on 20 March 2014
Of all branches of all the physical sciences, cosmology is by far the most far reaching. As far as we know for certain, biology is a science that is restricted to just one planet, in one solar system, in one galaxy, in one cluster of the universe. Yet cosmology is concerned with all those other planets, in other solar systems, in other galaxies, in other clusters. In short, it's about as close to a study of everything that we reasonably have a name for. This is a far cry from the social sciences, such as economics, which are wholly human inventions and have no basis in nature. It's this broad scope that has always fascinated me, though I admit this blog doesn't always reflect the amount of time I spend thinking about it and marveling at it.
So how can Peter Coles, in 127 pages, do justice to such a vast topic? He begins with beginnings. He gives us an overview of how past civilizations have thought of what we would now refer to as the universe, or cosmos or heavens. In particular, the idea of how they came to be. After all, it seems a very human question to ask "how did this all begin". The wealth and breadth of information that could be covered by any number of creation myths throughout history would be enough to fill the space Coles had available many times over. So he was given a tough hand to play with, knowing what to leave out and what level of detail to include. What he gives us is a few interesting pages that will require significant follow-up on the part of the interested reader. Only in chapter 2 does he really get motoring.
So it is that we jump straight into Einstein's general theory of relativity. This he does by wordy explanation and a few diagrams, all of which will be familiar to those who have studied the subject before. But this is an introduction and it should be accessible to the non-expert reader. In this, Coles does very well, I think. He avoids getting bogged down in too much detail. Though some readers may wonder "how do they know that" I can say that the answer lies in the mathematical detail from which we are spared. This is an inherent problem in any science writing, but Coles deals with it as well as anyone could reasonably be expected to.
From the basic equivalence of gravitation and acceleration, he looks at some of the large scale geometry of the universe and the principles of symmetry and isotropy. All this is laying the groundwork for a later chapter, though first he moves away from some of the theoretical side, which had been the focus so far, onto the experimental side. Specifically, this was the work of Edwin Hubble on the redshifts of galaxies.
I would imagine almost any reader who is interested enough to pick up the book will have some assumption or expectation that it will include the Big Bang at some point. In that, Coles doesn't disappoint us. What he does do though, is lead us along the historical path that (mostly) late 19th century into the 20th took. So having looked at the work of Hubble and Einstein he asks the reader "so what"? If we can show that the universe is expanding and, given what we know of general relativity, does this imply anything? It is this question to which the Big Bang is the answer we now give.
In his description, Coles takes in some important factors which may be new to some of the informed-but-not-expert readers, about particle physics and the unification of the forces of nature. Here, a very little quantum mechanics is thrown in, but not so much as to scare anyone off, hopefully. Interestingly, he makes reference here to the Higgs boson as the particle 'responsible' (if you will allow me such laxity with terminology) for mass. But it's worth noting that the book was first published in 2001 and so this section is already a little out of date. Indeed, with such an exciting, fast-moving science such as cosmology, one might almost hope or expect that any such book would be out of date soon. After a brief conversation with the author, he assures me that a revised version is the pipeline.
In some ways, the Big Bang is the highlight of the book. Or at least the climax of it. The early chapters led up to it while the later chapters show the consequences. In these, he looks carefully at the density of energy and matter in the universe, asking how this will affect the future of the universe. There is also a more astronomical take on cosmic structures, which is not something I got round to studying at university, but which is nonetheless fascinating and mind-boggling in its beautiful complexity.
The book closes almost with a recapitulation of the aims of Einstein in his later years. Here we return very much to the theoretical end of science (though some might harshly call it speculation) and ask questions about the unification of all known forces, as well as looking at the anthropic principles (strong and weak). The final chapter seems designed for the reader to ponder. These are open questions to which we don't have anything resembling a firm answer as yet. These are the questions which make us think, which make science interesting.
In giving his overview, Coles has done as good a job as anyone who had been tasked with such a feat might be expected. At the points where physics starts to overlap or infringe upon philosophy, some might disagree with his particular take, but that is no great criticism. Science is, after all, a human endeavour, subject to the whims and emphases we each put on it, even if that simply be in the questions we ask. For those who had not studied cosmology but were interested, then I would recommend it. For those who simply want to be a little more informed, this isn't a bad starting point, though there are plenty of references for further reading where one can get a little more depth than is covered here. I can't say it knocked my socks off, though that may come from over-familiarity with much of the topics covered, and they were done so in a "standard" way. So maybe not one for the expert reader. But good, nonetheless.