When I began studying the history of nuclear energy I did not think that images were important in themselves. I was wrong. Radioactive monsters, utopian atom-powered cities, weird ray devices, and many other images have crept into the way everyone thinks about nuclear weapons and power plants. The images, connecting with major social and psychological forces, have exerted a strange and powerful pressure on our history. This is no story of things locked away safely in the past: the images are as strong today as ever.

How can an investigator connect the colorful images in people’s heads with the attitudes that affect historical events? For an answer I rely on commonsense ideas that have been validated by rigorous experiment. Minds form associations between separate things; the sound of a can opener brings my dog to the kitchen and may even make her salivate. This mechanism is fundamental to all …