Brane Universes, AdS/CFT, Hamiltonian Formalism and the Renormalization Group

The AdS/CFT correspondence is developed from classical solutions on AdS_5 with two boundaries. The corresponding limits and the reduction of degrees of freedom are discussed, as well as the required renormalization on the field theory side. The Hamiltonian first-order approach towards the solution of coupled gravitational/matter equations of motion is introduced, and the RG interpretation is exposed. Finally we discuss a recent approach towards a naturally vanishing cosmological constant which is based on the AdS/RG correspondence.