The odds that we are not living in a simulated universe is "one in billions," said Elon Musk, CEO of SpaceX and Tesla Motors, at the Code conference in California last night.

Musk's logic that we're living in a simulated reality is predicated on the advancements in technology that we've seen over the last four decades. "40 years ago we had Pong; two rectangles and a dot," Musk said. "Now 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 1000, then it might happen 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 PC, and there would probably be billions of such computers, it would seem to follow that the odds we're in base reality is one in billions."

Musk, perhaps unsurprisingly, admitted that he has spent a lot of time pondering the topic of simulated reality. "I've had so many simulation discussions it's crazy," Musk said in response to a question from the audience. "It got to the point where nearly every conversation was the AI/simulation conversation, and my brother and I finally agreed that we would ban such conversations if we were ever in a hot tub."

Musk previously answered questions about simulated reality at a Vanity Fair conference in 2015, and the creator of No Man's Sky said earlier this year that the game's verisimilitude to reality led Musk to ask him: "What're the chances that we're living in a simulation?"

There are a few variations of the simulated reality hypothesis, but they generally go something like this: the universe we're living in right now isn't actually base reality. Instead, everything in our universe is being simulated by a very powerful computer, perhaps by another civilisation with sufficiently advanced technology. But of course, that advanced civilisation itself might also exist inside a simulation; it could be simulations (or hive-mind hallucinations?) all the way down.

In theory it would be quite easy to tell if we're in a simulation—there could quite literally be a glitch, like in The Matrix. Of all the alternate universe/reality hypotheses, though, simulated reality is probably one of the least psychologically and scientifically worrisome. The biggest risk is that the advanced civilisation (or one of the advanced civilisations in the chain) shuts down the simulation, ending our existence. But there probably isn't anything we can do about that, so why spend time thinking about it?

Remember, if your brain ever starts down that worrying "WHAT IS REALITY??!?!" path, you should always fall back on the most soothing of philosophical propositions: Cogito ergo sum. I think, therefore I am.

Listing image by Warner Bros.