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Comment by nitrogen | Hacker News Reader

There is a limit to the amount of computation that can be done by a given amount of matter that only new physics could change. Given that limit, at best you would need every particle in our universe just to simulate an identical one. It's more likely that the best possible simulation would have significantly reduced fidelity and/or size with respect to its host universe, thus the inevitability component of the simulation argument falls apart.

What would convince me we are a simulation is evidence (e.g. proof that quantum randomness is caused by floating point rounding errors, or that entanglement is caused by lazy expression evaluation), hard empirical measurements. Not arguments from pure logic and extrapolation.

That said, I agree that we have done some amazing things with computers; I just doubt (in the extreme) the simulation argument is valid.

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You don't need to simulate every particle in the universe to have a convincing simulation, from the perspective of a small number of observers (or just one).

How many particles are you currently observing, in sufficient detail, to be sure they are being individually modeled, rather than the subject of macro-approximations? The answer is likely 'zero', or at least a number much closer to zero than the number of particles in the rumored universe.

Also, if you are in a simulation, you can't reason about the size and computational capabilities of the physics of the simulating system. All the limits you've ever perceived may be arbitrary choices of the simulation, countless orders-of-magnitude more limited than the "host" universe.

> All the limits you've ever perceived may be arbitrary choices of the simulation

Such as the speed of light? That's the simulation tick rate.

More like step. There is no such thing as time. The simulation could be paused for (real) years, then continued and there would be no way for entities in the simulation to notice that. This is also why we technically don't need super fast computers for such a simulation; it would be slow to us, not to those inside. Although it's not practical to have a very slow simulation of course.

"Flatland" comes to mind with respect to the latter part of what you wrote.

As far as I can tell, you don't even disagree with the simulation argument. The simulation argument is that one of three propositions is true:

1. It is impossible to create a simulated world that people can live in.

2. People consistently do not choose to create such simulations.

3. We are almost certainly living in such a simulation right now.

You haven't said anything to undermine the basic logic of the argument at all; instead, you're arguing that statement 1 is true. But the simulation argument is that one out of statements 1-3 is true. Hence you agree with the simulation argument. You just don't think you do because you identify the whole argument with statement 3.

What if the simulation of the fidelity required surpasses the energy and time available in any sensible host universe? If the slowdown in a simulation universe is say 10, then it doesn't need many nested universes before life would never get the time to form in the client universe before the host dies (though of course you could set up the universe from 10 seconds ago, which seems like a cheat).

The argument seems to be missing a proposition:

4. It is possible to create and live in a simulated world, but not with the level of fidelity/flexibility necessary for the infinite regress that would make #3 convincing.

Just to nit-pick, the simulation argument doesn't rely on simulations-in-simulations, let alone an "infinite regress".

If we consider the proposed form of simulation to be feasible/reasonable/etc. then the existence of one simulation would give us 50/50 odds of being inside it. With two simulations running, we're more likely to be simulated than not.

The simulation argument claims that, if such simulations are possible at all, then there will be very many of them. In which case, the improbability of being in a particular simulation is more than compensated by the number of simulations.

The simulation could be lazy, only simulating what it needs to for the observers contained within. Keep in mind that if you are inside a simulation, your sense of time is artificial. When something requiring more fidelity is run, the entire simulation could slow down, or stop momentarily while lazy contexts are evaluated, and you wouldn't know it.

The problem isn't runtime, it's the memory. The earth is the most efficient storage of all the information about the positions/trajectories of all particles that make up earth.

That's missing the point, I think. In the simulation the Earth doesn't exist. Instead, some high-level model is used to generate the observations we make at the macro scale. Only when we perform sensitive experiments which require a finer resolution is that detail generated in such a way as to remain consistent with observations made so far.

Of course as someone who writes simulations I can tell you that it is not so easy in our computational models. Indeed it would seem very difficult, though not fundamentally impossible for a high level model to correct macro behavior in all cases. But we cannot know the constraints of the universe which contains our simulation, which may be very different from ours.

You can fold that into #1 if you want, or fold 1 and 2 together, but they're largely equivalent formulations.

I don't think it fits cleanly into 1 or 2. Maybe people choose not to live in deeply nested simulations because of the degradation, but that still misses the possibility that simulated people do want to keep the process going but it becomes increasingly difficult.

That's possible, but besides the point. The point is not to set up clear, unambiguous, "perfect" choices, but to wade into the long lasting philosophical question of whether our reality has a physical existence - one of the oldest questions of philosophy - and recast it in terms of technology.

The point is that unless there's some fatal logical flaw in the set of choices, some combination of the choices needs to be true, and whichever choice or combination is the correct one, it has profound implications on us.

The argument is wrong, or at least, incomplete. Another possibility is:

It's possible to create a simulated world, but it would be much smaller than the world we live in, hence our world is probably not simulated.

On the other hand, jail inmates and astronauts in the International Space Station will (eventually) reasonably be able to consider option (3).

Then, apart from some serious anthropomorphization in 1 and 2, the simulation argument as you have described it is a tautology. I also never agreed with 1; I don't think simulation is impossible, just infinitely recursive simulation.

Based on what you just said, the simulation "argument" is no argument at all. The three propositions cover all possible cases. How can you argue against that? What would be the counter-argument?

The counterargument would be simple: a counterexample where all three propositions are false at the same time.

The Simulation Argument is really a tool, and a challenge. It sets things up such that, if we manage to disprove 1 and 2 empirically, we get stuck with a shocking realization about the basic facts of our existence. It gives us an unusual way of indirectly testing whether or not we are living in a simulation. That's a lot out of something that "isn't an argument at all".

> The Simulation Argument is really a tool, and a challenge.

No it isn't. It is Pascal's Wager updated for the 21st century. The only way it can be "proved" is if we are living in a really bad, poorly maintained, fundamentally broken, cheaply outsourced simulation.

Except that there exist a #4: "We are unusual".

It's a big jump to conclude that we are usual in every way, one that normaly leads to flawed conclusions.

"There is a limit to the amount of computation that can be done by a given amount of matter that only new physics could change. Given that limit, at best you would need every particle in our universe just to simulate an identical one. It's more likely that the best possible simulation would have significantly reduced fidelity and/or size with respect to its host universe, thus the inevitability component of the simulation argument falls apart."

Or, potentially, one would only need to simulate the minds of any observesers in the simulation, not every particle in the simulated universe.

Or, potentially, one would only need to simulate the minds of any observesers in the simulation, not every particle in the simulated universe.

...for every possible interaction those minds could have with the simulated universe. The only lossless way to simulate a mind's interaction with a universe is to simulate the universe. Further, one must define "observer", as well as simulate accurately what happens to non-"observer" objects, animals, microbes, etc. while "observers" aren't looking.

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