# Many-Worlds Interpretation (MWI)

The Many-Worlds Interpretation (MWI) is a quantum mechanics theory proposed by Hugh Everett III in 1957. Everett, a physicist and mathematician, developed this hypothesis during his doctoral work at Princeton University. The MWI is a solution to the famous measurement problem in quantum mechanics, which involves the collapse of a wave function during a measurement. Everett’s work took the initial groundwork laid by scientists like Niels Bohr and Werner Heisenberg and proposed a radically different approach to interpreting the quantum phenomena.

According to MWI, all possibilities inherent in the quantum wavefunction are actualized in some “world” or universe. In essence, the theory suggests that for every possible outcome of a quantum event, there exists a separate universe. So rather than wavefunction collapse resulting in one outcome, every possible outcome occurs in a separate universe. This theory essentially postulates an infinite number of universes, which together comprise the “multiverse.”

Everett’s theory was a bold departure from the Copenhagen Interpretation, the prevailing interpretation at the time, which held that the act of measurement caused the wavefunction to “collapse” to a single possibility. The MWI eliminated the notion of wavefunction collapse and introduced the concept of a universal wavefunction that encompassed all possibilities.

Everettâ€™s theory was largely ignored during his lifetime. However, it later gained acceptance and today is considered one of the leading interpretations of quantum mechanics (“The Many Worlds of Hugh Everett” – Scientific American, 2008).

One of the most vocal supporters of MWI is David Deutsch, a physicist at the University of Oxford, known for his foundational work in quantum computation. In his book, “The Fabric of Reality,” Deutsch provides an articulate explanation and defense of MWI. He argues that quantum computation would involve computations across multiple parallel universes, leveraging the multiple states a quantum system can simultaneously exist in.

Deutsch considers MWI to be a cornerstone in our understanding of physical reality, a view not universally shared among physicists. However, this does not invalidate the scientific rigor of his work in quantum computation (“The Fabric of Reality: The Science of Parallel Universes–and Its Implications”, David Deutsch, 1997).

MWI remains a debated theory within the scientific community. A poll at a Quantum Foundations conference in 2013 found that the MWI was the second most popular interpretation among physicists present (“Quantum physicists agree: Cosmic inflation is proved”, Nature News, 2014).

MWI might one day be proof of parallel lives or even the possibility of time travel. The Many-Worlds Interpretation proposed by Hugh Everett III is a significant contribution to the interpretation of quantum mechanics. While controversial, it offers a fascinating perspective on the fundamental nature of reality.