A LABORATORY TEST OF THE EQUIVALENCE PRINCIPLE AS PROLOG TO A SPACEBORNE EXPERIMENT

2007 ◽  
Vol 16 (12a) ◽  
pp. 2245-2258 ◽  
Author(s):  
ROBERT D. REASENBERG ◽  
JAMES D. PHILLIPS
Keyword(s):  
Equivalence Principle ◽  
Degrees Of Freedom ◽  
Vacuum Chamber ◽  
Free Fall ◽  
Upward Motion ◽  
Principle Of Equivalence ◽  
Weak Equivalence Principle ◽  
Motion System ◽  
The Status ◽  
Capacitance Gauge

To test the equivalence principle (EP) to an accuracy of at least σ(Δ g)/g = 5 × 10-14, we are developing a modern Galilean experiment. In our principle-of-equivalence measurement (POEM), we directly examine the relative motion of two test mass assemblies (TMA) that are freely falling. Such an experiment tests both for a possible violation of the weak equivalence principle (WEP) and for new forces that might mimic a WEP violation. For the terrestrial version of the experiment, there are three key technologies. A laser gauge measures the separation of the TMA to picometer accuracy in a second as they fall freely in a comoving vacuum chamber. The motion system launches the TMA from their kinematic mounts inside the chamber and keeps the chamber on a trajectory that mimics free fall until the chamber nears the bottom of its motion. It then "bounces" the chamber back to upward motion in preparation for a new launch of the TMA. A capacitance gauge system measures an additional four degrees of freedom of the motion of each TMA. The resulting estimate of the rotation around and translation along the horizontal axes is used to correct systematic errors. We describe the status of POEM and discuss recent progress.

FALLING RIGHT WHILE MOVING SLOW: TRUE TESTS OF THE WEAK EQUIVALENCE PRINCIPLE FOR ANTIPARTICLES

2012 ◽  
Vol 21 (11) ◽  
pp. 1242016
Author(s):  
C. S. UNNIKRISHNAN ◽  
G. T. GILLIES
Keyword(s):  
Equivalence Principle ◽  
Free Fall ◽  
Weak Equivalence ◽  
Surprising Result ◽  
Intrinsic Properties ◽  
Weak Equivalence Principle ◽  
Quantum Numbers ◽  
Supernova 1987A ◽  
Relativistic Factor ◽  
Cold Matter

A significant question in experimental gravity is the nature of free fall of antiparticles under gravity and elaborate preparations are underway to directly test this with cold antihydrogen. Earlier, the Shapiro delay of supernova 1987A neutrinos was interpreted as testing the weak equivalence principle (WEP). We establish the surprising result that the Shapiro delay of relativistic particles does not test WEP for intrinsic properties or quantum numbers of particles or antiparticles. This is because essentially the entire gravitational mass of the relativistic neutrinos is contributed by kinetic energy, diluting to insignificance any EP violating contribution from intrinsic properties, by the relativistic factor. The crucial message here is that a true test of the WEP involving intrinsic properties of matter or antimatter — the foundation of relativistic gravity — necessarily requires nonrelativistic "cold" matter and antimatter.

Antihydrogen physics: gravitation and spectroscopy in AEgISThis paper was presented at the International Conference on Precision Physics of Simple Atomic Systems, held at École de Physique, les Houches, France, 30 May – 4 June, 2010.

2011 ◽  
Vol 89 (1) ◽  
pp. 17-24 ◽  
Author(s):  
R. Ferragut ◽  
A. S. Belov ◽  
G. Bonomi ◽  
I. Boscolo ◽  
R. S. Brusa ◽  
...  
Keyword(s):  
Equivalence Principle ◽  
Stark Effect ◽  
Rydberg State ◽  
Free Fall ◽  
Second Phase ◽  
General Description ◽  
Exchange Reactions ◽  
Weak Equivalence Principle ◽  
Atomic Systems ◽  
Subsequent Measurement

AEgIS (Antimatter experiment: gravity, interferometry, spectroscopy) is an experiment approved by CERN with the goal of studying antihydrogen physics. In AEgIS, antihydrogen will be produced by charge exchange reactions of cold antiprotons with positronium atoms excited in a Rydberg state (n > 20). In the first phase of the experiment, controlled acceleration by an electric field gradient (Stark effect) and subsequent measurement of free fall in a Moiré deflectometer will allow a test of the weak equivalence principle. In a second phase, the antihydrogen will be slowed, confined, and laser-cooled to perform CPT studies and detailed spectroscopy. In the present work, after a general description of the experiment, the present status of advancement will be reviewed, with special attention to the production and excitation of positronium atoms.

scholarly journals Microscope – A space mission to test the equivalence principle

