Wigner’s friend thought experiment

E98263

foundational quantum mechanics scenario interpretation-of-quantum-mechanics problem philosophy of physics concept thought experiment

Wigner’s friend thought experiment is a foundational quantum mechanics scenario that explores the role of observers and consciousness in measurement by considering how different observers can assign conflicting quantum states to the same system.

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All labels observed (5)

Label	Occurrences
Wigner’s friend thought experiment canonical	3
Schrödinger's cat	1
Wigner's friend thought experiment	1
Wigner’s friend	1
Wigner’s friend paradox	1

Statements (48)

Predicate	Object
instanceOf	foundational quantum mechanics scenario ⓘ interpretation-of-quantum-mechanics problem ⓘ philosophy of physics concept ⓘ thought experiment ⓘ
addresses	objectivity of measurement outcomes ⓘ observer relativity of quantum states ⓘ quantum measurement problem ⓘ
coreIdea	different observers can assign different quantum states to the same physical system ⓘ friend observes a definite outcome while Wigner may still assign a superposed state ⓘ tension between unitary evolution and collapse postulate ⓘ
field	foundations of quantum mechanics ⓘ philosophy of physics ⓘ quantum mechanics ⓘ
hasAuthor	Eugene Wigner ⓘ
hasInterpretationImplicationsFor	collapse theories ⓘ hidden-variable theories ⓘ objective collapse models ⓘ subjective Bayesian interpretations ⓘ
historicalPeriod	20th century ⓘ
involvesConcept	conscious observer ⓘ measurement outcome ⓘ observer-relative state assignment ⓘ superposition ⓘ unitary evolution ⓘ wave function collapse ⓘ
involvesEntity	Eugene Wigner ⓘ surface form: Wigner Wigner’s friend thought experiment self-linksurface differs ⓘ surface form: Wigner’s friend laboratory isolated from Wigner ⓘ quantum system in a superposition ⓘ
mainTheme	consciousness and quantum measurement ⓘ measurement problem in quantum mechanics ⓘ observer-dependent quantum states ⓘ role of observers in quantum measurement ⓘ
namedAfter	Eugene Wigner ⓘ
proposes	consciousness may play a role in wave function collapse ⓘ
questionRaised	whether all observers must agree on a single set of facts ⓘ whether consciousness is necessary to define measurement outcomes ⓘ whether quantum mechanics is universally valid for observers themselves ⓘ
relatedTo	Copenhagen interpretation of quantum mechanics ⓘ surface form: Copenhagen interpretation Everett many-worlds interpretation ⓘ Frauchiger–Renner paradox ⓘ QBism ⓘ Schrödinger's cat thought experiment ⓘ surface form: Schrödinger’s cat relational quantum mechanics ⓘ
usedInDebatesOn	consistency of quantum theory for multiple observers ⓘ objectivity vs subjectivity of quantum states ⓘ role of consciousness in physics ⓘ status of the wave function ⓘ

Referenced by (7)

Full triples — surface form annotated when it differs from this entity's canonical label.

Eugene Wigner → knownFor → Wigner’s friend thought experiment ⓘ

Eugene Wigner → notableIdea → Wigner’s friend thought experiment ⓘ

this entity surface form: Wigner’s friend paradox

Erwin Schrödinger → notableWork → Wigner’s friend thought experiment ⓘ

this entity surface form: Schrödinger's cat

Wigner’s friend thought experiment → involvesEntity → Wigner’s friend thought experiment self-linksurface differs ⓘ

this entity surface form: Wigner’s friend

Wigner Jenő Pál → knownFor → Wigner’s friend thought experiment ⓘ

Schrödinger's cat thought experiment → relatedTo → Wigner’s friend thought experiment ⓘ

this entity surface form: Wigner's friend thought experiment

wavefunction collapse → discussedInContextOf → Wigner’s friend thought experiment ⓘ