At age 8, Horowitz achieved distinction as the world’s youngest amateur radio operator. He went on to study physics at Harvard University (B.A., 1965; M.A., 1967; Ph.D., 1970), where he has also spent all of his subsequent career. His early work was on scanning microscopy (using both protons and X-rays). Horowitz has also conducted astrophysical research on pulsars and investigations in biophysics. His interest in practical electronics has led to a handful of inventions, including an automated voting machine and an acoustic mechanism for landmine detection. Since 1974 he has taught a practical course in electronics whose lecture notes became one of the best known textbooks in the field: The Art of Electronics (coauthored with Winfield Hill).