Tesla and SpaceX CEO Elon Musk. Mike Windle/Getty Images for Weinstein Carnegie Philanthropic Group Tesla and SpaceX CEO Elon Musk has spent so much time debating whether or not we exist in some advanced civilization's video game that he had to vow to stop discussing the topic in hot tubs.

The popular hypothesis is that we human beings are unwittingly just the characters in someone else's computer simulation.

"I've had so many simulation discussions it's crazy," Musk said on stage at Vox Media's Code Conference Wednesday night. "In fact, it got to the point where basically every conversation was the AI slash simulation conversation and my brother and I finally agreed that we'd ban any such conversations if we're ever in a hot tub. Because that really kills the magic."

Although he concedes that "it's not the sexiest conversation," he presented and defended his answer. He believes that there's only a one-in-billions chance that we're in "base reality" instead of a simulation. And if we are actually experiencing reality, that should make us nervous about the future of human kind.

Here's his reasoning in full:

The strongest argument for us probably being in a simulation is the following: 40 years ago we had Pong — 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. And soon we'll have virtual reality, augmented reality... If you assume any rate of improvement at all, then games will become indistinguishable from reality. Even if that rate of advancement drops by 1,000 from what it is right now. Then you just imagine 10,000 years in the future, which is nothing in the evolutionary scale. So it's a 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 a PC and there would probably be billions of such computers and settop 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?

He also explained why we should probably be pretty nervous about the future if we're not in a simulation:

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

Watch the whole interview here (and tune in at 1 hour 15 minutes in to hear his thoughts on simulations):