Planckian Energy Scattering, Colliding Plane Gravitational Waves and   Black Hole Creation
  In a series of papers Amati, Ciafaloni and Veneziano and 't Hooft conjectured that black holes occur in the collision of two light particles at planckian energies. In this paper we discuss a possible scenario for such a process by using the Chandrasekhar-Ferrari-Xanthopoulos duality between the Kerr black hole solution and colliding plane gravitational waves. We clarify issues arising in the definition of transition amplitude from a quantum state containing only usual matter without black holes to a state containing black holes. Collision of two plane gravitational waves producing a space-time region which is locally isometric to an interior of black hole solution is considered. The phase of the transition amplitude from plane waves to white and black hole is calculated by using the Fabbrichesi, Pettorino, Veneziano and Vilkovisky approach. An alternative extension beyond the horizon in which the space-time again splits into two separating gravitational waves is also discussed. Such a process is interpreted as the scattering of plane gravitational waves through creation of virtual black and white holes. 
I.Ya. Aref'eva, K.S. Viswanathan and I.V.Volovich