**Statement:** Nature prefers minimal description.
Hamilton's Principle: The path taken by a physical system extremizes the action:
The actual path minimizes (or extremizes) S. This is parsimony: nature takes the "shortest" path in configuration space.
Fermat's Principle: Light takes the path of least time. Parsimony in optics.
Feynman Path Integral: All paths contribute, but the classical path dominates because it extremizes the action. Quantum mechanics enforces parsimony.
Definition:
K(x) = length of shortest program that outputs x on universal Turing machine U.
Properties:
Invariance theorem: K is independent of choice of U up to additive constant. Parsimony is objective, not observer-dependent.