Comments on firewalls in JT gravity with matter

A bstract We present two discussions of firewalls in JT gravity. First we present an alternative, arguably simpler, derivation of the gray hole conjecture, applying uniformly to all probes of the firewall probability previously discussed. This derivation is based on the wormhole shortening picture using the handle-disk geometry. However we modify Saad’s story utilizing a “Wilsonian” effective gravitational description, adapted to the time scale probed, in which high frequency modes are integrated out generating the gravitational bulk geometries (dual to the genus expansion in the matrix integral side) whereas low frequency modes are more precisely resolved by being represented as eigenvalue D-branes where JT universes can end. This treatment results in an effective “twist factor cutoff” prescription which simplifies the discussion of long time quantities including the firewall probability. In the second part we discuss effects of matter loops on the firewall probability. While such effects lead to new firewall sources, we argue that these matter loop contributions are sub-dominant at late times.