But we can't perfectly simulate a rock, or a nuclear reaction. Perfect is an extremely high bar here.
It would probably be difficult to simulate a rock sufficiently well to fool someone with the combined skills of a geologist & 3D graphic designer.
It would probably be difficult to simulate a rock sufficiently well to fool someone with the combined skills of a geologist & 3D graphic designer.
There is also the question about how much simulation would be necessary to get approximately real life results that includes consciousness -There was a very detailed simulation of a cell[1], I think that used a library of known chemical interactions. This is not the way the universe works, but such an approach might still simulate life, including people, with enough running time.
[1] https://www.quantamagazine.org/most-complete-simulation-of-a...
That's an unsubstantiated belief, though.
If we simulate a rock right down to the quantum level - not even remotely possible with foreseeable technology, but let's assume it is - you don't end up with an actual rock in the physical universe. You end up with a model of a rock. There are important properties that it's missing due to not having a direct physical embodiment beyond its model. You can't bash someone in the head with it in the physical world, for example.
In the consciousness case, you're assuming you can "get around this" by using communication between the model and the host universe - communication could allow a model a way to have an effect beyond its host environment, unlike the simulated rock.
But this involves a lot of assumptions about the nature of consciousness, its physical basis, how a model of consciousness would behave, etc. Given the number of unknowns here, the claim that "it's theoretically possible" is supported just as well as the claim that it's theoretically impossible - which is to say, not at all.
You can bash someone in the head with it in the simulated world though, and if you simulate that person's head well enough it will be just as painful for them as it would be for a real world person.
How do you know you're not simulated yourself? Whether we live in a simulation or not does not really have any influence on us and our consciousnesses.
But keep in mind that a simulation is, well, a simulation. Artificial consciousness may be possible. It may also be possible to simulate something with a surface appearance indistinguishable from consciousness but not actually be consciousness, while actual consciousness would require very different methods.
When thinking about these things we have to draw a line between something that can fool gross human perception and something that is actually conscious. Right now we don't even know enough to know what the tools required to make such a determination would look like. It may very well be that, from an ethical standpoint, we'll need to ascribe consciousness to systems for year or decades before we're able to determine if it's real or the equivalent of a very convincing optical illusion.
Another (unsubstantiated) way of looking at it is that the universe is a kind of computer already, which we seek to emulate. We are already running on a computer if the universe can be considered one.