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Physicists used to think that superconductivity — electricity flowing without resistance or loss — was an all or nothing phenomenon. But new evidence suggests that, at least in copper oxide superconductors, it’s not so clear cut. Researchers observed electrons in these materials traveling in coherent pairs, a hallmark of superconductivity, at much higher temperatures than those at which the material superconducts. The observation constrains condensed matter theory, and may give clues to practical high-temperature conductors.