scholarly journals Coordinate time in the vicinity of the Earth

1986 ◽  
Vol 114 ◽  
pp. 299-313 ◽  
Author(s):  
D. W. Allan ◽  
N. Ashby
Keyword(s):  
General Relativity ◽  
Atomic Clock ◽  
Space Vehicles ◽  
Atomic Clocks ◽  
Coordinate Time ◽  
The Earth ◽  
Frequency Comparison ◽  
New Applications ◽  
Frequency Metrology

Atomic clock accuracies continue to improve rapidly, requiring the inclusion of general relativity for unambiguous time and frequency clock comparisons. Atomic clocks are now placed on space vehicles and there are many new applications of time and frequency metrology. This paper addresses theoretical and practical limitations in the accuracy of atomic clock comparisons arising from relativity, and demonstrates that accuracies of time and frequency comparison can approach a few picoseconds and a few parts in 1016, respectively.

scholarly journals The Brazilian time and frequency atomic standards program

2008 ◽  
Vol 80 (2) ◽  
pp. 217-252 ◽  
Author(s):  
Mushtaq Ahmed ◽  
Daniel V. Magalhães ◽  
Aida Bebeachibuli ◽  
Stella T. Müller ◽  
Renato F. Alves ◽  
...  
Keyword(s):  
Atomic Beam ◽  
Atomic Clock ◽  
Cold Atom ◽  
Telecommunication Networks ◽  
Atomic Clocks ◽  
Major Advance ◽  
Optical Cooling ◽  
Global Positioning ◽  
Frequency Metrology

Cesium atomic beam clocks have been the workhorse for many demanding applications in science and technology for the past four decades. Tests of the fundamental laws of physics and the search for minute changes in fundamental constants, the synchronization of telecommunication networks, and realization of the satellite-based global positioning system would not be possible without atomic clocks. The adoption of optical cooling and trapping techniques, has produced a major advance in atomic clock precision. Cold-atom fountain and compact cold-atom clocks have also been developed. Measurement precision of a few parts in 10(15) has been demonstrated for a cold-atom fountain clock. We present here an overview of the time and frequency metrology program based on cesium atoms under development at USP São Carlos. This activity consists of construction and characterization of atomic-beam, and several variations of cold-atom clocks. We discuss the basic working principles, construction, evaluation, and important applications of atomic clocks in the Brazilian program.

scholarly journals Testing General Relativity with Atomic Clocks

2009 ◽  
Vol 148 (1-4) ◽  
pp. 233-247 ◽  
Author(s):  
S. Reynaud ◽  
C. Salomon ◽  
P. Wolf
Keyword(s):  
General Relativity ◽  
Atomic Clocks

Relativistic synchronization of onboard clocks of navigation space vehicles with the aid of intersatellite measurements

2021 ◽  
pp. 56-66
Author(s):  
Nikolay N. Vasilyuk ◽  
Alexander P. Chervonkin
Keyword(s):  
Proper Time ◽  
Space Vehicle ◽  
Relativistic Correction ◽  
Point Of View ◽  
Space Vehicles ◽  
Satellite Measurements ◽  
Clock Drift ◽  
Coordinate Time ◽  
Upper Limit ◽  
Unambiguous Interpretation

The problem of the synchronization of onboard clocks of navigation satellites has considered from a relativistic point of view using the concept of “coordinate simultaneity”. This concept allows an unambiguous interpretation of the synchronization results within the framework of general relativity. The algorithm of intersatellite measurements processing has formulated in terms of a proper time of a space vehicle and the coordinate time of a reference frame. Rules of transformation between coordinate and proper time scales have indicated. An analytical expression has obtained for the periodic relativistic correction to the estimated value of the relative clock drift. This correction has expressed in terms of the coordinate time of a ground observer. The value of this correction exceeds the acceptable synchronization error and should be taken into account for the inter-satellite measurements processing. The error of the relativistic correction determination has calculated. This error provides an upper limit for the period of uploading of ephemeris data on the board of the space vehicle.

