"In the delayed choice experiment, the decision whether or not to quantum erase the "which way" information can be made long after the original photons hit the screen and make their marks there. So decoherence has set in, and any parallel universes have necessarily become different in some ways. According to your interpretation, therefore, there can then be no interference, because the worlds cannot come back together. But we can restore the interference pattern by quantum erasing the which way information (e.g., by measuring in an orthogonal basis). So it is not a matter of whether there are differences between parallel universes -- it is whether or not the which way information still exists in some form or the other. Deutsch simply got the explanation of interference in terms of interactions between parallel universes wrong. Bruce"
Zeilinger et al. wrote: "It is a general feature of delayed-choice experiments that quantum effects can mimic an influence of future actions on past events. However, there never emerges any paradox if the quantum state is viewed only as `catalogue of our knowledge' (Schroedinger, 1935) without any underlying hidden variable description. Then the state is a probability list for all possible measurement outcomes and not a real physical object. The relative temporal order of measurement events is not relevant, and no physical interactions or signals, let alone into the past, are necessary to explain the experimental results. To interpret quantum experiments, any attempt in explaining what happens in an individual observation of one system has to include the whole experimental configuration and also the complete quantum state, potentially describing joint properties with other systems. According to Bohr and Wheeler, no elementary phenomenon is a phenomenon until it is a registered phenomenon (Bohr, 1949; Wheeler, 1984). In light of quantum erasure and entanglement swapping, one might like to even say that some registered phenomena do not have a meaning unless they are put in relationship with other registered phenomena (Ma et al., 2012)." https://arxiv.org/abs/1407.2930 -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/everything-list/1553839621.1052415.1571240606545%40mail1.libero.it.
