PLANCKIAN SCATTERING BEYOND THE SEMICLASSICAL APPROXIMATION

Motivated by recent investigations of near-forward planckian energy collisions, we compare various approaches giving the same leading eikonal approximation. We stress the' need of going beyond this approximation in order to control impact parameters b congruent-to GE which are crucial for understanding S-matrix singularities ('t Hooft poles) and the physics of gravitational collapse (black hole formation). We point out a few problems that alternative methods have to tackle in order to improve on the direct calculations that we have discussed elsewhere.