Relational Quantum Mechanics (RQM) is an interpretation of quantum mechanics that removes the idea of an absolute state of a physical system. Instead, it posits that the properties of a quantum system are relative to the observer. The theory emphasizes the role of interactions, suggesting that physical systems only have definite properties when they are being observed or measured.
At the heart of RQM is the principle that the physical state of a system is not an intrinsic property, but rather depends on its relationship with other systems. Quantum properties, such as a particle's position or momentum, do not exist in a vacuum; they exist when there is an interaction between the observed system and an observing system.
According to RQM, the classic 'observer effect' in quantum mechanics is a built-in feature. The observer and the observed establish a relation, and it is this relation that dictates the properties of the quantum system. In some interpretations, this means multiple observers can have differing accounts of reality simultaneously. For example, two observers of a quantum event might report different outcomes, and both could be correct relative to their individual perspectives.
One of the most intriguing aspects of RQM is how it challenges classical conceptions of reality. By suggesting reality is observer-dependent, RQM aligns with a more philosophical standpoint, where objectivity is replaced by a network of subjective interactions. This continual dance of relationships dictates the universe's configuration at any given moment.
RQM also offers a fresh perspective on quantum entanglement. Instead of viewing it as a mysterious 'spooky action at a distance,' it posits entangled particles share information due to their relational properties. Thus, the connectivity seen in entanglement is a natural outcome of the relational framework.
Moreover, it provides an interesting stance on the measurement problem. Rather than spanning years puzzling over why measuring a quantum system seems to 'collapse' it into a definite state, RQM suggests that this collapse is no more than establishing a relational property between the observer and the system.
RQM was proposed by Carlo Rovelli and a small number of physicists advocate for this interpretation. It is generally embraced by those interested in merging quantum mechanics with philosophical inquiry and those seeking an alternative to more traditional interpretations like the Copenhagen interpretation.
While RQM hasn't become a mainstream pop culture phenomenon, its influence on narratives involving parallel realities and subjective experiences of reality is notable. Its echoes can be seen in films and books that explore the question of what it means for something to be 'real', often reveling in the idea that one's interpretation changes the nature of reality itself.
Almost manageable. RQM doesn't stray as far from mainstream physics as ideas like the Many-Worlds Interpretation, but its radical philosophical implications provide a rich ground for lively debate.