The Firewall Phenomenon
Black holes have presented us with some of the most baffling paradoxes in physics. From their original conception as dark stars, they have come to be understood as physical systems with their own thermodynamic behaviour. This same behaviour leads to parad
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The Firewall Phenomenon R.B. Mann
Abstract Black holes have presented us with some of the most baffling paradoxes in physics. From their original conception as dark stars, they have come to be understood as physical systems with their own thermodynamic behaviour. This same behaviour leads to paradoxical conflicts between some of the basic principles of physics whose resolution is not straightforward and that suggest a new structure— known as a firewall—may be present. This chapter provides an overview of the firewall problem, as it emerges from our understanding of black hole thermodynamics. Keywords Information paradox · Black hole thermodynamics · Firewall
3.1 Introduction Black Holes have presented us with paradoxical situations ever since their conceptualization in 1783 by the Reverend Michell [1]. Originally seeking a means for determining stellar masses by measuring the reduction in the speed of corpuscular light due to a given star’s gravitational pull, Michell reasoned that the maximal effect measurable would be limited by the escape velocity from the star. This would have to be the speed of light, most recently measured by Bradley to be 301,000 km/s [2]. Any star more massive than this upper bound (500 times the mass of the sun assuming the same average density) would not permit light to escape from its surface. While no theoretical constraints for objects having speeds greater than c were known at the time, there were no empirical measurements indicating such objects existed either. Paradoxically, such stars would be dark stars, invisible to an outside observer, though they could be indirectly inferred from their gravitational influence on nearby luminous objects. The relationship between their mass and radius is given by the same relativistic value R = 2GM/c2 for Schwarzschild black holes. Ironically, Michell’s proposal for measuring the mass of a star by measuring its speed of light R.B. Mann (B) Department of Physics and Astronomy, University of Waterloo, Waterloo, Canada e-mail: [email protected] © Springer International Publishing Switzerland 2015 X. Calmet (ed.), Quantum Aspects of Black Holes, Fundamental Theories of Physics 178, DOI 10.1007/978-3-319-10852-0_3
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fails because light moves through space at constant speed regardless of the local strength of gravity. It would take nearly two centuries before the paradoxes associated with dark stars—now referred to as black holes—would dawn upon the physics community at large. Their inexorable gravitational chokehold on matter turns from puzzle to paradox once the quantum information content of the matter is taken into account. At this point in time there is no consistent understanding of how quantum physics allows information to either be retained in or escape from a black hole. Over the past two years this conundrum has received a new degree of scrutiny. It appears that a profound conflict between three core principles of physics—unitary, locality, and the equivalence principle—indicates that black holes may erect around them
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