This blog entry is clearly a glimpse into the future of gravity measurements, far beyond EGSIEM, which is maybe also of interest for some readers. Today, and in EGSIEM, measurements of satellites such as those of the GRACE mission are the backbone for our understanding of gravity and mass variations. In the future, new possibilities will emerge on the horizon. One of these is the measurement of the “gravitational redshift” of time and frequency. Due to general relativity, clocks in a stronger gravity field run slower.. In the near future, ultra-precise atomic clocks are expected to be useful sensors for spatial and temporal variations of Earth gravity. Recently, the first long-distance transfer and comparison of optical frequencies generated by Strontium clocks in Braunschweig, Germany, and Paris has been successful. The long-distance frequency transfer to the remote location is done through optical communication fibers. Results and possible applications in geodesy were presented in April at the 2015 Joint Conference of the IEEE International Frequency Control Symposium & European Frequency and Time Forum in Denver, Colorado.
