A trip to South Africa

Calculation of distances in cosmological models with small-scale inhomogeneities and their use in observational cosmology: a review

“…Beware that sometimes the same distance is denoted by different symbols, e.g. d prop by Weinberg (1972), L by Harrison (1993), d by Sandage (1995), D by Davis & Lineweaver (2004), d p by Heacox (2015), d p by Ryden (2017), and sometimes also by different names, though it is clear from the discussion that the same distance as that called the proper distance by Weinberg (1972) is being discussed, e.g. 'distance between two fundamental particles at time t' (D 1 ) by Bondi (1961), 'tape-measure distance' (L) by Harrison (2000), 'instantaneous physical distance' by Carroll (2019); the term 'line-of-sight comoving distance' is also sometimes used, as opposed to the 'transverse comoving distance', which is very confusingly called the 'angular size distance' by Peebles (1993), who uses the term 'angular diameter distance' for what is called the angular-size distance by almost everyone else-indeed, the two terms are usually considered to be equivalent; the transverse comoving distance is the same as the proper-motion distance; see KHS.…”

Space‐time curvature and recession velocities

“…Which distance, which time? When we choose the distance on the space t = const = t 0 , we obtain velocities that exceed the speed of light (Davis & Lineweaver 2003;Lineweaver & Davis 2005). When we choose the length of the path of the light signal, we obtain 1 + z = c/(c − v).…”