Wednesday 3 June 2015

Universe is a computer simulation

The Week

"Whoa." It's the familiar refrain of Neo (Keanu Reeves) in 1999's The Matrix, the celebrated cyberpunk thriller that imagines reality as a grandiose computer simulation. It's also how a few sci-fi fans are reacting to mind-bending new research that suggests the film's conceit might not be so far-fetched after all. Right now, University of Washington physicists are conducting experiments to determine whether or not the universe in which we're living is actually just one, gigantic computer simulation. Here's what you should know:

How could the universe be a computer simulation?In 2003, a British philosopher named Nick Bostrom from the University of Oxford published a highly controversial but widely read paper in which he suggested, says Ray Villard at Discovery News, that "our far-evolved distant descendants might construct such a program to simulate the past and recreate how their remote ancestors lived." Any supercivilization, argues Bostrom, would inevitably create such a program. 
Is that even possible?Well, we already have simulation games like The Sims. But if you're going to reconstruct reality as we know it, you'd have to start at the most basic, fundamental level. Right now, the planet's most advanced supercomputers use a technique called lattice quantum chromodynamics (LQC) to model subatomic particles — stuff like quarks and gluons. In their paper "Constraints on the Universe as a Numerical Simulation," UW physicists argue that a super-super-super-super computer in the future could stack these basic subatomic building blocks together like Legos to recreate anything: Plants, animals, the human brain, oceans, planets, entire galaxies... you name it. Essentially, such a powerful computer could model space-time as a simulation from the Big Bang forward.
How would we be able to tell if we're living inside a computer-generated universe?It's really complicated, but essentially UW researchers suggest that we could be living in an intelligently designed reality they're calling The Lattice. Like all software simulations, The Lattice should contain telltale evidence (or "signatures") that the space-time continuum as we know it was being modeled in some sort of omniscient computer. All you'd need to do was identify these "signatures," says Matt Peckham at TIME, say, "something like a limitation in the energy produced by cosmic rays." At the frayed boundaries of The Lattice, for instance, these cosmic rays would behaved in strange, unexpected ways.
How can we test it?The paper doesn't specify. Physicist Martin Savage, one of the project's researchers, says that if the simulations run long enough, "and have the same laws as our universe, then something like our universe will emerge within that simulations, and the situation will repeat itself within each simulation." In other words, all we have to do is find a simulation within a simulation for evidence that our reality is, indeed, a simulation. You know what that means, says Villard: God could be a computer programmer rather than "a bearded old man living in the sky." Whoa, indeed.