 In the event, studies of quantum mechanical systems in black hole spacetimes have revealed several surprises that threaten to overturn the views of space, time, and matter that general relativity and quantum field theory each on their own suggests or relies on. Since the ground-breaking work of Wheeler, Penrose, Bekenstein, Hawking and others in the late 1960s and early 1970s, it has become increasingly clear that there are profound connections among general relativity, quantum field theory, and thermodynamics. This area of intersection has become one of the most active and fruitful in all of theoretical physics, bringing together workers from a variety of fields such as cosmology, general relativity, quantum field theory, particle physics, fluid dynamics, condensed matter, and quantum gravity, providing bridges that now closely connect disciplines once seen as largely independent. 