A Non-empty Bouncing Milne Model for the Universe
15
must admit that a much deeper justification for this, on the basis of a true quantum
field or similar theory, is needed here.
4 Discussion
The first coasting model for the universe, which was conceived by Milne, has been
an attractive idea, primarily for its simplicity. Though it is an empty model and
is devoid of any gravitational effects, the model is not forgotten even after three
quarters of a century. The non-empty ‘always coasting’ cosmology in [11, 12] was
proposed at a time when the universe was considered to be decelerating at the present
epoch, i.e. well before the discovery of the unnatural dimming of SN Ia at large
redshifts that led to the claim that the universe is accelerating. The solution of the
cosmological problems, including the age and coincidence problems, was one of the
strong motivations for its prediction. Presently, the model is more relevant in the
context of the synchronicity problem, for the currently popular -CDM model has
no easy way out of it. The former model shall always remain a potential rival to the
latter, unless more sophisticated data shows that H 0 t 0 = 1. (As mentioned by [8], if
this value is very near to unity and is not exactly equal to it, there would be an even
worse synchronicity problem.)
A caveat similar to that in the case of negative energy density is there also when
the energy of the field φ is assumed to contribute to the energy of matter/radiation and
the time-variable dark energy. Similar is the case for the creation of matter/radiation
from dark energy, as envisaged in this model. One can only view these predictions
as providing outlines of a future broader theory. But since we have the result from
quantum cosmology that there is exact classical to quantum correspondence for this
new model, the above pointers from the classical theory seem to be in the right
direction.
References
1. P.J.E. Peebles, Principles of Physical Cosmology (Princeton University Press, Princeton, 1993)
2. S. Weinberg, Gravitation and Cosmology (Wiley, New York, 1972)
3. J.V. Narlikar, Introduction to Cosmology (1993)
4. J.A. Peacock, Cosmological Physics (Cambridge University Press, London, 1999)
5. A.H. Guth, Phys. Rev. D 23, 347 (1981)
6. W.L. Freedman et al., Nature (London) 371, 757 (1994)
7. M.J. Pierce et al., The Hubble constant and Virgo cluster distance from observations of Cepheid
variables. Nature (London) 371, 385 (1994)
8. A. Avelino, R.P. Kirshner, Astrophys. J. 828, 35 (2016)
9. E.A. Milne (The Clarendon Press, Oxford, 1935)
10. J.T. Nielsen, A. Guffanti, S. Sarkar, Sci. Rep. (2016)
11. M.V. John, K.B. Joseph, Phys. Lett. B 387, 466 (1996)
12. M.V. John, K.B. Joseph, Class. Quantum Gravity 14, 1115 (1997)
15
must admit that a much deeper justification for this, on the basis of a true quantum
field or similar theory, is needed here.
4 Discussion
The first coasting model for the universe, which was conceived by Milne, has been
an attractive idea, primarily for its simplicity. Though it is an empty model and
is devoid of any gravitational effects, the model is not forgotten even after three
quarters of a century. The non-empty ‘always coasting’ cosmology in [11, 12] was
proposed at a time when the universe was considered to be decelerating at the present
epoch, i.e. well before the discovery of the unnatural dimming of SN Ia at large
redshifts that led to the claim that the universe is accelerating. The solution of the
cosmological problems, including the age and coincidence problems, was one of the
strong motivations for its prediction. Presently, the model is more relevant in the
context of the synchronicity problem, for the currently popular -CDM model has
no easy way out of it. The former model shall always remain a potential rival to the
latter, unless more sophisticated data shows that H 0 t 0 = 1. (As mentioned by [8], if
this value is very near to unity and is not exactly equal to it, there would be an even
worse synchronicity problem.)
A caveat similar to that in the case of negative energy density is there also when
the energy of the field φ is assumed to contribute to the energy of matter/radiation and
the time-variable dark energy. Similar is the case for the creation of matter/radiation
from dark energy, as envisaged in this model. One can only view these predictions
as providing outlines of a future broader theory. But since we have the result from
quantum cosmology that there is exact classical to quantum correspondence for this
new model, the above pointers from the classical theory seem to be in the right
direction.
References
1. P.J.E. Peebles, Principles of Physical Cosmology (Princeton University Press, Princeton, 1993)
2. S. Weinberg, Gravitation and Cosmology (Wiley, New York, 1972)
3. J.V. Narlikar, Introduction to Cosmology (1993)
4. J.A. Peacock, Cosmological Physics (Cambridge University Press, London, 1999)
5. A.H. Guth, Phys. Rev. D 23, 347 (1981)
6. W.L. Freedman et al., Nature (London) 371, 757 (1994)
7. M.J. Pierce et al., The Hubble constant and Virgo cluster distance from observations of Cepheid
variables. Nature (London) 371, 385 (1994)
8. A. Avelino, R.P. Kirshner, Astrophys. J. 828, 35 (2016)
9. E.A. Milne (The Clarendon Press, Oxford, 1935)
10. J.T. Nielsen, A. Guffanti, S. Sarkar, Sci. Rep. (2016)
11. M.V. John, K.B. Joseph, Phys. Lett. B 387, 466 (1996)
12. M.V. John, K.B. Joseph, Class. Quantum Gravity 14, 1115 (1997)