I will present a method of determining the mass density along the line of sight using variations of times of arrival of electromagnetic signals, as measured by two ensembles of free falling, precise clocks. The whole set-up may be considered a type of an extended gravitational compass, i.e. a device measuring directly the spacetime curvature using an ensemble of communicating clocks. I will also discuss the geometric interpretation of this measurement.
Mikolaj Korzyński (Poland): Weighing spacetime along the line of sight using times of arrival of electromagnetic signals
