Life gets complicated but it never goes over the edge

A new addition to the shelf of books explaining the science of complexity and simplicity needs to work hard to justify its existence. Here, John Gribbin takes simplicity theory deep into space and time, looking at its applications to astronomy and the origin of life.

In astronomy, the so-called three-body problem has long defied analysis. In essence, it shows that the gravitational interaction between two bodies can be calculated simply, but with a third body interacting the outcome becomes unpredictable. Complexity theory addresses this problem, and with it interesting issues such as whether the solar system is stable.

In biology, we have long known that both living cells and whole creatures are little pockets of energy and information that defy the universal tendency to disorder in obedience to the laws of thermodynamics. Now, because of the Gaia theory and other advances, we appreciate that the Earth itself is a similar zone in which energy is used to maintain order and keep life intact. More intriguingly, there is evidence that planets are common in our own galaxy, which suggests that life may be repeating Earth's trick at many locations across the universe.

Gribbin shows that life on Earth has developed by reiterating simple rules over long periods. In many systems, complexity increases when repeated bifurcations of possible pathways become more frequent, until chaos ensues.

Life has learnt to opt for complexity while staying one step short of chaos.

Big claims are often made for these findings, for instance that they can predict the stock market. Gribbin's more modest approach is interesting because it has something definite to say. For example, an earthquake of magnitude 8 on the Richter scale is 20 billion times more powerful than a quake of magnitude 1 - the difference between cities being demolished and a slight rumbling sensation. But their frequencies follow a single "power law", proof that they are the same phenomenon.

Deep Simplicity is not Gribbin's best work, and it has numerous rambling and inessential diversions. But it does point to deep insights, now being united into solid theory, into the laws behind living and non-living systems on Earth and elsewhere.

Martin Ince is contributing editor, The Times Higher .