I don't know if this is a travesty that they awarded the prize to work on non-physical systems to jump on a bandwagon or that there was nothing else obvious enough to the board in actual physics to give this to. If I was the awardee I'd consider declining just out of respect to the field.
"The Hopfeld network utilises physics that describes a material’s characteristics due to its atomic spin – a property that makes each atom a tiny magnet. The network as a whole is described in a manner equivalent to the energy in the spin system found in physics, and is trained by fnding values for the connections between the nodes so that the saved images have low energy"
"Hinton used tools from statistical physics, the science of systems built from many similar components."