Is the whole universe one big computer program? Nobody really knows. But if you read
some news stories this week you might be excused in thinking we've got it all sorted out. Many news outlets reported on a scientific article recently published in the journal Science Advances as proof that our universe is not a simulation. However, the truth is a little more complicated.
For decades, researchers have been trying to use computers to simulate quantum systems. If scientists could learn how to create functional systems of quantum particles, it would be much easier to study how they behave. In particular, if scientists can simulate a quantum computer using a standard computer, there would be no need to build actual quantum computers in the first place. This would save a lot of people a lot of time.
Now, chances are we can't simulate complex quantum computers with regular computers. There's a reason we've spent years trying to build real-life quantum computers, after all. But it's difficult to prove that quantum computers are really necessary, which is what the study's authors were trying to do. So the researchers took an easier path, simply proving that one of the most common techniques for simulating quantum particles—quantum Monte Carlo—is not enough to simulate an entire quantum computer.
This is an important result, and it means there's a good chance that simulating a quantum computer is completely impossible, which is what scientists suspected all along. If we're going to study quantum mechanics using quantum computers, we're going to have to actually go and build one. Which, again, we were doing anyway, but it's nice to be sure we're not wasting our time.
So what does this have to do with the universe being a simulation? Well, nothing, which is the point. That wasn't the question the researchers set out to solve, so to claim they answered it by showing that our universe if far too complex to be simulated is a bit presumptuous. In fact, there's a pretty good chance we'll never find out if our universe is "real" or not, so it's probably not worth worrying about. The universe is real to us, and that's all that matters.
http://www.popularmechanics.com/science/news/a28505/scientists-dont-prove-were-not-living-in-a-simulation/
