Thesis

Origin of the Arrow of Time in the Universe

• Call:

  PT-CERN Call 2022/1

• Academic Year:

  2022

• Domain:

  Astroparticle Physics

• Supervisor:

  Marina Cortês

• Co-Supervisor:

  Andrew Liddle

• Institution:

  FCUL (Universidade de Lisboa)

• Host Institution:

  IA - Instituto de Astrofísica e Ciências do Espaço

• Abstract:

  We always remember the past, never the future. This time asymmetry is universal: from Earth up to cosmological scales. We receive light that galaxies emitted long ago but never light they emitted in the future. Physics laws usually avoid reflecting this asymmetry, working in the same way whether time is increasing or decreasing. Therefore, we attribute the cosmological arrow of time to very specific initial conditions after the Big Bang, whose probability is around exp(10^(-90)) or less. Why the universe started in such an unlikely state is an unanswered question in Cosmology. In this work I will investigate whether the time asymmetry may already be present in fundamental laws, avoiding such very special initial conditions. My goal is to study time symmetry as an emergent phenomenon and provide a new perspective of different scenarios such as black holes, entropy, and quantum gravity; then support my results with numerical simulations.