Many futurists and science fiction writers are adherents of the theory that we're heading towards "Vearth," a state where the entire world is essentially replaced by a giant virtual reality made of "computronium." (Computronium is Charles Stross' jokey term for matter that's optimized for computing.) You see this fantasy cropping up in movies like The Matrix, where the world of 1999 has been completely replaced by a computer simulation; and in countless novels ranging from Greg Bear's Blood Music to Rudy Rucker's latest Postsingular. Now Rucker himself is railing against this idea of Vearth, in a terrific essay on why virtual reality will always suck compared to the real thing.
Rucker, a retired mathematics professor, says, "We tend to very seriously undervalue quotidian reality." He then goes on to scold the starry-eyed futurists who predict smashing up the real world to make way for a virtual world as varied and granular as the one we live in now:
I might ask why someone would passionately want to believe that we can be translated from flesh into bits? There's something ascetic and life-hating about the notion. It's a bit like a religious belief; one thinks of the old "work now, get rewarded in heaven" routine.
We know that our present-day videogames and digital movies don't fully match the richness of the real world. What's not so well known is that computer science provides strong evidence that no feasible VR can ever match nature.
This is because there are no shortcuts for nature's computations. Due to a property of the natural world that I call the "principle of natural unpredictability," fully simulating a bunch of particles for a certain period of time requires a system using about the same number of particles for about the same length of time. Naturally occurring systems don't allow for drastic shortcuts . . . Natural unpredictability means that if you build a computer sim world that's smaller than the physical world, the sim cuts corners and makes compromises, such as using bitmapped wood-grain and cartoon-style repeating backgrounds. Smallish sim worlds are doomed to be dippy Las Vegas/Disneyland/Second Life environments . . .
Come on, if you want to smoothly transform a blade of grass into some nanomachines simulating a blade of grass, then why bother pulverizing the blade of grass at all? After all, any object at all can be viewed as a quantum computation! The blade of grass already is an assemblage of nanomachines emulating a blade of grass. To the extent that you can realize an accurate VR world, the exercise becomes pointless.
Fundamental Limits to Virtual Reality