Visions of Iris flitting through the universe with a peeled grape

To quote from the first sentence of Hans Christian von Baeyer's first chapter: "Information gently but relentlessly drizzles down on us in an invisible, impalpable electric rain." Scientists in California predict that humans and their machines will create more information in the next three years than in the previous 300,000 years of history. But much of the information on the internet turns out to be garbled, badly organised or just plain wrong. Furthermore, the concept of information is vague and ill defined. "Is it a scientifically useful idea? Can it be measured? Will it yield to mathematical analysis? Such questions are the stuff of this book."

Information: The New Language of Science consists of 25 chapters, grouped into four sections: "Background", "Classical information", "Quantum information" and "Work in progress". Each chapter is a well-structured and elegantly written essay that circumnavigates its topic with poetic quotation, literary allusion, biographical anecdote, personal reminiscence, mathematical paradox and metaphysical musing, all expressed in a clear and vivid prose style. Many of the familiar topics in expositions of popular science are touched upon: atomic physics, information theory, genetics, probability theory, computer science and quantum theory. These are illustrated by interesting examples and placed in context by a generous helping of scientific philosophy.

Like all good essays, the chapters abound in apposite quotations and references. Classical references include Homer for the messenger goddess Iris, flitting through the Iliad ; Hipparchus, for the first visual estimates of the magnitude of stars; Democritus, as the father of the atomic theory of matter; and Lucretius, for his scientific reductionism, in explaining even the soul as constituted from atoms.

Quotations from more recent authorities include Goethe (among scientists "analysis and synthesis should alternate as naturally as breathing out and breathing in"); Wittgenstein ("We cannot think of any object apart from the possibility of its connection with other things"); and the Canadian humourist Stephen Leacock who was inspired by quantum theory to suggest that a rider can jump on his horse and gallop off in all directions. There are even more significant and lengthy quotations from the great names of science,Boltzmann, Bohr, Einstein, Feynman and Schrodinger, all of whom have thought deeply and written extensively on the philosophy of science.

The really big questions addressed by this book were inspired by the philosophical physicist John Archibald Wheeler, for whom Baeyer expresses the greatest admiration: How come existence? Why the quantum? A participatory universe? What makes meaning? It from bit? The author adds one further question: What is information? He is inspired by the vision that information will be as fundamental to the unified understanding of science in this century as the concept of energy has been in the last century. He summarises the discoveries of Boltzmann, the information theorist Claude Shannon and Einstein, and finds them wanting. This is partly because the theories do not recognise the subjective aspects that make information relative to its understanding and use (the "participatory universe" of Wheeler), and partly because of the theories fail to recognise the more basic concepts of quantum physics, which replace the classical discrete unitary bit (binary digit) of information by the quantum bit, or qubit. The author suggests that the last of Wheeler's questions should be replaced by "It from qubit?".

But this is not the book in which you will find an answer to the fascinating questions that it poses. Characteristically, the book ends in pure poetry: "The qubit, which floats through my mind in the form of a soft translucent sphere, a peeled, seedless grape shimmering indistinctly in all the colours of the rainbow at once, is an inexhaustible source of possibilities from which only one can be realised... To me, the qubit is the ultimate source of wonder."

A sense of wonder is an essential prerequisite to an appreciation of the discoveries of science, and wonderment is the emotion that will be most pleasantly evoked in the reader of this book.

Sir Tony Hoare is senior researcher, Microsoft Research.