One nice thing about writing science columns is that I can pick subjects that interest me. With all of science to play with, there's always something fascinating, and I never have to grind away on a dull topic simply because it's due.
All very well until it comes time to collect these essays into a book Publishers insist that books have a central theme, or failing that, at least be neatly organized. Fortunately, when I began work on this collection, I found that most of the columns organized themselves into sections, each with a definite theme. Survival with style, black holes, space flight, energy; all relatively cohesive topics.
But there were a few leftovers. For the life of me I can't think of a theme to unite essays on holographic brains, flying saucers, terraforming Venus, and interstellar empires. It seemed a shame, though, to eliminate them just because they didn't fit into a neat package with the others. Besides, they illustrate just how rich and varied our future can be—and that is the point of the book.