English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

In the Schroedinger equation, time plays a special role as an externalparameter. We show that in an enlarged system where the time variable denotesan additional degree of freedom, solutions of the Schroedinger equation giverise to weights on the enlarged algebra of observables. States in theassociated GNS representation correspond to states on the original algebracomposed with a completely positive unit preserving map. Application of thismap to the functions of the time operator on the large system delivers thepositive operator valued maps which were previously proposed by two of us astime observables. As an example we discuss the application of this formalism tothe Wheeler-DeWitt theory of a scalar field on a Robertson-Walker spacetime.

Time in quantum physics: From an external parameter to an intrinsic observable