In its most general sense, the term "world" refers to the totality of entities, to the whole of reality or to everything that was, is and will be. The nature of the world has been conceptualized differently in different fields. Some conceptions see the world as unique while others talk of a "plurality of worlds". Some treat the world as one simple object while others analyze the world as a complex made up of many parts. In scientific cosmology the world or universe is commonly defined as "[t]he totality of all space and time; all that is, has been, and will be". Theories of modality, on the other hand, talk of possible worlds as complete and consistent ways how things could have been. Phenomenology, starting from the horizon of co-given objects present in the periphery of every experience, defines the world as the biggest horizon or the "horizon of all horizons". In philosophy of mind, the world is commonly contrasted with the mind as that which is represented by the mind.