  Thermal duality is a relationship between the behaviour of heterotic string
models of the $E(8)x E(8)$ 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 Hagedon 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. This 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.
