Thermal duality and gravitational collapse

Thermal duality is a relationship between the behaviour of heterotic string models of the E(8)xE(8) or SO(32) types at inversely related temperatures, a variant of T duality in the Euclidean regime. This duality would have consequences for the nature of the Hagedorn transition in these string models. We propose that the vacuum admits a family of deformations in situations where there are closed surfaces of constant area but high radial acceleration (a string regularized version of a Penrose trapped surface), such as would be formed in situations of extreme gravitational collapse. This would allow a radical resolution of the firewall paradox by allowing quantum effects to significantly modify the spacetime geometry around a collapsed object. A string bremsstrahlung process would convert the kinetic energy of infalling matter in extreme gravitational collapse to form a region of the deformed vacuum, which would be equivalent to forming a high temperature string phase. A heuristic criterion for the conversion process is presented, relating Newtonian gravity to the string tension, suggesting an upper limit to the strength of the gravitational interaction. This conversion process might have observable consequences for charged particles falling into a rotating collapsed object by producing high energy particles via a variant of the Penrose process. PACS numbers: 11.25.Sq, 11.25.Mj, 04.70Dy. 1 Black holes and discrete symmetries The family of classical black hole solutions is parameterised by mass, charge (standard model gauge charges) and angular momentum. Consider the effect of discrete symmetries on them. Whereas C and P are satisfactory T is not, as time reversed black holes are not (usually) allowed. This represents a radical violation of T and by extension CPT symmetry, and because of