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 Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

We present a definite formulation of the Principle of General Covariance(GCP) as a Principle of General Relativity with physical content and thussusceptible of verification or contradiction. To that end it is useful tointroduce a kind of coordinates, that we call quasi-Minkowskian coordinates(QMC), as an empirical extension of the Minkowskian coordinates employed by theinertial observers in flat space-time to general observers in the curvedsituations in presence of gravitation. The QMC are operationally defined bysome of the operational protocols through which the inertial observersdetermine their Minkowskian coordinates and may be mathematically characterizedin a neighbourhood of the world-line of the corresponding observer. It is takencare of the fact that the set of all the operational protocols which areequivalent to measure a quantity in flat space-time split into inequivalentsubsets of operational prescriptions under the presence of a gravitationalfield or when the observer is not inertial. We deal with the Hole Argument byresorting to de idea of the QMC and show how it is the metric field thatsupplies the physical meaning of coordinates and individuates point-events inregions of space-time where no other fields exist. Because of that the GCP hasalso value as a guiding principle supporting Einstein's appreciation of itsheuristic worth in his reply to Kretschmann in 1918.

On the Meaning of the Principle of General Covariance