Entropy and Evolution

For the description of a quantum system, no more than three ingredients are required: the generators of the algebra of observables (such as position and momentum), the structure of the algebra (such as the one defined by the Heisenberg commutation relations), and the Hamiltonian, which serves as energy operator and, at the same time, generates the time evolution of the system. This is an extremely elegant scheme, and when dealing with other systems like neural nets or macroeconomics one can only glance with envious and greedy eyes at the beauty and conciseness of the algebraic formulation of quantum physics.