The Many-Worlds Interpretation (MWI) of quantum mechanics is one of several interpretations attempting to explain the behavior of quantum systems. According to the MWI, when a quantum measurement occurs, the universe branches into multiple parallel worlds, each corresponding to a different outcome of the measurement.
In the Many-Worlds Interpretation, these alternate worlds are considered real, not just metaphorical or illustrative constructs. Each world represents a different possibility or outcome that could arise from a quantum measurement. These worlds are seen as existing in a kind of parallel reality, with each world evolving independently according to the laws of quantum mechanics.
However, it's important to note that the MWI is just one interpretation of quantum mechanics, and there are other interpretations as well, such as the Copenhagen interpretation or the pilot-wave theory. Different interpretations propose different ways of understanding and explaining the behavior of quantum systems, and the choice of interpretation often depends on personal philosophical and scientific preferences.
While the MWI suggests the existence of multiple parallel worlds, it's worth mentioning that these worlds are not directly observable or accessible in a practical sense. They exist as theoretical constructs to explain the probabilistic nature of quantum mechanics and the apparent collapse of the wavefunction upon measurement.
Ultimately, whether one considers these parallel worlds as "real" or as useful metaphors depends on their philosophical stance and interpretation of quantum mechanics. The MWI provides a consistent mathematical framework for understanding quantum phenomena, but the question of the ontological status of these parallel worlds remains a topic of debate and interpretation.