We demonstrate the existence of sudden finite-time singularities, with constant scale factor, expansion rate, and density, in expanding Bianchi type-IX universes with free anisotropic pressures. A new type of nonsimultaneous anisotropic sudden singularity arises because of the divergences of the pressures, which may be of barrel or pancake type. The effect of one or more directions of expansion hitting a sudden singularity is tantamount to dimensional reductions as the nonsingular directions continue expanding and can see the sudden singularity in their past.

• Received 25 June 2020
• Accepted 9 July 2020

DOI:https://doi.org/10.1103/PhysRevD.102.024073