Retrocausality Revisited
“If retrocausality is a feature of the quantum world, then it would have vast implications for physicists’ understanding of the foundations of quantum theory. Perhaps the biggest significance is the implication for the Bell tests, showing that distant particles really cannot influence each other, but rather—as Einstein and others believed—that quantum theory is incomplete. If the new results are true, then retrocausality may be one of the missing pieces that makes quantum theory complete.
‘I think that different interpretations [of quantum theory] have different implications for how we might go about generalizing standard quantum theory,’ Leifer said. ‘This might be needed to construct the correct theory of quantum gravity, or even to resolve some issues in high-energy physics given that the unification of the other three forces is still up in the air in the light of LHC results. So I think that future theories built on the ideas of existing interpretations are where we might see a difference, but admittedly we are quite far from figuring out how this might work at present.
‘Speculatively, if there is retrocausality in the universe, then it might be the case that there are certain eras, perhaps near the big bang, in which there is not a definite arrow of causality. You might imagine that a signature of such an era might show up in cosmological data, such as the cosmic microwave background. However, this is very speculative, and I have no idea what signatures we might expect yet.'”
the observer effect 