Why Does E=mc2?: (and Why Should We Care?) [Hardcover]

Before I start this review, just let me tell you where I stand re: popular science. I'm a complete beginner! The most amateur of amateurs. I'm intrigued, interested verging on passionate - but I've only read a handful of science books. So, I came to this book knowing nothing about the famous equation other than "energy equals mass times the speed of light squared" which, pre facto, was pretty much meaningless to me.

As I understand it, the success of this book varies wildly depending on the individual reader's pre-existing knowledge of science/quantum physics etc. As such, this is a review for people like me: utter beginners in the field.

In brief: the first half of the book is brilliant! Informative, well-written and mind-blowing in the way that high-concept astronomy often is. The second half of the book, however, is an incredibly difficult, long-winded explanation of vectors and the so-called 'master equation', most of which flew right over my head. I read it all, and bits of it made sense to me but, like many people here; this just feels like two books. The first half is clearly for people like me (beginners) whereas the second half is a radically different reading experience, which I imagine is much more suited to hardened afficianados of popular science.

Now for more detail: The first 150 pages or so don't explain the famous equation, as such; rather, they explain the things we *need* to know in order to understand the equation; such as the relative nature of time and space. All of this is articulated with very helpful diagrams, metaphors and fictional anecdotes. Any basic maths here (such as Pythagoras) is re-capped for the forgetful student(i.e. me) and parts of the book are also strikingly funny. I can imagine Brian Cox's lilting Manchester tones narrating.

The second half, however, carries a massive tonal shift, which is characterised by an increase in technical diagrams, equations and much more intense demands on the reader's mathematics. Similarly, very new (to me) terms are introduced at a frightening rate and explained very quickly 'muon', 'vectors', 'tachyon', 'higgs', 'neutrinos', 'W' and 'Z' particles etc. etc. The reader is then expected to have a perfect and instant recall of ALL of this information, sometimes tens and tens of pages later. This, added to the massive equations makes an awful lot of demands on the reader's memory, especially for a beginner.

All of this is fine, except that it's so at odds with the initial 150 pages (or so). Stylistically, there're two different books here. The first half takes a long time to explain basic maths like Pythagoras' theorem, but the second half rushes into incredibly difficult algebra with only the most cursory attempts to elucidate; there's too much of a disparity here.

How is it written? Well, again, this is a book of conflicts. The early descriptions of space and time and wonderful; enlightening, understandable and articulate (but a warning: some of the metaphors used to explain things (such as a man on a bike riding through a desert) are often more baffling than the physics itself). I really dug the first 150 pages - but then things changed (for the worse).

The phrase 'more about this later' is used ALL the time, which makes me think that maybe the book's chapter structure isn't optimal. Similarly, the phrase 'this is all you really need to know' is used SO much that I often felt patronised/spoken down to by the writers. And I know they're physicists, not writers, but some of the sentence construction (especially with regard to negative articles) is terrible, like this little blighter:

"Might spacetime not be the same everywhere, and might this not lead to consequences that we can observe: the answer is emphatically yes!"

The negatives here took quite a few minutes of de-coding before I realised that was actually going on. With subject matter so difficult, poor sentence structure really damages this book's eloquence.

So... the first half is truly excellent (almost worth the price of the whole book); but, if you're a beginner like me, expect to find the second half difficult, confusing, poorly written: it makes a lot of demands on the reader.

If you've read A LOT of popular science, then I imagine this book will be fine.

I really enjoyed this book. Recommended by my son who is interested in all things cosmic, I anticipated a better understanding of modern physics, something I never got to grips with at school.

It wasn't an easy read because of the formulae and maths - I think a few more occasions where the formulae were written out in words would have helped. I found myself having to flip back to remember what the letters stood for until they eventually sunk in.

Having said that, once past the fog, it was great, and very satisfying to gain some understanding of curved space, mass and the speed of light. Now I wish I had paid more attention at school. The writing style is entertaining, engaging and not at all patronising.A great journey, well guided - I intend to read it again to make sure it stays in my head.

With so many books to read and so little time to read them, it's rare to find one worthy of being read repeatedly; however, for me, why does E=mc˛ certainly fits into that category and I found my latest reading to be just as enjoyable as the first. Undoubtedly, Cox and Forshaw have produced one of the outstanding introductory texts to Einstein's theories of relativity, presenting their arguments in an absorbing prose that stimulates the imagination and challenges one's intellect. That said, this book is not without its shortcomings and, consequently, I am not quite convinced that it qualifies as a popular science "classic".

Firstly, whilst acknowledging that Cox and Forshaw did not intend to write "a book about mathematics", the concept of special relativity does benefit from a comprehensive mathematical explanation: its simplicity is what makes the idea so beautiful and the authors fail their readers by simply presenting information without bothering to demonstrate its derivation (for instance, the time dilation equation (p.127)). In essence, readers without the requisite scientific or mathematical training are simply required to accept such assertions (or seek their explanations elsewhere) and that dilutes the impact of the reasoning. Ironically, this is as much a presentational failing as anything else and the authors could have avoided this problem, without a significant increase in explanatory text, by simply improving the quality of some diagrams and including the stepwise transformations of Pythagoras' theorem.

Secondly, notwithstanding my (genuine) praise for the authors' lucidity, there are times when the prose becomes unnecessarily convoluted. In part, I suspect that this over-elaboration arises as an artefact of collaborative authorship and, in part, that relativistic concepts can be extremely counter-intuitive. However, if this is your first foray into relativity, be prepared to re-read passages in order to elicit understanding.

Many of those that have read the book will (rightly) view my criticisms as overly harsh and, to be sure, this is an extraordinary book. The authors' chatty style, occasional humour, and constant detours make the subject matter interesting and accessible as well as making for a thoroughly good read!