2009 ◽  
Vol 5 (S261) ◽  
pp. 423-425 ◽  
Author(s):  
Meike List ◽  
Hanns Selig ◽  
Stefanie Bremer ◽  
Claus Lämmerzahl
Keyword(s):  
High Precision ◽  
Equivalence Principle ◽  
Free Fall ◽  
Space Mission ◽  
Drop Tower ◽  
Weak Equivalence ◽  
Weak Equivalence Principle ◽  
Space Agency

AbstractMICROSCOPE is a ESA/CNES space mission for testing the validity of the weak equivalence principle. The mission's goal is to determine the Eötvös parameter η with an accuracy of 10−15. The French space agency CNES is responsible for designing the satellite which is developed and produced within the Myriade series. The satellite's payload T–SAGE (Twin Space Accelerometer for Gravitation Experimentation) consists of two high–precision capacitive differential accelerometers and is developed and built by the French institute ONERA.As a member of the MICROSCOPE performance team, the German department ZARM performs free fall tests of the MICROSCOPE differential accelerometers at the Bremen drop tower. The project's concepts and current results of the free fall tests are shortly presented.

Methodology and instrumentation for testing the weak equivalence principle in stratospheric free fall

1998 ◽  
Vol 69 (12) ◽  
pp. 4146-4151 ◽  
Author(s):  
V. Iafolla ◽  
S. Nozzoli ◽  
E. C. Lorenzini ◽  
V. Milyukov
Keyword(s):  
Equivalence Principle ◽  
Free Fall ◽  
Weak Equivalence ◽  
Weak Equivalence Principle

Higher-order gravity and the classical equivalence principle

2017 ◽  
Vol 32 (34) ◽  
pp. 1750185
Author(s):  
Antonio Accioly ◽  
Wallace Herdy
Keyword(s):  
Gravitational Field ◽  
Equivalence Principle ◽  
Free Fall ◽  
Higher Order ◽  
Tree Level ◽  
Weak Equivalence ◽  
Weak Equivalence Principle ◽  
Quantum Particles ◽  
Higher Order Gravity ◽  
Energy Dependent

As is well known, the deflection of any particle by a gravitational field within the context of Einstein’s general relativity — which is a geometrical theory — is, of course, nondispersive. Nevertheless, as we shall show in this paper, the mentioned result will change totally if the bending is analyzed — at the tree level — in the framework of higher-order gravity. Indeed, to first order, the deflection angle corresponding to the scattering of different quantum particles by the gravitational field mentioned above is not only spin dependent, it is also dispersive (energy-dependent). Consequently, it violates the classical equivalence principle (universality of free fall, or equality of inertial and gravitational masses) which is a nonlocal principle. However, contrary to popular belief, it is in agreement with the weak equivalence principle which is nothing but a statement about purely local effects. It is worthy of note that the weak equivalence principle encompasses the classical equivalence principle locally. We also show that the claim that there exists an incompatibility between quantum mechanics and the weak equivalence principle, is incorrect.

scholarly journals The GBAR experiment

2014 ◽  
Vol 30 ◽  
pp. 1460263 ◽  
Author(s):  
D. P. van der Werf ◽  
Keyword(s):  
Present Status ◽  
Equivalence Principle ◽  
Free Fall ◽  
Weak Equivalence ◽  
Antiproton Annihilation ◽  
Weak Equivalence Principle ◽  
Fall Time ◽  
Gravitational Fields ◽  
Free Fall Acceleration

The classical Weak Equivalence Principle has not yet been tested using antimatter in matter gravitational fields. The GBAR (Gravitational Behaviour of Antihydrogen at Rest) experiment, recently approved by CERN, proposes to measure the free-fall acceleration of antihydrogen. In this experiment, positive antihydrogen ions will be produced, and subsequently cooled down using laser cooled Be + ions. Then, when a temperature of around 20 μK has been reached, the excess positron will be detached and the free-fall time will be measured using the antiproton annihilation products. An overview of the experiment will be given together with its present status.

scholarly journals Development of a cold atomic muonium beam for next generation atomic physics and gravity experiments

2021 ◽  
Author(s):  
Anna Soter ◽  
Andreas Knecht
Keyword(s):  
Atomic Physics ◽  
High Intensity ◽  
Equivalence Principle ◽  
Gravitational Interaction ◽  
Free Fall ◽  
Weak Equivalence ◽  
Weak Equivalence Principle ◽  
Paul Scherrer ◽  
Atomic Muonium ◽  
Low Emittance

A high-intensity, low-emittance atomic muonium (M =\mu^+ + e^-=μ++e−) beam is being developed, which would enable improving the precision of M spectroscopy measurements, and may allow a direct observation of the M gravitational interaction. Measuring the free fall of M atoms would be the first test of the weak equivalence principle using elementary antimatter (\mu^+μ+) and a purely leptonic system. Such an experiment relies on the high intensity, continuous muon beams available at the Paul Scherrer Institute (PSI, Switzerland), and a proposed novel M source. In this paper, the theoretical motivation and principles of this experiment are described.

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.

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