This essay was originally published in Slate.
That we’re living in a computer simulation—it sounds like a paranoid fantasy. But it’s a possibility that futurists, philosophers, and scientific cosmologists treat increasingly seriously. Oxford philosopher and noted futurist Nick Bostrom estimates there’s about a 1 in 3 chance that we’re living in a computer simulation. Prominent New York University philosopher David J. Chalmers, in his recent book, estimates at least a 25 percent chance. Billionaire Elon Musk says it’s a near-certainty. Let’s consider the unnerving cosmological and theological implications of this idea. If it’s true that we’re living in a computer simulation, the world might be weirder, smaller, and more unstable than we ordinarily suppose.
If it’s true that we’re living in a computer simulation. Before getting into the implications, it’s worth asking how remote, exactly, is this “if”? Suppose that the following three things are true.
First, suppose that it’s possible to create artificially intelligent machines capable of having human-like experiences. This is, of course, an old staple of science fiction from Isaac Asimov through Westworld, and it’s a long-standing hope of ambitious A.I. researchers.
Second, suppose that such humanlike A.I. systems could exist entirely in a computational reality, experiencing simulated input as if they live in an ordinary world of physical objects. Imagine that these A.I. systems are like the characters in The Sims, except genuinely conscious, like you and me.
Third, suppose that high-tech societies somewhere in the cosmos have created many such A.I. systems that mistakenly believe they are living in nonsimulated realities. In the vast cosmos, maybe such high-tech, simulation-creating societies exist somewhere.
None of these three ideas is wholly implausible. They seem, at least, like real possibilities. Join these possibilities together and the simulation hypothesis looks viable. We ourselves might be sims without realizing it. The high-tech society that created us would not be visible through our telescopes (any more than the characters of The Sims could see us through their simulated telescopes). But that society would be providing the computer servers on which the world as we know it is instantiated.
Suppose we are now willing to regard it as a live possibility that we really are living in a simulation. How much would it matter? Should it profoundly shake our understanding of the cosmos and our place in it?
Perhaps surprisingly, advocates of the simulation hypothesis tend to downplay any radical implications. No reason to be alarmed, they say! That mountain outside your window—close your eyes and open them, and it will still be there. Plan a hike—it will still be there. Dig your fingers into the dirt—you will experience everything you expect to experience. Mountains and motorbikes and mayonnaise still exist, they argue, even if underneath are computer bits rather than physical particles. And we still have all our friends, family, and neighbors, who are just other A.I. systems like us, sharing this same virtual reality.
But in this matter, science fiction writers might be guiding us better than philosophers. If we are actually living in a simulation, things might be very different than we suppose, in important ways. The people trapped in The Matrix are ignorant of humanity’s true history, subject to the whims of machine governance, and have access to magic-like powers. The inhabitants of Daniel F. Galouye’s Simulacron-3, who exist as part of an experiment in marketing research, don’t realize how small and brief their reality is.
It’s anyone’s guess what bizarre things might be true if the world as we know it is a computer program running on someone else’s machine. But we should expect some bizarre things to be true. After all, simulations are created worlds—created by someone, for some purpose unknown to us, and subject to whatever hazards might bring an end to the program.
Our creators would be, literally, from our perspective, gods. What is a god, after all? They designed and launched the world. Presumably, they could stop it at any moment. Presumably, they could interfere with the program, introducing miracles. Maybe they could rewrite history, going back to save points and altering the outcomes of events. In a sense, our creators are everywhere and nowhere at once, standing outside our spatiotemporal manifold. Even if they are mortals in their own world, with respect to our simulated world, their godlike powers put Zeus to shame.
In standard scientific cosmologies, we live on a large, stable rock governed by changeless laws of nature. If that’s so, then there’s excellent reason to think this rock has endured for billions of years and will endure for billions more. In standard monotheistic cosmologies, a perfectly benevolent God likewise ensures that the world is a stable, well-ordered place.
But if this is a sim, our god might be a sadistic adolescent. Maybe he launched this program 10 minutes ago, with all our seeming-memories already in place. Maybe he’ll surprise us with a plague of Godzillas. Or maybe he’ll spill a soda on his computer, frying the hard drive and destroying us all.
If we are A.I. systems living in a computational reality, the world might be much briefer than we think. And if you are an A.I. system living in a computational reality, the world might be much smaller than you think—maybe just you here right now. How sure can you be that there’s really a world beyond your walls? How recently have you tested the boundaries of your reality?
Maybe our simulator gods launched our world billions of years ago (in our time clock, which might not match theirs), with billions upon billions of galaxies. But why think so? If the simulations we ourselves run are any evidence, then most simulations are not large or long-enduring. They are brief experiments or playthings. If the simulations we ourselves run are no evidence, then we’re even more in the dark about the typical fate of simulated entities.
Do distant galaxies even exist? If this is a simulation, it would presumably require massive computational resources to create galaxies’ worth of simulated matter. Imagine computationally simulating at the micro level every single complex interaction of a universe’s worth of fast-moving particles, many completely unobserved in the centers of distant stars. Why would the simulators bother? Maybe the stars are all fake—a high-tech muslin backdrop to a soap-opera Earth full of entertaining death and war and music and marriage, like the backdrop in the 1998 classic Truman Show movie. Will we all—following in the footsteps of Jim Carrey’s Truman character, and pliable Emmet in The Lego Movie—come to discover we are in someone’s else foreordained show? To the extent we take seriously the possibility that we live in a simulation, we should be cosmologically and theologically discomfited. We should be rocked with doubt. A simulated world is likely to be much less predictable and sensibly governed than a world grounded on a large, planetary rock or on the immutable word of a benevolent God.
Eric Schwitzgebel
Eric Schwitzgebel is Professor of Philosophy at the University of California, Riverside, and the author of A Theory of Jerks and Other Philosophical Misadventures. His areas of interest include philosophy of psychology, philosophy of mind, moral psychology, classical Chinese philosophy, epistemology, metaphilosophy, and metaphysics.
