1. Inconsistent Histories Revealed by Quantum Measurement A New Class of Paradoxes and their Implications Avshalom Elitzur and Shahar Dolev Bar-Ilan University

2. Overview: The RationaleThe Rationale The three views concerning timeThe three views concerning time The issue of time-asymmetry and indeterminismThe issue of time-asymmetry and indeterminism Two types of QM experiments: Spatial and temporal paradoxesTwo types of QM experiments: Spatial and temporal paradoxes Our strategyOur strategy Inconsistent histories?Inconsistent histories? Back to timeBack to time

3. The Rationale: QM challenges our basic notions of space and time. QM challenges our basic notions of space and time. Therefore, a better understanding of the quantum riddles will come from a deeper account of spacetime. Therefore, a better understanding of the quantum riddles will come from a deeper account of spacetime. Conversely, a better understanding of spacetime might emerge from investigating into quantum riddles Conversely, a better understanding of spacetime might emerge from investigating into quantum riddles

4. Three Views of Time: “Block Universe” “Block Universe” “Becoming” “Becoming” “Extreme Presentism” “Extreme Presentism”

5. The Issue Of Time-Asymmetry And Indeterminism Run Simulation!

6. The Issue Of Time-Asymmetry And Indeterminism

8. Two Types Of QM Experiments: Experiments presenting spatial peculiarities: Experiments presenting spatial peculiarities: E-V Experiment EPR Experiment

9. Two Types Of QM Experiments: Experiments presenting temporal peculiarities: Experiments presenting temporal peculiarities: Delayed Choice HBT Experiment Schrödinger’s cat

10. Aharonov’s and Cramer’s unifying theories: Aharonov’s and Cramer’s unifying theories: All type-A experiments are in fact type-B experiments. All type-A experiments are in fact type-B experiments. The problem: Block Universe again. The problem: Block Universe again. Aharonov’s and Cramer’s proposal 1.Offer 2.Confirmation 3.Negotiation 4.Handshake xx ? xx ?

11. Our Strategy: Postpone the Quantum-classical Interaction. Postpone the Quantum-classical Interaction. Pursue the bomb idea Pursue the bomb idea This was first taken up by Hardy. This was first taken up by Hardy.

12. Results: The first result (Hardy, 1992): EPR formed by a single particle in an MZI: The first result (Hardy, 1992): EPR formed by a single particle in an MZI: 1.Particles in superpositions (but not entangled) 2.“Silent” Detector clicks 3.The particles become entangled

13. Results: Second result (Hardy, 1992): a quantum mechanical bomb more intriguing than EV Second result (Hardy, 1992): a quantum mechanical bomb more intriguing than EV 1.Particle in a superposition 2.“Silent” Detector clicks 3.The particle must have “collapsed” into the crossing box 4.The photon must have gone through the opposite path!

14. Inconsistent Histories? A new class of paradoxes: When the measurement measures not only a state but an entire evolution, then A new class of paradoxes: When the measurement measures not only a state but an entire evolution, then –indeed sometimes an entire evolution seems to be formed; –sometimes that evolution looks like a Schrödinger cat with a history of a dead cat but traces of a live one.

15. Inconsistent Histories? Non sequential behavior of the wave function: Non sequential behavior of the wave function: 1.Particles in superposition (but not entangled) 2.“Silent” Detector clicks 3.The middle particle was measured and found to have “collapsed” into the intersecting box 4.All other particles returned to their original superposition!

16. (Elitzur, Dolev, Zeilinger 2001) … or better call it: RPE Inverse EPR…

17. Inverse EPR 1.Particles in superposition (but not entangled) 2.“Silent” Detector clicks 3.The particles become entangled

18. Inverse EPR With an inconsistent history? With an inconsistent history? 1.To test non-locality, test for Bell Inequality 2.Use Spin measurement in 3 directions: x, y, and z 3.Spin x (“which box”) measurement allows only one history for the photon 4.Consequently, the entanglement disappears

19. Inconsistent Histories? THIS SENTENCE HAS NEVER BEEN WRITTEN :-)

20. Back To Time Could there be a transactional model in which spacetime itself is subject to dynamics? Could there be a transactional model in which spacetime itself is subject to dynamics?