Five Photons - James Geach ****

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 microwave background radiation to that from around black holes.

All that makes this book sound like a fairly straightforward cosmological title, even if it does have the rather nice 'five photons' hook. What makes it different (and definitely not for everyone) is the depth that Geach goes to - not in a mathematical sense, but in describing subtleties of the work of astrophysicists and cosmologists that popular science titles usually gloss over. Each chapter opens fairly gently, but soon we're plunged into the detail.

A good example is the opening of the fourth chapter, Dark Energy's Imprint. Geach starts by telling us a cosmology joke from a seminar: 'I once sat in a cosmology seminar that opened with the line "What is the integrated Sachs-Wolfe effect?" This prompted a few moments of awkward silence from the audience until the speaker continued, "It's like the Sachs-Wolfe effect... only integrated!"' As Geach says, maybe you had to have been there. But Geach goes onto describe what the Sachs-Wolfe effect is - a variation in gravitational redshift of photons emerging from the early universe as the cosmic background, depending on the density of the region they emerge from - and, indeed also explains the integrated effect, which brings in similar variations on the photon's journey due to dark energy.

I need to stress again that Five Photons is only for the advanced cosmology buff. Think of it as a sequel to A Brief History that explains some of the real detail of what has been discovered and brings in factors cosmologists have to consider that you won't see anywhere else in a popular science title and you won't go far wrong. And if you are in the audience for that, it's great.

Hardback:

Using these links earns us commission at no cost to you

Review by Brian Clegg

Comments

Roger Highfield - Stephen Hawking: genius at work interview

Roger Highfield OBE is the Science Director of the Science Museum Group. Roger has visiting professorships at the Department of Chemistry, UCL, and at the Dunn School, University of Oxford, is a Fellow of the Academy of Medical Sciences, and a member of the Medical Research Council and Longitude Committee. He has written or co-authored ten popular science books, including two bestsellers. His latest title is Stephen Hawking: genius at work . Why science? There are three answers to this question, depending on context: Apollo; Prime Minister Margaret Thatcher, along with the world’s worst nuclear accident at Chernobyl; and, finally, Nullius in verba . Growing up I enjoyed the sciencey side of TV programmes like Thunderbirds and The Avengers but became completely besotted when, in short trousers, I gazed up at the moon knowing that two astronauts had paid it a visit. As the Apollo programme unfolded, I became utterly obsessed. Today, more than half a century later, the moon landings are

Space Oddities - Harry Cliff *****

In this delightfully readable book, Harry Cliff takes us into the anomalies that are starting to make areas of physics seems to be nearing a paradigm shift, just as occurred in the past with relativity and quantum theory. We start with, we are introduced to some past anomalies linked to changes in viewpoint, such as the precession of Mercury (explained by general relativity, though originally blamed on an undiscovered planet near the Sun), and then move on to a few examples of apparent discoveries being wrong: the BICEP2 evidence for inflation (where the result was caused by dust, not the polarisation being studied), the disappearance of an interesting blip in LHC results, and an apparent mistake in the manipulation of numbers that resulted in alleged discovery of dark matter particles. These are used to explain how statistics plays a part, and the significance of sigmas . We go on to explore a range of anomalies in particle physics and cosmology that may indicate either a breakdown i

Splinters of Infinity - Mark Wolverton ****

Many of us who read popular science regularly will be aware of the 'great debate' between American astronomers Harlow Shapley and Heber Curtis in 1920 over whether the universe was a single galaxy or many. Less familiar is the clash in the 1930s between American Nobel Prize winners Robert Millikan and Arthur Compton over the nature of cosmic rays. This not a book about the nature of cosmic rays as we now understand them, but rather explores this confrontation between heavyweight scientists. Millikan was the first in the fray, and often wrongly named in the press as discoverer of cosmic rays. He believed that this high energy radiation from above was made up of photons that ionised atoms in the atmosphere. One of the reasons he was determined that they should be photons was that this fitted with his thesis that the universe was in a constant state of creation: these photons, he thought, were produced in the birth of new atoms. This view seems to have been primarily driven by re

Search This Blog