Comment 3
Lenny's book will not be comprehensible to the math-illiterate New Age
reader. He opens up with the math of black holes in different coordinate
representations nicely presented in a way that implicitly clearly shows
why Hal Puthoff's PV alternative to the black hole is not a good theory.
But you need to remember (or look up) your high school logarithms and
the trigonometry formula for the tangent of the half-angle to show from
eqs (1.1.2) to (1.1.4) that a signal from the black hole surface horizon
never reaches the distant observers. The Penrose diagram makes that
instantly obvious of course. Hal uses isotropic coordinates inside the
event horizon where they are not appropriate. He says he can do that
because his exponential metric does not have an event horizon. But in
that case his solution does not obey Einstein's vacuum GR equation Ruv =
0. Therefore, PV theory conflicts with GR. Indeed, PV theory is not
consistent with Diff(4) tensors and therefore, it violates the
equivalence principle. In spite of that Hal Puthoff claims he is not
offering a theory different from GR but only an "engineer's" way to do
it. This, of course, is self-contradictory. Note that in George
Chapline's "dark star" theory there is dark energy behind the event
horizon, i.e. not Ruv = 0, but the same equation I use

Guv + /\zpfguv = 0

We do seem to need Gennady Shipov's torsion field beyond 1915 GR to allow

/\zpf^,v =/= 0 at the event horizon boundary because the Bianchi
identities without torsion demand /\zpf^,v = 0.