Can the radiation era extend back to the bang?

April 28, 2026 PIRSA:26040119 Conference Cosmology

Conference/School: Cosmological Frontiers in Fundamental Physics 2026

Vaibhav, V. (2026). Can the radiation era extend back to the bang?. Perimeter Institute. https://pirsa.org/26040119

Vaibhav, Vatsalya. Can the radiation era extend back to the bang?. Perimeter Institute, Apr. 28, 2026, https://pirsa.org/26040119

@misc{ pirsa_PIRSA:26040119,
  doi = {10.48660/26040119},
  url = {https://pirsa.org/26040119},
  author = {Vaibhav, Vatsalya},
  keywords = {Cosmology},
  language = {en},
  title = {Can the radiation era extend back to the bang?},
  publisher = {Perimeter Institute},
  year = {2026},
  month = {apr},
  note = {PIRSA:26040119 see, \url{https://pirsa.org}}
}

Abstract

Recent work has shown that a cosmological model in which the radiation era extends back to the Big Bang, with CPT-symmetric initial conditions, can provide a minimalistic explanation for many of the observed features of the early universe (homogeneity, isotropy, flatness, the CMB acoustic oscillations, dark matter,...). But is it consistent for the radiation era to extend back to the bang? Does this lead to over-production of dark matter? Does it lead to a relic thermal graviton background? We answer these questions in the context of quadratic gravity (aka Stelle gravity).