Geoffrey Endean has published some interesting papers on Cosmology in Conformally Flat Spacetime , but Laurent Querella  claims that "the arguments leading to Endean's conclusions are incorrect, and we reject his CFS cosmology". However, this section (3.1) of Querella's paper seems to be based on a non-standard (mis)interpretation of the identity [tex]d\tau_0 \equiv dt_0[/tex]. The standard meaning of this identity is that the rates of two clocks are defined to be the same in the current epoch, but Querella seems to have (wrongly) assumed that Endean was defining [tex]d\tau \equiv dt[/tex] so that the rates of these two clocks are defined to be the same in every epoch. Do you think that this statement by Querella makes sense, or do you think that he has misinterpreted the meaning of [tex]d\tau_0 \equiv dt_0[/tex]?  Geoffrey Endean, Cosmology in Conformally Flat Spacetime, The Astrophysical Journal, 479: 40-45, 1997 April 10.  Laurent Querella, Kinematic Cosmology in Conformally Flat Spacetime, The Astrophysical Journal, 508:129-131, 1998 November 20, http://arxiv.org/abs/gr-qc/9807020. .