From Osher Doctorow

A division of opinion has begun to emerge between several Korean
theorists for example (Xian-Hui Ge and Sun G-Won Kim) and some of the
U. K. traditional GR "old timers" like G. F. R. Ellis of Capetown
South Africa and Malcolm A. H. MacCallum of Queen Mary U. London U.K.
and Roy Maartens of U. Portsmouth UK (Maartens is an Afrikaner name of
South Africa, if I recall).

My "bets" are on the Koreans. Nevertheless, readers should look at
both sides of the arguments, although Ellis et al don't seem to give
as much courtesy to the Koreans as they give to the Ellis et al
faction. See:

1) "Probing extra dimensions with higher dimensional black hole
analogues?" by Ge and Kim, both Asian-Pacific Center for Theoretical
Physics Korea, and Kim also of Ewha Woman's U. Seoul Korea, arXiv:
0705.1404 v2 [hep-th] 15 May 2007, 16 pages.

2) "Acoustic Metric," Wikipedia.

3) "Causality and the speed of sound," by Ellis, Maartens, and
MacCallum, arXiv: gr-qc/0703121 25 Mar 2007, 6 pages.

Ellis is very well published including on arXiv, but his paper is
mostly a repetition of the usual criticism of the "Mainstream" against
superluminality, against tinkering with the Holy Grail of SR, the Holy
Grail of GR as "gravitation encoded in spacetime curvature", etc.
The Koreans at least have equations, which Ellis et al seem to have
forgotten in their new sudden philosophical role (I wonder why?).

Osher Doctorow