Relativity, Gravitation and Cosmology (Cheng)

July 2005 Corrections

page	location	correction
121	line above Eq(7.19)	Insert sidebar number ‘4’ to read: “or equivalently a critical energy density^4 of” and add new sidebar: “ ^4 In the natural unit system of quantum field theory, this energy per unit volume is approximately (2.5×10^-3eV)^4/(ħc)^3, where ħ is Planck’s constant (over 2p) with ħc ≈ 2×10^-5eV∙cm.”
184	subtitle: Possible resolution ...	Change ‘L’ to ‘dark energy’ and add sidebar superscript ‘5’ in title to read: “Possible resolution through a nonvanishing dark energy^5” and add the new sidebar: “ ^5Dark energy is defined as the “negative equation-of-state energy”, w < 0 in Eq. (8.4). It gives rise to a gravitational repulsion (cf. Sec 9.1.1). The simplest example of a dark energy is Einstein’s cosmological constant, with w = -1. NB: One should not confuse this with the energies of neutrinos, black holes, etc., which are also ‘dark’, but are counted as parts of the “dark matter” (cf. Sec 7.1.4), as the associated pressure is not negative.”
185	sidebar ^6 (sidebar ^5 before renumbering on p.184)	Change sidebar to read: “ ^6A Hubble curve (as in Fig 9.7) is a plot of the luminosity distance versus the redshift (measuring recession velocity). A straight Hubble curve means a cosmic expansion that is coasting. This can only happen in an empty universe (cf. Sec 7.1.3 and Fig 8.2). If the expansion is accelerating, the expansion rate H must be smaller in the past. From Eq. (7.5): H∆r = z, we see that, for a given redshift z, the distance ∆r to the light-emitting supernova must be larger than that for an empty or decelerating universe.”
282	2^nd line above Eq. (A.21)	Insert ‘is’ before ‘associated’ and replace ‘rX ≈ rc’ by ‘, being comparable to the critical density rcc^2 [cf. Eq. (7.19)],’ to read: “is associated with the dark energy. The observed dark energy, being comparable to the critical density rcc^2 [cf. Eq. (7.19)], then corresponds to…”