The shedding of light
Oct 11th 2007
From The Economist print edition
PHOTOSYNTHESIS is the basis of life on Earth. Thermodynamics is the order and disorder in the universe. Put them together and you have the makings of a book that may re-order the way you think about the world. And that is what Oliver Morton, news editor at Nature (and who once worked for this paper), has done.
Mr Morton's thesis is that modern biology has become so focused on the movement of information, in the form of genes, that it has neglected the processes needed to move that information around: in essence, thermodynamics. People talk glibly of "using up" energy when in fact they are doing no such thing. What is actually used up is order. An energy flow drives the process, but it is disorder (or "entropy", to use the jargon) that changes, by increasing.
A highly ordered system such as a living thing thus needs an abundant supply of negative entropy (or unentropy, or call it what you will) to maintain its internal order. That negative entropy comes from the sun and is captured by photosynthesis, which uses light to split water molecules and combines the resulting hydrogen with carbon dioxide to form sugars. The sugars are a store of negative entropy that can be used elsewhere. The waste product, conveniently for the animals of Earth, is oxygen.
The book, then, is in part a refrain in praise of photosynthesis, the Earth's energy and order currency-exchange market. It is also an entertaining history of how the subject arrived where it is today-and an illuminating insight for the non-scientist into how the magisterial pronouncements of science are every bit as much the result of sausage-making as Bismarck's description of the process of legislation.
The text is peppered with vignettes and asides that highlight science's faltering march forward on the backs of researchers, who are by turns quirky and visionary. The process of discovery is not chronological but is forever folding back on itself, revisiting half-solved problems. Mr Morton is careful to point out where progress has been impeded by hubris or tucked away in academic literature.
There is also, of course, the inevitable warning. Having perfected the energy-into-order recipe over billions of years, photosynthesis has left a great deal of waste in the Earth, as well as contributing oxygen to the atmosphere. That buried waste-coal, oil and natural gas-is what powers the industrial revolution still sweeping the Earth.
By reuniting the two waste products of photosynthesis-oxygen in the air and carbon in the ground-this revolution has fuelled a rise in atmospheric carbon dioxide three times higher than any previous rise that can be measured. The system-the interaction between life and its surroundings: the atmosphere, the oceans and the upper levels of the Earth's crust-has been pushed out of equilibrium.
Mr Morton argues that the way in which industrialised humanity is interfering with the homeostatic process can be undone-not by way of a single, magic bullet, but by pursuit of a number of ultimately achievable goals. The damage is done but it is, he says, reparable. Humanity had better hope he is right.
Eating the Sun: How Plants Power the Planet.
By Oliver Morton.
HarperCollins; 457 pages; $26.95
Fourth Estate; £25