into how chemistry works is really helpful.
I had considered the idea that a Shaper could just send parts of their enemy's body into the aether and decompose them. I'm just going to lay down a rule that it's easiest to affect your own body, more difficult to affect things outside your body, and nearly impossible to directly affect another living thing capable of cognition.
I really like the idea of freezing things to gain energy to work with. I've been wondering though- how much energy do you think it would take to force atoms into forming compounds- if any at all. I've read that atoms forming compounds actually releases energy. If that's the case- then how much would it take to rip apart-say- a rock into silicon and whatever else composes it?
How much energy does it take to burn something at 100% efficiency?

I basically need to know which actions require energy to take, and which actions produce energy.

NichG
2012-09-11, 11:54 PM
Thank you so much for your advice- any insight into how chemistry works is really helpful.
I had considered the idea that a Shaper could just send parts of their enemy's body into the aether and decompose them. I'm just going to lay down a rule that it's easiest to affect your own body, more difficult to affect things outside your body, and nearly impossible to directly affect another living thing capable of cognition.
I really like the idea of freezing things to gain energy to work with. I've been wondering though- how much energy do you think it would take to force atoms into forming compounds- if any at all. I've read that atoms forming compounds actually releases energy. If that's the case- then how much would it take to rip apart-say- a rock into silicon and whatever else composes it?


Generally speaking forming stuff if you had source material in the form of free atoms would release energy. That said, you never get this because they can so easily combine with things to release energy, so they do so. If you want specific numbers you can generally look them up. Generally speaking you're looking for 'enthalpy of formation', which tells you the change in energy to make something from elemental substances. For instance, the enthalpy of formation for glucose sugar is -1270 kJ/mol, which means that a mole of glucose sugar (about 180g) releases 1270 kJ of energy when formed from H2, O2, and C. This seems counter-intuitive - glucose stores energy - but H2, O2, and C are at a high energy state compared to CO2 and H2O, which is what you get when you burn it. Another way to think about it is, someone who is using your system to make this stuff will likely be using water - they won't have a good source of H2.

In some sense, trying to do this system right is really tricky and bookkeeping intensive. You'll be looking up a lot of stuff rather than spending your time just going with the flow of play. If you want to know, e.g., whether it would take energy to convert a pound of someone's flesh into wax, it'd involve looking up a lot of facts about the composition of human flesh, what kind of wax, etc. I think its easier to basically say 'these common things are high energy, and these are low energy' and don't worry too much about the details of high->high or low->low, just make those free.

High energy stuff:
- Many elemental gasses: F2,Cl2,Br2,I2,H2
- Elemental metals
- Anything described as 'highly reactive'

Middle energy stuff:
- Biological compounds

Low energy stuff:
- Ionic compounds (basically minerals and salt)
- Water, CO2 (combustion byproducts), N2
- Anything described as 'inert'

Actually, if you're ignoring entropy, pretty much any transformation is free since it can be paid either by taking thermal energy from the environment or putting thermal energy into the environment. So it might be a good idea to care about entropy here if you really want people to have to jump through hoops to power this.



How much energy does it take to burn something at 100% efficiency?


It releases energy. When you do this in reality, you need to get the thing over an energy barrier and then its all downhill. Where you end up depends on what barriers your materials are able to cross and how available the necessary stuff is. Real combustion makes a whole bunch of side products that aren't completely broken down because either their energy barriers are higher or because there wasn't enough stuff at the site of the combustion to form the lowest energy stuff (this is related to why things with huge surface areas like flour dust burn better than things that are very dense, like a wood log).

Oh, another couple tricks someone could do in your system: separate dissolved materials from water (costs energy), get elemental metals from the environment really easily - these people would have more aluminum than they could shake a stick at, since its ridiculously common in minerals but very uncommon as an elemental metal, etc. This'd make it pretty good for chemical analysis, at least for inorganic things. You could tell if your soup has arsenic in it because when decomposing it magically there's a little nub of an additional elemental metal, etc.

mrsuspicious
2012-09-12, 12:14 AM
Again, thank you. All of this is better advice than I've been able to get anywhere else. Forgive me for sounding ignorant- I'd just prefer to make as few assumptions as possible and listen to someone who obviously understands this all better than I do.

This system is highly labor intensive. However, my primary concern right now is just figuring out how it would work in a novel, almost. Once I figure out how it actually works, I can build gameplay mechanics off of it.

Entropy has to do with temperatures gradually moving toward equilibrium, correct? Would you mind telling me how this would affect the system if I chose to care about it? I'd like to, if possible.

I'm operating under the assumption that the handling of large amounts of energy and matter in the Aether would be a physically and mentally strenuous task- that would have consequences if done too frequently. I'm thinking semi-permanent intelligence or wisdom damage.

