8
M. V. John
coasting solution is unique, since it has identical classical and quantum evolution, as
in the case of free particles described by plane waves in ordinary quantum mechanics.
2.4 Other Coasting Models
In a well-known work, Kolb [20] has discussed at length the implications of a coasting
cosmological model. In this, the universe is presently dominated by some exotic Kmatter and is coasting, with equation of state p K = −ρ K /3. However, the model is
different from the ‘eternal coasting’ models, for during the major part of its history
in the early epochs, the universe is dominated by radiation and matter and hence
its expansion rate is not uniform. Another cosmological model where the universe
undergoes coasting evolution for part of its history was the one proposed by Sahni
[21].
Some other realistic coasting models have also appeared in the literature since
then. Nucleosynthesis in a different coasting model was discussed by Lohiya and
co-workers in [22–24]. This issue is pursued in several works, including some recent
ones [25]. They have also investigated the status of realistic coasting models with
regard to other cosmological observations, such as the SNe Ia data [26].
Recently, another cosmological model named ‘R h = ct model’ [27], which has
an expansion history coinciding with that of the Milne model, is suggested as the
true model of the universe [28, 29]. It is claimed that one-on-one comparative tests
carried out between this model and the CDM model using over 14 cosmological
measurements and observations give conclusive evidence in support of the R h = ct
model [30]. In the context of the latest synchronicity problem in cosmology and the
analysis of JLA catalogue mentioned above, this model assumes great significance.
Possibly due to this, in the literature, there are growing concerns regarding the fundamental basis of the theory itself [31, 32]. For instance, the latest paper on this
subject [32] contends that R h = ct is a vacuum solution. Addressing this criticism,
it is shown in [30] that the R h = ct model is not empty and hence not the same as
the Milne model.
In a recent paper [33], it was pointed out that the R h = ct model is identical to
the ‘eternal coasting cosmological model’ suggested by the author and Prof. Joseph
[15]. Between these two models, there exist only some minor differences, and even
these find their origin in certain vague and unsupported features assumed in the
R h = ct model. The pre-existing models in [11, 12, 15] were proposed even before
the release of the sensational SNe Ia data in 1998. The authors of the R h = ct model
have performed almost the same kind of data analysis as in our case and reaches
similar conclusions. Though these differently named models originated on different
theoretical grounds, they all end up at the same cosmological solution for all practical
purposes. It was specifically stated that the R h = ct model coincides with the coasting
model in [15], for k = 0.
It was also pointed out that the only provision for the ‘R h = ct model’ to claim
any difference with the ‘eternal coasting model’ is with regard to variation of the den-
M. V. John
coasting solution is unique, since it has identical classical and quantum evolution, as
in the case of free particles described by plane waves in ordinary quantum mechanics.
2.4 Other Coasting Models
In a well-known work, Kolb [20] has discussed at length the implications of a coasting
cosmological model. In this, the universe is presently dominated by some exotic Kmatter and is coasting, with equation of state p K = −ρ K /3. However, the model is
different from the ‘eternal coasting’ models, for during the major part of its history
in the early epochs, the universe is dominated by radiation and matter and hence
its expansion rate is not uniform. Another cosmological model where the universe
undergoes coasting evolution for part of its history was the one proposed by Sahni
[21].
Some other realistic coasting models have also appeared in the literature since
then. Nucleosynthesis in a different coasting model was discussed by Lohiya and
co-workers in [22–24]. This issue is pursued in several works, including some recent
ones [25]. They have also investigated the status of realistic coasting models with
regard to other cosmological observations, such as the SNe Ia data [26].
Recently, another cosmological model named ‘R h = ct model’ [27], which has
an expansion history coinciding with that of the Milne model, is suggested as the
true model of the universe [28, 29]. It is claimed that one-on-one comparative tests
carried out between this model and the CDM model using over 14 cosmological
measurements and observations give conclusive evidence in support of the R h = ct
model [30]. In the context of the latest synchronicity problem in cosmology and the
analysis of JLA catalogue mentioned above, this model assumes great significance.
Possibly due to this, in the literature, there are growing concerns regarding the fundamental basis of the theory itself [31, 32]. For instance, the latest paper on this
subject [32] contends that R h = ct is a vacuum solution. Addressing this criticism,
it is shown in [30] that the R h = ct model is not empty and hence not the same as
the Milne model.
In a recent paper [33], it was pointed out that the R h = ct model is identical to
the ‘eternal coasting cosmological model’ suggested by the author and Prof. Joseph
[15]. Between these two models, there exist only some minor differences, and even
these find their origin in certain vague and unsupported features assumed in the
R h = ct model. The pre-existing models in [11, 12, 15] were proposed even before
the release of the sensational SNe Ia data in 1998. The authors of the R h = ct model
have performed almost the same kind of data analysis as in our case and reaches
similar conclusions. Though these differently named models originated on different
theoretical grounds, they all end up at the same cosmological solution for all practical
purposes. It was specifically stated that the R h = ct model coincides with the coasting
model in [15], for k = 0.
It was also pointed out that the only provision for the ‘R h = ct model’ to claim
any difference with the ‘eternal coasting model’ is with regard to variation of the den-