Wave packets in minisuperspace of quantum gravity are explicitly constructed for a Friedmann model containing either a massless or a massive homogeneous scalar field. Unparametrized tubelike standing waves corresponding to classically returning paths in configuration space can be constructed if a ‘‘final condition’’ with respect to the scale factor a is assumed to hold. Sensible wave packets are only obtained for certain discrete values of the mass and only in regions not too close to the classical turning point. Therefore it is meaningless in minisuperspace of quantum gravity to extend classical paths through this region to a recollapsing phase. This suggests that we introduce higher degrees of freedom which can produce classical paths by continuous measurement.

• Received 28 March 1988

DOI:https://doi.org/10.1103/PhysRevD.38.1761