Cyclic Universe
[361] "Turnaround in Cyclic Cosmology" by L. Baum and P.H. Frampton.
Phys. Rev. Lett. 96, 071301 (2007). hep-th/0610213.
[365]"Entropy of Contracting Universe in Cyclic Cosmology"
by L. Baum and P.H. Frampton.
Mod. Phys. Lett. A22, 2587 (2007). hep-th/0703162.
[367]"Cyclic Universe and Infinite Past" by P.H. Frampton.
Mod. Phys. Lett. A22, 2587 (2007). arXiv:0705.2730.
[379]"Constraints on Deflation from the Equation of State of Dark Energy"
by L. Baum, P.H. Frampton and S. Matsuzaki.
JCAP 04:032 (2008). arXiv:0801.4420 [hep-th]
It was argued in [361] that dark energy in a brane world can reconcile an infinitely
cyclic cosmology with the second law of thermodynamics. Using phantom dark energy,
the universe turns around a trillion trillionth of a second (or less) before the would-be
Big Rip. At this time, the universe fragments into a large number of causal patches,
only one of which is retained. The entropy thereby drops to zero. The contracting
universe contains only dark energy, together with a small number of low energy photons.
Other causal patches each spawn a separate contracting universe.
In [365], the content of the contracting
universe was examined and the entropy shown
to be
accurately zero because only a negligible number
of spawned universes contain
a photon.
An anthropic argument was presented of why
the dark energy equation of state
w should not be too close to w=-1.
The issue of time goes to minus infinity was discussed in [367].
It was shown that there can
exist an infinite length
null geodesic. The number of universes is infinite
and has been equal
to a constant infinite number, Aleph-zero,
for an arbitrarily
long time into the past.
The "comes back empty" (CBE) condition, meaning that the contracting universe
contains no matter including no black holes, relates the dark energy equation
of state to the number of causal patches at turnaround. In [379], the values
of critical energy density are constrained by the smallest bound system
disintegrated at deflation, be it a nucleon or a "presently point particle" (PPP)
now regarded as pointlike, like a quark, but which is really a bound state
if seen at unexplored higher energy; the energy required to disintegrate such
PPPs effects the number of causal patches.
Open questions about cyclic universe:
(i) Just before the would-be Big Rip how does one calculate entropy?
(ii) In fragmentation how does the scale factor reduce by a factor
which is more than the cube root of a googol?
<-- Research homepage