Do we live in a simulation? Chances that we are the Sims can’t be more than 50%

In Monica Hughes’ sci-fi thriller Invitation to the Game (pictured above), teens with nothing better to do after school play a VR simulation that keeps getting more and more real, until they realize they aren’t plugged in anymore. What was virtual is now their new reality.

Science fiction wouldn’t be what it is without visions of possible simulations, from the alternate civilization of The Matrix to a computer-fabricated ’50s Middle America on Mars in Ray Bradbury’s The Martian Chronicles (right down to the immaculately manicured lawns and ice-cold lemonade). But could we be living in a simulation, right now, with no nodes or plugs connecting us because we are part of that simulation? Elon Musk wants to believe we are. Others aren’t so sure. Now, astronomer David Kipping has analyzed the odds and figured out that there is less than a 50:50 chance we could be living in a simulation.

What even makes us wonder whether our reality is actually real? We live in an era fraught with existential dread, which seems to have made escapism stronger than ever –– and even the Apollo era in the ‘60s and ‘70s was overcast with doubt about the limits of space travel. Kipping, who recently published a study in MDPI Universe, believes that just how real we are is something that human beings have wondered about since we became human.

“I think it’s only natural to wonder about the nature of reality,” Kipping tells SYFY WIRE. “It’s something humanity has done since antiquity. Interest in the simulation hypothesis is largely fueled by the advancements in computing we see around us. As our capabilities grow, we wonder what the limits of this technology might be.”

Substitute magic for computers and it is easier to imagine how our ancestors could have thought we existed in some otherworldly realm. As science advanced, so did curiosity. Fast-forward to Oxford University philosopher Nick Bostrom’s mind-blowing 2003 paper, in which he argues that at least one of three propositions must be true. The first proposition states that civilizations always go extinct before evolving enough technologically to create a simulation on such a large scale. The second seems to agree by stating that even if that kind of tech evolution did happen, we wouldn't be interested in simulating ourselves anyway. The last proposition counters that we probably already live in a huge simulation.

Kipping looked at Bostrom’s trilemma through the Bayesian lens. This type of reasoning uses 18th century English statistician Thomas Bayes’ thinking that you have to make assumptions about what you want to analyze, giving it a “prior” probability, before you actually calculate the odds of it actually happening, which is the “posterior” probability. Kipping did exactly that with each of Bostrom’s propositions.

“Saying that I give 50:50 odds to the possibility we live in a simulation is kind of missing the point of what I found,” he says. “A more precise statement is that I found the odds must be less than 50%. Since there are only two possibilities, then it is statistically disfavored and thus my view is that it is unlikely we are living in a simulation. I want to stress that that less than 50% number is in many ways the most generous probability one could come up with, too.”

Kipping took the original trilemma and cut it down to a dilemma, since the first and second propositions basically cancel each other out into one thing, which is the chance that we don’t live in a simulation. The third proposition states the chance that we almost certainly live in the Game or the Matrix or whatever you want to think of it as. That put the odds somewhere between under 33% to under 50%. He also decided to ignore model complexity, or the different features of a predictive model, since it can get subjective. Models that are highly complex are also difficult to determine and at higher risk for a more subjective interpretation. That was something Kipping did not want to get in the way.

“The hypothesis we live in a simulated reality is an intrinsically more complicated scenario than that which we don’t, so it should be disfavored on those grounds alone,” he says. “My point is that even being as generous as you can be, the odds still suggest it’s improbable.”