Any other helpful advice for how to make this work would be greatly appreciated.

mrsuspicious
2012-09-12, 12:19 AM
Forgive the... triple pose. :smalleek: Several errors.

TuggyNE
2012-09-12, 02:29 AM
Entropy has to do with temperatures gradually moving toward equilibrium, correct? Would you mind telling me how this would affect the system if I chose to care about it? I'd like to, if possible.

Temperature is one of the more obvious cases of it, yes. However, in general it refers to levels of energy (of various types) becoming equal; because energy is only useful when moving from one place to another, and because this only happens when there's a difference in energy levels between the two places, the capacity to do useful things diminishes. (In a very real sense, the universe is powered by differences, and when those erode away, stuff stops.)

In your system, I'd assume entropy doesn't apply to the alternate magic dimension, but it probably would apply to the portals/whatever to and from that dimension. Consider limiting Shapers by how much energy and/or matter they can manipulate in one go, by the amount of complexity in the reactions they perform, by the precision of their pulling and placing of energy and matter in the environment, and by the amount of initial "borrowing" they can do (e.g., can they break the bonds in, say, cellulose, in order to push only certain atoms through for processing, or do they have to dump the whole molecule through before they can do anything on it?).

There's also the fact that some reactions take quite some time; catalysts (such as enzymes, to name one good example) can often be used to speed these up by factors of a thousand times or more, but are they automatically available, or does the Shaper have to e.g. carry them around? (Hey look, spell components.)

P.S. Click Edit on each of your extra posts in order to be able to delete them.

NichG
2012-09-12, 03:49 AM
A simple example to think about entropy with regards to the whole availability of energy issue:

Imagine you had a number of marbles colored red, and a number of otherwise identical marbles colored blue, and you mix them all together. The idea of increasing (or at least non-decreasing) entropy in the universe is that as the number of these marbles gets higher, the chance that you observe them spontaneously separating into red clusters and blue clusters when you shake them around goes to zero. Instead of marbles, you could think of bits of motion, where the red bits are hot and the blue bits are cold, so the overall temperature is roughly how much red you have to how much blue. If your system allows a mage to point to the thing and the blue and red bits separate, it is allowing your mage to decrease the entropy of the system.

Why this could be a problem: you can use this to create perpetual motion machines. If you're against that idea, its worth keeping in mind. Also, there's a huge amount of basically useless (due to entropy) energy available at all times. Being able to tap that, focus it, etc, means that you can create big effects pretty simply. Move all the heat in a room to a point and you've flash-frozen most of the room, burnt stuff around that one point to a crisp, and you're about to have a devastating pressure wave as the hot point expands into the room. Entropy considerations would make this prohibitive (somehow the caster would have to pay for the effect with an equivalent increase in entropy elsewhere, which means their limits are much closer to what a person could do mundanely by, e.g., building a heat pump and powering it with coal or something).

Why you might not have to care: Let the caster decrease entropy, but make them do it through a sheer act of understanding. There's a thought-experiment in thermodynamics called 'Maxwell's Demon', the idea that if you somehow had a creature that could observe the motion of every atom and open or close a shutter, he could beat entropy by only allowing the fast (or slow) atoms through while stopping the other ones. The trick is, the Demon's task gets harder and harder the more of a difference he creates, as the opportunities to open/close the shutter that would increase the difference become rarer and rarer very quickly. So if the caster's willpower is somehow playing the role of Maxwell's Demon they might be able to create certain anti-entropic effects but they'd eventually be limited by the fact that it would exceed their mental capabilities. Effectively this would mean that a given caster could power a perpetual motion machine of a certain magnitude indefinitely, but couldn't do arbitrarily big things.

mrsuspicious
2012-09-12, 09:40 AM
I like the idea the Shaper's willpower acting as Maxwell's demon. Would it make sense to set a rule in place that says it's easier to draw energy from an actual power source than from the effectively useless energy? There are lots of limitations I've been considering. For example- If the Shaper forgets to specify the source of of an element or a quantity of energy when casting, the component he needs is taken from his body, or the closest source to the him.

Another thing I was wondering though-
As I see it, there would be two ways of drawing energy from, say, a bunch of grass. The shaper could either freeze it, or burn it efficiently. Which would be more effective?
Since the grass would be separated from interference from other elements in the aether, there wouldn't be any fire- so, I guess I'm trying to wrap my head around what the efficient burning of a compound would be like.

Also- how much trouble would it give me to say that Shapers can ignore chemical reactions as long as the energy in the physical world remained the same?

