Laureate Biography
John Lewis Hall, known to many as Jan, shared half of the 2005 Nobel Prize in Physics with Theodor Hänsch for developing laser-based precision spectroscopy. (Roy Glauber received the other half of the Prize.) Hall developed techniques that enabled lasers to measure both time and distance with exquisite precision, and this was instrumental in transforming the laser from a laboratory curiosity into a fundamental tool of modern science.
Hall was born in Denver, Colorado on 21 August 1934. His father was an electrical engineer and worked on hydro-electric projects for the US Bureau of Reclamation. His mother taught at an elementary school and was also a singer.
Hall’s early interests in physics led him, as a child, to build and experiment with black-powder rockets, though as he grew older he favoured more sociable activities, including the Scouts and his church youth group.
On leaving school he received a Westinghouse Scholarship to the Carnegie Institute of Technology (now Carnegie Mellon University) to study physics, and there he completed his BS in 1956, his MS in 1958 and his PhD in 1961. He then became a National Research Council Fellow at the National Bureau of Standards (NBS, now NIST) in Washington, DC before joining a new NBS research group — the Joint Institute for Laboratory Astrophysics (or JILA) at the University of Colorado at Boulder.
Here, Hall developed Theodor Hänsch’s idea for the optical frequency comb technique – where ultra-short pulses of laser light create a set of precisely spaced frequency peaks, resembling the evenly spaced teeth of a comb. These teeth act as a kind of atomic ruler that can separate different frequencies of light (i.e. colours) emitted from atoms and molecules and measure them to an accuracy of fifteen digits. Hall’s research was essential in making the optical frequency comb technique work, and this led to its considerable practical applications, including the development of highly accurate clocks and improvements in satellite navigation systems, such as GPS.
Hall also helped to develop the methane-stabilized helium-neon laser, which was used to measure the speed of light in a vacuum at 299,792,458 metres per second — at least 100 times more accurately than any previous effort. This ultimately led to a fundamental redefinition of the metre, on the basis of the speed of light measurement, as the distance that light travels in a vacuum in 1/299,792,458 of a second.
Hall married a fellow graduate of Carnegie Mellon, Marilyn ‘Lindy’ Robinson, who taught seventh-grade English in Boulder, and they have three children. The family built their mountain cabin at Marble, Colorado themselves, and Hall takes great pride in the fact that the State inspectors could find no fault with the plumbing and wiring, all of which he installed himself.
Hall retired in 2004, having been at NIST at Boulder since 1967. However, he is still involved with JILA. He also continues to work at his consultancy company, Hall Stable Lasers and he now holds ten US patents. In 2002 he received the Max Born Award of the Optical Society of America and in 2004 he received the Légion d’Honneur, the highest award given by the French Republic.
Further reading
Nobel Prize in Physics 2005
Wikipedia: John Hall
