On Falsifying the Simulation Hypothesis | Hacker News Reader

On Falsifying the Simulation Hypothesis

lorenzopieri.com

8 pointslorepieri7 comments

This whole post hinges on the assumption that whatever universe is simulating our own follows the same set of rules as we do.

Musing about concepts like simulation complexity or energy requirement is essentially worthless if you don't know the rules on the outside.

Would seem worth noting that, to appreciate a concept of "the outside", such an outside would need to be sufficiently logically aligned to be [bound](https://en.wikipedia.org/wiki/Binding_problem).

For example, suppose that there's some root-universe (or much-more-root-than-apparent-universe, anyway) which simulates a child-universe, that simulations a child-child-universe, and so forth. If the rules of simulation and mechanics are distorted/reduced along the way, then it may be the case that higher-level universes would lack any logic to be parallel to a lower-level universe, making the lower-level universes fundamentally beyond conception.

(Example of "beyond conception": Imagine if a god appeared before you to truthfully explain a new type of physical particle/whatever that exists in the universe. However, the particle described operates according to a complexity so vast that making any predictions based on knowledge of its existence would be infeasible -- you'd need a computer larger than the observable universe to make even the most trivial of predictions in the simplest of cases. Then, even if you looked and tried to find examples of the particle, you couldn't, because you couldn't compute a prediction to align with the hypothesis that you're looking or not looking at one.)

And so, an analysis of apparent-complexity would seem insufficient to eliminate the concept of being a simulation within some more-root-universe.

That said, we can still consider notions of universes more ontologically local to the apparent-universe. And so it might be more interesting to consider not the question of IF the apparent-universe is being simulated, but rather what the space of productive notions of plausible outside-universes might be.

Not necessarily, it's enough to have some notion of finiteness of computational resources for the outside, in whatever form they may appear. This is a pretty small assumption as we don't know any system which doesn't behave this way. So, by Occam's Razor, why postulating new physics (simulators without any kind of resource finiteness) if we can explain what we experience with traditional physics?

Also, if in the future we start simulating universes, all these constraints will apply to us and all the simulations we do.

If the crux of the argument is that there are many more simple simulations than complex ones, and therefore we should be in a simple simulation but do not appear to be, then I don't buy it.

So why wouldn't complex life (humans) be correlated with more complex simulations? Anthropic principle of the simulated universe?

Furthermore, the simulation hypothesis has the same get-out-of-jail-free card that creation myths do: There's no reason to think the universe didn't just start half a second ago.

And here we are, fully realized humans with brains, sitting above layers of rock with fossils and below a long train of photons that looks an awful lot like the cosmic microwave background, all just paused, tweaked, and started from T not equal to zero.

The counting is done inside a chosen reference class of "human civilisation". Pick one definition that makes sense, and the argument applies there. So yes, by definition you are counting simulations of civilisations, not of simpler phenomena (say ants-only simulations).

In the space of all simulations, we are very likely to be pretty close to the simpler possible simulation inside the reference class, but there is no way of probing this. What we can do is make comparison with more complex versions of our current reality. If you think that we are not that simple, then you should believe that we are not in a simulation after all.

True, the universe may have been started 1 second ago, but among all the 1-second simulations some are simpler than other nevertheless. For instance a 1-second simulation in which we have colonised the entire milky way is far more complex than our current experience.

tl;dr for the article -- In order for the universe to be a simulation, there'd need to be someone who'd want to simulate it. The plausibility of them wanting to simulate the universe would seem to decrease as the cost of the simulation goes up. So, the more complex the universe can be established to be, the less likely it'd seem to be a simulation.

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Seems like a neat line of consideration, though perhaps not too compelling as an overall assessment so much as an exploration into a thought-experiment.

For example of an obvious limitation, let's say that Alice wants to figure out if she's living in a simulation, so she goes about trying to establish the complexity of the universe, perhaps working to establish higher values for the lower-bound to better evidence the proposition that the universe isn't a simulation. While it might seem like Alice could seek to arbitrarily raise that bound, Alice herself would seem to be finite in complexity -- and so if we consider Alice as a finite-state-machine, then the lower-bound of a full solution to tricking her would be of finite-complexity. And even a requirement for that much complexity would still rely on an assumption that Alice's mind is perfect and outside of any mechanic that might frustrate such an analysis.

This is, an analysis based on the universe's total complexity might make more sense if someone wanted to assume a specific form of the universe. However, if someone wants to prove that they're not a brain-in-a-jar, then they'd seem to have more trouble establishing a significant lower-bound.

Beyond that, the idea of a straight simulation -- like in a straight physical program run on a modern-day electronic computer -- would seem like a naive background assumption. Neat as a starting place for a thought-experiment, though perhaps not so useful as an actual mode of analysis.

All of that said, thought-experiments like this might help motivate conceptions of what kinds of simulations might be more plausible. Because while the concept of ANY simulation would be pretty general, arguments like this might be applied to assess the plausibility of specific types of simulations. For example, it'd seem reasonable enough to say that the universe's complexity seems to be of sufficient vastness that the universe probably isn't a simulation maintained for the specific purpose of calculating 1+1=2.

Very good tl;dr apart for a detail: it's not about the complexity of a single simulation, it's about the ratio of complexity of two simulations. In this way we can factor out our ignorance of the details (are we a brain-in-a-vat? Is the simulation run on an abacus? Is it written in Phyton?) and clearly establish which simulation is more complex.

Now, since by a counting argument we are more likely to be in a simple simulation, by looking at "optional" complexity around us we can establish if we are in a simulation. Reaching 5 sigma of confidence should be enough, so if we find out that the universe could have been 10 million times easier than what we experience, then we can be pretty confident that we are not sims (I assumed a linear scaling of the simplicity assumption here).

Now the tricky question is, which complexity is "optional"? I would argue open space which we would probe if we do interstellar travel, but maybe there are better ways to find optional complexity.

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