Thursday, October 25, 2012

Gravimetry

Gravity map of the Southern Ocean around the Antarctic continent
This gravity field was computed from sea-surface height measurements collected by the US Navy GEOSAT altimeter between March, 1985, and January, 1990. The high density GEOSAT Geodetic Mission data that lie south of 30 deg. S were declassified by the Navy in May of 1992 and contribute most of the fine-scale gravity information.
The Antarctic continent itself is shaded in blue depending on the thickness of the ice sheet (blue shades in steps of 1000 m); light blue is shelf ice; gray lines are the major ice devides; pink spots are parts of the continent which are not covered by ice; gray areas have no data.

Gravimetry is the measurement of the strength of a gravitational field. Gravimetry may be used when either the magnitude of gravitational field or the properties of matter responsible for its creation are of interest. The term gravimetry or gravimetric is also used in chemistry to define a class of analytical procedures, called gravimetric analysis relying upon weighing a sample of material.


 See Also:
Atom interferometry: In light-pulse atom interferometers, atomic matter waves are split and recombined using pulses of laser light. The splitting occurs because when an atom interacts with the photons of a laser beam, it exchanges the momentum of a number of photons. The atom may thus continue on either of two spatially separate paths, the interferometer arms. When the paths are recombined, the probability that the atom is found depends upon the phase difference between them, which determines whether the matter waves will add or cancel. This phase is shifted by the atom’s coupling to electromagnetic fields, gravity, inertial forces, and other influences. By selecting the geometry of the interferometer, the atomic species, and its quantum state, one can maximize the wanted influence and minimize others. Advances in the control of the quantum state of atoms and photons have led to an extraordinary sensitivity and accuracy.




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