Cosmological tests of general relativity.
General relativity theory could be tested on a cosmological scale by measuring the Hubble constant and the deceleration parameter, if, in addition, everything could be known about the matter filling the universe. If, on the other hand, nothing could be presupposed about the matter content of the universe, general relativity could not be tested by measuring any number of time derivatives of the scale factor. But upon making the assumption of a universe filled with a non-interacting mixture of non-relativistic matter and radiation we can in principle test general relativity by measuring the first five derivatives of the scale factor. In the following, some general relations are presented using this assumption.
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The Astronomical Institute, Utrecht, The Netherlands.