A Neglected Route to Realism about Quantum Mechanics

Abstract

Bell's Theorem assumes that hidden variables are not influenced by future\nmeasurement settings. The assumption has sometimes been questioned, but the\nsuggestion has been thought outlandish, even by the taxed standards of the\ndiscipline. (Bell thought that it led to fatalism.) The case for this reaction\nturns out to be surprisingly weak, however. We show that QM easily evades the\nstandard objections to advanced action. And the approach has striking\nadvantages, especially in avoiding the apparent conflict between Bell's Theorem\nand special relativity.\n The second part of the paper considers the broader question as to why\nadvanced action seems so counterintuitive. We investigate the origins of our\nordinary intuitions about causal asymmetry. It is argued that the view that the\npast does not depend on the future is largely anthropocentric, a kind of\nprojection of our own temporal asymmetry. Many physicists have also reached\nthis conclusion, but have thought that if causation has no objective direction,\nthere is no objective content to an advanced action interpretation of QM. This\nturns out to be a mistake. From the ordinary subjective perspective, we can\ndistinguish two sorts of objective world: one "looks as if" it contains only\nforward causation, the other ``looks as if'' it involves a mix of backward and\nforward causation. This clarifies the objective core of an advanced action\ninterpretation of QM, and shows that there is an independent symmetry argument\nin favour of the approach.\n