There seems to be a new breed of popular science book around aimed at families. These range from the ‘for children but adults will like it too’ book like Richard Dawkins’ The Magic of Reality to ‘for adults but children will like it too’ in the case of my own Inflight Science. I’d put Adam Hart-Davis’s latest in the latter category. It is pitched at adults, but never gets so heavy that older children would appreciate it too.
What’s more, the format is one that seems designed to appeal to those younger readers. It’s the size of a small coffee table book and has pages that have the sort of mix of text, photographs, zappy little mottos and factoids that you would expect to find in a children’s science book. The contents, though, are meaty enough for an adult reader to get their teeth into them – which is just as well, as, in writing about time, Hart-Davis is taking on a non-trivial topic.
One of the hardest things about time is to define what it is, especially up front where you can’t really go into block universes or the ‘becoming present’ and other philosophical concepts. However before long we are launched into the philosophical side and beginning to get a feel for the way human beings have struggled with the concepts of time since the earliest days through to modern philosophy. We then move on to time in nature, how we fix the units of time, how we measure the passing of time and a ‘time and science’ section that pulls together the various scientific implications and considerations of time from the speed of light and relativity to the big bang.
On the whole this all handled very well, at a level that won’t challenge, but will keep the interest going with some truly fascinating factoids and entertaining histories. I was slightly surprised that there was nothing much about thermodynamics with its implications for ‘time’s arrow’, but most of the important areas were covered. One of the difficulties in taking a relatively light approach is not over-simplifying. This doesn’t happen often, but, for instance, in talking about pendulums, there is no mention that Galileo’s idea that the period of pendulum does change with the size of its swing is wrong (despite often being repeated). In a conventional pendulum it only holds true for a small swing – once the pendulum moves more than about 15 degrees either side of the vertical, the force acting on it cease being linear, no longer producing a consistent frequency.
There is also one out-and-out error. We are told that, because of special relativity, the clocks on GPS satellites run slow by about 38 microseconds a day. Unfortunately, GPS satellites are also subject to general relativity – and this says that with lower gravity, clocks run faster. The lower gravitational pull on the satellites compared with the Earth’s surface means that they run fast, and this effect is stronger than the slowing from special relativity. In reality, the combination of the two effects means that GPS satellites run fast by 38 microseconds each day.
My only other concern is that as an adult reader, I find the busy visual presentation something of a distraction. I have nothing against illustrations in a book, but when you are having to jump here and there to read boxes and quotes and factoids, I find I lose the flow and don’t really get into the book in the same way I would with a conventional layout. I know this isn’t a problem for everyone – if you like this kind of layout, you will love this book – but it’s not my favourite approach.
Overall, this is an excellent introduction to the concepts of time, measuring it and its importance to science. It is pitched just right so that an adult can feel they are getting some worthwhile material, but a younger reader can also enjoy it. There is plenty to capture the interest, and a good balance of the historical and the scientific. Although the approach won’t work for everyone, and occasionally can over-simplify, I would still heartily recommend it, as time is subject that really isn’t covered enough in popular science.
Hardback: 
Also in paperback:
Review by Brian Clegg
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