scholarly journals Rotation Sensing Lasers in General Relativity: Some Technical Notes and Current Advances

Universe ◽  
2019 ◽  
Vol 5 (9) ◽  
pp. 190 ◽  
Author(s):  
K. Ulrich Schreiber ◽  
André Gebauer ◽  
Jan Kodet ◽  
Caroline L. Anyi ◽  
Jon-Paul R. Wells
Keyword(s):  
General Relativity ◽  
Rotation Rate ◽  
Ring Laser ◽  
Laser System ◽  
Physical Models ◽  
Current Status ◽  
Rotation Sensing ◽  
General Relativistic ◽  
Laser Gyroscopes

We review the current status of large ring laser gyroscopes having the potential to contributeto terrestrial measurements of general relativistic precessions. At this point in time, although thesedevices possess the raw sensitivity for such a measurement, they remain limited by long-term geometricinstability, detection noise and imperfections in the physical models required to isolate geophysicaleffects. Furthermore, minute non-reciprocal biases provide a null-shift error and therefore no currentlyconstructed laser system meets the requirement of absolute rotation rate sensing. Nevertheless, we are ofthe view that these are surmountable problems and the ability of ring laser gyroscopes to measure lowfrequency to DC signals has vastly increased in the last decade.

Large ring laser gyroscopes: towards absolute rotation rate sensing

2015 ◽  
Author(s):  
Robert B. Hurst ◽  
Nishanthan Rabeendran ◽  
Jon-Paul R. Wells ◽  
K. Ulrich Schreiber
Keyword(s):  
Rotation Rate ◽  
Ring Laser ◽  
Large Ring ◽  
Laser Gyroscopes

scholarly journals Probing general relativity with radar astrometry in the inner solar system

2009 ◽  
Vol 5 (S261) ◽  
pp. 183-188 ◽  
Author(s):  
Jean-Luc Margot ◽  
Jon D. Giorgini
Keyword(s):  
General Relativity ◽  
The Sun ◽  
Solar Oblateness ◽  
Wide Range ◽  
Perihelion Shift ◽  
Orbital Drift ◽  
General Relativistic ◽  
Near Earth Objects ◽  
Dynamical Measurement

AbstractWe describe a long-term program designed to obtain and interpret high-precision radar range measurements of a number of near-Earth objects (NEOs) that have trajectories reaching deep inside the gravitational well of the Sun. Objects in our sample have perihelion shift rates 1.5 to 2.5 times that of (1566) Icarus (10″/cy) and span a wide range of inclinations and semi-major axes, allowing for an unambiguous separation of general relativistic and solar oblateness effects. Four objects have been observed at Arecibo on at least two apparitions since 2000, with typical uncertainties of a few hundred meters. Within the next three years, we anticipate securing a total of 15 observations of 5 different NEOs. This program is expected to provide a purely dynamical measurement of the oblateness of the Sun (J2 at the 10−8 level) and to constrain the Eddington parameter β at the 10−4 level. Although our objects are selected to minimize Yarkovsky orbital drift, we also anticipate measuring Yarkovsky drift rates, which are orthogonal to the GR and J2 signatures.

Passive ring laser gyroscopes to access fast variations in EOPs

2021 ◽  
Author(s):  
Simon Stellmer ◽  
Oliver Heckl
Keyword(s):  
Ring Laser ◽  
Gain Medium ◽  
Optical Clock ◽  
Short Term ◽  
Earth Orientation Parameters ◽  
Long Term Stability ◽  
European Collaboration ◽  
Orientation Parameters ◽  
Laser Gyroscopes

<p>Quite generally, the Earth Orientation Parameters (EOPs) as obtained via VLBI and GNSS lack short-term sensitivity on (sub-)diurnal timescales. To access these fast dynamics, large <em>active</em> ring laser gyroscopes have been devised and are currently operated in geodesy and seismology. Here, we propose a novel type of gyroscope, namely <em>passive</em> ring lasers. By placing the gain medium outside of the optical resonator, the passive variant may remove many of the systematic limitations of active gyroscopes, and holds the potential to increase sensitivites by two orders of magnitude. Interfacing the gyroscopes with our optical clock technology will improve long-term stability as well. We will report on preliminary work and on the design and anticipated performance parameters of two demonstrators, as put forward by a recently established European collaboration.</p>

scholarly journals High-Accuracy Ring Laser Gyroscopes: Earth Rotation Rate and Relativistic Effects

