A Mathematical Model for Simulators

A bitstring exists if some physical configuration encodes it. In a computable universe where does exist but only occurs once, and a perfect fidelity simulation of that universe is run within it on an unphysically large computer (except without the existence of the hardware running that simulation), then occurs twice, because it is specified in some way on the hardware of the computer on which that simulation is run. If refers to the simulated bitstring:

  • What should distinguish , as a bitstring existing in a real external world, and ?

  • If our simulation was run on a hypercomputer such that it could infinitely recur in perfect fidelity, is ‘more real’ than ?

These are the kinds of questions I want to find answers to, because I want to be able to prove things about simulators. As a first step, let’s carve up the simulator.


Given the probability space where is the sample space, is the event space, and is the probability measure, mapping events in to the interval , let refer to individual outcomes in , each of which describe a discrete simulacrum, and as individual discrete events in . Classifying simulacra as programs, we denote the maximum Kolmogorov complexity with respect to a universal Turing machine for any given space as .

Proceeding, let be the complete set of simulacra for some Cartesian object , where individual simulacra are addressed by as sets of actions indexed by . Let be a function that maps from choices for each to a world , where $= refers to the world in the set of possible worlds for the object, and indexes the object describes possible worlds for, culminating in .

By modeling the coupling of the probability space and its contained simulacra as a dynamical system, the following are considered to describe sampling tokens from a simulation state at time-step given the complete simulation history prior as a trajectory through states, where states are given by the set of worlds for all objects realized in the set of actualized objects at time-step , :

  • The token selection function , where is a distribution over all tokens in an alphabet .

  • The evolution operator which evolves a trajectory to by appending the token sampled with .


Assuming the model defined above, the simulation forward pass becomes a simple operation delineated as follows:
We begin at simulation state , which denotes the empty or null state, whereby , which is also maximally entropic.

is applied for one time-step:

  • selects from under , aggregating the set of realized worlds in as

  • The token selection function is applied to the current state as

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