The fantastic first book in the Sunday Times bestselling Science of Discworld series When a wizardly experiment goes adrift, the wizards of Unseen University find themselves with a pocket universe on their hands: Roundworld, where neither magic nor common sense seems to stand a chance against logic. The Universe, of course, is our own. And Roundworld is Earth. As the wizards watch their accidental creation grow, we follow the story of our universe from the primal singularity of the Big Bang to the internet and beyond. Through this original Terry Pratchett story (with intervening chapters from Cohen and Stewart) we discover how puny and insignificant individual lives are against a cosmic backdrop of creation and disaster. Yet, paradoxically, we see how the richness of a universe based on rules, has led to a complex world and at least one species that tried to get a grip of what was going on. Terry Pratchett is the acclaimed creator of the global bestselling Discworld series, the first of which, The Colour of Magic, was published in 1983. Raising Steam is his fortieth Discworld novel. His books have been widely adapted for stage and screen, and he is the winner of multiple prizes, including the Carnegie Medal, as well as being awarded a knighthood for services to literature. After falling out with his keyboard he now talks to his computer. Occasionally, these days, it answers back. www.terrypratchett.co.uk @terryandrob Professor Ian Stewart is the author of many popular science books. He is the mathematics consultant for New Scientist and a Professor of Mathematics at the University of Warwick. He was awarded the Michael Faraday Prize for furthering the public understanding of science, and in 2001 became a Fellow of the Royal Society. Dr Jack Cohen is an internationally-known reproductive biologist, and lives in Newent, Gloucestershire. Jack has a laboratory in his kitchen, helps couples get pregnant by referring them to colleagues, invents biologically realistic aliens for science fiction writers and, in his spare time, throws boomerangs. Jack, who has more letters to his name than can be repeated here, writes, lectures, talks and campaigns to promote public awareness of science, particularly biology. He is mostly retired.

The planet Earth has picked up a parasite life-form - elves. They get everywhere. And they like humans to be superstitious, fearful and frightened of thunder. They're after our future and must be stopped... but by who? Enter the wizards of the Unseen University who, in the best-selling "Science of Discworld," unwittingly created Earth and our own universe. At the time they quite failed to notice humanity. (Well, we've only been around for a million years, so we're easily overlooked...) But now, at last, they've found us. "The Globe" is a unique book, weaving together a fast-paced Discworld novelette with cutting-edge scientific commentary on the evolution and development of the human mind, culture, language, art, and science. The result - as the wizards grapple with the nature of Good and Evil, and history is rewritten several times over - is a fascinating and brilliantly original view of the world we live in.

Roundworld is in trouble again, and this time it looks fatal. Having created it in the first place, the wizards of Unseen University feel vaguely responsible for its safety. They know the creatures who lived there escaped the impending Big Freeze by inventing the space elevator—they even intervened to rid the planet of a plague of elves, who attempted to divert humanity onto a different time track. But now it's all gone wrong—Victorian England has stagnated and the pace of progress would embarrass a limping snail. Unless something drastic is done, there won't be time for anyone to invent spaceflight and the human race will be turned into ice-pops. Why, though, did history come adrift? Was it Sir Arthur Nightingale's dismal book about natural selection? Or was it the devastating response by an obscure country vicar called Charles Darwin, whose bestselling Theology of Species made it impossible to refute the divine design of living creatures? Either way, it's no easy task to change history, as the wizards discover to their cost. Can the God of Evolution come to humanity's aid and ensure Darwin writes a very different book? And who stopped him writing it in the first place?

The wizards of Unseen University are again called upon to defend their creation, Roundworld, this time in a courtroom—where its very existence hangs in the balance. The Omnians fervently believe that the world is round, not flat, and view the discovery of Roundworld as a vindication of their faith. To leave this artifact in the hands of the wizards would be unacceptable. Not only do the academics hold that Discworld is flat, but by creating the Roundworld universe, they have elevated themselves to the level of gods. Ankh-Morpork’s venerable tyrant Lord Vetinari agrees to a tribunal, where the wizards Ridcully, Rincewind, and Ponder Stibbons can present their case—with key assistance from a Roundworld librarian named Marjorie Daw. JUDGMENT DAY weaves together explorations of such Earthly topics as big science, creation, subatomic particles, the existence of dark matter, and the psychology of belief—a treat for Discworld fans and readers of popular science alike. From the Trade Paperback edition.