From Planck’s 1900 quantum hypothesis to Bell’s theorem, the EPR paradox, and the no-cloning theorem — the 80-year scientific prelude that made quantum computing possible. Quantum computing did not arrive in 1980. It arrived in 1900, when Max Planck reluctantly proposed that energy might come in discrete packets; again in 1905, when Einstein took the idea seriously enough to apply it to light; and again across the next eight decades, as the implications worked their way through theory, experiment and information science. By the time Paul Benioff, Yuri Manin, Richard Feynman and David Deutsch began asking whether quantum mechanics could be turned into a computational substrate, almost everything they needed was already in place. This article walks the eighty-year scientific prelude to quantum computing, from the trouble with black-body radiation through Bell’s theorem, the Aspect experiments, the no-cloning theorem and BB84. Table of Contents The Trouble With Black Bodies The opening problem was prosaic. By the late nineteenth century, classical physics could describe the radiation given off by a hot body across most of the spectrum, but at short wavelengths, the predictions diverged from experiment in a way that nobody could fix. The mathematics insisted that an ideal radiator should emit infinite energy at ultraviolet frequencies, which was both physically absurd and contradicted by every measurement ever made. The discrepancy became known as the ultraviolet catastrophe, and through the 1890s it was the most embarrassing unresolved puzzle in theoretical physics. On 14 December 1900, Max Planck presented a paper to the German Physical Society in Berlin proposing a solution that he himself disliked. If electromagnetic radiation could only be emitted in discrete packets of energy, with each packet proportional to the frequency through a small constant later named after him, then the catastrophe disappeared, and the observed black-body spectrum fell