2016 ◽  
Vol 723 ◽  
pp. 012061 ◽  
Author(s):  
N Beverini ◽  
A Di Virgilio ◽  
J Belfi ◽  
A Ortolan ◽  
K U Schreiber ◽  
...  
Keyword(s):  
Rotation Rate ◽  
Earth Rotation ◽  
Ring Laser ◽  
Relativistic Effects ◽  
High Accuracy ◽  
Laser Gyroscopes

scholarly journals Simulation of general relativistic corrections in long term numerical integrations of planetary orbits

1986 ◽  
Vol 114 ◽  
pp. 105-111
Author(s):  
Anna M. Nobili ◽  
Ian W. Roxburgh
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Computer Time ◽  
Substantial Improvement ◽  
Numerical Integrations ◽  
Planetary Orbits ◽  
General Relativistic ◽  
Theory Of Gravitation ◽  
The Stability

Long term numerical integrations of planetary orbits designed to study the stability of the Solar System over timescales comparable to its age have become very promising thanks to the availability of very powerful computers and to a substantial improvement in our methods of investigating the stability of hierarchical dynamical systems. The stability of such numerical integrations relies on the ability to control all possible sources of error. Among the errors caused by the inadequacy of the physical model are those due to the fact that Newton's theory of gravitation is used instead of general relativity. We show that the secular advance of perihelia predicted by general relativity can be simulated exactly by a 1/r2 perturbing potential with almost negligible additional cost in computer time.

Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

scholarly journals Does general relativity highlight necessary connections in nature?

Synthese ◽  
2021 ◽  
Author(s):  
Antonio Vassallo
Keyword(s):  
General Relativity ◽  
Laws Of Nature ◽  
Coupling Mechanism ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Bianchi Identities ◽  
Physical Role ◽  
General Relativistic ◽  
Differential Relations ◽  
Necessary Connections

AbstractThe dynamics of general relativity is encoded in a set of ten differential equations, the so-called Einstein field equations. It is usually believed that Einstein’s equations represent a physical law describing the coupling of spacetime with material fields. However, just six of these equations actually describe the coupling mechanism: the remaining four represent a set of differential relations known as Bianchi identities. The paper discusses the physical role that the Bianchi identities play in general relativity, and investigates whether these identities—qua part of a physical law—highlight some kind of a posteriori necessity in a Kripkean sense. The inquiry shows that general relativistic physics has an interesting bearing on the debate about the metaphysics of the laws of nature.

scholarly journals Dryland Food Security in Ethiopia: Current Status, Opportunities, and a Roadmap for the Future

2021 ◽  
Vol 13 (11) ◽  
pp. 6503
Author(s):  
Yu Peng ◽  
Hubert Hirwa ◽  
Qiuying Zhang ◽  
Guoqin Wang ◽  
Fadong Li
Keyword(s):  
Food Security ◽  
Current Status ◽  
Future Research ◽  
Systematic Research ◽  
Security Assessment ◽  
Security Issue ◽  
Sustainable Development Goal ◽  
Zero Hunger ◽  
The Impact

Given the impact of COVID-19 and the desert locust plague, the Ethiopian food security issue has once again received widespread attention. Its food crisis requires comprehensive and systematic research to achieve the United Nations Sustainable Development Goal of zero hunger. This review discusses the current situation and the causes of food security in Ethiopia. We focus on the challenges in the food security assessment field. The article lists seven typical causes of food insecurity and three roots of food security in Ethiopia. Long-term food security assessment and a comprehensive understanding and manageability for food security causes are considered as the main existing research challenges. Climate-resilient management, water management, and long-term ecosystem network monitoring and data mining are suggested as potential roadmap for future research.

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