On Sat, 15 Apr 2017 21:29:20 EDT, Eric Flesch wrote:
[[Mod. note --
2. There's an extensive history of people studying what the consequences
of a gravitational scalar field might be. See, for example, section
5.3 of Clifford M Will, "Theory and Experiment in Gravitational Physics"
(Cambridge University Press, 1981, 1985), or section 3.3.2 of Will's
review paper "The Confrontation between General Relativity and
Experiment" (open-access at http://www.livingreviews.org/lrr-2014-4 ).

Thank you for this outstanding reference which I'll be reading for
days. I wasn't aware of Clifford Will's work.

[[Mod. note -- Will is also the author of the excellent popular book
"Was Einstein Right?" (Basic Books, paperback 2nd Edition 1993) on
experimental tests of general relativity.
-- jt]]