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AKPhil: Arbeitskreis Philosophie der Physik

AKPhil 5: Quantentheorie

AKPhil 5.3: Vortrag

Dienstag, 4. März 2008, 15:45–16:15, KGI-HS 1015

Objectivity vs. Locality in Quantum Physics — •Ernst-Walther Stachow — Vorgebirgstr. 35, 50677 Köln

A quantum logical account of different steps of a measuring process of a two-valued observable  is given. Since the typical interaction forces depend on positions ŷ, pre-measurements are considered which couple  to ŷ and ŷ is measured. After the pre-measurement, the proposition (AΛx)v (ÃΛy) is true, whereby the propositions A and à correspond to  and 1- and v is the quantum logical "or". After the final step (called Registration) of the measuring process, (AΛx) υ (ÃΛy) is true, υ designating the logical "or". The question arises, whether it can consistently be assumed [Objectivity assumption (O)] that already before Registration and after the pre-measurement either AΛx or ÃΛy is true. It is then shown that (O) together with a Locality assumption (L) leads to a contradiction with experimental results. (L) states that, if AΛx is true and Registration is performed at y at time t, this cannot have any influence on x at time ť if (y, t) and (x,ť) are space-like. (O) and (L) can also be applied to the often discussed EPR experiment. It is shown that from both assumptions (together with trivial ones) Bell's inequality follows, implying again that, if (L) is maintainted, (O) must be rejected , and vv.