THE CONFRONTATION BETWEEN GENERAL RELATIVITY AND EXPERIMENT: A 1992 UPDATE

1992 ◽  
Vol 01 (01) ◽  
pp. 13-68 ◽  
Author(s):  
CLIFFORD M. WILL
Keyword(s):  
General Relativity ◽  
Equivalence Principle ◽  
Experimental Tests ◽  
Advanced Technology ◽  
Theoretical Frameworks ◽  
Binary Pulsar ◽  
Tests Of General Relativity ◽  
Lunar Motion ◽  
The Status ◽  
Einstein's Equivalence Principle

The status of experimental tests of general relativity and of theoretical frameworks for analysing them are reviewed. Einstein’s equivalence principle is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Tests of general relativity have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected to half a percent using the binary pulsar, and new binary pulsar systems promise further improvements. The status of the “fifth force” is discussed, along with the frontiers of experimental relativity, including proposals for testing relativistic gravity with advanced technology and spacecraft.

scholarly journals General Relativity confronts experiment

1986 ◽  
Vol 114 ◽  
pp. 355-367
Author(s):  
Clifford M. Will
Keyword(s):  
General Relativity ◽  
Equivalence Principle ◽  
Experimental Tests ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Tests Of General Relativity ◽  
Lunar Laser ◽  
The Status ◽  
Perihelion Shift ◽  
Strong Equivalence Principle

We review the status of experimental tests of general relativity. These include tests of the Einstein Equivalence Principle, which requires that gravitation be described by a curved-spacetime, “metric” theory of gravity. General relativity is consistent with all tests to date, including the “classical tests”: light deflection using radio interferometers, radar time delay using Viking Mars landers, and the perihelion shift of Mercury; and tests of the strong equivalence principle, such as lunar laser ranging tests of the “Nordtvedt effect”, and tests for variations in G. We also review ten years of observations of the Binary Pulsar, in which the first evidence for gravitational radiation has been found.

scholarly journals Testing the weak equivalence principle with macroscopic proof masses on ground and in space: A brief review

2014 ◽  
Vol 30 ◽  
pp. 1460254 ◽  
Author(s):  
Anna M. Nobili
Keyword(s):  
General Relativity ◽  
Equivalence Principle ◽  
Free Fall ◽  
Experimental Tests ◽  
Torsion Balance ◽  
Experimental Fact ◽  
Weak Equivalence ◽  
Weak Equivalence Principle ◽  
Tests Of General Relativity ◽  
The Earth

General relativity is founded on the experimental fact that in a gravitational field all bodies fall with the same acceleration regardless of their mass and composition. This is the weak equivalence principle, or universality of free fall. Experimental evidence of a violation would require either that general relativity is to be amended or that another force of nature is at play. In 1916 Einstein brought as evidence the torsion balance experiments by Eötvös, to 10-8–10-9. In the 1960s and early 70s, by exploiting the "passive" daily rotation of the Earth, torsion balance tests improved to 10-11 and 10-12. More recently, active rotation of the balance at higher frequencies has reached 10-13. No other experimental tests of general relativity are both so crucial for the theory and so precise and accurate. If a similar differential experiment is performed inside a spacecraft passively stabilized by 1 Hz rotation while orbiting the Earth at ≃ 600 km altitude the test would improve by 4 orders of magnitude, to 10-17, thus probing a totally unexplored field of physics. This is unique to weakly coupled concentric macroscopic test cylinders inside a rapidly rotating spacecraft.

scholarly journals The confrontation between general relativity and experiment

2009 ◽  
Vol 5 (S261) ◽  
pp. 198-199
Author(s):  
Clifford M. Will
Keyword(s):  
General Relativity ◽  
Gravitational Wave ◽  
Equivalence Principle ◽  
Gamma Ray ◽  
Strong Field ◽  
Weak Field ◽  
X Ray ◽  
Spacetime Geometry ◽  
Tests Of General Relativity ◽  
Laser Interferometric

AbstractWe review the experimental evidence for Einstein's general relativity. A variety of high precision null experiments confirm the Einstein Equivalence Principle, which underlies the concept that gravitation is synonymous with spacetime geometry, and must be described by a metric theory. Solar system experiments that test the weak-field, post-Newtonian limit of metric theories strongly favor general relativity. Binary pulsars test gravitational-wave damping and aspects of strong-field general relativity. During the coming decades, tests of general relativity in new regimes may be possible. Laser interferometric gravitational-wave observatories on Earth and in space may provide new tests via precise measurements of the properties of gravitational waves. Future efforts using X-ray, infrared, gamma-ray and gravitational-wave astronomy may one day test general relativity in the strong-field regime near black holes and neutron stars.

