Dear all, I'm a bit confused about non-relativistic applications of holography, like e.g. in https://arxiv.org/pdf/0812.0530v1.pdf and https://arxiv.org/abs/1306.0638 In these papers people try to connect holographically non-relativistic condensed matter systems, like the Quantum Hall Effect, to backgrounds in the bulk exhibiting non-relativistic isometries or non-relativistic theories of gravity, like Newton-Cartan. But in the AdS/CFT correspondence we have a duality between strongly coupled and weakly coupled theories. Shouldn't one expect to describe non-relativistic condensed matter systems by ultra-relativistic theories of gravity and vice versa? It probably has to do something with the fact that the correspondence involves the 't Hooft coupling. Can anyone comment on my confusion? Many thanks!