Dude, What if This is All, Like, An Illusion?

by on August 15, 2007 · 6 comments

I normally love John Tierney’s work, but boy is this silly. “Man, what if, like, we’re not real, man. What if we’re just a computer simulation like on the Matrix?” Beyond the dorm-room-bull-session character of the whole premise, the argument doesn’t make any sense:

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.

It might be true that at some point we’ll have the computing power to run precise, molecule-by-molecule simulations of the human brain. But that doesn’t really get you where Bostrom wants to take us. What he wants is a molecule-by-molecule simulation of the entire universe, or at the very least of the entire surface of Planet Earth. Human brains don’t exist in isolation. Their development is intimately shaped by their interaction with the real world. To develop a realistic simulation of the brain, you need a realistic simulation of the world the brain interacts with.

And accurately simulating any given system requires a computer system at least as complex as the system being simulated. We’re only able to simulate things like the weather and car crashes because we make assumptions that radically simplify our models. But that, of course, makes the details of their predictions wrong, especially over long time frames. That’s why weather predictions further out than 10 days are worthless. If you’re trying to simulate a long-term process like the evolution of human society, such radical simplifications wouldn’t be acceptable. If virtual Milikan performs his oil-drop experiment, the simulation had better be detailed enough to keep track of individual electrons, or the physicists of your virtual world will be very confused, and the “science” of our virtual world will evolve in a very different direction.

So an accurate simulation of the world would have to be roughly as complex as the world itself. And since any given computer will presumably only be a small part of the world, the maximum complexity of the worlds it can simulate will necessarily be far simpler than the real world the computer occupies. So while I suppose it’s possible we’re being simulated by a computer in a mind-bogglingly more complex universe, the more plausible explanation is that we’re in the “real” world, whatever that means.

Did the New York Times really just print that?

Update: Tom Lee had almost exactly the same reaction. Although he’s obviously cooler than me, as his college students had a dime bag in addition to their copy of The Matrix.

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