Nikolaos Tetradis

Equations for the perturbationsPoisson equations∇ 2 δφ = − a 2 ∑ iβ i δρ i ≡ −3 ∑ iβ i H 2 Ω i δ i∇ 2 Φ = 1 2 a2∑ iδρ i ≡ 3 2 H2 ∑ iΩ i δ i ,with Ω i (τ) ≡ ¯ρ i a 2 /(3H 2 ).Continuity and Euler equationsδ ˙ρ i + 3Hδρ i + ∇[(¯ρ ⃗ i + δρ i )δ⃗v i ] = − β i˙¯φδρiδ ˙⃗v i + (H − β i˙¯φ)δ⃗vi + (δ⃗v i · ⃗∇)δ⃗v i = − ∇Φ ⃗ + β i∇δφ.⃗N. Tetradis University of AthensThe inhomogeneity of the Universe and the cosmological model