The concept of background independence is primarily associated with theories of quantum gravity and their attempts to reconcile general relativity with quantum mechanics. It refers to the idea that the laws of physics should not depend on a fixed background structure or geometry.
Coherence, in the context of quantum mechanics, refers to the property of a quantum system where its components are in a superposition or entangled state, exhibiting interference and wave-like behavior. Coherence is a fundamental feature of quantum systems, and it can be observed in various contexts, such as interference experiments.
However, coherence itself is not directly tied to the concept of background independence. Background independence primarily concerns theories of gravity and the nature of space and time at a fundamental level. It is about formulating physical theories in a way that does not rely on pre-existing structures or geometries, such as fixed spacetime backgrounds.
In the realm of quantum gravity, where background independence is a key concern, researchers are exploring approaches such as loop quantum gravity, causal sets, and string theory. These approaches aim to describe the behavior of spacetime itself in a quantum mechanical framework, where the structure of spacetime emerges dynamically from more fundamental entities.
In these theories, the nature of quantum effects and coherence within a background-independent framework is an active area of research. While it is difficult to make definitive statements about the specific details or implications of these theories, there are ongoing investigations into how quantum effects and coherence might manifest in a background-independent description of reality.
It's important to note that our understanding of quantum gravity is still a subject of active research, and there is no universally accepted theory that fully combines general relativity and quantum mechanics in a background-independent manner. Therefore, the precise relationship between coherence, quantum effects, and background independence in a complete theory of quantum gravity remains an open question.