Bedeviled

How scientists through the ages have conducted thought experiments using imaginary entities—demons—to test the laws of nature and push the frontiers of what is possible Science may be known for banishing the demons of superstition from the modern world. Yet just as the demon-haunted world was being exorcized by the enlightening power of reason, a new kind of demon mischievously materialized in the scientific imagination itself. Scientists began to employ hypothetical beings to perform certain roles in thought experiments—experiments that can only be done in the imagination—and these impish assistants helped scientists achieve major breakthroughs that pushed forward the frontiers of science and technology. Spanning four centuries of discovery—from René Descartes, whose demon could hijack sensorial reality, to James Clerk Maxwell, whose molecular-sized demon deftly broke the second law of thermodynamics, to Darwin, Einstein, Feynman, and beyond—Jimena Canales tells a shadow history