This thesis concerns the study of high-temperature string theory on curved
backgrounds, generalizing the notions of Hagedorn temperature and thermal
scalar to general backgrounds. Chapter 2 contains a review on string
thermodynamics in flat space, setting the stage. Chapters 3 and 4 contain the
detailed study of the random walk picture in a general curved background.
Chapters 5 and 6 then apply this to Rindler space, the near-horizon
approximation of a generic (uncharged) black hole. Chapters 7 and 8 contain a
study of the AdS3 and BTZ WZW models where we study the thermal spectrum and
the resulting random walk picture that emerges. Chapters 9 and 10 attempt to
draw general conclusions from the study of the two specific examples earlier:
we draw lessons on string thermodynamics in general and on (perturbative)
string thermodynamics around black hole horizons. For the latter, we point out
a possible link to the firewall paradox. Finally, chapter 11 contains a
detailed discussion on the near-Hagedorn (and high-energy) stress tensor in a
generic spacetime, the results of which are applied to provide a description of
the Bekenstein-Hawking entropy in terms of long string equilibration.Comment: PhD Thesis, based on arXiv:1305.7443, arXiv:1307.3491,
arXiv:1402.2808, arXiv:1408.6999, arXiv:1408.7012, arXiv:1410.8009 and
arXiv:1505.04025. v2: corrected typos and added reference
