> a simulation is just something that runs as an informational phenomenon on top of some physical substrate A simulation is a simulation of something; it's by

> a simulation is just something that runs as an informational phenomenon on top of some physical substrate A simulation is a simulation of something; it's by definition not the reality being simulated. If you want to say you can have a simulation without simulating something, that "reality" is itself a simulation, then we're into turtle territory; this simulation models that simulation, which models another simulation, all the way down. That path leads to solipsism, which I think is a stultifying view. It's a view that I once entertained, but eventually rejected.