String Gas Cosmology: Basics and Brandenberger-Vafa Scenario

  • Horaţiu NăstaseEmail author
Part of the Fundamental Theories of Physics book series (FTPH, volume 197)


In this chapter we address the first truly stringy cosmological model, the string gas model, started by Brandenberger and Vafa. The reason for the model starts with a very simple observation: If inflation lasts for more than 70 e-folds (which admittedly is not necessary, we need more than 50–60 e-folds, but restricting \(N_e<70\) would not be needed for experimental reasons, only for calculational reasons, which seems unreasonable), then current cosmological scales, \(\sim H_0^{-1}\), that leave an imprint in the CMBR, were less than Planck size \(l_\mathrm{Pl}\) at the initial time. But then we cannot trust the effective field theory of inflation, and we would need a full quantum gravity theory, like string theory.

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© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Instituto de Física Teórica, UNESPSão PauloBrazil

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