WHAT if the Easter Rising hadn't taken place? Or Britain had created a nine county state of Northern Ireland in 1921? Or just supposing Jack Charlton had never been born?
What if... what if. This kind of game with the past, with its clouds of possibilities and might have beens, has a long history itself. Today it is a boom area in science fiction writing, particularly since the genre's aliens-'n'-ray guns stuff was jettisoned into the wormhole of the Fifties.
One much acclaimed sci fi "alternative history" was Bruce Sterling and William Gibson's The Difference Engine (1988), in which Charles Babbage's legendary computer - designed in the 1820s but for many reasons never built - is actually completed. Victorian England enters the computer age a century ahead of time, creating (for the reader at least) a severe bout of historical vertigo.
Their novel, and the British Science Museum's project six years ago to build a real Difference Engine, are key catalysts in Cultural Babbage, a dazzling collection of 13 overlapping essays about technology, culture and forgotten or imaginary histories.
The approach is often deliberately off kilter, such as in Simon Schaffer's essay about apparent ephemera: the exotic automata which packed the Victorian showrooms and museums of Babbage's youth. Yet the inventor himself owned an exotic mechanical dancer, and Schaffer makes several mind boggling comparisons between Victorian chess playing machines - which cleverly concealed a human player - and today's main "intelligence test" for computers: the Turing Test.
It, too, explicitly involves a machine deceiving an audience. Schaffer concludes that we have a tech no culture where human labour - especially in apparently human free computing - must always remain invisible.
SCATTERED throughout the book are the magic lanterns, kaleidoscopes and other optical toys of the Victorian age. Isobel Armstrong's essay on the meaning of transparency in 19th-century glass (from conservatories to crystal palaces) is a particularly sublime form of media studies. When glass is blown, Armstrong says, the observer is looking through the residues of somebody else's invisible breath. The most apparently useless debris of the planet - sand - is transformed into a new medium which you both look though and look at.
Tom Paulin pitches Edmund Burke's hatred of science against the stance of William Hazlitt and Joseph Priestley. He concludes by reprinting in full the United Irishmen's pamphlet defending Priestley after his lab was destroyed - and shortly before he was hounded to North America. Burke features again, alongside T.H. Huxley and Thomas Jefferson, in Irish writer Neil Belton's examination of English culture's "scorn of the scientific".
The book also puts the scientist under the microscope, looking at the romanticisation of Edison and his stress on showmanship. Marina Benjamin enlarges a footnote in the annals of Victorian science, John Benjamin Dancer and his microphotography (photographs shrunk down to minuscule dots on a standard glass slide). And Alex Soojung Kim Pang throws new light on the architect inventor R. Buckminster ("Bucky") Fuller - best known today for his geodesic domes which inspired researchers to nickname the structure of Carbon 60 the Bucky Ball.
While the dome was a symbol of Sixties hippy communes, Pang unearths its real roots a decade before. Fuller comes across as a Cold War technocrat, a leading proponent of the "dispersal" idea: with the threat of nuclear destruction, cities should be scattered, using these cheap, mass produced, robust domes. The parallels with the Internet's origins and form are obvious, but Pang also looks at the dome's role on the ideological battle ground of international trade fairs, from Kabul to Poznan. "The dome's greatest success . . . was not as a product of capitalism but as a symbol of capitalism."
EVEN more surprising is Anne Joseph and Alison Winter's essay about DNA testing and earlier forensic evidence such as anthropometry and fingerprints, and their allure in detective fiction and the public imagination. It's a pity, though, that they couldn't discuss the growing use of experts who analyse the narrative structures within police confessions.
Yet it's hard to do justice to the collection's dense web of offbeat connections, and the opening and closing essays by editors Uglow and Spufford provide even greater focus. If anything seems slightly blurry, it's Lavinia Greenlaw's piece about science and poetry, and Jon Katz's Wired article about Tom Paine. His central thesis (if the great democrat were alive today, he'd feel completely at home on the Internet) is too crude and jarring compared with the delicate "what if" exercises that Spufford proposes.
Even so, there is plenty to make this playful book essential reading in the ongoing debate about science and culture today.