NichG
2012-09-12, 05:55 PM
Another thing I was wondering though-
As I see it, there would be two ways of drawing energy from, say, a bunch of grass. The shaper could either freeze it, or burn it efficiently. Which would be more effective?

This is sort of what I meant when I said this system would be bookkeeping intensive. The answer depends on how cold you let people make something, what material it is, etc.

The total thermal energy of something at a given temperature is its heat capacity times that temperature. To make things worse, heat capacity depends on temperature, so its not even necessarily just a linear relationship. For simplicity, lets assume that grass has the same heat capacity as water, and that we're talking about a kilogram of grass to make the math easy.

The heat capacity of water at standard temperature and pressure is roughly 4kJ/(kg K), which means for each degree Kelvin your shaper can lower its temperature, they're getting 4kJ of energy. Here's where 'how cold do you let them make it' comes in - the human range of temperatures is roughly 273-300K. So lets call that roughly 290K available at any time, which'd mean you could get 1160kJ from your 1kg of grass thermally.

Now as far as burning it, we have to somehow figure out the chemical energy of that grass. For simplicity, lets assume that the grass is entirely cellulose - this is a really bad assumption since there's a lot of water, etc in there, so we're going to overestimate the available energy by a factor of 2. Now we need to do some chemistry though, because we have to figure out how cellulose burns.

Cellulose is a polymer with a C6 H10 O5 monomer. We need to factor this into CO2 and H2O to figure out the energy balance. One cellulose must give us 5 H2O to balance the hydrogen, and 6 CO2 to balance the carbon, which means we need 6 O2 molecules per monomer of cellulose to burn it. Okay, so our shaper grabs some air too.

The enthalpy of formation of C6H10O5 is -733 kJ/mol. The enthalpy of formation of water is -242 kJ/mol (and keep in mind we have five of these to one cellulose monomer), and for CO2 its -394 kJ/mol. So our total energy balance is that we pay 733kJ, but we get back 3574kJ, for a total of 2841kJ/mol of energy released.

One mole of cellulose is 162g, so we have roughly 6 mol of the stuff. So we'd get about 18000kJ by burning it or 1160kJ by freezing it. Now of course, this is assuming grass is pure cellulose. Living plant matter is only about 30% cellulose, so its probably closer to 1160kJ vs 6000kJ. Plus you had to pull in some oxygen to do the burning.

Water has a really high heat capacity - if I did this same thing with iron, for instance, I get a factor of 8 less energy from freezing it. Generally speaking, liquids will be the best for this, especially if you also count the Heat of Fusion (the energy involved in liquid-solid transition). Gasses should have a higher heat capacity I think, but the tradeoff is that their densities are a factor of 1000 lower than liquids generally, so you lose out there.

Oh, by the way, this leads to a very counterintuitive result. Something like a torch flame is a really awful way to get energy if you can just pull thermal energy from the environment, because it basically has almost no density. This is one of those realism things that will frustrate your players to no end, since they'll think 'hey a fire, great place to get energy from!'.

If we say a fire is white-hot, which is something like 2500K, but comprised of gaseous CO2, we can figure out which has more energy - a volume of fire or an equal volume of water at room temperature (~290K).

The CO2 has a specific heat of around 1.5 kJ/(kg K) at those temperatures, but it has a density of 2kg/m^3. Water has a density of 1000kg/m^3. So basically, there is 500 times less CO2 in a given volume than water. The energy per kg of the CO2 is 3750kJ whereas for water its just 1160kJ, but thats only about a factor of 4. So basically, its literally 100 times more efficient to pull thermal energy from a lake to power your stuff than it is to pull it from a bonfire. This is all because you can ignore entropy.

In real life, the bonfire is much better because its hotter than its surroundings so we can use that energy, whereas the lake is roughly the same temperature as its surroundings.



Since the grass would be separated from interference from other elements in the aether, there wouldn't be any fire- so, I guess I'm trying to wrap my head around what the efficient burning of a compound would be like.


What I mean by 'efficiency' is that rather than requiring some kind of process, you're basically saying 'state X has this much energy, state Y has that much energy, so I do X->Y and pocket the difference'. Real processes have wastage, incomplete burning, production of other byproducts than the most efficient ones, etc. 'Burning' here basically means convert fuel + oxygen to CO2+H2O + residue.



Also- how much trouble would it give me to say that Shapers can ignore chemical reactions as long as the energy in the physical world remained the same?

