I suggest Christopher Michael Langan, as roland said. His "Cognitive-Theoretic Model of the Universe (CTMU)" ( download it at http://ctmu.org ) is very logical and conflicts in interesting ways with how Yudkowsky thinks of the universe at the most abstract level. Langan derives the need for an emergent unification of "syntax" (like the laws of physics) and "state" (like positions and times of objects) and that the universe must be a closure. I think he means the only possible states/syntaxes are very abstractly similar to quines. He proposes a third category, not determinism or random, but somewhere between that fits into his logical model in subtle ways.

QUOTE: The currency of telic feedback is a quantifiable self-selection parameter, generalized utility, a generalized property of law and state in the maximization of which they undergo mutual refinement (note that generalized utility is self-descriptive or autologous, intrinsically and retroactively defined within the system, and “pre-informational” in the sense that it assigns no specific property to any specific object). Through telic feedback, a system retroactively self-configures by reflexively applying a “generalized utility function” to its internal existential potential or possible futures. In effect, the system brings itself into existence as a means of atemporal communication between its past and future whereby law and state, syntax and informational content, generate and refine each other across time to maximize total systemic self-utility. This defines a situation in which the true temporal identity of the system is a distributed point of temporal equilibrium that is both between and inclusive of past and future. In this sense, the system is timeless or atemporal.

When he says a system which tends toward a "generalized utility function", I think he means, for example, our physics follow a geodesic, so geodesic would be their utility function.