Some well-known generalizations of general relativity are analyzed. According to the author, two gravitational theories are said to be physically equivalent if: (a) the gravitational field has the same vacuum dynamics; and (b) the coupling between the gravitational metric (or the gravitational connection) and any kind of matter is the same for both theories. The cases considered correspond to: purely affine (gravitational field described by a symmetric linear connection), metric-affine (metric and connection considered as independent variables in the variational principle), scalar-tensor and higher-order derivative theories. It is argued that, as far as criterion (a) is concerned, the theories considered are physically equivalent, up to some field redefinitions, to general relativity.
Are there metric theories of gravity other than general relativity?
MAGNANO, Guido
1996-01-01
Abstract
Some well-known generalizations of general relativity are analyzed. According to the author, two gravitational theories are said to be physically equivalent if: (a) the gravitational field has the same vacuum dynamics; and (b) the coupling between the gravitational metric (or the gravitational connection) and any kind of matter is the same for both theories. The cases considered correspond to: purely affine (gravitational field described by a symmetric linear connection), metric-affine (metric and connection considered as independent variables in the variational principle), scalar-tensor and higher-order derivative theories. It is argued that, as far as criterion (a) is concerned, the theories considered are physically equivalent, up to some field redefinitions, to general relativity.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.