Vikramaditya Mondal (IACS Kolkata)

Lorentzian path integrals in bouncing cosmological scenarios

Bouncing models are alternatives to inflationary cosmology that replace the initial Big-Bang singularity by a `bouncing' phase. A deeper understanding of the initial conditions of the universe, in these scenarios, requires knowledge of quantum aspects of bouncing models. We find that many bouncing models can be studied with great analytical ease and hence, provide a test-bed for investigating more profound problems in quantum cosmology of bouncing universes. Our model's two key ingredients enable us to do straightforward analytical calculations: (i) a convenient parametrization of the minisuperspace of FRLW spacetimes and (ii) two distinct choices of the effective perfect fluids that source the background geometry of the bouncing universe. We study the quantum cosmology of these models using both the Wheeler-de Witt equations and the recently proposed Lorentzian path integral approach. We also investigate the consequences of having anisotropy and torsion in the early universe.