# Cosmology

If you could see the notes they’re taking . . .

As time increases without bound, the probability of
existing within a simulated reality approaches unity.

There are exactly two possibilities: either we exist in a simulated reality, or we do not. If we’re simulated, this almost certainly evidences a creating group of entities in the enclosing universe with a reason for doing it.

At this point, you can speculate on motive. For example, maybe they’re doing a simulation: a group of cosmological grad students. (The idea of a “god” in the classic sense seems cretinous; what depraved being would build a toy universe and then have trite interactions inside of it for eternity?) But these lines of inquiry become dull rather quickly.

More interesting is to speculate on the existence of the parent universe itself. By applying the same logic recursively, we find that they’re probably simulated too. So you have us, inside a parent universe, inside a parent universe, inside, inside, and so on until you reach some root universe. It will always reach a root universe in a finite number of nested universes. (Why? Because by assumption, the probability of existing in a simulated reality only approaches unity. And even if we were to know we’re in a simulated universe, you toss the problem to the next one up, and so on until an assumption breaks. Anyway, you can’t have turtles all the way up.)

For example, let’s say that we think the probability of existing in a simulated reality is ps=0.93. Assuming this is constant for each universe (each universe likes simulating universes approximately the same as itself), we’d expect on average to be the 14th or 15th universe down. If it’s ps=0.5, on average we’re the first universe down.

What’s fascinating is that this implicitly involves a problem: we can’t define time very well. If you observe a universe right at the big bang and then live through until its end, your ps grows monotonically from 0 to 1 but the truth remains constant. What the original conceit really is saying is about time in the root universe. That, as time progresses, the number of recursively simulated beings collectively grows faster than the number of real-lifes. It’s a hyperexponential growth, too, since each simulated reality makes its own recursively simulated universes too.

This suggests something interesting: we can devise an a-priori experiment to see whether we’re in a simulated reality. See, this hyperexponential growth starts exactly when the root universe starts simulating things. The population growth in the root universe continues at an ordinary exponential rate, so the simulated universes very quickly outpopulate the real one.

This means that after the root universe develops universe simulation, your chances of being born in the real world drop abruptly, asymptotically, to zero.

In the absence of better data, we assume that any parent universes are like ours, since people are interested in creating applicable simulations. So:

1. If we are simulating our own universes, then probably we are the child of a parent universe that is also simulating universes (one of which is us).
2. If we’re not simulating universes, then we don’t have a parent universe, because that parent universe wouldn’t be simulating us either. So we wouldn’t exist (and yet clearly we do).

The intriguing thing is that the simpletons who authorize science funding get the implication backwards, reasoning that if we don’t invent universe simulation, then we’ll be living in real life (as if such post-hoc decisions could influence the very nature of reality). If this carries back up to the root universe, then no child universes will ever exist (which makes the fallacious chain of reasoning even more appealing).

Ed. note: this isn’t actually strictly fiction.