 # The Enigma Of The Universe ► 1 ►What is the Universe? ► (B) Space And Time ► 4. General Theory Of Relativity ► Features of Gravitational Field

Posted: 21.09.2014

The structure of the gravitational field depends upon mass and velocity of the body, and is determined by the field-equations given by Einstein. Also just as the path of the motion of a piece of iron in a magnetic field is decided by the structures of the field, so that of a body in a gravitational field is decided by the geometrical structures of the gravitational field.

Einstein showed mathematically that the geometric properties of space suffer a change in going over from an inertial to a non-inertial frame of reference, which is equivalent to a gravitational field. Here geometry becomes non-Euclidean, as distinct from conventional geometry.

As the magnetic fields and the electrical fields are physical realities, so are the gravitational fields. But, unlike the former, the latter emanate from all physical entities, and these include particles and fields. Particles are characterized by mass and fields by energy. Common to both is energy, which is to say that any kind of energy is responsible for a gravitational field. However, gravitational interaction becomes important only when bodies of appreciable mass are involved.

Another remarkable feature of the gravitational fields is that through a number of identical, transformations of the equations, the equations can be turned into the "equations of motion" of the physical system responsible for the gravitational field concerned. Thus the gravitational field equations incorporate the equations of the matter which creates the field. It should be noted, however, that the gravitational field equations do not determine completely the distribution and motion of matter

 Footnotes:  Cf. The Universe and Dr, Einstein, p. 90  We shall discuss this point in "Non-Euclidean Geometry" in the next article.  Cf. B. Ivanov, Contemporary Physics, Peace Publishers, Moscow.