Criticisms of The Many-Worlds Interpretation

Interpretation of quantum mechanics which denies the collapse of the wavefunction.

The Many-Worlds Interpretation (MWI) of quantum mechanics, also known as Everettian Quantum Theory, has been a subject of intense debate since its inception. While it offers a solution to the measurement problem in quantum mechanics and eliminates the need for wave function collapse, it also raises a host of questions and criticisms. This article will explore some of the main criticisms of the MWI.

Lack of Empirical Testability

One of the most common criticisms of the MWI is the perceived lack of empirical testability. Critics argue that if every possible outcome of a quantum measurement occurs in some world, it becomes impossible to empirically test the theory. This is because we can only observe the outcomes in our own world, not the infinite other worlds that the MWI postulates. This criticism is closely related to the philosophical question of falsifiability: if a theory cannot be proven false by any conceivable experiment, is it still a scientific theory?

The Preferred Basis Problem

The preferred basis problem is another significant criticism of the MWI. In the MWI, the universe is constantly splitting into different worlds, each representing a different outcome of a quantum measurement. However, the theory does not specify a "preferred basis" for these splits. In other words, it does not explain why the universe splits in the way it does, or why it splits into the particular worlds that it does. This lack of a preferred basis is seen by some as a major flaw in the MWI.

The Issue of Probability

The issue of probability in the MWI is a complex and controversial one. In the traditional Copenhagen interpretation of quantum mechanics, the probabilities of different outcomes are given by the square of the wave function's amplitude. However, in the MWI, all outcomes occur with certainty in some world. This raises the question of how to interpret probabilities in the MWI. Some proponents of the MWI argue that probabilities in the MWI can be understood in terms of the "measure" of the worlds in which each outcome occurs, but this interpretation is not universally accepted.

The "Reality" of the Many Worlds

Finally, the very concept of the "many worlds" in the MWI is a subject of criticism. Some critics argue that the idea of an infinite number of unobservable worlds is metaphysically extravagant and ontologically problematic. Others question whether these "worlds" are real in the same sense that our observable universe is real, or whether they are merely mathematical constructs.

In conclusion, while the Many-Worlds Interpretation offers a unique and intriguing perspective on quantum mechanics, it also raises a host of questions and criticisms. These criticisms are an important part of the ongoing debate about the interpretation of quantum mechanics, and they continue to inspire new research and new ideas in the field.