...ical models. In the quantum cosmology the Wheeler-DeWitt (WD) equation in minisuperspace which determines the wave function of the Universe, can be constructed using ADM decomposition of the geometry =-=[32]-=- in the Hamiltonian formalism of general relativity. The presence of matter in quantum cosmology needs further consideration and can be described by fundamental fields, as done in Ref. [33]. Using WKB...

...-worlds interpretations of quantum mechanics. Pacs:98.80.Qc, 04.40.Nr, 04.60.Ds 1 Introduction In recent years supernova Ia (SNIa) observations show that the expansion of the universe is accelerating =-=[1]-=- contrary to Friedmann-Robertson-Walker (FRW) cosmological models, with non-relativistic matter and radiation. Also cosmic microwave background radiation (CMBR) data [2, 3] is suggesting that the expa...

...se space. However, even in the minisuperspace, general exact solutions are hard to find, the Hilbert space structure is obscure and it is a subtle matter to recover the notion of a semiclassical time =-=[34, 33]-=-. In the present work, we describe matter as a chaplygin gas. This description is essentially semiclassical from the start, but it has the advantage of furnishing a variable, connected with the matter...

...cribed by a perfect fluid obeying an exotic equation of state [11] p = − A ρα, (1) where A is a positive constant and 0 < α ≤ 1. The standard Chaplygin gas [9] corresponds to α = 1. Some publications =-=[12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30]-=- and reviews [24, 25] which studied the Chaplygin gas cosmological models have already appeared in the literature. Recently, quantum mechanical description of a FRW model with a generalized Chaplygin ...