Monday, August 13, 2007

Sims R Us

An interesting update on the idea familiar to every reasonably bright 11-year-old: What if our world and everything in it, including me, is just part of someone's dream? How would we know? Would we know? Would it make a difference?

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.

We couldn't tell we were part of a simulation, unless very subtle errors were introduced and clues left to point us toward them. But what sort of inconsistency/error in our observed world leads to the inescapable conclusion "The universe is actually a simulation"? Some oddness in the binary expansion of pi, as hypothesized in Contact? No, not really... the law of large numbers demands that if you follow pi out far enough, and its digits are essentially random (as they appear to be, though there are some interesting properties that no one's quite explained, such as why the digit 5 doesn't appear quite as often as it should)....sooner or later, you're going to get some whopping big coincidences, that not having whopping big coincidences would itself be extremely unlikely. Including something that could be interpreted as ASCII if you looked at it right.

And that's the issue. Strictly speaking, it's not a scientific hypothesis, since there's no way to disprove it. It's an interesting bit of logic, but ultimately one possibility among many:

But there are a couple of alternative hypotheses.... One is that civilization never attains the technology to run simulations (perhaps because it self-destructs before reaching that stage). The other hypothesis is that posthumans decide not to run the simulations.
To draw a comparison: Suppose I spend the evening playing Sims. To whatever extent they're "real," would knowing they're in a simulation make their immediate wants any less "real" to them? If they knew they were just data files and onscreen renderings, would they have a crisis of faith? Suicidal despair? Not likely.

If I turn out to be a sim in someone else's game...what difference does it make when I get up in the morning? What do I do differently, knowing I'm a sim? It may only be a simulated job and a simulated apartment, but it beats sleeping on the simulated streets.

Update: Someone's already been giving some thought to how to live as a simulation.

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