My answer to the questions he reassess in the preface is that the best we can do is seek a logically coherent framework to explain what we see. Why ‘logical’?—because that is the only way we know how to operate. Best I can tell from the preface, he agrees. I see ‘logical’ as a product of evolution, perhaps like the eye, because there is no better plan.
On page 25 Krauss notes that the mass of the dark matter seems to be 10 times the mass of the visible matter, stars and gas. He then implies that this ratio is so large that it cannot be ordinary matter. I do not agree. Perhaps Earth size blobs, scattered at random thru out the Galaxy would produce enough infra-red to be noticed, at by instruments soon to be available, but any substantially smaller size blobs, down to centimeter size should provide an opportunity to hide that much ordinary stuff. (Too much smaller and the number of blobs begins to block light—a surface to volume argument.) Perhaps there are theories about how supernovas yield such matter that are incompatible with this. They should then be mentioned.
I like Krauss’ description of how virtual particles explained the small discrepancies in the Hydrogen spectrum.
On page 107 Krauss worries about the astrophysicists who can no longer see the Galaxies that have disappeared over the event horizon 2 trillion years from now. I guess they will just to make do with the pictures we made of them in this era. He also worries that the upcoming merger of the neighborhood galaxies will produce plasma that is opaque to the era’s remaining CMB. I would hope that the astrophysicists of that time would have a planning horizon and technology, and budget, to go outside the meta-galaxy to do their observations.
On page 126 Krauss finally comes to the anthropic principle as he considers other values of the cosmological constant.
Two thirds of the way thru the book I tended to categorize the book as being unable to say anything concrete for lack of equations, like so many other popular books. Then Krauss made a claim, relating to the cosmological constant that I thought was plain wrong. I reverted to other books, with equations, and found that Krauss was right. I had long been confused about the rôle of the cosmological constant. Later in the book there is actual physics which is new to me. Partly it is novel ways of describing the counterintuitive world, but there is new stuff too. The ‘logic’ of a book like this with few or no equations, is as obscure as the old religious books that seemed to bottom out in faith. This is unfortunate.
The last chapter concerns arguments for God based on nature. He sees no such possibility. Here is what I think is a significant determiner of one’s God stance.