By far the best moment of Recode's annual Code Conference was when Elon Musk took the stage and explained that though we think we're flesh-and-blood participants in a physical world, we are almost certainly computer-generated entities living inside a more advanced civilization's video game.

Don't believe me? Here's Musk's argument in full:

The strongest argument for us being in a simulation probably is the following. Forty years ago we had pong. Like, two rectangles and a dot. That was what games were. Now, 40 years later, we have photorealistic, 3D simulations with millions of people playing simultaneously, and it's getting better every year. Soon we'll have virtual reality, augmented reality. If you assume any rate of improvement at all, then the games will become indistinguishable from reality, even if that rate of advancement drops by a thousand from what it is now. Then you just say, okay, let's imagine it's 10,000 years in the future, which is nothing on the evolutionary scale. So given that we're clearly on a trajectory to have games that are indistinguishable from reality, and those games could be played on any set-top box or on a PC or whatever, and there would probably be billions of such computers or set-top boxes, it would seem to follow that the odds that we're in base reality is one in billions. Tell me what's wrong with that argument. Is there a flaw in that argument?

This came in response to a question from journalist Josh Topolsky, who pressed Musk further. "The argument makes sense," Topolsky said. "But what do you think?"

"There's a one in billions chance we're in base reality," Musk replied. He continued:

Arguably we should hope that that's true, because if civilization stops advancing, that may be due to some calamitous event that erases civilization. So maybe we should be hopeful this is a simulation, because otherwise we are going to create simulations indistinguishable from reality or civilization ceases to exist. We're unlikely to go into some multimillion-year stasis.

In this answer, Musk is repeating one of my favorite thought experiments. It comes from philosopher Nick Bostrom's aptly titled paper "Are You in a Computer Simulation?" You can read the whole thing here, but the core is more or less as Musk describes it:

One thing that later generations might do with their super-powerful computers is run detailed simulations of their forebears or of people like their forebears. Because their computers would be so powerful, they could run a great many such simulations. Suppose that these simulated people are conscious (as they would be if the simulations were sufficiently fine-grained and if a certain quite widely accepted position in the philosophy of mind is correct). Then it could be the case that the vast majority of minds like ours do not belong to the original race but rather to people simulated by the advanced descendants of an original race. It is then possible to argue that, if this were the case, we would be rational to think that we are likely among the simulated minds rather than among the original biological ones. Therefore, if we don’t think that we are currently living in a computer simulation, we are not entitled to believe that we will have descendants who will run lots of such simulations of their forebears. That is the basic idea.

The argument basically resolves down to three options, which Wikipedia summarizes thusly:

"The fraction of human-level civilizations that reach a posthuman stage (that is, one capable of running high-fidelity ancestor simulations) is very close to zero," or "The fraction of posthuman civilizations that are interested in running ancestor-simulations is very close to zero," or "The fraction of all people with our kind of experiences that are living in a simulation is very close to one."

Musk is picking the third option here. It's worth noting that Bostrom doesn't share Musk's confidence. He's said that he doesn't see any obvious way to choose between the three options:

If (1) is true, then we will almost certainly go extinct before reaching posthumanity. If (2) is true, then there must be a strong convergence among the courses of advanced civilizations so that virtually none contains any relatively wealthy individuals who desire to run ancestor-simulations and are free to do so. If (3) is true, then we almost certainly live in a simulation. In the dark forest of our current ignorance, it seems sensible to apportion one’s credence roughly evenly between (1), (2), and (3).

This is a fun paper, and it's led to lots of debate. If you want to dive deep into it, head to the simulation argument website, and you can spend days digging into the debate. For what it's worth, I side with critics who think the three options aren't actual exhaustive: I don't see a reason to believe that even very advanced civilizations will manage to easily simulate consciousness.

But that's just what a simulated consciousness who believes he's a special participant in base reality would say, isn't it?

You can watch the whole exchange here, beginning at about the 1:14:00 mark: