It took Alynn two days to escape the villagers, her would-be killers. Two days - the same amount of food she'd taken in her rush to escape.

Being magical was all very well, but its reliance on her eating was sometimes annoying. Getting food might not be a problem, but if she couldn't find enough she wouldn't have as much energy the next day - then even less after that.

Now, stuck in the Chiral Forest five days away from the nearest friendly town, Alynn felt doom impending: how could she keep going?

Alynn's back! Last week I asked about the scientific principles behind her magic. The answers there confirmed the viability of what I'd come up with. Alynn has magical energy, which she can use, converting with 100% efficiency, on any task she can think of.

The amount of energy is dictated by how much she eats: she gets half a Calorie's worth of magical energy (2000J) for every Calorie she eats. This means, on a normal day, she'd end up with about 4MJ of energy.

Now, she's stuck. Five days away from her target, where she'll try to start her life again, she's out of food and water, and has no shelter. And no experience with this sort of thing: while she can kill animals easily, they run away because they hear her coming; and she couldn't tell the difference between a sloe berry and a deadly nightshade berry.

How can she keep herself walking? This is the first day, so you have 4MJ to spend on getting her enough food, water, and shelter to get to the next day. After that, she'll have the energy you gave her in that consumption.

Her energy can be used for pretty much anything - apart from creating matter. She can synthesise things apparently out of thin air by finding the correct molecules (yes, her brain can do this) and reacting them to form the correct compounds, but only if she can make the correct conditions for the reaction. She cannot create new atoms or molecules.

Also note, if she creates an exothermic reaction, she won't absorb any energy from it (or any other energy source for that matter).

  • $\begingroup$ What sort of landscape is she in? $\endgroup$ – Samuel Apr 30 '15 at 21:29
  • $\begingroup$ @Samuel - thanks for the edit, I couldn't work out which it was - forest (the story part is meant to convey that but perhaps doesn't do that good a job of it...) $\endgroup$ – ArtOfCode Apr 30 '15 at 21:32
  • $\begingroup$ Ah, yes my mistake, the racemic forest ;) Would that be like a regular deciduous forest? $\endgroup$ – Samuel Apr 30 '15 at 21:36
  • $\begingroup$ @Samuel - probably a more mixed deciduous/coniferous forest $\endgroup$ – ArtOfCode Apr 30 '15 at 21:37
  • $\begingroup$ Actually, I don't think you need to simply ban creating matter, just apply the standard energy cost $E=mc^2$ to creating matter. $\endgroup$ – March Ho May 1 '15 at 5:16

She can eat wood.

Presumably she won't know how to create her own cellulase, but by finding some termites she can either observe how they do it (assuming she can also observe things on the molecular scale) or she can gather the cellulase from them. She can also eat the termites.

Humans wouldn't need significant modification to digest cellulose (wood/plant matter). By using cellulase to help break down the cellulose, she will be able to extract more energy than she puts in, a net positive. Water would be liberated from the plant material during digestion.

Surviving for five days in the forest is actually not too hard for regular people. Her abilities will just allow her to come out much stronger than a regular person might. She can still forage berries, drink from streams (she can boil it to destroy the parasites, ~80 Cal/liter), and eat other (non-colorful) bugs that she finds.

Additionally, to further optimize her own energy usage she can make other slight modifications to her body while she's in escape mode. Like turning off hair and fingernail growth (might save 10 Cal a day) and slightly lowering body temperature during the day.

  • 1
    $\begingroup$ Fun fact - eating tree bark requires no magic to be effective. Well-known fact to survival types and anyone who read the survival manuals in the military. $\endgroup$ – Sean Boddy May 1 '15 at 4:34
  • 1
    $\begingroup$ @SeanBoddy Fun correction - only certain types of tree bark are edible, a well-know fact to anyone who read the article you linked :) Also note that bark is not wood. $\endgroup$ – Samuel May 1 '15 at 4:53
  • $\begingroup$ Certainly. Typical persons wouldn't eat the wood, and as you are suggesting, she could manage it. I merely wished to point out this fact to persons running across this. $\endgroup$ – Sean Boddy May 1 '15 at 5:14
  • $\begingroup$ @SeanBoddy Good to know, I certainly didn't consider it before. $\endgroup$ – Samuel May 1 '15 at 5:16
  • 2
    $\begingroup$ Actually this sounds like a fun thing in and of itself. Like a day in the life of Radagast the Brown or something. There's a book in there somewhere. $\endgroup$ – Sean Boddy May 1 '15 at 5:20

This is really, really easy unless Alynn doesn't know very much about how to use her magic or about the natural sciences. If you want to make it a challenge, you'll need to decide what she doesn't know (once you learn more yourself than she would know).

Firstly, as has already been pointed out, Alynn doesn't need food to survive, just water, and maybe not even that (depending on the weather). There are plenty of cases of people lasting far longer. As long as she didn't get lost (she might), and didn't waste too much time searching for food she couldn't find, she'd be okay.

