Observing many body entanglement in strange metals.

In particular the cuprate strange metals represent arguably the most notorious mystery in condensed matter physics. An exciting possibility is that their strangeness is rooted in dense many-body entanglement, of a kind that can only be cracked by a quantum computer. However, it appears that the holographic duality discovered in string theory is a mathematical machinery that may generate universal phenomenological theories describing the physics of such compressible quantum matter. It has proven to be a fertile source of unusual questions to pose to experiment and I will review the state of the art of this development. This includes the relatively mature holographic transport theory revolving around hydrodynamics and Planckian dissipation. Also the latest developments will be highlighted revolving around the instabilities of strange metals, showing that the most salient features of the intertwined order arise naturally from the fanciful black hole haircuts generic in the gravitational dual.