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Cavendish found that the Earth's density was 5.448 ± 0.033 times that of water (although due to a simple arithmetic error, found in 1821 by Francis Baily, the erroneous value 5.480 ± 0.038 appears in his paper). [10] [11] The current accepted value is 5.514 g/cm 3.
Precision tests of QED have been performed in low-energy atomic physics experiments, high-energy collider experiments, and condensed matter systems. The value of α is obtained in each of these experiments by fitting an experimental measurement to a theoretical expression (including higher-order radiative corrections) that includes α as a parameter.
The gravitomagnetic effect in the Cassini radioscience experiment was implicitly postulated by B. Bertotti as having a pure general relativistic origin but its theoretical value has never been tested in the experiment which effectively makes the experimental uncertainty in the measured value of gamma actually larger (by a factor of 10) than 0. ...
The spin magnetic moment of a charged, spin-1/2 particle that does not possess any internal structure (a Dirac particle) is given by [1] =, where μ is the spin magnetic moment of the particle, g is the g-factor of the particle, e is the elementary charge, m is the mass of the particle, and S is the spin angular momentum of the particle (with magnitude ħ/2 for Dirac particles).
The accuracy of the measured value of G has increased only modestly since the original Cavendish experiment. [19] G is quite difficult to measure because gravity is much weaker than other fundamental forces, and an experimental apparatus cannot be separated from the gravitational influence of other bodies.
The value of the constant G was first accurately determined from the results of the Cavendish experiment conducted by the British scientist Henry Cavendish in 1798, although Cavendish did not himself calculate a numerical value for G. [5] This experiment was also the first test of Newton's theory of gravitation between masses in the laboratory.
The next stage of muon g − 2 research was conducted at the Brookhaven National Laboratory (BNL) Alternating Gradient Synchrotron; the experiment was known as (BNL) Muon E821 experiment, [17] but it has also been called "muon experiment at BNL" or "(muon) g − 2 at BNL" etc. [7] Brookhaven's Muon g − 2 experiment was constructed from 1989 to 1996 and collected data from 1997 to 2001.
Gravity Probe B (GP-B) was a satellite-based experiment to test two unverified predictions of general relativity: the geodetic effect and frame-dragging. This was to be accomplished by measuring, very precisely, tiny changes in the direction of spin of four gyroscopes contained in an Earth-orbiting satellite at 650 km (400 mi) of altitude ...