  Semi-classical gravity is an approximation to quantum gravity where gravity
is treated classically and matter quantum mechanically. Matter is described by
quantum field theory on curved space-time, whereas gravity is described by a
space-time metric which satisfies Einstein's field equations. In the usual
approach to semi-classical gravity, the matter source term in Einstein's field
equations is given by the expectation value of the energy-momentum tensor
operator. In this paper, we suggest an alternative approach based on Bohmian
mechanics. In Bohmian mechanics, a quantum system is described by an actual
configuration (e.g., an actual scalar field), which evolves under the influence
of the wave function. The idea is to consider the actual energy-momentum tensor
corresponding to this configuration as the matter source term in Einstein's
field equations. This approach is expected to improve upon the usual approach.
