Summary

Explores Wheeler’s delayed-choice experiment at cosmic scale. Photon from distant galaxy billions of years ago encounters gravitational lensing, remains in superposition. Experimenter’s choice today determines whether to measure wave/particle properties—delayed choice shapes quantum history description. Key insight: Measurement doesn’t alter past, but retroactively determines narrative assigned to undefined quantum events. Pre-measurement: objective probability = quantum coherence (superposition). Post-measurement: decoherence creates distinct branches, subjective probability aligns with observed branch. QBU integration: Quantum histories relational/measurement-dependent until observed, even at cosmological scales. Challenges classical causality, embraces contextual/relational reality.

Tags

Cross-References

  • Related: Wheeler, Everett
  • Related: QBU framework

Notes

  • Dramatic illustration of quantum non-classicality
  • “Quantum history as narrative” theme
  • Presages later work on time, causality, block universe
  • Cosmological scale emphasizes robustness of quantum effects