Abstract: Wolfgang Pauli famously dismissed solid-state physics as “the physics of dirt.” As much as it pains me to admit, there is a grain of truth in his quip: electronic properties such as resistivity are often dictated by extrinsic “dirt,” i.e. impurities and sample defects. Recently, however, a new class of materials has emerged where electrons behave collectively as a viscous fluid. In this regime, scattering off individual impurities is suppressed, and transport instead admits a universal description in which Ohm’s law is supplanted by the richer Navier–Stokes equation. This new paradigm of “viscous electronics” not only opens avenues for novel device concepts, but also provides a fresh perspective on how quantum mechanics constrains and enriches hydrodynamics.