SATELLITE TEST OF THE EQUIVALENCE PRINCIPLE: OVERVIEW AND PROGRESS

2007 ◽  
Vol 16 (12a) ◽  
pp. 2215-2225 ◽  
Author(s):  
JEFFERY J. KOLODZIEJCZAK ◽  
JOHN MESTER
Keyword(s):  
Present State ◽  
Equivalence Principle ◽  
Free Fall ◽  
Development Plan ◽  
Current Status ◽  
Technology Readiness ◽  
Gravity Probe B ◽  
Universality Of Free Fall ◽  
Recent Advances ◽  
Gravity Probe

STEP, the Satellite Test of the Equivalence Principle, is reviewed and the current status of the project is discussed. This space-based experiment will test the universality of free fall and is designed to advance the present state of knowledge by over five orders of magnitude. The international STEP collaboration is pursuing a development plan to improve and verify the technology readiness of key systems. We discuss recent advances with an emphasis on accelerometer fabrication and tests. Critical technologies successfully demonstrated in flight by the Gravity Probe B mission also contribute to progress.

The geodetic precession as a 3D Schouten precession and a gravitational Thomas precession

2014 ◽  
Vol 92 (10) ◽  
pp. 1082-1093
Author(s):  
E.P.J. (Paul) de Haas
Keyword(s):  
B Physics ◽  
Parallel Transport ◽  
Free Fall ◽  
De Sitter ◽  
Thomas Precession ◽  
Gravity Probe B ◽  
Curved Space ◽  
Geodetic Precession ◽  
The Status ◽  
Gravity Probe

The Gravity Probe B (GP-B) experiment measured the geodetic precession due to parallel transport in a curved space–time metric, as predicted by de Sitter, Fokker, and Schiff. The Schiff treatment included Thomas precession and argued that it should be zero in a free fall orbit. We review the existing interpretations regarding the relation between the Thomas precession and the geodetic precession for a gyroscope in a free fall orbit. Schiff and Parker had contradictory views on the status of the Thomas precession in a free fall orbit, a contradiction that continues to exist in the literature. In the second part of this paper we derive the geodetic precession as a global Thomas precession by use of the equivalent principle and some elements of hyperbolic geometry, a derivation that allows the treatment of GP-B physics in between special and general relativity courses.

A nonmetric theory of gravity

2016 ◽  
Vol 25 (11) ◽  
pp. 1640017 ◽  
Author(s):  
Wei-Tou Ni
Keyword(s):  
Time Reversal ◽  
Coordinate Transformation ◽  
Equivalence Principle ◽  
Free Fall ◽  
Weak Equivalence ◽  
Time Reversal Invariance ◽  
Weak Equivalence Principle ◽  
Universality Of Free Fall ◽  
Reversal Invariance ◽  
Theory Of Gravity

A nonmetric theory of gravity is presented, which agrees with all experiments to date. It possesses a Lagrangian-based nonmetric (i.e. nonminimum) coupling between electromagnetism and gravity which has complete continuous-coordinate-transformation symmetry but violates parity and time-reversal-invariance. The theory predicts the universality of free fall for test bodies, i.e. it obeys the Weak Equivalence Principle (WEP). But due to the nonmetrical coupling between electromagnetism and gravity, it violates the Einstein Equivalence Principle (EEP). Hence, this theory disproves the conjecture due to Schiff which states that any gravitation theory that obeys the WEP must also, unavoidably, obey the EEP. Further examination of the empirical status implications of the EEP is therefore urged.

PATCH EFFECT IN CYLINDRICAL GEOMETRY: THE STEP ACCELEROMETER

2012 ◽  
Vol 12 ◽  
pp. 131-135
Author(s):  
VALERIO FERRONI ◽  
ALEXANDER SILBERGLEIT
Keyword(s):  
Precision Measurement ◽  
Equivalence Principle ◽  
Free Fall ◽  
Metallic Surfaces ◽  
Actual Distribution ◽  
Differential Motion ◽  
Universality Of Free Fall ◽  
Finite Distance ◽  
Set Up ◽  
Cylindrical Test

