mångvärldstolkning

Mångvärldstolkningen, often translated as the many-worlds interpretation (MWI), is a quantum-mechanical interpretation proposed by Hugh Everett III in 1957. It attempts to resolve the measurement problem in quantum mechanics by suggesting that every quantum measurement causes the universe to split into multiple parallel universes, each corresponding to a different possible outcome of the measurement.

In classical quantum mechanics, a quantum system exists in a superposition of states until a measurement is performed. This measurement causes the wave function to collapse into a single, definite state. The nature of this collapse and what constitutes a "measurement" has been a long-standing puzzle. The many-worlds interpretation avoids the concept of wave function collapse altogether. Instead, it posits that all possible outcomes of a quantum event are realized in separate, non-interacting universes.

For example, if a quantum system can be in state A or state B, a measurement will cause the universe to branch. In one universe, the outcome is A, and in another, the outcome is B. Observers in each universe will perceive only one outcome, unaware of the other branches. This interpretation is deterministic, as the evolution of the universal wave function is governed by the Schrödinger equation without any probabilistic collapse.

The many-worlds interpretation is one of several interpretations of quantum mechanics, including the Copenhagen interpretation and hidden-variable theories. It is favored by some physicists for its mathematical elegance and its straightforward adherence to the principles of quantum mechanics without introducing new postulates like wave function collapse. However, it is also criticized for its ontological extravagance, postulating an immense number of unobservable universes.