I don't have this book of Hugh's but will check the PR article
today. From the title it sounds like a special relativity confirmation
- in GRT space _isn't_ strictly isotropic.
The equivalence principle has been confirmed observationally to
very high accuracy, but that's a presuuposition of GRT which is also
consistent with (though not demanded by) Newtonian theory (& other
gravitational theories). Tests of peculiarly GRT predictions - light
deflection, orbital precession &c - do not have the degree of precision
that a QED prediction like the Lamb shift does. (By "peculiarly
GRT" I mean effects predicted by Einstein's gravitational field
equations.) & there are _more_ tests of distinctive QED effects.
None of which is meant as a criticism of GRT!
Shalom,
George
George L. Murphy
gmurphy@imperium.net
http://www.imperium.net/~gmurphy