(Cheng) Relativity, Gravitation and Cosmology April 2005 Corrections



page location correction thanks to
105 Fig. 6.9
The middle of the bottom arrows should be extended
to reach the next Lightlike worldline.
Phil
Fraundorf
118
Add a sidenote
just below (7.4)
Redshift comes about because of the increase in
the distance between emitter and receiver of a light
signal. In the familiar Doppler situation this is due
to the relative motion of emitter and receiver. This
language is being used here for this initial discussion
of Hubble's law. However, as we shall show in Sec 7.3,
especially Eq. (7.53), the proper description of this
enlargement of the cosmic distance reflects the
expansion of the space itself, rather than the motion
of the emitter in a static space.
Dan Wu
281
Add a sidenote
just below (A.15)
The summation of the modes in (A.15) involves
the enumeration of the phase space volume in units of
the Planck's constant EΛ ~  MATH cf (A.16). Since
the vacuum energy mode has no dependence on position,
we obtain a simple volume factor ∫d3x = V and the result
that the energy per unit volume $E_{\Lambda }V^{-1}$ is a constant with
respect to changes in volume. As explained on p.167,
this constant energy density implies a MATH force that
is attractive, pulling in the piston in Fig.9.1. This is the
key property of the cosmological constant and is the
origin of the Casimir effect --- an attractive force
between two parallel conducting plates.