Cosmological change of G and the structure of the Earth.
Abstract
Hoyle and Narlikar (1973) have noted that a constant of gravitation (G) decreasing with time would imply a decreasing acceleration of gravity with the earth with a consequent reduction of compressional forces and would therefore be accompanied by an expansion of the planet as a whole. This effect is investigated by regarding the earth as a twozone body consisting of a liquid core surrounded by a solid mantle and by assuming that this system will undergo homologous evolution as G decreases. It is shown that this procedure is not mathematically valid because the requirement of pressure continuity across the interface between the two zones cannot be satisfied under the assumption of homologous evolution. An accurate numerical solution to the problem is obtained, yielding an expansion of no more than onefourth that claimed on the invalid homology basis. Some physical considerations are examined which indicate that discussion of the problem posed cannot be limited solely to the effect of a decreasing G.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 August 1977
 DOI:
 10.1093/mnras/180.3.471
 Bibcode:
 1977MNRAS.180..471L
 Keywords:

 Cosmology;
 Earth Planetary Structure;
 Gravitational Constant;
 Continental Drift;
 Density (Mass/Volume);
 Earth Core;
 Earth Mantle;
 Internal Pressure;
 Magma;
 Mathematical Models;
 Numerical Analysis;
 Radii;
 Astrophysics