But there are much better opportunities than that. She can use her energy to replenish her cellular ATP stores. Turns out that human metabolism is only about 40% efficient. If she gets 50% more from magic, she can cut her food consumption in half just by regenerating her own ATP, or power herself for more than one extra day from the stored energy alone.

But then, why is she walking? Walking isn't very efficient. Cyclists going 20 mph (over 5x walking pace) use only about 100W to overcome air resistance. If she can perform any sort of levitation (and how could she not, being able to move molecules so easily?), her 4 MJ would let her travel for some 40,000 seconds at 20 mph, giving her a range of some 220 miles. I suppose she can't use this, though, or she'd have lost her pursuers in a few minutes instead of two days.

So suppose she wants to hunt. Animals don't do very well without oxygen; all she needs to do is pull the oxygen away from an animal and wait for it to collapse. Or she could depressurize the sky around a flying bird, and go pick it up after it crashed to the ground.

But you don't even need to go after animals. Trees have sugar in them; pull it out and eat it. You can get water from trees, or from the soil. Even bacteria use sugars and fats to store energy; if you can manipulate molecules you can summon hunks of fat, sugar, and water right out of the bacteria in the soil. Or, since forests have high humidity, just pull water out of the air.

So this isn't an issue, really, of what's magically possible with this kind of magic. It's an issue of what Alynn's limited knowledge and experience allow her to do. And there, the best choices are ones that fit with other parts of her story.


My initial thought was that: Well five days? Just keep going. Spend as little magic as possible.

Especially on food she would spend as little as is bearable. Given the amount of energy of (bodily) fat (40 kJ/g) she will lose only a few pounds along the trip.

Water is a little more tricky as it is not that simple to go without. Two approaches come to mind: 1) minimize loss of water (think Dune's Stillsuits) but making one of those with just 4 MJ seems a little tricky (maybe do the math later). 2) don't try to use your magical energy to directly "make" water, use magic only as leverage to find naturally existant water. I'd like to suggest to "make it rain" but I'd assume that the energy needed to do so would be prohibitive. But then again maybe the climatic conditions are not that bad to assume that potable water might be found with little effort.

Also summon a kind of shelter the first night that is easy to carry along (think rescue blanket) and be used repeatedly without resorting to magic. And while she's at it summon the "Ten Essentials" all along: at least a knife and matches would be great to have non-magical tools at hand. And according to the rules "summon" would mean to transform nearby and existing materials to something useful. (But it is really hard to put some numbers on those processes without making some awefully long-winded guesses.)

One final thought. As stated Alynn is not exactly the Ranger-kind-of-a-gal. So she is not knowing anything about how to survive in the wilderness and not knowing what berries to eat. It therefore seems prudent to get herself some help... and while conjuring a little helper seems out of the game given the restrictions in available energy it could be possible to influence existing creatures to be helpful towards her? Say "mindtrick" a wolf or an eagle into supplying her with some game? While she's at it she can also literally depend on the eagle's eyes to watch out for her chasers. In that case make it an owl for superior night vision.

  • $\begingroup$ Directly condensing water (40kJ/mol) from humidity gives you approximately 1.8 L of water per day on 4MJ $\endgroup$ – March Ho May 1 '15 at 5:22

Five days is easy for anyone who knows two simple rules - stay warm, and drink water.

A person who does not follow these rules can die in less than 24 hours of hypothermia in surprisingly temperate environments due to simple evaporative cooling. Day one, first thing, she needs to reinforce her wardrobe with anything she can find, get, or make. At night, even if it's unsafe to sleep, she needs to stop moving and take whatever shelter she can find or build. This should be pretty easy for a mage, and so should starting a fire - this would have a relative caloric gain by reducing the amount of energy required to maintain the body's core temperature.

As far as water goes, Alynn has the unique advantage of being able to simply extract what is needed from nearby plant life - this would be far, far simpler than attempting to manufacture it. Large trees can transpire 100 gallons in a day, so its safe to say that, unless these trees are all dead, there is sufficient water nearby - especially so for someone who can manipulate atomic interactions.


Everyone knows the three Requirements of survival. Shelter, food, and water. Being in a deciduous/coniferous forest it means that the trees drop whatever is no longer needed, leaves, branches, pine cones, this generally makes a covered floor which will house a large amount of edible bugs and grubs. As long as she can get by the 'ick' factor food is no trouble at all. Sh can find these under large piles of leaves or in dead logs the the forest drops. Now she may not understand this since she has never been in this type of situation before but she would know that she needs shelter and she needs water.

One way of addressing it since it has already been determined she can use magnetic fields IS the Raizen's Method http://www.utexas.edu/opa/blogs/research/2010/04/26/atom-stopper/

Using this method she could slow the atoms in a Tree trunk effectively freezing the water in the trunk itself. When the water freezes in the trunk it expands and often will explode felling the tree, Providing shelter. Increase the area of the magnetic field and it will generate frost on the leaves which can also be used to drink like ice chips. The generation of the magnetic fields would be a restrictive field instead of a propulsion field and would require the same amount of energy to stop a copper bullet. The difference here is that it needs to be constant for a period of time instead of instant. This prevents other atoms from exciting the encased atoms in which they will eventually slow.


Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.