Astronomical tests of relativity: beyond parameterized postNewtonian formalism (PPN), to testing fundamental principles
Abstract
By the early 1970s, the improved accuracy of astrometric and time measurements enabled researchers not only to experimentally compare relativistic gravity with the Newtonian predictions, but also to compare different relativistic gravitational theories (e.g., the BransDicke ScalarTensor Theory of Gravitation). For this comparison, Kip Thorne and others developed the Parameterized PostNewtonian Formalism (PPN), and derived the dependence of different astronomically observable effects on the values of the corresponding parameters.
Since then, all the observations have confirmed General Relativity. In other words, the question of which relativistic gravitation theory is in the best accordance with the experiments has been largely settled. This does not mean that General Relativity is the final theory of gravitation: it needs to be reconciled with quantum physics (into quantum gravity), it may also need to be reconciled with numerous surprising cosmological observations, etc. It is, therefore, reasonable to prepare an extended version of the PPN formalism, that will enable us to test possible quantumrelated modifications of General Relativity.
In particular, we need to include the possibility of violating fundamental principles that underlie the PPN formalism but that may be violated in quantum physics, such as scaleinvariance, Tinvariance, Pinvariance, energy conservation, spatial isotropy violations, etc. In this paper, we present the first attempt to design the corresponding extended PPN formalism, with the (partial) analysis of the relation between the corresponding fundamental physical principles.
 Publication:

Relativity in Fundamental Astronomy: Dynamics, Reference Frames, and Data Analysis
 Pub Date:
 January 2010
 DOI:
 10.1017/S1743921309990159
 Bibcode:
 2010IAUS..261...56K
 Keywords:

 Gravitation;
 relativity;
 celestial mechanics;
 etc