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The Infinite Tree: How Hugh Everett Invented the Quantum Multiverse

Niels Bohr taught that observing a quantum particle mysteriously collapses all alternate possibilities out of existence; Hugh Everett III proved that the mathematical equations of quantum physics never collapse at all, meaning every possible outcome actually happens in a branching parallel universe. Published in 1957 to career-ending ridicule, Everett’s "Many-Worlds Interpretation" is now one of the dominant frameworks of theoretical physics, driving modern quantum cosmology and quantum computing theory.

Author
Hugh Everett
Published
1957
Journal
Reviews of Modern Physics
Last updated
September 2026
The Infinite Tree: How Hugh Everett Invented the Quantum Multiverse

In standard quantum mechanics, a subatomic particle can exist in multiple places at once, like a spinning coin in mid-air. The traditional Copenhagen interpretation said that the instant a human looks at the particle, the wave function magically "collapses" into a single reality—an unscientific rule that treated human observers like magic wizards.

Princeton graduate student Hugh Everett III looked at the raw mathematics of the Schrödinger equation and asked: what if the wave function never collapses? He showed that when a measurement happens, the universe splits in two: in one branch, the coin lands heads, and in an equally real parallel branch, the coin lands tails.

Ostracized by Niels Bohr, Everett left academic physics, but his idea conquered theoretical physics decades later. By eliminating magical wave function collapse, by enabling modern quantum decoherence theory, and by anchoring quantum cosmology, the Many-Worlds interpretation decoded quantum reality.

Reference

Everett, H. (1957). “Relative State” Formulation of Quantum Mechanics. Reviews of Modern Physics, 29(3), 454–462.

Title

"Relative State" Formulation of Quantum Mechanics

Abstract

The task of quantizing general relativity raises serious questions about the meaning of the present formulation and interpretation of quantum mechanics when applied to so fundamental a structure as the space-time geometry itself. This paper seeks to clarify the foundations of quantum mechanics. It presents a reformulation of quantum theory in a form believed suitable for application to general relativity. The aim is not to deny or contradict the conventional formulation of quantum theory, which has demonstrated its usefulness in an overwhelming variety of problems, but rather to supply a new, more general and complete formulation, from which the conventional interpretation can be deduced. The relationship of this new formulation to the older formulation is therefore that of a metatheory to a theory, that is, it is an underlying theory in which the nature and consistency, as well as the realm of applicability, of the older theory can be investigated and clarified.

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