I was assuming thats what you were doing. Otherwise, Shapers don't really do anything at all - if they're reacting things traditionally, you could do it just by putting the stuff together. A 'reaction' isn't really a discrete thing, its a path of least resistance for stuff to move along. If you make things hot enough, nothing respects any sort of single reaction pathway anymore - things just fall apart then fall back together in different shapes when you cool it.

mrsuspicious
2012-09-12, 07:10 PM
I'm beginning to think that accounting for entropy could be a good idea. What considerations would I need to make?- (more in terms of the system itself rather than gameplay )

I also need to know if shapers would be handling huge quantities of energy just to break down small amounts of compounds into their components or to put them back together.

NichG
2012-09-12, 08:47 PM
I'm beginning to think that accounting for entropy could be a good idea. What considerations would I need to make?- (more in terms of the system itself rather than gameplay )


This gets tricky, but the idea would be that a Shaper could only pull from energy gradients, not just 'energy'. A simple way to explain it in terms of the system would be that they have to create a conduit through the Aether along which the energy flows, as well as submit the 'material to be transmuted' to the Aether which will be exchanged for equal material in a different form, using that flow.

So tricks they could still do would be things like instantly balancing out the heat between a hot object and a cold object, or causing stuff to dissolve/diffuse in a liquid much more quickly than should normally happen, or causing ice in a warm room to melt instantly, rather than taking minutes.

It'd also be interesting if they could basically resist this flow somehow, so they could do stuff like suspend a drop of ink in water indefinitely without it diffusing or blending with the water at all.

Mostly you could do it by just restricting the sources that the Shaper can use. Just treat entropy as a sort of 'there is energy here, but it can be very difficult to work with' principle. That leaves you with things that are generally known to be 'energy sources' in real life: heat gradients, gravitational potential (so they could e.g. drop an object through a vertical conduit attached to the earth and harvest that gravitational potential while simultaneously slowing the object's impact), chemical potential (fuel compounds that can be burned, like sugar, flour, gasoline, alcohol, etc), etc.



I also need to know if shapers would be handling huge quantities of energy just to break down small amounts of compounds into their components or to put them back together.

Well thats basically up to you and what you consider to be 'huge'. Heating a pot of water (1kg of water) to a boil is roughly 280kJ of energy, to give you a rough idea of the scale of things. Actually boiling it is a lot more though.

Or to put it in other terms, lets say the caster wanted to feed this process with energy from their own metabolism. One food 'calorie' is actually a kilo-calorie of heat, which is 4kJ or in other terms the energy needed to heat one kilogram of water one Kelvin. So if your Shaper wanted to, e.g., turn water and CO2 into 1kg of grass with energy from their body, it'd cost them something like 1500 food calories to do (so a Shaper who ate twice the normal amount could pull this off once a day).

mrsuspicious
2012-09-12, 09:11 PM
So, in this way, The caster could still potentially use the energy around them, it would just be easier to use something like gravitational potential or a torch? So the Maxwell's Demon thing would be available only to experienced shapers? I really like the freezing things to get energy idea. Perhaps it just gets more difficult the higher or lower a shaper wants to raise the temperature from that of the environment it came from.

Just to clarify: It is more likely that a shaper would have to find a way to deal with excess energy after forming a compound than that a shaper would have to worry about finding a source of enough energy to break a compound into it's components.

NichG
2012-09-12, 11:57 PM
So, in this way, The caster could still potentially use the energy around them, it would just be easier to use something like gravitational potential or a torch?

Gravitational potential is an extremely weak source for these things unfortunately. On the other hand, that means that if you can in fact tap it its easy to, e.g., make a flying machine. It costs 10J to move 1kg up 1m in a gravitational field similar to Earth's. J, not kJ! You might want to prevent Shapers from using gravity unless its their special technique or training, so it does make it easy to stop falls, levitate things, give things huge velocities, etc.

A torch though would be a reasonable energy source.


So the Maxwell's Demon thing would be available only to experienced shapers? I really like the freezing things to get energy idea. Perhaps it just gets more difficult the higher or lower a shaper wants to raise the temperature from that of the environment it came from.


I'd say that yes, it should get more difficult the more you fight entropy. It could be a think where basically entropy is just a soft limit, not a hard limit like energy or matter. The difficulty of a working would be some combination of how complex the final product is plus how much you had to fight entropy to pay for it. Thus, if you can build it with a bonfire its easier than if you have to freeze a lake, but freezing the lake is more potent.



Just to clarify: It is more likely that a shaper would have to find a way to deal with excess energy after forming a compound than that a shaper would have to worry about finding a source of enough energy to break a compound into it's components.

Well, they may more often end up with excess energy, but I imagine thats sort of a good situation for them - they can just discard that energy into the environment without any entropy problems (thats actually the way entropy wants it to go) or they can use it for their next working or whatever.

The exception would be if they want to create high-energy stuff - explosives, acids, other reactive materials. Things at higher temperatures, like if they wanted to exchange lead for molten lead.