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Investigation of firewalls inside the event horizon of black holes


This project is a literature review and mathematical investigation of the controversy surrounding firewalls inside the event horizon of black holes, specifically analyzing the firewall construction in the recent paper, "Black Holes and the Butterfly Effect," by Stephen H. Shenker and Douglas Stanford. Firewalls are a controversial attempt to solve the information paradox by suggesting a wall of heat existing inside the event horizon, providing energy to disentangle infalling particles. Shenker and Stanford construct a theoretical scenario in which a firewall could be created. We intend to demonstrate that this scenario is unphysical. In the Shenker paper, a specifically-tailored shock wave is sent into the black hole. This wave is highly blueshifted as it falls in, gaining energy as the wavelength decreases, and exhibiting properties like those of a firewall. We will be testing whether the wavelength could reach scales less than the Plank length, which are forbidden by modern physics. We will drop free-fall observers from different positions in time outside the black hole and evaluate the geodesic equation for their paths. We will then calculate the energy density where these paths cross the predicted shock wave, in order to determine whether a shock wave is physically present. We want to see whether the shock produces a firewall of sufficient magnitude to disentangle particles, and on a relevant scale to be observed. We think this calculation will reveal that the shock wave produces super-Plankian energies, which are unphysical. This could invalidate the particular shock wave method for constructing firewalls, while contributing to a larger body of evidence against the existence of firewalls in general.


Berglund, Kallan, "Investigation of firewalls inside the event horizon of black holes" (2015). Summer Research Symposium. Brown Digital Repository. Brown University Library.



  • Summer Research Symposium

    Each year, Brown University showcases the research of its undergraduates at the Summer Research Symposium. More than half of the student-researchers are UTRA recipients, while others receive funding from a variety of Brown-administered and national programs and fellowships and go …