De Rham, ClaudiaAlharbi, Ohoud Khader2023-10-092023-10-092023-09-29https://hdl.handle.net/20.500.14154/69348In the pursuit of finding a quantum field theory for gravity, theories of massive gravity have regained interest. Massive gravity in de Sitter and Anti-de Sitter spaces gives rise to a particularly promising avenue known as the theory of ‘Partially Massless Gravity’. Despite the inconsistencies and challenges found in many non-linear formulations of partially massless gravity, recent research indicates a potential breakthrough by considering non-unitary theories of multiple partially massless fields. This dissertation delves into the construction of partially massless gravity and its most recent progress, a nonunitary theory of multiple partially massless spin-2 fields, which we refer to as ‘Nonunitary Multi-field Partially Massless Gravity’. We present the consistency of the theory along with its implications and derive a simple test for the consistency of the theory for two fields in the mini-superspace ansatz. We highlight that the field is still in its recent stages, and numerous tests, enhancements, and discoveries are actively being made, paving the way to find a consistent description of gravity in the realm of quantum fields.71enQuantum GravitySpin-2 FieldsModified GravityPartially Massless GravityThesis