The actual distribution of charges on a metal does not guarantee its surface to be equipotential because of the impurities and microcrystal structure of the material. This phenomenon, known as patch effect, is responsible for the mutual force and torque between two metallic surfaces at a finite distance. Patch effect is important for any precision measurement whose set-up includes conducting surfaces in a closed proximity to each other. This is particularly true for the Satellite Test of the Equivalence Principle experiment where the differential motion of cylindrical test masses will be used to test the universality of free fall to an unprecedented accuracy of about 1 part in 1018.

scholarly journals Two cylindrical masses in orbit for the test of the equivalence principle

2009 ◽  
Vol 5 (S261) ◽  
pp. 402-408
Author(s):  
Ratana Chhun ◽  
Pierre Touboul ◽  
Vincent Lebat
Keyword(s):  
Magnetic Susceptibility ◽  
Electrical Properties ◽  
Equivalence Principle ◽  
Free Fall ◽  
Gravity Gradients ◽  
Electrostatic Levitation ◽  
Satellite Gravity ◽  
Universality Of Free Fall ◽  
Definition Of ◽  
Gravity Acceleration

AbstractTwo pairs of solid test-masses have been considered to perform in space the test of the universality of free fall with an accuracy of at least 10−15. These cylindrical masses are precisely at the heart of the MICROSCOPE mission instrument comprising two differential electrostatic accelerometers. These masses shall exhibit material quality, shapes, positions and alignments in regard to stringent experimental requirements. Indeed the space experiment is based on the control of the two masses submitted to the same gravity acceleration along the same orbit at 810 km altitude with an accuracy of 10−11 m. Thus effects of Earth and satellite gravity gradients shall be contained as well as any other disturbances of the mass motions induced by their magnetic susceptibility or electrical dissymmetries, by outgassing of the materials or radiation emissivity. Furthermore, the electrostatic levitation of the two masses depends dramatically on the mass shapes and electrical properties in particular for the definition of the sensitive axes orientation. All these aspects will be presented from the mass characteristics to the space MICROSCOPE experiment performance.

On the universality of free fall, the equivalence principle, and the gravitational redshift

2013 ◽  
Vol 81 (7) ◽  
pp. 527-536 ◽  
Author(s):  
A. M. Nobili ◽  
D. M. Lucchesi ◽  
M. T. Crosta ◽  
M. Shao ◽  
S. G. Turyshev ◽  
...  
Keyword(s):  
Equivalence Principle ◽  
Free Fall ◽  
Gravitational Redshift ◽  
Universality Of Free Fall

scholarly journals Some remarks on an old problem of radiation and gravity

2014 ◽  
Vol 23 (12) ◽  
pp. 1442008 ◽  
Author(s):  
C. S. Unnikrishnan ◽  
George T. Gillies
Keyword(s):  
Gravitational Field ◽  
Equivalence Principle ◽  
Charged Particles ◽  
Free Fall ◽  
Magnetic Component ◽  
Far Field ◽  
Universality Of Free Fall ◽  
Global Nature

The assumed universality of the equivalence principle suggests that a particle in a gravitational field has identical physics to one in an accelerated frame. Yet, energy considerations prohibit radiation from a static particle in a gravitational field while the accelerating counterpart emits. Solutions to the fundamental problems of radiation from charges in a gravitational field and consequences to the equivalence principle usually contrast the far-field and global nature of radiation with the local validity of the equivalence principle. Here, we suggest reliable physical solutions that recognizes the essential need for motional currents and the magnetic component for radiation to occur. Our discussion reiterates the need for a fresh careful look at universality of free fall (UFF) for charged particles in a gravitational field.

scholarly journals Exploring the foundations of the physical universe with space tests of the equivalence principle

2021 ◽  
Author(s):  
Baptiste Battelier ◽  
Joël Bergé ◽  
Andrea Bertoldi ◽  
Luc Blanchet ◽  
Kai Bongs ◽  
...  
Keyword(s):  
Equivalence Principle ◽  
Free Fall ◽  
White Paper ◽  
The Other ◽  
Physical Universe ◽  
Universality Of Free Fall ◽  
Future Space

AbstractWe present the scientific motivation for future space tests of the equivalence principle, and in particular the universality of free fall, at the 10− 17 level or better. Two possible mission scenarios, one based on quantum technologies, the other on electrostatic accelerometers, that could reach that goal are briefly discussed. This publication is a White Paper written in the context of the Voyage 2050 ESA Call for White Papers.

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