Anisotropic solutions as analogs for Kasner solutions in the presence of higher powers of extrinsic
curvature have first been studied in [142], although without considering refinements of the discreteness
scale. These solutions have already shown that anisotropic models also exhibit bounces when such
corrections are included phenomenologically, i.e., disregarding quantum backreaction. The issue
has been revisited in [128, 42] for models including refinement (and a free, massless scalar as
internal time) with the same qualitative conclusions. Similar calculations have been applied to
Kantowski–Sachs models, which classically provide the Schwarzschild interior metric, without refinement
in [231, 232] and with two different versions of refinement in [42]. They can thus be used to obtain
indications for the behavior of quantum black holes, at least in the vacuum case. Then, however, one
cannot use the arguments, which in isotropic cosmological models allowed one to conclude that
higher-power corrections are dominant given a large matter content. Correspondingly, bounces of
the higher-power phenomenological equations happen at much smaller scales than in massive
isotropic models. They are thus less reliable because other corrections can become strong in those
regimes.
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