The 4% Universe – Richard Panek ****

The ‘four percent’ in the title of this book refers to the apparently true but bizarre fact that only 4% of the universe seems to be ordinary stuff – from planets to stars – with twenty-odd percent of the remainder dark matter and the rest dark energy, the unknown phenomenon that is forcing the expansion of the universe to accelerate.

Don’t come to this book hoping to find out what dark matter and dark energy are – because there’s a long way to go before those questions can be definitively answered – but instead you will find an in-depth history of the process by which the (probable) existence of dark matter and dark energy were discovered.

Richard Panek is at his best when describing human beings in action, rather than covering the details of physics or cosmology. He really takes the reader in to experience the astronomers, astrophysicists and cosmologists (surprisingly different beasts) at work. We begin to understand how these people work, what drives them and what they really think. We also see that these really are human beings, particularly in the rivalry and at times downright antagonism between two teams, one primarily astronomers, the other primarily physicists, who were at the forefront of the discovery of dark energy in the late 1990s.

There are two problems with this approach, though. One is that we are dealing with quite a large cast, few of whom are given big enough parts to really stand out – so often the reader, for example, can forget which of the two camps a particular scientist belongs to. Although we get a real feeling of knowing a couple of the names, it does get a bit overwhelming. What also gets overwhelming is the depth Panek goes into with the detail of discovery.

There’s a parallel here with the book A Grand and Bold Thing, where Ann Finkbeiner goes into a lot of detail of what happened in the development of the Sloane Digital Sky Survey. Our reviewer loved it, but I have seen another review bemoaning the Finkbeiner’s approach of covering ever little step. Similarly, if I’m honest, I got a touch bored with some of the trivia of discovery that Panek explored. The suspicion has to be that, having got access to detailed information from those involved, he was reluctant not to mention everything he heard – but this could have done with tighter editing.

The other problem with the focus on the people is that I’m not entirely sure that Panek always understands the science – there are one or two moments when he makes a statement that seems entirely wrong as far as the physics goes, but is swept away by the flow of the narrative so you don’t really notice it. For example he tells us that the anthropic principle is the term for the idea that inflation implies that there are 10500 inflationary bubbles, each its own universe. First of all, inflation doesn’t require this, it is just one possible implication, but secondly, the anthropic principle (which comes in two distinct forms) is not anything to do with inflation per se. It merely would explain why, if there were 10500 universes, we happened to live in this one.

A final niggle – the writing can be a touch pretentious. This doesn’t come across when Panek is at his best, telling us the personal stories of scientists and their work. But when he tries to take the overview we get sentiments like ‘… the award ceremony at Cambridge wasn’t only about posterity. It was about history, and history was something else. History was posterity in motion.’ Groan.

Don’t get me wrong. This is a great book for getting into the minds of those involved in these discoveries and for understanding more about how modern astronomy and cosmology works. I do recommend it. But the book’s limitations are strong enough that they can’t be entirely overlooked.

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Review by Brian Clegg