So I'm still reading Richard's Book. On pp. 329-342, he talks about the physics of virtual worlds. One thing he makes clear (that we non-devs frequently forget) is how challenging it is to code reality in a way that bears any similarity to the physical world we all know and love. Virtual worlds are not made of atoms and molecules, but are generally assembled with discrete software "objects" (in the programming sense of that word) that interact with each other and have specific properties. Modeling reality by way of such objects poses some interesting challenges.
As Richard says:
Given that virtual objects are, on the whole, intended to exhibit behaviors at the physics level that are consitent with reality, it might be expected that there are common problems that recur whenever some particular aspect or other of reality is considered. This is indeed the case: Some facts of reality are easy to implement and others are downright impossible.
So when you're modeling real objects, what's easy and what's impossible?
Well, it turns out that coins, bricks, and keys are easy. However, xylophones, water, fire, and decks of cards are hard. Why?
Assemblies like xylophones pose problems because players are tempted to break down these assembled objects into component pieces. To do this, one would need to make each object consist of multiple sub-objects capable of disassembly and reassembly. Decks of cards are assemblies too (one only has a deck when one has 52 cards). Bags, Christmas trees, and hat racks, it turns out, are not too hard to model and actually they have something in common -- they are all containers. Bags are endocontainers, enclosing what they hold, whereas Christmas trees and hat racks are exocontainers, "wearing" the things they hold. (I'm afraid I will never look at a Christmas tree again without thinking of exocontainers -- thanks a lot, Richard...)
But the real messiness starts with liquids, gases, and plasmas. What happens when your avatar puts sugar in a bowl of water or dips an apple into honey? Even if we program the honey to get stuck on the apple and slowly drip off the apple, Richard notes that this will surely lead to a player wondering (at some juncture) why honey drips off kittens at the same rate it drips off apples. And fire is just full of problems, e.g., if your avatar applies fire to trees, how does this affect the tree objects constituting the forest? If you apply fire to water, will you get steam?
What is interesting here is not the fact that this "object problem" exists (it's actually a lot of fun for us that don't have to grapple with it), but the fact that that it exists as a "problem" per se. It reveals how one of the goals of a contemporary virtual world designer is to struggle to replicate reality in a convincing way, presumably down to the nitty-gritty modeling of the adhesion and viscosity of honey on furred surfaces. Reuben Klamer certainly didn't stay up at nights wondering how to make the blue pegs and the pink pegs more accurate representations in the Game of Life. But part of the appeal of virtual worlds is that they are so immersive and realistic -- the general obedience to the expectations and rules of reality means that breaking them (e.g. by flying or casting great balls of fire) is all the more fun.
Of course, as Richard suggests, reality in all its glory can never actually be modelled (which is why we'll never be able to accurately forecast the weather). So the pursuit of virtual realism must ultimately end in failure or only partial success. Statues will only come to life in Greek Myths and science fiction. And even in the virtual world genre, there are alternatives to the reality fetish -- Ludicorp's The Game Neverending is the one that comes most readily to mind.
For the most part, though, we're still in an era where verisimilitude is a common goal. If one sees virtual world design as an art form, this is somewhat interesting. In fine art, this moment essentially passed after the time of Durer's rabbit (though it resurfaced, to some extent, with the Pre-Raphaelites, the photorealists, and contemporary realism). I wonder how long virtual worlds designers will pursue verisimilitude? At what point (if ever) will Picassos and Rothkos of virtual world design predominate?