Gravitational “Doppler Boosting / De-boosting” Effect within the Framework of General Relativity

2021 ◽  
Vol 10 (4) ◽  
Author(s):  
Mark Zilberman ◽  
Keyword(s):  
General Relativity ◽  
Gravitational Field ◽  
Special Relativity ◽  
Spectral Index ◽  
Equivalence Principle ◽  
Relativistic Effect ◽  
Gravitational Redshift ◽  
Astronomical Observations ◽  
Complete Set ◽  
Einstein's Equivalence Principle

The “Doppler boosting / de-boosting” relativistic effect increases / decreases the apparent luminosity of approaching / receding sources of radiation. This effect was analyzed in detail within the Special Relativity framework and was confirmed in many astronomical observations. It is however not clear if “Doppler boosting / de-boosting” exists in the framework of General Relativity as well, and if it exists, which equations describe it. The “Einstein’s elevator” and Einstein’s “Equivalence principle” allow to obtain the formula for “Doppler boosting / de-boosting” for a uniform gravitational field within the vicinity of the emitter/receiver. Under these simplified conditions, the ratio ℳ between apparent (L) and intrinsic (Lo) luminosity can be conveniently represented using source’s spectral index α and gravitational redshift z as ℳ(z, α) ≡ L/Lo=(z+1)^(α-3). This is the first step towards the complete set of equations that describe the gravitational "Doppler boosting / de-boosting" effect within the General Relativity framework including radial gravitational field and arbitrary values of distance h between emitter and receiver.

scholarly journals EINSTEIN'S EQUIVALENCE PRINCIPLE AND THE GRAVITATIONAL RED SHIFT

2002 ◽  
Vol 17 (20) ◽  
pp. 2759-2759 ◽  
Author(s):  
PETROS S. FLORIDES
Keyword(s):  
General Relativity ◽  
General Theory ◽  
Equivalence Principle ◽  
Classical Mechanics ◽  
Red Shift ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Almost All ◽  
Einstein's Equivalence Principle ◽  
The Relationship

Long before the general theory of relativity was finally formulated in 1916, it was claimed that the following argument, based on (the strong) Einstein's equivalence principle (EP for short), predicted the well known and experimentally observed phenomenon of the gravitational red shift; precisely the same argument is being used to this day in almost all books on general relativity to derive the same phenomenon (see, for example, Refs. 1, 2): Consider "Einstein's elevator" at rest on the Earth's surface with an emitter (E) fixed on the floor of the elevator, and a receiver (R) fixed on the ceiling directly above E and distance h from it. Let E send light signals, at frequency νE, to R and let the frequency at which they are received by R be νR. To find the relationship between νE and νR we invoke the EP and consider, instead, E and R as fixed in an elevator which is accelerating relative to an inertial frame S in gravitation-free space with constant acceleration g in the direction [Formula: see text], g being the acceleration due to gravity on the Earth's surface. At time t = 0, when E is assumed to be at rest in S, E emits a light wave towards R. The time it takes the wave to reach R is roughly t = h/c, where c is the speed of light in S. But in this time R has acquired the velocity [Formula: see text] and, therefore, there is a consequent Doppler shift given by [Formula: see text]. By the EP the same result must hold when E and R are fixed near the Earth's surface. In this case gh = △Φ = Φ(R) - Φ(E), so that in the Earth's gravitational field we have [Formula: see text], which is the standard formula for the gravitational red shift. Simple and straight forward as the above argument may seem, we shall show in this lecture that it is, in fact, fundamentally flawed in two important respects. We shall present a new argument, entirely within the framework of classical mechanics (just as the above argument), which is free from these two flaws. Alas!, it leads to zero gravitational red shift for the case dealt with in the above argument. It is argued that this result not only does it not invalidate the general theory of relativity but it strengthens it; for, the full theory of general relativity alone, irrespective of its historical development, can correctly and unambiguously predict the observed gravitational red shift.

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