If there's one thing that gets a touch tedious in science reporting it's the news headlines that some new observation or experiment 'proves Einstein right' - as if we're still not sure about relativity. At first glance that's what this book does too, but in reality Clifford Will and Nicolas Yunes are celebrating the effectiveness of the general theory of relativity, while being conscious that there may still be situations where, for whatever reason, the general theory is not sufficient. It's a genuinely interesting book - what Will and Yunes do is take experiments that are probably familiar to the regular popular science reader already and expand on the simplified view of them we are usually given. So, for example, one of the first things they mention is the tower experiments to show the effect of gravitational red shift. I was aware of these experiments, but what we get here goes beyond the basics of the conceptual experiment to deal with the realities ...

There is a temptation on seeing this book to think it's another one of those physics titles that is thin on content, so they put it in an odd format small hardback and hope to win over those who don't usually buy science books. But that couldn't be further from the truth. In Jim Al-Khalili's The World According to Physics , we've got the best beginners' overview of what physics is all about that I've ever had the pleasure to read. The language is straightforward and approachable. Rather than take the more common historical approach that builds up physics the way it was discovered, Al-Khalili starts with the 'three pillars' of physics: relativity, quantum theory and thermodynamics. In simple language with never an equation nor even a diagram in sight, the book lays out what physics is all about, what it has achieved and what it still needs to do. That bit about no diagrams is an important indicator of how approachable the text is. Personally, I...

It's something of a truism that science tends to go through stages, where each new stage can be typified as 'It's more complicated than we thought.' This book demonstrates that this assertion is also true of history of science. It examines the 1919 eclipse expeditions and their conclusions used to bolster Einstein's general theory of relativity, and how those results have been treated. This is a very tightly focussed subject for a whole book, and there is a distinct danger here of the material of an article being stretched out to book length - it often did feel that Daniel Kennefick was dragging out a handful of conclusions by repeating the same assertions over and over in subtly different ways. However, this isn't entirely fair as he does give exhaustive detail of the two expeditions which wouldn't have fit in an article, covering how their results were produced and how the controversy (if it could really be called that) arose. Like many physics pr...

There's no doubt that Jim Baggott is one of the best popular science writers currently active. He specialises in taking really difficult topics and giving a more in-depth look at them than most of his peers. The majority of the time he achieves with a fluid writing style that remains easily readable, though inevitably there are some aspects that are difficult for the readers to get their heads around - and this is certainly true of his latest title Quantum Space , which takes on loop quantum gravity. As Baggott points out, you could easily think that string theory was the only game in town when it comes to the ultimate challenge in physics, finding a way to unify the currently incompatible general theory of relativity and quantum theory. Between them, these two behemoths of twentieth century physics underlie the vast bulk of physics very well - but they simply can't be put together. String theory (and its big brother M-theory, which as Baggott points out, is not actually...

It is generally acknowledged that Stephen Hawking's A Brief History of Time  is one of the most common books to be bought but not read beyond the first few pages. If you are the kind of popular science reader who found Hawking hard going, you can stop now - Five Photons is not for you. If, on the other hand, you found  A Brief History of Time  a piece of cake and wished you could get into more depth without resorting to heavy mathematics or a tedious textbook style, Five Photons could be just up your street. Astrophysicist James Geach starts of fairly gently with a chapter on the nature of light that mostly sets aside quantum physics, leading up to the observation that light is our vehicle for for stripping back the history of the universe to its earliest times (or, at least, the point where the universe became transparent). From here on, the five photons of the title take us on different journeys, from the oldest surviving light of the cosmic ...

This is the first book I've read where I had to force myself to stop thinking about the author's name - and specifically from asking myself if his middle name is 'To' (I bet he hasn't heard that one before) - to be able to concentrate on the subject. It's the second book I've read on gravity and gravitational waves in the last few weeks, and it didn't work for me as well as the Pierre Binétruy title  Gravity!   In part it's down to A Zee's writing style, which is extremely mannered (not to mention constantly referring to his other books), but the content also simply didn't put the information across very well. Things start in a promising way (despite the style). The first lines of the prologue give a suitable feel: 'Finally, finally, the long wait was over: we the human race on planet earth collective heard the song of the universe. Yes, we, a rather malevolent but somewhat clever species, can now proudly say we have detected the rip...

I had to really restrain myself from adopting the approach taken by The Register in referring to Yahoo! by putting an exclamation mark after every word in the text when faced with reviewing Gravity! One thing to be said about the punctuation, though, is it makes it easier to search for amongst a whole lot of books on gravity and gravitational waves (the subtitle is 'the quest for gravitational waves') since their discovery in 2015. Despite the subtitle, Pierre Binétruy gives us far more - in fact, gravitational waves don't come into it until page 160, which makes it really more of a book about gravity with a bit on gravitational waves tacked on than a true exploration of the quest.  However, those early pages aren't wasted - Binétruy gives us plenty of detail on all kinds of background, for example plunging in to tell us about element synthesis, something you wouldn't expect in a book on gravitational waves. I also really liked a little section on experimen...

There's good news and bad news. The good news is that The Order of Time does what A Brief History of Time seemed to promise but didn't cover: it attempts to explore what time itself is. The bad news is that Carlo Rovelli does this in such a flowery and hand-waving fashion that, though the reader may get a brief feeling that they understand what he's writing about, any understanding rapidly disappears like the scent of a passing flower (the style is catching). It doesn't help either that the book is in translation so some scientific terms are mangled, or that Rovelli has a habit of self-contradiction. Time and again (pun intended) he tells us time doesn't exist, then makes use of it. For example, at one point within a page of telling us of time's absence Rovelli writes of events that have duration and a 'when' - both meaningless terms without time. At one point he speaks of a world without time, elsewhere he says 'Time and space are real phenom...

The message of this book is summed up in its subtitle: 'How Einstein’s spacetime ripples reveal the secrets of the universe.' Gravitational waves really do reveal secrets – astronomical phenomena that can’t be observed any other way. The Einstein connection comes via general relativity – his alternative to Newton’s theory of gravity which is, notoriously, almost indistinguishable from it for most practical purposes. There are a few situations where the two theories make slightly different predictions, and in these cases general relativity comes out on top. When the Laser Interferometer Gravitational Wave Observatory (LIGO) reported the detection of gravitational waves in February 2016, most journalists treated it as just another of these academic “ticks in the box” for Einstein. That’s underselling one of the most exciting breakthroughs in modern science – and this book aims to put the record straight. According to Brian Clegg, the LIGO announcement 'signalled the begin...

I am always suspicious when a book has a comment on the back from a physics professor recommending it for the 'general reader', as in my experience, physics professors have little clue as to what works for a non-technical audience. But in the case of The Little Book of Black Holes , Roger Penrose has got it right... with one proviso. As long as the general reader has absorbed a good popular science title on special and general relativity first. Without ever venturing into heavyweight maths, Steven Gubser and Frans Pretorius take us through the way that both Schwarzschild's non-rotating black hole and Kerr's rotating version were derived from Einstein's equations. And they help the reader explore many of the implications for such a body were it to exist in the real universe, from familiar aspects such as time dilation to the delightful zoom-whirl orbit. For an unfortunate individual passing towards the singularity we not only get spaghettification (though not nam...