Outside of our current pictures or knowledge of the universe lies plasma which is comprised of electrons and nuclei. Due to the lack of knowledge, it is quite difficult to review the behavior of the plasma. However, scientists are aware that the plasma behavior indicates low viscosity behavior resulting in irregularities. Separately, depending on the positioning of the plasma along the magnetic field lines, speculation is that viscosity could vary.
While RheoSense viscometers haven't been directly used on space plasma, we work with many samples that are not always homogenous including samples such as emulsions. Being able to characterize different types of applications have been a strong suit in our network.
“Suppressed effective viscosity in the bulk intergalactic plasma.” Zhuravleva et al,Nature Astronomy, June 17, 2019. DOI: 10.1038/s41550-019-0794-z