Einstein and the Quantum Revolutions

Nobel Prize–winning physicist Aspect (coeditor of Bose-Einstein Condensates and Atom Lasers) offers a brisk if occasionally superficial overview of how Albert Einstein set off two 20th-century upheavals in physics. In 1909, Einstein resolved scientific debate over the nature of light by proposing it “was both a particle and a wave,” Aspect explains, noting that the discovery underpinned the development of computers and “lasers that enable the processing and transmission of information” through optical fibers. The second revolution followed Einstein’s 1935 postulation that, according to quantum mechanics, there are circumstances under which two subatomic particles can be “entangled” and act on each other regardless of the distance separating them. Aspect recounts how this idea remained the purview of abstract philosophical inquiry until the 1970s, when he and other physicists began developing techniques to work with entangled photons and paved the way for research that promises to produce quantum computers capable of performing calculations in a fraction of the time current computers require. Aspect does a solid job of covering how Einstein’s innovations have changed the world, but he sometimes relies on assertions rather than explanations to make his point. For instance, he contends that quantum cryptography will enhance internet security, but it’s not clear why or how. This intrigues, but only intermittently enlightens. (Oct.)