2013/08/31 by Carlo Rovelli · 2 citations
Physics and Astronomy · #hep-th #gr-qc
paper · pdf · doi:10.1007/s10701-013-9768-7
published as Foundations of Physics 44 (2014) 91-104 · 8 pages (references added)
arxiv created 2013/11/13 · arxiv updated 2016/07/06
The world appears to be well described by gauge theories; why? I suggest that gauge is more than mathematical redundancy. Gauge-dependent quantities can not be predicted, but there is a sense in which they can be measured. They describe "handles" though which systems couple: they represent real relational structures to which the experimentalist has access in measurement by supplying one of the relata in the measurement procedure itself. This observation leads to a physical interpretation for the ubiquity of gauge: it is a consequence of a relational structure of physical quantities.