Theoretical physicist Rolf Landauer, the German-born pioneer of the physics of information processing and computing devices, died Tuesday night at his home in Westchester County, New York, after a short illness. He was 72.
Landauer, who spent more than 40 years at IBM research labs, is perhaps best known for his theories about the physical limits of information processing, such as the minimum energy required to perform a computation. In the early 1960s, he refuted the prevailing thinking of the day--that every step in a computer's binary calculation consumes a minimum amount of energy--and replaced it with a principle now bearing his name. The Landauer principle holds that what consumes energy is not processing the information but erasing old values to make room for new ones. Disregarded for years, his ideas are now at the forefront of many experimental computing technologies. Landauer "was the prime mover" in bringing the physics of computing into the limelight, says IBM colleague Charles Bennett, an expert on quantum computing.
Landauer also left his mark on the study of electron transport in small spaces. The Landauer formulation, for instance, describes the movement of electrons in nanometer-scale conductors, which are essential to the development of nanoelectronics.
Although Landauer's musings always wandered on the verge of the feasible--and often trespassed that line--he had a sharp eye for practicality. Pessimistic about quantum computing, a field that, in large part, grew out of his theories, Landauer suggested that disclaimers be added to papers, saying, "Warning: Quantum computers are unlikely to work in the real world."