E.p. implies no gravitational shielding?; Feynman?

[bcrowell]

One interesting point to mention about all this is that a bunch of this discussion changes completely in Brans-Dicke gravity. In B-D gravity, you do get gravitational shielding effects, and the pedagogical device described by MTW for defining Lorentz frames fails. It's probably not a coincidence that B-D gravity also lacks the equivalence principle.

 

[PAllen]

One interesting point to mention about all this is that a bunch of this discussion changes completely in Brans-Dicke gravity. In B-D gravity, you do get gravitational shielding effects, and the pedagogical device described by MTW for defining Lorentz frames fails. It's probably not a coincidence that B-D gravity also lacks the equivalence principle.

According to the particular way Clifford Will classifies equivalence principles, he claims Branse-Dicke satisfies WEP (weak equivalence principle), EEP (Einstein equivalence principle), but not SEP (strong equivlence principle. He claims a particular theory of Nordstrom is the only case besides GR that he knows of, that satisfies SEP; but it makes radically false predictions (e.g. light not deflected by gravity).

On my construction in #98: I believe I cancel total g, but only one gradient direction. I don't know offhand how to improve the construction. I thought about a ring of matter, but I think that doesn't really work.