2003/06/30 by Robert Oeckl
Physics and Astronomy · #gr-qc #hep-th #quant-ph
paper · pdf · doi:10.1088/0264-9381/20/24/009
published as Class.Quant.Grav. 20 (2003) 5371-5380 · 12 pages, 3 figures, LaTeX + AMS + eps; introduction, section numbers and two references added
arxiv created 2003/10/15 · arxiv updated 2009/11/30
I review basic principles of the quantum mechanical measurement process in view of their implications for a quantum theory of general relativity. It turns out that a clock as an external classical device associated with the observer plays an essential role. This leads me to postulate a ``principle of the integrity of the observer''. It essentially requires the observer to be part of a classical domain connected throughout the measurement process. Mathematically this naturally leads to a formulation of quantum mechanics as a kind of topological quantum field theory. Significantly, quantities with a direct interpretation in terms of a measurement process are associated only with amplitudes for connected boundaries of compact regions of space-time. I discuss some implications of my proposal such as in-out duality for states, delocalization of the ``collapse of the wave function'' and locality of the description. Differences to existing approaches to quantum gravity are also highlighted.