Causality and Non-Locality in Quantum Mechanics: An argument for retrocausation

Master thesis English OPEN
Mjelva, Jørn Kløvfjell (2017)
  • Subject: Philosophy of Physics | Non-locality | Philosophy of Science | EPR | Bayes nets-theories | Locality | Quantum Entanglement | Retrocausation | Bell | Causality | causal asymmetry | Quantum Mechanics | Causal Markov Condition | Separability | Causation | Relativity | Direction of causation | Time | Screening-off Criterion | Metaphysics | Causal models | Special Theory of Relativity | Principle of the Common Cause
    arxiv: Physics::History of Physics

It has been claimed that quantum mechanics is a non-local theory, i.e., that the predictions of quantum mechanics are at odds with a conception of the world where all the interactions are mediated by local mechanisms. The cited reason is the violation of the Bell inequality in cases where measurements are performed on quantum systems of particles that have interacted in the past. Quantum mechanics predicts that the state of the particles in such a system are correlated, a result obtained from considering a thought-experiment often known as EPR. In this thesis, I will argue that the violation of the Bell inequality in EPR forces us to either accept that causes sometimes act both backwards and forwards in time, or give up some widely-held assumptions about causal relations or the role of causal explanations. First, I will present three principles regarding causality that I take be widely accepted. I will then present the background for the claim the quantum mechanics is a non-local theory, and discuss the implications of non-local causal influences in light of the Special Theory of Relativity. One argument against a causal explanation of the EPR-correlations will be discussed, and different models for the causal structure of EPR will be assessed. I will argue that a retrocausal model – models that include instances of retrocausation, where the direction of causation is the opposite of the direction of time – is the only viable option if we want to uphold the three principles presented in chapter 1. I will discuss the plausibility of rejecting one of these principles, and argue that at least one of the can be restricted in a way that still accounts for our commitment to it. Finally, I will assess the non-local models against the retrocausal models, and argue that a retrocausal model offers interpretational advantages over the non-local alternatives.
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