Generating a cosmological constant with gravitational waves

A technique is given to derive the well known Bell–Szekeres solution of the Einstein–Maxwell vacuum field equations describing the space-time and the Maxwell field following the head-on collision of two homogeneous, plane, electromagnetic shock waves. The analogue of this technique is then utilized to construct the space-time model of the gravitational field following the head-on collision of two homogeneous, plane, gravitational shock waves. The latter collision, which is followed by a pair of impulsive gravitational waves and a pair of light like shells traveling away from each other, provides a mechanism for generating a cosmological constant which may be important in the theoretical description of dark energy.