Did Time Begin? Will Time End? Maybe the Big Bang Never Occurred

This is a delightful little book (100 pages), well written and didactic. 80% of it is relatively easy to understand. (One comment only: in page 22 it is claimed that the diameter of the present visible universe is roughly 30 billion light-years whereas other sources such as Wikipedia give a number about 5 times larger due to the expansion of the universe). Regarding the origin and fate of the universe there are four possibilities: origin and end in finite time, origin and end in infinite time, origin in finite time and duration forever, and an infinitely old universe with an end in a finite time from now.It seems the last possibility is hardly ever considered and the present orthodoxy is the second possibility: our universe (or rather our bubble universe) originated 13.7 billion years ago and will never end. However the author finds more aesthetically pleasing a cyclic universe, infinitely old and never really ending. I tend to agree with him. Naturally he has to deal (as others who favor cyclic universes do)with the second law of thermodynamics as the new universe has to restart with low entropy. This is the most obscure part of the book and is explained quickly in the last pages invoking the concepts of 3 branes and causal patch (in about a trillion years the Big Rip disconnects the universe in an astronomical number of patches devoid of matter, with a vanishing number of photons and dark energy which has zero entropy. Our universe is a 3-brane, but is accompanied by another 3-brane, both existing in (at least) a five dimensional spacetime. This system introduces a critical term in the Friedman equation and this is responsible for the change from expansion to contraction and the bounce back of one of the patches into a new universe. As we can see, scientists are entering the realm of philosophy , although with sophisticated mathematical arguments. At present, these are speculations which are attractive, but none of these speculations is still a testable (at least in the short term) well grounded theory.