Some Possible Physical Reasons of Time Variation of Earth´s Gravity Some Possible Physical Reasons of Time Variation of Eath´s Gravity Field
The gravity field of the Earth is a resultant of three different fields, the gravitational, the centrifugal and the tidal one. Time variation of each component causes the time variation of gravity. At present the measurements by gravimeters reach such high accuracy that non-tidal variations of gravity need to be taken into consideration. The nGal sensitivity of the most modern superconducting gravimeters may require the taking into consideration of some special new gravity effects. Two peculiar effects are discussed here. The supposed time variation of gravitational constant (suggested by the Nobel prise winner physicist Dirac in 1937) may cause the decreasing of gravity by the value of 0.1 mu Gal/year. The other effect is the supposed expanding Earth (suggested by the Hungarian geophysicist Egyed in 1970) which may cause the decreasing of gravity by the value of 0.2 mu Gal/year.