Time-reparametrization invariance: from Glasses to toy Black Holes

Abstract: Glassy dynamics have time-reparametrization softness': glasses fluctuate, and respond to external perturbations, primarily by changing the pace of their evolution. Remarkably, the same situation also appears in toy models of quantum field theory such as the Sachdev-Ye-Kitaev (SYK) model, where the excitations associated to reparametrizations play the role of an emerginggravity'. I describe here how these two seemingly unrelated systems share common features, arising from a technically very similar origin. This connection is particularly close between glassy dynamics and supersymmetric variants of the SYK model, which I discuss in some detail. Apart from the curiosity that this correspondence naturally arouses, there is also the hope that developments in each field may be useful for the other.