Stuck with me (again) since watching Inception (not to mention other movies and sources like The Matrix) is the notion of simulated reality, and more specifically, the (perhaps surprising) idea that it’s statistically more probable than not that we are in fact living in a simulation.

From Wikipedia:

Simulated reality is the proposition that reality could be simulated—perhaps by computer simulation—to a degree indistinguishable from "true" reality. It could contain conscious minds which may or may not be fully aware that they are living inside a simulation. In its strongest form, the "simulation hypothesis" claims it is entirely possible and even probable that we are living in a simulated reality.

This is quite different from the current, technologically achievable concept of virtual reality. Virtual reality is easily distinguished from the experience of "true" reality; participants are never in doubt about the nature of what they experience. Simulated reality, by contrast, would be hard or impossible to separate from "true" reality.

…the philosopher Nick Bostrom investigated the possibility that we may be living in a simulation. A simplified version of his argument proceeds as such:

i. It is possible that an advanced civilization could create a computer simulation which contains individuals with artificial intelligence (AI).

ii. Such a civilization would likely run many, billions for example, of these simulations (just for fun, for research or any other permutation of possible reasons.)

iii. A simulated individual inside the simulation wouldn’t necessarily know that it is inside a simulation — it is just going about its daily business in what it considers to be the "real world."

Then the ultimate question is — if one accepts that the above premises are at least possible— which of the following is more likely?

a. We are the one civilization which develops AI simulations and happens not to be in one itself?

b. We are one of the many (billions) of simulations that has run? (Remember point iii.)

Kind of crazy, huh? I’m not advocating one way or the other but it’s tremendously interesting to read and speculate about. In particular, the question of, "How would we know or find out we’re living in a simulated reality?"

The Matrix, for instance, posits bugs and artifacts of various sorts present in the system that might well reveal the simulation (though the general populace is completely unaware). Inception raises the good point that in a dream reality, even the craziest dream seems completely normal to the dreamer, so there may well not be any way to determine what is real (other than by waking up, although the use of the totem can help if you suspect you are in a dream… maybe).

Of course, this all spirals into much more existential philosophical points (the nature of consciousness, perception vs. reality, and so on) than I’m going to go into here. Suffice to say, it’s pretty thought-provoking.