In case you haven’t read Philip Pullman’s His Dark Materials, or seen the movie The Golden Compass, or even seen the trailer, a quick recap:
In the world where Lyra, the protagonist, lives, everyone has a dæmon, a sort of external soul, which takes the form of an animal. Children’s dæmons can change shape at will (they take a permanent form at puberty). Dæmons are also intelligent (since they’re really a part of the human they’re attached to).
So as I’m rereading His Dark Materials, a question started nagging at me: what would vending machines in Lyra’s world look like?
Obviously, most vending machines we have in our world wouldn’t work: the one on my floor at work has a flap which you push open to pick up the snack. But pushing this flap raises another, which blocks the way up toward the unpurchased snacks. In Lyra’s world, a child could open the flap, let her dæmon change to a sparrow and fly into the dispensing bin; then lower the flap, clearing the way so that the sparrow-dæmon can fly up and retrieve bags of potato chips and whatnot.
So vending machines would need to be more elaborate, so that there is never a path from the outside to the snacks. Perhaps something like a lazy susan with wedge-shaped spaces through which the snacks are dispensed.
The mechanism should also be one-way at all times: if buying a snack opens up a path to the inside, then a child might buy one bag of chips and use the opportunity to slip her dæmon inside the machine, where it can then steal other snacks.
Presumably a good engineer might be able to come up with something, even if I can’t. But another problem raises its head: no mechanism is foolproof, and children will try all sorts of weird things. So there’s a risk that a child’s dæmon might get inside the machine and be unable to come out. In Lyra’s world, being more than a few feet from one’s dæmon is painful, so a child whose dæmon got trapped this way would effectively be stuck.
One possible solution would be to have a trap door by which the dæmon could exit, perhaps one that opens only from the inside, or which opens only when a button inside is pressed at the same time as one on the outside. But of course this reintroduces the problem of theft: if the dæmon can get out, so can snacks.