In The Powers of Ten by Charles and Ray Eames, a view of two people enjoying a picnic zooms up and away to show their surroundings, moving progressively farther into space, then zooms back in for a close-up of the hand of the picnicker, travelling deep into the microscopic realm. This is one of the most iconic examples of the "cosmic zoom," a trope that has influenced countless media forms over the past seventy years. Horton uses the cosmic zoom as a starting point to develop a cross-disciplinary theory of scale as mediated difference. He considers the origins of our notions of scale, how scalar mediation functions differently in analog and digital modes, and how cosmic zoom media has influenced scientific and popular views of the world. Analyzing literature, film, digital media, and database history, Horton establishes a much-needed framework for thinking about scale across multiple domains and disciplines.