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Comment by feoren | Hacker News Reader

Of the 3 assertions in the abstract, the obviously false one is #2: "Any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history". When you realize that running a simulation of the universe requires more processing power than is available in the universe, this is very obviously false.

I respect people who believe in a bearded White omnipotent homophobic God who lives in a sky palace more than I respect people who believe in this insane drivel about the probability of living in a simulation. At least the former were indoctrinated as their brain was forming.

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Isn't it possible that our universe is really just an approximation meant to look as detailed as possible? You don't need a universe of processing power to simulate a universe. You just need to make it look believable enough that it fools whoever is in your simulation.

I agree with you, and even if it's not an approximation, it doesn't matter; we can't make assumptions about the size of a parent reality (and its limits on processing power) relative to our own.

The simulation hypothesis seems as theistic as the creationist hypothesis. Maybe the main difference being that with the simulation there would likely have been many creators (programmers) whereas the creationists would say there is one (although there are polytheistic creation narratives, so maybe not so different). Other than that, they both seem to fall into the theistic category since a higher intelligence is posited who created (the simulation | the real world).

Who says humans and/or earth are an interesting or even desirable phenomenon in a simulated universe scenario?

> Of the 3 assertions in the abstract, the obviously false one is #2: "Any posthuman civilization is extremely unlikely to run a significant number of simulations of their evolutionary history". When you realize that running a simulation of the universe requires more processing power than is available in the universe, this is very obviously false.

I think you've expressed a number of confusions.

First, I think you contradicted yourself. The line you quote says that posthuman civilizations are unlikely to create simulations, but you say this is false because a universe simulation requires more power than available in the universe. So you're agreeing with the outcome while saying you're disagreeing.

Second, I suggest reading the the paper fully, because Bostrom explains that we don't need full universe simulations, we need only consciousness simulations (kind of like the Matrix). The very premise of a post-human civilization is that they have knowledge sufficiently advanced that they have algorithms to simulate human minds.

Much like how video games only render the part of the world that is visible to the players, so a consciousness simulation only needs to simulate minds and their perceptions of a macroscopic, classical world, they do not have to simulate a full quantum universe. Our brains are great at filling in information that we expect to be there, so even the parts that we directly perceivedon't need to be simulated with complete fidelity.

Frankly, I don't think you've given the argument sufficient thought, but by a happy accident you picked exactly the outcome that I think is most likely, and I elaborate on why here:

https://higherlogics.blogspot.com/2021/02/why-we-are-likely-...

> Our brains are great at filling in information that we expect to be there, so even the parts that we directly perceive don't need to be simulated with complete fidelity.

Right, but the simulation is nonetheless bottlenecked by whichever system requires the greatest fidelity, and the more technology advances, the more of a problem that becomes. For instance, medieval times would likely be far easier to simulate than modern times, because the latter requires simulating our entire computer infrastructure.

And I think that infrastructure is harder to simulate than you'd think: I could use a solver on a big NP problem (we'll assume that P != NP), get a solution after an hour, and in theory, with some practice, I could probably check if the answer is correct in my head. So the simulator can't simply give me what I "expect". It has to actually compute the thing, and then it's clear that the faster our computers get, the slower the simulation has to run.

Alternatively, the simulation could mess with our minds so we never notice anything out of place, but at that point I'm not sure I understand the point of it. Might as well wonder if this is all a dream.

> For instance, medieval times would likely be far easier to simulate than modern times,

Agreed.

> because the latter requires simulating our entire computer infrastructure.

Maybe, that isn't clear. There are probably plenty of optimisations here too if given some thought.

> I could use a solver on a big NP problem (we'll assume that P != NP), get a solution after an hour, and in theory, with some practice, I could probably check if the answer is correct in my head.

Yes, but note that we very rarely solve NP or EXPTIME problems exactly due to the costs. We often solve them heuristically or approximately, which wouldn't pose a problem for a simulation either.

Then there's also the possibility that we are simply not free to choose the problem to solve. When running a solver for an NP problem, we just need to input any kind of NP problem, and a simulation could easily have large sets of precomputed solutions available.

> Alternatively, the simulation could mess with our minds so we never notice anything out of place, but at that point I'm not sure I understand the point of it

Depends on whether any such changes affects the point of the simulation. If the simulation is to test world-scale economic models, then isolated tribes wouldn't have much influence on those outcomes.

Then again, maybe the point is simply entertainment. Maybe we're just The Sims for post-humans, in which case there's no point anyway.

If the computer code running this simulation is that good to never have bugs, then the simulation is functionally identical to the meatspace real universe from our POV. So I don't know if there's any point thinking about it other than idle curiosity. But I do worry that for some simulation believers it could become an excuse to have less empathy towards fellow humans.

If "the simulation" and "reality" have the same properties, what would "being in the simulation" even mean? A thing/person/etc would "be" in both by definitions, be in neither by others, etc.

> So I don't know if there's any point thinking about it other than idle curiosity.

Idle curiosity is drives a lot of human behaviour, particularly in philosophy!

First, I think you contradicted yourself. The line you quote says that posthuman civilizations are unlikely to create simulations, but you say this is false because a universe simulation requires more power than available in the universe

No, they are saying the opposite. The argument that simulating the universe requires more atoms than the universe says that a later civilization would not simulate the entire universe. IE, #2 of the refutations really true.

When the simulator shows a previously unseen object, it must first simulate all its history accounting for all effects to ensure that the shown state is legit and doesn't expose the conspiracy. This state should also account for all future investigations. The easiest way to achieve this is to run a precise simulation, so it doesn't save any resources.

> When the simulator shows a previously unseen object, it must first simulate all its history accounting for all effects to ensure that the shown state is legit and doesn't expose the conspiracy

The simulation only needs to produce observations that are consistent with the knowledge of the first observer. Sometimes bit even that, as I describe in the blog post, because eyewitness testimony is known to be quite unreliable.

I'm not sure what sort of history you're thinking of specifically.

Existence of Neptune was conjectured before it was observed, the testimony came from instruments. If such consistency with contemporary observers was used, scientific revolutions wouldn't happen as observers would never observe what contradicts their knowledge.

I agree, there are necessarily some background facts that must be consistent with the environment. Science might eventually be able to trace the trajectory of the asteroid that killed off the dinosaurs, but that doesn't necessarily mean you would need to simulate every asteroid in the solar system since its initial formation.

The amount of information science could infer on many questions is strictly bounded and in those cases we could only reason stochastically. The data presented at time of first observation can then be generated randomly from the set of answers consistent with what's already known.

Maybe, but if you can segment out the unobserved items, and back-calculate it lazily, you could save a lot of processing and memory.

The place to implement an optimization like this would be at the items with the biggest O in your world, which is usually the smallest building block--what you'd have the "most" of, which would drive the largest memory and processing demands.

Fine, you got me: the assertion that is obviously true, but goes further in that it invalidates the need for any of this discussion. If your goal was to engage me in a thought-measuring contest, sure, you win: you've spent more time thinking about this utterly ridiculous nonsense than I have. Congrats?

I bet you could make your points without insulting others. What do you think?

I think my tone was no different than naasking's.

Yeah, saying I think you're likely confused, as I did, is not remotely the same as calling subjects that interest some people "insane drivel", or "utterly ridiculous nonsense". You definitely need to recalibrate your scale IMO.

If you're not interested in philosophical discussions, then why engage at all, particularly only to denigrate people who like exploring thought experiments?

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