Many-worlds interpretation

An interpretation of quantum mechanics in which the universal wavefunction never collapses; interactions produce branches containing distinct outcomes, all of which occur.

Universal wavefunction: The quantum state assigned to the entire universe, encompassing all matter and interactions. Many-worlds treats this state as real and continuously evolving, rather than collapsing during measurement.
Hugh Everett III: American physicist who proposed the relative-state formulation of quantum mechanics in 1957. Everett introduced the account later known as the many-worlds interpretation.
Objective collapse theory: A family of theories in which quantum states physically collapse through stochastic dynamics. Unlike many-worlds, these theories modify quantum evolution to produce single outcomes.
Probability in many-worlds: The problem of explaining why observers should assign Born-rule probabilities to outcomes across branches. All outcomes occur, so ordinary uncertainty about which outcome happens needs reinterpretation.
Schrödinger equation: A differential equation describing how a quantum state changes over time. Its uninterrupted evolution is the central dynamical rule in many-worlds.
Relative state formulation: Everett's formulation in which quantum states describe correlations between subsystems rather than absolute outcomes. This was the original framework from which many-worlds developed.
Bohmian mechanics: A deterministic quantum theory in which particles have definite positions guided by a wavefunction. It retains a single actual configuration rather than treating every outcome branch as real.
Branching in quantum mechanics: The emergence of approximately independent quasi-classical histories from quantum evolution and decoherence. The theory does not supply a unique, exact boundary defining when one branch becomes many.
Quantum decoherence: The suppression of observable interference when a quantum system becomes entangled with its environment. Decoherence makes branches behave approximately independently without deleting any of them.
Copenhagen interpretation: A family of quantum interpretations that uses measurement outcomes and, in some formulations, wavefunction collapse. Everett's proposal rejected the need for a distinct collapse at measurement.

Linked from 35 pages