Coordinate Time On and Near the Earth

1985 ◽  
Vol 54 (3) ◽  
pp. 254-254 ◽  
Author(s):  
Neil Ashby ◽  
David W. Allan
Keyword(s):  
Coordinate Time ◽  
The Earth

scholarly journals Perihelion advances for the orbits of Mercury, Earth, and Pluto from extended theory of general relativity (ETGR)

2014 ◽  
Vol 92 (12) ◽  
pp. 1709-1713
Author(s):  
Luis Santiago Ridao ◽  
Rodrigo Avalos ◽  
Martín Daniel De Cicco ◽  
Mauricio Bellini
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Flat Manifold ◽  
Force Component ◽  
Extended Theory ◽  
Ricci Flat ◽  
The Earth ◽  
Canonical Metric ◽  
Planetary Orbits ◽  
Good Agreement

We explore the geodesic movement on an effective four-dimensional hypersurface that is embedded in a five-dimensional Ricci-flat manifold described by a canonical metric, to applying to planetary orbits in our solar system. Some important solutions are given, which provide the standard solutions of general relativity without any extra force component. We study the perihelion advances of Mercury, the Earth, and Pluto using the extended theory of general relativity. Our results are in very good agreement with observations and show how the foliation is determinant to the value of the perihelion’s advances. Possible applications are not limited to these kinds of orbits.

Chronometric measurements in geodesy and geophysics

2020 ◽  
Author(s):  
Pacôme Delva ◽  
Guillaume Lion
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
High Spatial Resolution ◽  
Relativistic Effects ◽  
Atomic Clocks ◽  
Fundamental Physics ◽  
Geodynamic Processes ◽  
New Ideas ◽  
Mass Transfers

<p>At the beginning of the 20th century the theories of special and general relativity were developed by Einstein and his contemporaries. These physical theories revolutionize our conceptions of time and of the measurement of time. The atomic clocks, which appeared in the 1950s, are so accurate and stable that it is now essential to take into account many relativistic effects. The development and worldwide comparisons of such atomic clocks allowed for some of the most stringent of fundamental physics, as well as new ideas for the search of dark matter. On a more applied level, when taking general relativity for granted, distant comparisons of atomic clocks can be used for navigation and positioning, as well as the determination of the geopotential. I will show how the chronometric observables can fit and be used within the context of classical geodesy and geophysics, presenting various applications: determination of the geopotential with high spatial resolution, vertical reference system, and discussing the possible applications associated to the geodynamic processes related to mass transfers.</p>

Geological Time Versus Astronomical Time: Are Scientific Theories Falsifiable?

1989 ◽  
Vol 8 (2) ◽  
pp. 167-169 ◽  
Author(s):  
Norriss Hetherington
Keyword(s):  
General Relativity ◽  
Homogeneous Model ◽  
Scientific Theories ◽  
Geological Time ◽  
Astronomical Observations ◽  
The Earth ◽  
Geological Age ◽  
Astronomical Time ◽  
Edwin Hubble ◽  
The Universe

During the 1930s when a relativistic, expanding, homogeneous model of the universe lead to an age for the universe embarrassingly less than the geological age of the earth, the astronomer Edwin Hubble, influenced by philosophical values, persisted in his support for a theory in conflict with observation and prediction. Notwithstanding well attested and unrefutable evidence of geological time, and various astronomical observations as well, the theory of a homogeneous, expanding universe of general relativity proved, in practice, not falsifiable.

INFLUENCE OF EARTH’S GRAVITY ON (g−2) MEASUREMENTS

1988 ◽  
Vol 03 (13) ◽  
pp. 1227-1229 ◽  
Author(s):  
A. WIDOM ◽  
C.C. CHEN
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Magnetic Moment ◽  
Anomalous Magnetic Moment ◽  
Space Time ◽  
The Earth ◽  
Background Space

Experimental probes of the anomalous magnetic moment of the muon, which are sufficiently sensitive to probe electro-weak unification contributions to (g−2), are also sufficiently sensitive to test an interesting feature of general relativity. The gravitational field of the earth produces a background space-time metric which will influence (g−2) measurements.

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