By David K. Johnson, Ph.D., King’s College
In the film, The Thirteenth Floor, set in 1990’s LA, Hannon Fuller and Douglas Hall have invented a simulated world of 1937 LA. Its inhabitants do not know they are simulated people living in a simulation, and Fuller has been visiting the simulated world at night, controlling another person within it.
A World within Another World
After Fuller’s death, Hall discovers Fuller left a note for him in the virtual 1937 world. He goes in to find it, only to discover that the simulated person Fuller left the note with read it and then discovered the simulated nature of his reality.
The note asked him to drive somewhere he would never consider going otherwise. When Jerry did this, he saw that just beyond the city and its outskirts the simulation broke down into a green wireframe model. Hall realizes that Fuller meant for him to do this in the 1990 LA world that he lives in—and when he does, he realizes that his world is simulated too.
Hall then learns that his world is just one of the thousands of simulated worlds. Eventually, Hall escapes into the real world by taking over the body of someone else. The movie ends set in 2024 LA, with Hall looking out over the sea.
This is a transcript from the video series Sci-Phi: Science Fiction as Philosophy. Watch it now, on Wondrium.
Could Hall Predict Living in a Simulation?
In the last moment of the film, we realize that things still may not be as they seem. The image at the end collapses to a thin line and then goes dark, just like a computer monitor switching off. Does this not suggest that the 2024 world is a simulation as well?
Obviously so. But, in reality, that’s what we should have concluded even before we saw the ‘the monitor switching off’ clue. In fact, no matter how far up he goes, no matter how many simulations he wakes up from, Hall should always conclude that the world he’s in is a simulation. But why?
What Hall discovers is that his world is only one among thousands of simulated worlds. That means that of the worlds that exist, most of them are simulated. There is one physical world, and that physical world contains thousands of simulated ones, some of which themselves contain simulated worlds.
But if that’s true, what should Hall conclude about the nature of any world in which he finds himself? He can’t think the world he’s in is real simply because he came up into it from a simulation, because simulated worlds can contain simulated worlds. It doesn’t even matter if he drives to the edge of town and doesn’t see the simulation breakdown; he could just be in a bigger simulated world.
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Probabilities Go against Hall
Ultimately, since he can’t tell from inside whether his world is simulated, all Hall could do is go on the odds of probability. There are at least 1000 simulated worlds, but only one physical one. So for any given world Hall finds himself in, what are the chances that it’s a physical one? Only one in 1000.
And so for any given world that Hall finds himself in, he should conclude that he is in a simulated world. In fact, Hall should have concluded this as soon as he and Fuller created the simulated 1937 world. Why?
Because by doing so, they would have proven that simulated worlds exist. And if they exist, they’re likely in one. Such an argument was first presented by Nick Bostrom, a professor at Oxford.
Nick Bostrom’s Argument for Simulated Worlds
Consider the entire history of the universe. In that history, either simulated worlds will be created or they won’t. If they are not, then they’re not, and the only world that exists is the physical world. Okay, fair enough. But if simulated worlds will be created in the physical world, the physical world won’t contain just one simulated world.
That kind of technology will simply be too useful. It will be like the iPhone. Everyone will have one—for everything from games to scientific research. So, in the entire history of the universe, either no simulated worlds exist, or millions of them do—it could even be billions, if possible alien life is factored in.
Okay, so again, either (first option) one physical world exists and that’s it, or (second option) one physical world exists alongside at least millions of simulated ones—entire worlds full of sentient beings in all of those worlds.
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Million to One Chance
Now, we don’t know which is true. However, if we start creating simulated worlds, we’ll know it’s not option one—that just the physical world exists. We’ll know that, in addition to the physical world, there are also millions of simulated worlds.
But at that point, what should we conclude about the kind of world we live in? Since there is no way to test, and we can’t tell from the inside, all we’d have to go on is the odds. But since there are millions of simulated worlds, the chances that we are in the one real universe would be a million to one. So we should conclude that we are in a simulated world.
Common Questions about How Likely It Is We Are Living in a Simulation
After Fuller’s death, Hall discovers Fuller has left a note for him asking him to drive just beyond the city and its outskirts. Here he sees the simulation broken down into a green wireframe model. Then he realizes that his world was simulated too.
Hall shouldn’t think the world he’s in is real simply because he came up into it from a simulation. Hall discovers that his world is only one among thousands of simulated worlds, which means that of the worlds that exist, most of them are simulated. So, he should always conclude that the world he’s in is a simulation.
As Nick Bostrom puts it, the possibility we are living in a simulation only increases when we know it’s possible to construct a simulation. So as long as simulations haven’t been invented, the odds are good we are in the real world. But if simulations are built, then the odds against that increase.
