Do We Live In A Simulation? Elon Musk Thinks So, Here's Why

Just Elon Musk's name is enough to evoke an emotional response in many people, ranging from hope and glee in some to anger and disgust in others. But how about existential dread? It's true that one of Musk's primary drivers in founding SpaceX — his spacecraft manufacturing and launch company — was to create a self-sustaining colony on Mars. This lofty goal would make humanity a multiplanetary species, thereby reducing the risk of human extinction from global catastrophes such as pandemics, nuclear war, or asteroid impacts. But there's another threat Musk is concerned about that can't be evaded anywhere in the universe, from Mars to the Andromeda Galaxy: the fact that we could be living in an enormous computer simulation.

That's right, Elon Musk suspects that he himself — along with you, everyone you know, and indeed the entirety of the observable universe itself — are merely simulations. He's said as much many times throughout the years, admitting, "I've had so many simulation discussions it's crazy," during a Q&A at the 2016 Code Conference.

Taking the argument at face value leaves one grappling with some seriously heady questions. If reality is a simulation, how could we ever know? Would it render all life meaningless? And what happens if someone trips over a power cord and the whole simulation shuts off? To tease out the answers, we'll have to take it from the top.

What is the simulation hypothesis?

At first blush, the idea that we're all NPCs in some sort of cosmic game of "Sims" sounds like the kind of pseudo-scientific technobabble expected from a philosophy minor and an overenthusiasm for "The Matrix." However, it's actually a question that's been around for thousands of years: how can we be sure that reality is real? The technological bent to what's now called the simulation hypothesis was formalized in the paper "Are we living in a computer simulation?" by Nick Bostrom in 2003.

The argument starts something like this: computer processing power will continue to improve. Compare the convincing graphics and immersive experience of today's best VR games to, say, Frogger. Now project that amount of technological advancement forward a few decades. Then consider another few decades after that, and again, and again. Eventually, simulations will become so advanced they'll be indistinguishable from reality. Not only that, but with enough processing power they could theoretically simulate people, along with their memories, thoughts, and fears around finding out that they're simulated.

Given this technological trajectory, there are only three possible outcomes. First, no intelligent species survives long enough to ever create this type of simulation. Second, even though they become capable, no intelligent species ever creates such a simulation. In both of these scenarios, we are not in a simulation, because none ever exists. The third possibility is different though: an intelligent species reaches the threshold to create a simulated reality, and then does so. And this is where the bottom falls out, and we descend into the rabbit hole.

Never tell me the odds

Let's take a closer look at this third scenario: some intelligent species — and it needn't necessarily be humans — achieves the capability to create a fully convincing reality simulation, and in fact boots one up. The inhabitants of this simulation will go about their simulated lives none the wiser, and this could last for seconds or years or eons. What's important is the beings of this simulated reality are locked to the same three potential outcomes as their creators: die off before achieving a high-tech civilization, choose to never create a simulated reality, or do create a reality simulation.

This is a critical concept: simulated realities can spawn more simulated realities. If reality simulating technology ever became as ubiquitous as, say, smartphones (which themselves seemed like pure science fiction not so long ago), there would be a great many simulations running all the time. Even very conservatively, if "base reality" started up just two simulations, and each of those simulations started two more, the power of doubling quickly leads to millions or billions (or more) of simulated realities, and only one truly real universe at the top.

This means that if any civilization anywhere in the universe at any point in time ever creates even one reality simulation, the conclusion is that most conscious beings should assume they are living in a simulation. What's more, due to the hierarchical nature of these nested simulations within simulations, the majority of conscious thinking beings will be at the very bottom of the hierarchy, in what's been termed the "sewer of reality."

Science or philosophy?

Now we understand why Musk and others believe our chances of living in a simulation are billions of times greater than our chances of living in reality. But before spiraling into despair at your place in the simu-verse, it's worth pondering for a minute whether any of this really matters. From a practical perspective, if a simulation is indistinguishable from reality, then it may as well be treated as reality. It's also an important pillar of science that theories must be testable. Ideas that can't be tested also can't be proven or falsified, making them somewhat meaningless for practical purposes.

The simulation hypothesis has generally been unable to clear this obstacle, but not for a lack of trying. Scientists have proposed looking for glitches in the simulation, such as changes to the laws of nature or procedural rendering conflicts. However, Bostrom notes in his original proposal that if a glitch were ever detected, whoever was running the simulation "could skip back a few seconds and rerun the simulation in a way that avoids the problem."

If these experiments fail to detect a glitch, does that prove we're indeed living in base reality, or does it instead reflect that we're in a simulation that has been patched and rebooted? The answer is, of course, we simply don't know, and further have no way to know. And while that's not likely to change, perhaps the one-in-billions conjecture is a miscalculation. Let's take another look.

Closer to a coin toss

In yet another scientific paper, instead of proposing an experiment to test the simulation hypothesis, the fundamentals of the simulation hypothesis' probabilities are reexamined. There are not three possible outcomes, only two: at least one reality simulation is started, or no simulations are ever started. If no reality simulations are ever run, the reasons why don't really matter.

Looking at the only data point we have available — that the world appears real — we have an equal likelihood of existing in either a universe that includes reality simulations or a universe without. If we live in the former, then yes, our chances of being simulated are one in billions. But our chances of living in the latter scenario are 50%. This means our overall chances of living in reality are closer to 50% plus a billionth. Rejoice!

There's a dark side to this argument though. If humans ever do manage to create a reality simulation of our own, the two possibilities of this calculation drop down to one. We'll know for a fact that we live in a universe where reality simulations are possible, and therefore the odds that we're simulated ourselves will be billions to one. So if Elon Musk is certain that we live in a simulated reality, either he's got his math wrong, or he already knows of an existing reality simulation. Forget Tesla; what's happening over at Neuralink?