> I'm not convinced that simulating an infinitesimal portion of the universe is sufficient.

Being not convinced is not an unreasonable position to hold, but it hardly counts as an argument that renders the premise a nonstarter.

I am pretty sure that one can estimate approximately how much information would be needed to simulate a minimal universe consistent with everthing that humanity currently thinks it has been able to verify - in fact, I have a vague memory that Scott Aaronson presented something like that in one of his blog posts.

Then there are the uncomfortable gaps in our physical knowledge - the incomaptibility of relativity and QM, our inability to test, and choose between, string theories: suppose they cannot be resolved? I am not proposing that this is likely, but if it were, it would not mean that the universe could not continue, whether simulated or not.

I have read a bunch of "this is obviously wrong" claims, and one frequently-occurring aspect is that of begging the question somewhere, by assuming that something or other in what we seem to know about the universe is necessarily so. To be fair, proponents of the simulation belief sometimes also do this.

Personally, I don't have an opinion as to whether I am in a simulation; I put Bostrom's paper away in the file containing metaphysical solipsism, p-zombie arguments, and ontological proofs of the existence of God, as evidence for the futility of trying to reason oneself to ultimate truths.

I'm fine with saying it's unknowable. Likewise with the existence of God, it's hard to falsify but very easy to point out that the certain interpretations sounds extraordinarily silly and the proponents who claim to be certain aren't providing enough evidence.

> In general, I don't think you can ad-hoc "fill in the details" of a particular piece of a simulation and have it make sense because you weren't simulating the inputs in that much detail.

It's well documented that the human brain ignores or fills in inputs for things that mostly match its expectations. You're already ignoring vast swaths of your sensory input at this very moment by focusing on this text.

A simulation of a world of minds, rather than a simulation of its physics, would be many orders of magnitude more feasible because the simulation itself would have knowledge of each mind's sensory input. Therefore, it would know exactly how much fidelity it needed at any given moment, and where.

Furthermore, such an advanced simulation would have knowledge of what its simulated objects are, rather than the constitution of their matter requiring a simulation of its physics. This merely requires a simulation of the interface with the outputs having the right kind of noise. You wave this away via some absurd "sensory deprivation" remark, but this is explicitly the possibility discussed in the Simulation hypothesis.

Whatever science simulated people do, they simply cannot violate the simulation parameters. Advanced humans with knowledge of what algorithms constitute a human mind would simply need to track the inferences minds make in order to avoid seeing through the simulation.

And I don't find your analysis of Bostrom's argument complete. His argument is airtight:

1. Simulations cannot be built: simulations are impossible, advanced civilizations go extinct before they're built, etc.

2. Simulations will not be built: future humans have no interest in ancestor simulations, they have ethical qualms against doing so, etc.

3. We are almost certainly in a simulation: the number of simulated people far outnumber the number of non-simulated people, so you are likely a simulation.

You simply can't be unconvinced by this argument.

I admit to not having read his book and I think his argument is technically "airtight". I will grant that. But the real problem, besides me strongly believing 1 and 2 are true, is that Bostrom (or more charitably, his fans) are conflating several concepts:

"a computer simulation"

"a universe simulation"

"an ancestor simulation in which the lived experience is indistinguishable from our current experience, which necessarily won't be able to simulate the entire universe nor anything at a high level of fidelity and so requires constant tricks to convince the inhabitants things are real"

The last one is required for this argument to work and I think that's what's being slipped in. Sure, everybody loves computer simulations. We run them all the time. Video games are computer simulations, so look at that. We all love them.

We're talking about a very, very specific type of simulation and the more specific you define it, the less likely it is anyone will ever build one.

"Sensory deprivation tank" isn't absurd. That seems to be what we're talking about here. I suppose I will have to read the book because the noise argument you are presenting seems bizarre to me. Do you think your lived experience can be characterized as sensory noise? I absolutely do not understand how you can just simulate minds without an environment unless we are talking about dreams or hallucination.

I don't think scaling down the fidelity in certain places works. Humans expect natural processes to occur even when they're not looking. The evidence will be there long afterwards. There is no particular place that we wouldn't look for such evidence.

>Furthermore, such an advanced simulation would have knowledge of what its simulated objects are, rather than the constitution of their matter requiring a simulation of its physics.

No I don't think so. The number of possible "simulated objects" is infinite. Even the most advanced simulation you imagine would not be written in such a way to account for them.

>Advanced humans with knowledge of what algorithms constitute a human mind would simply need to track the inferences minds make in order to avoid seeing through the simulation.

Not convinced on this point either, but anyway this would conflict with reality considering a great many people already believe with certainty that they are living in a simulation.

> which necessarily won't be able to simulate the entire universe nor anything at a high level of fidelity and so requires constant tricks to convince the inhabitants things are real"

No tricks. Simulating the minds is the entire point. Simulating physics isn't the interesting part of these kinds of simulations.

> I absolutely do not understand how you can just simulate minds without an environment

Each simulated mind contains a set of beliefs about the local environment. The intersection of the belief-sets of the people in close physical proximity dictates the local reality. If some belief-sets conflict, choose the set that has more believers.

Global consistency can be assured if all beliefs that survive a conflict satisfy certain conditions.

> I suppose I will have to read the book because the noise argument you are presenting seems bizarre to me.

You don't need to simulate the LHC, you only need to simulate what outputs the scientists believe the LHC should produce, ie. they expect results consistent with the statistical models of quantum mechanics. Introduce some random errors here and there as a demonstration of human fallibility (like the FTL neutrinos mistake a few years back due to a loose cable).

> No I don't think so. The number of possible "simulated objects" is infinite

The number at any given time is not. Every simulated object will have logical properties associated with it, particularly at its interface. Satisfy the logical properties of the interface, and a simulated mind wouldn't know the difference.

> Not convinced on this point either, but anyway this would conflict with reality considering a great many people already believe with certainty that they are living in a simulation.

They may believe it but they can never prove it, and so they're not actually seeing through the simulation.

Indeed, the Free Will Theorem of quantum mechanics makes short work of Bostrom's hope that it would be possible to just rewind the Universe and get the desired outcome, as if creating a tool-assisted speedrun.

Edit: Imagine that you are simulating a qubit. You want the qubit to behave a certain way, but it refuses to do what you want. You try rewinding it over and over with your magic time-rewinder, but it still refuses to give you the measurement that you expect. That's the Free Will Theorem.

Now imagine that you're simulating a human. You want the human to behave a certain way...

The Free Will Theorem has nothing to do with anything. It doesn't even say that people or particles have free will, it says only that experimenters and particles have the same amount of freedom. That could still be zero, because deterministic interpretations of QM exist.

If you are simulating a qbit, why would you necessarily want it to go a certain way, let alone need it to do so? Ditto for a simulated human.

If we are in a simulation, we would have no reason to assume that the physics of the universe in which the simulation runs are as they appear to us. If, however, we chose to assume that is so, it would be consistent to also expect our simulated world to have free will up to the point that the entity running the simulation has.