This article from the NY Times (link is good at the moment, though I’m not sure it won’t disappear behind some paywall at some point and be inaccessible) covers the sufficiently weird theory/philosophy proposed by Nick Bostrom that we are likely (actually, almost mathematically certainly) living inside a computer simulation.

("Living" wouldn’t quite be the correct term, of course.)

It’s a theory I’ve encountered before, though the NY Times does a good job of simplifying it and squirting it out into the public consciousness:

You couldn’t, as in “The Matrix,” unplug your brain and escape from your vat to see the physical world. You couldn’t see through the illusion except by using the sort of logic employed by Dr. Bostrom, the director of the Future of Humanity Institute at Oxford.

Dr. Bostrom assumes that technological advances could produce a computer with more processing power than all the brains in the world, and that advanced humans, or “posthumans,” could run “ancestor simulations” of their evolutionary history by creating virtual worlds inhabited by virtual people with fully developed virtual nervous systems.

Some computer experts have projected, based on trends in processing power, that we will have such a computer by the middle of this century, but it doesn’t matter for Dr. Bostrom’s argument whether it takes 50 years or 5 million years. If civilization survived long enough to reach that stage, and if the posthumans were to run lots of simulations for research purposes or entertainment, then the number of virtual ancestors they created would be vastly greater than the number of real ancestors.

There would be no way for any of these ancestors to know for sure whether they were virtual or real, because the sights and feelings they’d experience would be indistinguishable. But since there would be so many more virtual ancestors, any individual could figure that the odds made it nearly certain that he or she was living in a virtual world.

I don’t know about this "virtual ancestors" scenario necessarily—I mean, why not just run a simulation for the heck of it, a là The Sims or something? The author considers that:

And if owners of the computers were anything like the millions of people immersed in virtual worlds like Second Life, SimCity and World of Warcraft, they’d be running simulations just to get a chance to control history — or maybe give themselves virtual roles as Cleopatra or Napoleon.

Anyway. I followed this up by finding Simulated reality on Wikipedia, which contains a rundown of Bostrom’s theory as well as broad coverage of others. Interesting stuff, and it got me thinking as to how one would go about determining whether one lives in a computer simulation.

(As a start, consider how one might determine whether or not one is dreaming. After all, dreams are a type of simulated reality, no?)

Of course, it all hinges on whether or not consciousness itself is a computable phenomenon. I’m a little torn on that question; I certainly think the brain is a computational entity of some sort—Steven Pinker’s How the Mind Works is an excellent book, by the way—but does that make consciousness computable as well, or something more? Or is it merely an illusory side-effect of some process? Or is it ultimately indeterminable?

From a science fictional standpoint, I like the idea of the brain being an advanced quantum computer of some sort, with whatever wackiness extending from that. That’s probably neither here nor there, but I just wanted to throw that out there.

Hmmm… I guess it doesn’t all hinge on the computability of consciousness.

Would the simulations (ie, us) becoming aware that they are a simulation qualify as becoming "self aware" in the "real world"? I mean, we have a term for it when a computer program does: Strong Artificial Intelligence. (Okay, that’s theoretical too, since we don’t currently have Terminators or a Data running around.) Does "self awareness" count if it’s only theoretical and there’s no way to prove it?

Good thoughts. Random, but good.