Also the simulation doesn't really even have to involve particles. Stephen Wolfram did some interesting writing on concept of our reality / laws of physics emerging from simple computational systems like cellular automaton [0]. Also Eliezer had some interesting points about how a continous interpretation of causal networks gives rise to some concepts we recognize from physics, like space, time and the speed of light binding them together [1].

[0] - http://www.wolframscience.com/nksonline/toc.html

[1] - http://lesswrong.com/lw/fok/causal_universes/