While most are familiar with string theory as a proposed means to quantize gravity and unify the forces of nature, gauge string duality -- an idea which arose out of string theory -- can be used as a tool to address problems in other, lower energy fields of physics. Gauge string dualities are also known as AdS/CFT correspondences and gauge gravity dualities. Through the duality, I will discuss how certain classical theories of gravity may be interpreted as strongly interacting quantum field theories. I will then discuss recent efforts to apply gauge string duality to high temperature superconductors and also to the calculation of entanglement entropy.