Paul Horowitz

Lore & Background

Horowitz studied physics at Harvard University, where he spent his entire subsequent career. His early research included scanning microscopy using protons and X-rays, as well as astrophysical work on pulsars and investigations in biophysics. His interest in practical electronics led to inventions such as an automated voting machine, an acoustic mechanism for landmine detection, and an electronic Morse Code/Baudot code keyboard using a diode matrix and 66 TTL integrated circuits for amateur radio use. Since 1974 he has taught a practical electronics course whose lecture notes became the textbook The Art of Electronics.

Horowitz was one of the pioneers of the search for intelligent life beyond Earth and a leader behind SETI. This work attracted both admiration and criticism. Harvard biologist Ernst Mayr sharply criticized Horowitz for wasting university resources and graduate student efforts on SETI. Carl Sagan provided a strong rebuttal to Mayr's criticism, noting that many eminent biologists and biochemists had endorsed SETI. Sagan is believed to have based the main character in his novel Contact partly on Horowitz.

Horowitz led the META and BETA SETI projects. During project META, Horowitz and Sagan reported the detection of 37 signals that survived all cuts and could not be positively identified. On September 10, 1988, the university's 84-foot radio dish detected an enormous spike 750 times noise; converted to audio it would sound like a tone, like a flute. All 37 signals were single events never heard again. The software company 37signals was named after these signals.

Reader's Guide

Horowitz's significance lies in his dual contributions to practical electronics education and to the search for extraterrestrial intelligence. His textbook The Art of Electronics, derived from his Harvard course, became one of the best-known references in the field, shaping how generations of engineers and hobbyists learn circuit design. His inventions, including an automated voting machine and a landmine detection mechanism, reflect a commitment to applying electronics to real-world problems. In SETI, Horowitz was a pioneer, leading the META and BETA projects that scanned the skies for artificial signals. The detection of 37 unexplained signals, including a dramatic spike 750 times background noise, remains a notable episode in the history of SETI, though none were ever repeated. The naming of the software company 37signals after these signals underscores their cultural resonance. Horowitz's work also placed him at the center of a scientific debate: Ernst Mayr's criticism of SETI as a waste of resources was countered by Carl Sagan's defense, highlighting the contentious nature of the field. Horowitz's career, spanning physics, engineering, and astrophysics, and his role in the JASON Defense Advisory Group, mark him as a figure who bridged academic research, practical invention, and speculative science.

Did You Know?

• At age 8, Horowitz became the world's youngest amateur radio operator.
• He coauthored The Art of Electronics, one of the best-known electronics textbooks.
• He led the META and BETA SETI projects, which detected 37 unexplained signals.
• The software company 37signals was named after those 37 signals.