What is dust? Anybody who has read Philip Pullman's splendid trilogy, His Dark Materials, will know this question is one of its central conundrums.
That, and how Lyra's alethiometer works, or how the subtle knife can cut holes between parallel universes.
By his own admission in the introduction, Pullman's work draws on a limited scientific understanding to create an imaginative work about a fictional world. Mary and John Gribbin's book is their attempt to show what relation Pullman's work bears to reality and to explain the underlying science.
The authors have a long pedigree of producing popular science books that endeavour to make modern science comprehensible. They have a talent for expressing ideas in clear, simple language, and for finding good analogies for complex ideas. They rise to the challenge of explaining the Northern Lights, the Big Bang, the origin of the elements, dark matter, which they infer is the model for dust, atoms and consciousness, not to mention quantum physics, parallel universes, quantum entanglement and more.
However, the truth is that any one of these could be the subject of a book in itself and, hard as the authors try, the reader is left with the feeling that the genre has been overstretched.
Perhaps inevitably in attempting to cover such a broad range of modern science, some of the complex ideas are given minimal explanations.
Nevertheless, this book will be valuable as a companion volume, where the index can be used to find supplementary scientific explanations of Lyra's world.
Fundamentally, Pullman's trilogy works because it is an excellent story, where the science is just an instrument for his imagination. Putting the science to the fore without a story achieves neither the magic of the book nor the magic of science.
Jonathan Osborne is professor of science education at King's College London