Razieh Pourhasan (26/02/15)

Benedikt Magnússon, febrúar 25, 2015

Málstofa í stærðfræði

Fyrirlesari: Razieh Pourhasan, Háskóli Íslands
Titill: Out of the white hole: a holographic origin for the Big Bang

Staðsetning: Naustið, Endurmenntun (hér)
Tími: Fimmtudagur 26. febrúar, frá 15:00-16:00.


While most of the singularities of General Relativity are expected to be safely hidden behind the event horizons by the cosmic censorship conjecture, we happen to live in the causal future of the classical big bang singularity, whose resolution constitutes the active field of early universe cosmology. Could the big bang be also hidden behind a causal horizon, making us immune to the decadent impacts of a naked singularity? We describe a braneworld description of cosmology with both 4d induced and 5d bulk gravity (otherwise known as Dvali- Gabadadze-Porati, or DGP model), which exhibits this feature: The universe emerges as a spherical 3-brane from the gravitational collapse of 5d matter, in the process of formation of a 5d Schwarzschild black hole. That is, in this holographic picture, it is possible to avoid the big bang singularity. We further propose a holographic origin for the big bang: a pressure singularity of the holographic fluid, which happens inside the white hole horizon, and thus need not be real or imply any pathology.

This is a talk based on my recent paper published in JCAP 04 (2014) 005 [arXiv:1309.1487], a collaboration with Niayesh Afshordi at the Perimeter Institute and Robert B. Mann at the University of Waterloo. Because of the novelty of the model, this work attracted a great deal of attention in the media particularly featured in Nature News in September 2013, and also in the August 2014 edition of Scientific American as the cover article.