Is Many-Worlds the Best Interpretation of Quantum Mechanics?

Check out this answer from Consensus:

The Many-Worlds Interpretation of quantum mechanics presents a radical yet compelling view of reality. Its theoretical foundations and practical implications, particularly in quantum computation, make it a strong contender among quantum interpretations. However, the lack of experimental evidence and unresolved issues like the problem of probability continue to challenge its acceptance. Whether MWI is the best interpretation remains an open question, but it undoubtedly provides a fascinating framework for understanding the quantum world.

The interpretation of quantum mechanics has been a subject of intense debate since the inception of the theory. Among the various interpretations, the Many-Worlds Interpretation (MWI) has garnered significant attention. This article explores whether MWI is the best interpretation of quantum mechanics by examining its theoretical foundations, practical implications, and the criticisms it faces.

Theoretical Foundations of Many-Worlds Interpretation

The Many-Worlds Interpretation was first proposed by Hugh Everett in 1957. According to MWI, every quantum event results in a branching of the universe into multiple, non-interacting parallel worlds, each representing a different outcome of the event8. This interpretation eliminates the need for wave function collapse, a concept central to the Copenhagen interpretation, and asserts that the wave function describes the entire universe deterministically8.

Practical Implications

One of the most compelling arguments in favor of MWI is its application in quantum computation. David Deutsch and others have suggested that MWI is the only interpretation capable of explaining the efficiency of quantum computers over classical ones2. This is because MWI treats the universal state vector as representing real ontological features, which is crucial for explaining quantum computational efficiency2. Additionally, the neo-Everettian theory, a modern version of MWI, provides several advantages for quantum computation, including a local interpretation and a robust framework for understanding quantum mechanics7.

Criticisms and Counterarguments

Despite its theoretical elegance and practical applications, MWI faces several criticisms. One common objection is the “problem of probability,” which questions how probabilities can be meaningfully assigned in a deterministic multiverse7. However, proponents argue that this problem can be addressed through self-locating uncertainty and understanding probability in the context of branching worlds3.

Another criticism is the lack of experimental evidence for MWI. While some propose that communication among parallel worlds could provide direct evidence for MWI, such experiments remain speculative and technically challenging10. Moreover, the interpretation’s reliance on decoherence to explain the appearance of wave function collapse is seen as subjective, depending on the choice of the environment5.

Comparative Analysis

When compared to other interpretations, MWI offers a unique perspective by treating the wave function as a real, physical entity. This contrasts with the Copenhagen interpretation, which views the wave function as a tool for predicting measurement outcomes without providing a physical description of reality1. The Consistent Histories and Bohm interpretations also offer alternative views but have not gained as much traction among physicists1.

Is many-worlds the best interpretation of quantum mechanics?

Stephen Boughn has answered Unlikely

An expert from Haverford College in Physics, Cosmology

Many worlds is not the best interpretation of quantum mechanics; however, I hasten to add that interpretations of quantum mechanics are, in a sense, metaphysical or philosophical and can be highly subjective.  The fact is that such interpretations are rarely, if ever, necessary in “doing” quantum mechanics.  I personally see no need to go beyond Niels Bohr’s circa 1930 Copenhagen interpretation.  

As a point of information:  The originator of the many worlds interpretation did not so label his interpretation.  It was Bryce DeWitt and Neil Graham that labeled Hugh Everett’s interpretation as “many worlds”.  Everett never described his interpretation in terms of branching universes.  I find his more nuanced presentation preferable to that of DeWitt and Graham and, for that matter, to wave function collapse interpretations.  However as mentioned above, if one insists on subscribing to a metaphysical interpretation, I find l Bohr’s original as the most reasonable.

I have written more about this in a recent article titled “Make Sense of the Many Worlds Interpretation” on Arxiv.