Is Causality Preserved in Quantum Mechanics?

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SUMMARY

The discussion centers on the preservation of causality in quantum mechanics (QM), particularly in relation to entanglement swapping as demonstrated by Anton Zeilinger et al. Participants explore whether causality can act retroactively and the implications of this for interpretations of QM. Key points include the deterministic nature of the Schrödinger equation and the probabilistic outcomes of observations, highlighting that while the state is causal, the results of measurements may not be. The conversation concludes that interpretations of QM vary, with retrocausality being a less common perspective.

PREREQUISITES
  • Understanding of Schrödinger's equation in quantum mechanics
  • Familiarity with quantum entanglement and Bell-state measurements
  • Knowledge of interpretations of quantum mechanics, including retrocausality
  • Basic grasp of the Heisenberg Uncertainty Principle
NEXT STEPS
  • Study the implications of Bell's theorem on causality in quantum mechanics
  • Learn about different interpretations of quantum mechanics, focusing on retrocausal theories
  • Explore the concept of entanglement swapping and its experimental setups
  • Investigate the role of the Heisenberg Uncertainty Principle in quantum measurements
USEFUL FOR

Students of quantum mechanics, physicists exploring the foundations of quantum theory, and researchers interested in the philosophical implications of causality in quantum systems.

  • #61
entropy1 said:
So, if there is no realism, a particle may not even exist if not measured? What does the qualification 'local' mean in this context?
That is a good question. Adopting a no realism/epistemic interpretation does appear to avoid ontic, non-local causal influences (and maintain a fully relativistic account of physical goings-on). But, at the same time, it's not clear that a non-realist interpretation actually saves locality because in adopting that kind of interpretation, the distinction between 'local' and 'non-local' would not even appear to apply.
 
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  • #62
bohm2 said:
That is a good question. Adopting a no realism/epistemic interpretation does appear to avoid ontic, non-local causal influences (and maintain a fully relativistic account of physical goings-on). But, at the same time, it's not clear that a non-realist interpretation actually saves locality because in adopting that kind of interpretation, the distinction between 'local' and 'non-local' would not even appear to apply.
Thank you. It seems to me that, if you don't measure the event, there is at least no 'informational' connection established between the observer and the event - concerning a measurement. (?)
 
  • #63
The initial question has been answered a long time ago. Yes, QM is causal.

Time to close the thread.
 
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