8 - Tests of the Strong Equivalence Principle

Summary

We discuss tests of the Strong Equivalence Principle. We derive the observable consequences of the Nordtvedt effect, a violation of the equality of acceleration of massive, self-gravitating bodies, that occurs in many alternative theories of gravity, although not in general relativity. We discuss the bounds obtained on this effect via lunar laser ranging, and via measurements of pulsar-white dwarf binary systems. We derive a number of observable consequences of preferred-frame effects in binary orbits and in the structure of self-gravitating bodies, and review the bounds that have been placed on the relevant PPN parameters by a wide range of observations.