The Noether theorem for Hamiltonian constrained systems is revisited. In particular, our review presents a novel method to show that the gauge transformations are generated by the conserved quantities associated with the first class constraints. We apply our results to the relativistic point particle, to the Friedberg et al. model and, with special emphasis, to two time physics.

Motivated by two time physics theory we revisited the Noether theorem for Hamiltonian constrained systems. Our review presents a novel method to show that the gauge transformations are generated by the conserved quantities associated with the first class constraints.

Novel static, time-dependent and spatial-temporal solutions of Einstein field equations, displaying singularities, with and without horizons, and in several dimensions are found based on a dimensional reduction procedure widely used in Kaluza-Klein type theories. The Kerr-Newman black-hole entropy as well as the Reissner-Nordstrom, Kerr and Schwarzschild black-hole entropy are derived from the corresponding Euclideanized actions. A very special cosmological model based on the dynamical interior geometry of a Black Hole is found that has no singularities at t = 0 due to the smoothing of the mass distribution. We conclude with another cosmological model equipped also with a dynamical horizon and which is related to Vaidya's metric (associated with the Hawking-radiation of black holes) by interchanging t ↔ r which might render our universe as a dynamical black hole.