By any objective standard, the theory of computational complexity ranks as one of the greatest intellectual achievements of humankind – along with fire, the wheel, and computability theory. That it isn't taught in high schools is really just an accident of history. In any case, we'll certainly need complexity theory for everything else we're going to do in this book, which is why the next five or six chapters will be devoted to it. So before we dive in, let's step back and pontificate about where we're going.

What I’ve been trying to do is show you the conceptual underpinnings of the universe, before quantum mechanics comes on the scene. The amazing thing about quantum mechanics is that, despite being a grubby empirical discovery, it changes some of the underpinnings! Others it doesn't change, and others it's not so clear whether it changes them or not. But if we want to debate how things are changed by quantum mechanics, then we'd better understand what they looked like before quantum mechanics.

• 1950s: Late Turingzoic

• 1960s: Dawn of the Asymptotic Age

• 1971: The Cook–Levin Asteroid; extinction of the Diagonalosaurs

• Early 1970s: The Karpian Explosion

• 1978: Early Cryptozoic

• 1980s: Randomaceous Era

• 1993: Eruption of Mt Razborudich; extinction of the Combinataurs

• 1994: Invasion of the Quantodactyls

• Mid-1990s to present: Derandomaceous Era