ABSTRACT

The problem of the origin of rotational inertia is examined within the framework of the relativistic theory of gravitation. It is argued that gravitomagnetic effects cannot be interpreted in terms of the relativity of rotation. Absolute and relative motion are discussed on the basis of the hypothesis that these are complementary classical manifestations of movement.

What is the origin of inertia? For instance, with respect to what does the Earth rotate around its axis? The rotation of a body does not generate any basic new gravitational effect in the Newtonian theory. This is not the case, however, in Einstein's theory of gravitation. The striking analogy between Newton's law of gravitation and Coulomb's law of electricity has led to a description of Newtonian gravity in terms of a gravitoelectric field. Any theory that combines Newtonian gravity with Lorentz invariance is expected to contain a gravitomagnetic field in some form; in general relativity, the gravitomagnetic field is usually caused by the angular momentum of the source of the gravitational field. The first gravitomagnetic effects were described by de Sitter soon after Einstein's fundamental work on general relativity. The question of relativity of rotation was also discussed by de Sitter following his investigation of the astronomical consequences of Einstein's relativistic theory of gravitation; de Sitter concluded that the problem of inertia did not have a solution in the general theory of relativity.