Are we just a bunch of simulacrums living in a massively computer-generated universe? If so, would there be a way to check?

Reuters

I’ve started making my way (skeptically) through Ray Kurzweil’s How to Create a Mind, and at the recommendation of a friend, I’ve also started keeping tabs on KurzweilAI, a Kurzweil-blessed site devoted to futurism coverage — everything from the latest 3D printer tech and anti-cancer drugs to brain-based pacemakers and “exploding killer plasmonic nanobubbles.”

This morning, I noticed a story that sort of coincides with one I wrote a couple weeks ago about our brains, the Internet and the universe. Does the possibility that the universe is structured like an extremely complex network — that our brains and the things we create with them, like the Internet, may resemble the universe’s underlying structure — also imply that we exist in an incomprehensibly sophisticated computer-like simulation?

“You take the blue pill, the story ends, you wake up in your bed and believe whatever you want to believe,” says Laurence Fishburne’s character Morpheus in that eminently quoted scene from The Matrix. “You take the red pill, you stay in Wonderland, and I show you how deep the rabbit hole goes.”

University of Oxford physics professor Nick Bostrom wasn’t the first person to suggest reality could be computer-fied — the idea’s been around since I was a kid, at least, reaching a kind of pop-cultural critical mass in the Matrix films — but he may have been the first to take a stab at a “red pill” explanation, laying out his theory in an actual paper published in 2003. Call it another version of the strong anthropic principle, except the universe’s catalyst would in this instance be an advanced civilization running an unfathomably sophisticated massively multiplayer, um, cosmos game.

In his paper, Bostrom argued that at least one of the following things must be true:

(1) the human species is very likely to go extinct before reaching a “posthuman” stage; (2) any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history (or variations thereof); (3) we are almost certainly living in a computer simulation.

That third point is almost surely true, argues, Bostrom, if the first and second points prove false. So if we actually survive to a “posthuman” stage (the so-called “singularity,” or point at which it’s assumed machine intelligence will transcend human), and assuming that we can’t help ourselves — that designing and running what Bostrom calls an “ancestor simulation” is ineluctable — then, according to Bostrom, we’re almost certainly living in a computer simulation created by an advanced civilization. (Don’t faint or anything, though I guess fainting would be simulated, too.)

How do you test for something like that? Can you? Bostrom argues that we’ll know his third claim is true if we’re ever able to create an ancestor simulation ourselves (in other words, not for a really long time). But a group of University of Washington researchers has suggested there may be a way to start testing soon if we want to verify Bostrom’s supposition.

Start with the assumption that we’ll actually be able to simulate the universe, or small portions of it, perfectly someday — a pretty big assumption, since we’re still trying to reconcile disparate physical and cosmological theories like quantum mechanics and general relativity, to say nothing of Stephen Hawking’s and Leonard Mlodinow’s idea in The Grand Design that “ours is just one of many universes that appeared spontaneously out of nothing, each with different laws of nature.” (In fact most days, we’re lucky if we’re getting the weather right.)

But according to University of Washington physics professor Martin Savage, we could test our universe for computational artifice by looking for the sort of “signatures” you’d find in current-day simulations. Supercomputers currently use a technique called lattice quantum chromodynamics (LQC) to model aspects of physical reality, say molecules, or quarks and gluons. If our universe were crafted from a lattice-driven simulation, we ought to be able to find evidence of the underlying, interlacing imprint.

According to the UW summary, supercomputers using LQC chop space-time into a four-dimensional grid, which allows researchers to inspect something called the “strong force” — one of the four building-block forces (along with electromagnetism, the weak force and gravity) that hold subatomic particles together.

“If you make the simulations big enough, something like our universe should emerge,” says Savage.

At that point, you could start poking around, looking for a “signature,” say something like a limitation in the energy produced by cosmic rays. According to a paper posted by the researchers titled “Constraints on the Universe as a Numerical Simulation,” in which the participants state they “have taken seriously the possibility that our universe is a numerical simulation,” they note that the simulation might reveal itself if it turned out that cosmic rays behaved in unexpected ways at the boundaries of the lattice.

“This is the first testable signature of such an idea,” adds Savage.

So when can we run the test? The paper doesn’t say. It only notes that several elements necessary to simulate our universe “have not yet been established.” Bummer. But assuming the universe is finite, the team argues that since the resources of potential simulators would have to be finite, “a volume containing a simulation will be finite and a lattice spacing must be non-zero.”

In other words, given all of that, “there always remains the possibility for the simulated to discover the simulators.”