In this talk, I will discuss very general ways to reason about electrical resistivity in metals, beyond the conventional Fermi liquid theory. This will lead to a proposal for a new mechanism for resistivity that we call "critical drag", where the resistivity originates from critical fluctuations. This is strikingly different to more conventional resistivity mechanisms that involve violation of conservation laws such as momentum conservation. Furthermore, I will argue on general grounds that critical drag is the only resistivity mechanism that is likely to be compatible with the experimental observations on the "strange metal" seen in materials such as cuprates.
The arguments of this talk are based on powerful theoretical concepts such as emergent symmetries and anomalies, invoking ideas that originated in the study of topological phases of matter.