Author's note

This wasn't included in the ARC of Invisible Things, so I thought I would post it here for those who might be curious. (It also includes some bonus paragraphs that we didn't have space for in the book itself, on the library research I did while writing the novel!)

THE AUTHOR'S NOTE

As I wrote in the note printed at the end of The Explosionist, which tells the earlier part of Sophie’s story, I have always been in love with the idea of north. My father is Scottish, and I spent quite a bit of time in Edinburgh and its environs as a child. Over the summers between 2000 and 2004, I was lucky enough to visit St. Petersburg in Russia, Tallinn in Estonia, Stockholm in Sweden and Copenhagen in Denmark. (København is the Danish spelling, which I have retained here for the slight sense of alienation and estrangement it gives to English-language readers.)

Like Edinburgh, these are cities of striking natural and artificial beauty, and I began to dream about what it would be like to live in an alternate universe in which these northern cities, so strongly united by culture and geography, were also politically connected. What if a new Hanseatic League (the Hanse was the name for the medieval trade alliance that spanned the Baltic and the North Sea) had come about in the wake of an event that did not happen in our world, but did take place in Sophie’s – Napoleon’s defeat of Wellington at the Battle of Waterloo on June 18, 1815?

There is a by now well-established genre of fiction called alternate history. Many alternate histories take a single event (often a famous battle) and change its outcome, considering what might have happened had history continued along another prong of the fork in the road. Novels of this sort might be set in worlds where the South won the American Civil War or Germany won World War II, to take two of the most popular examples.

Sophie is coming of age in a 1930s that looks in many respects much like the decade we knew (more about this in a moment), but that is in other respects quite different. As in our world, the 1910s in Sophie’s world saw a Great War; in Sophie’s world, though, that war lingered well into the 1920s and ended with England falling to Europe. The countries in the Hanseatic League (chiefly Scotland, the Netherlands, Denmark, Norway and Estonia) are able to hold out against the Europeans only because they are also the world’s premier suppliers of top-quality munitions, which Europe needs. Thus the secular patron saint of the modern Hanseatic states is Alfred Nobel, the Swedish chemist and industrialist whose invention of dynamite in 1867 changed the landscape of Sophie’s Europe even more decisively than our own.

The world I imagined comes out of real places and real history but also out of fairy tales and counterfactual paths not taken. Of course, if we really think about how history works, a world that split off more than a hundred years prior to the events of Invisible Things would have much less in common with our own world. In Sophie’s world, it is Ludwig Wittgenstein (in real history, a philosopher rather than a physicist), not Werner Heisenberg, who collaborates with Niels Bohr and comes upon the notion of the uncertainty principle; in our world, Denmark was occupied by the Germans in April 1940, whereas the world of Invisible Things sees a German-dominated European Federation invading Denmark in October 1938. But Sophie’s world remains quite recognizably entwined or entangled with our own world and its history; not just Niels Bohr but Paul Dirac, Wolfgang Pauli, Otto Robert Frisch, Lise Meitner and others were real historical characters with the same names and birthdates and personal histories that they possess in Invisible Things. Logically speaking, it is monumentally unlikely that if history had taken such a different turn there would even be such a person as Niels Bohr: he would have to have been the product of a particular meeting of sperm and egg contributed by parents who might never even have existed in the world of Invisible Things, let alone been born and met and married and conceived exactly the same child at the same exact moment and given him the same name as they did in ours. This is a very great liberty, given the rules of alternate history, and I have taken it ruthlessly and without remorse.

I consulted too many books while researching this novel to name them all here, but these are a few of the ones I found especially useful or enjoyable:

On Niels Bohr and the (real) Institute for Theoretical Physics, Niels Bohr: A Centenary Volume, edited by A. P. French and P. J. Kennedy; Niels Bohr: His life and work as seen by his friends and colleagues, edited by S. Rozental; Ruth Moore’s biography, Niels Bohr: The Man, His Science, and the World They Changed; Peter Robertson’s The Early Years: The Niels Bohr Institute, 1921-1930; Hilde Levy’s George de Hevesy: Life and Work; and Otto R. Frisch’s What Little I Remember.

On the idea of north and Sophie’s Lapland travels: Frank Hedges Butler’s Through Lapland with Skis & Reindeer; Barbara Sjoholm’s The Palace of the Snow Queen: Winter Travels in Lapland; Vendela Vida’s Let the Northern Lights Erase Your Name; Piers Vitebsky’s The Reindeer People: Living with Animals and Spirits in Siberia; and Peter Davidson’s The Idea of North.

On Alfred Nobel, Nicholas Halasz’s A Biography of Alfred Nobel and Ragnar Sohlman and Henrik Schück’s Nobel: Dynamite and Peace; and on brainwashing, Dominic Streatfield’s Brainwash: The Secret History of Mind Control.

Particular thanks are due to Felicity Pors at the Niels Bohr Archive, who told me the story of Hevesy’s cats that prompted me to get hold of Hevesy’s delightfully titled collection of scientific papers, Adventures in Radioisotope Research, and to the friends who made my northern travels so pleasurable, especially Troy Selvaratnam, Vijai Maheshwari and Tarvo Varres. Brent Buckner hosted much of the writing, kept me more or less sane in times of adversity and gave useful comments on several rounds of draft. My father Ian Davidson offered scientific fact-checking at various stages. The book benefited immeasureably from editorial comments from Zareen Jaffery and Ruth Katcher. Thanks, too, to Kathleen Anderson, Liz Gately and others at Anderson Literary Management. So many friends, family members and students facilitated the writing of the book in one way or another that I really cannot begin to list them here, but I am immensely grateful for their contributions, and for the work of everyone at HarperTeen. Finally, I would like to thank the bloggers who greeted The Explosionist with such enthusiasm and clamored for the sequel. I hope Invisible Things will meet or exceed their expectations.

The original inspiration for this story was Hans Christian Andersen’s “The Snow-Queen,” a tale I have loved ever since I first encountered it as a small child reading Andrew Lang’s Pink Fairy Book. Go and read it if you have not already!