6 papers
Versal transition scenarios in inflationary cosmology: slow roll, ultra-slow roll, and oscillatory exit
Spiros Cotsakis
We develop a physics-facing version of the persistence/transition-variety framework for scalar-field cosmology, tailored to inflationary dynamics. The guiding idea is that observat…
Persistence and Transition Varieties in Scalar Field Cosmology
Spiros Cotsakis
We develop a unified bifurcation-theoretic description of Friedmann--Robertson--Walker cosmologies with a scalar field, a barotropic fluid of index , and spatial curvature. For…
Mode interactions in scalar field cosmology
Spiros Cotsakis, Ignatios Antoniadis
We study the dynamics of spatially homogeneous Friedmann--Robertson--Walker universes filled with a massive scalar field in a neighbourhood of the massless transition . At thi…
Cosmic acceleration as a saddle-node bifurcation: background identities and structure
Spiros Cotsakis
We show that the late-time acceleration of the universe can be understood as a codimension-one bifurcation of the Friedmann dynamical system in the variables . At a critica…
Structural stability and general relativity
Spiros Cotsakis
We review recent developments in structural stability as applied to key topics in general relativity. For a nonlinear dynamical system arising from the Einstein equations by a symm…
Friedmann-Lemaître universes and their metamorphoses
Spiros Cotsakis
We analyze the dynamics of the Friedmann-Lemaître universes taking into account the different roles played by the fluid parameter and the cosmological constant, as well as the deg…