This is a book of two halves. The first presents an account of the Standard Model of particle physics and describes where it fails to cover all the facts. The second considers various proposed solutions to the problems raised in the first part and finds that all of them are metaphysics ("fairy science") rather than real science.
The first part is fairly tough going in places, especially the discussion of Bell's theorem and non-locality. In fact, I think there may be too much space given to the Standard Model. For me, the main interest of the book comes in the second part, which is quite hard-hitting.
As a glance at my review subject headings for science and cosmology will show I've read a number of the popular books that Baggott castigates as metaphysical, notably those of Brian Greene. Baggott admits to enjoying such books himself but he criticises them for putting forward mathematical theories that make no predictions and are almost certainly untestable. Among the subjects he places in this category are string theory with its offshoot M-theory, the anthropic principle and the multiverse hypothesis.
Publishers present books on these themes in a way that makes them sound exciting, as Baggott illustrates by quoting from the blurbs of books by Lisa Randall, Brian Greene, and Stephen Hawking. The authors themselves may not be entirely to blame for this. Greene, for example, admits that he doesn't believe in string theory. "But he insists that, despite the conspicuous absence of testable predictions from superstring theory, it remains one of the best bets for providing a unified theory."
As for the multiverse hypothesis, it's clear that a major reason for its popularity with many cosmologists is that it seems to be pretty well the only idea in sight that could answer the fine tuning question, which in turn offers an opening to supporters of so-called intelligent design ("a non-sequitur if ever there was one").
The universe is characterised by a lot of numerical values for constants that are extremely critically adjusted to permit the existence of life. If some of these were only very slightly different there would be no stars or galaxies, for example. There is no known reason for these values to be what they are, which seems to some to leave the field wide open for a divine Designer.
The multiverse hypothesis provides a way out. If there is a near-infinite number of other universes, all with randomly arrived-at different values for these numbers, there will by chance be some which are exactly right for life, and of course we wouldn't be there in those that are unsuitable for life. This is a version of the anthropic principle.
Unfortunately the multiverse hypothesis is almost certainly untestable, so is not scientific by Baggott's criteria. However he is no intelligent designer, so what is his solution?
As he frankly admits, he doesn't have one.
How do I explain the fine-tuning of the universe? My hands are in the air. It's a fair cop. I have no explanation because science does not have an explanation. We may be here because, by happy accident or the operation of some complex natural physical mechanism we have yet to fathom, the parameters of the universe just happen to be compatible with our existence.Scientists, he insists, should not feel obliged to provide all the answers.
Baggott is not alone in criticising much modern physics for, as he sees it, abandoning science for metaphysics; see, for example, The Trouble with Physics by Lee Smolin and The End of Science by John Horgan. But it seems it's difficult for a young physicist to make a career at present without subscribing to what has become the prevailing orthodoxy, namely string theory.
It seems to me that the basic problem is that science can't answer the existential questions that draw readers to the books that Baggott criticises. Even if "some complex natural physical mechanism" were found to explain fine tuning, it wouldn't tell us why said mechanism existed in the first place. That will always be a metaphysical question. Whether you find it absorbing or meaningless seems to depend on whether you possess what Thomas Nagel calls the religious temperament. You can have this even if you are, like Nagel himself, an atheist.