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Judah Levine

Judah Levine was born and raised in New York City. Since most of his relatives were rabbis, his mother and her family really wanted him to be a rabbi, too. To prepare for this career, he played around with batteries and light bulbs as well as his erector and chemistry sets. “I discovered I had a natural aptitude for playing around,” Levine recalls.

Because of his family’s influence, Levine enrolled in the pre-rabbinical program at Yeshiva College in New York. Although he didn’t yet know what it meant to be a scientist at that time, Levine decided to major in physics. He then pursued graduate studies in physics at New York University, earning a M. S. in 1964 and a Ph. D. in 1966.

The first of Levine’s two postdocs (1966–1967) was under the direction of Pat Sandars and Kem Woodgate at the Clarendon Laboratory at Oxford. At Oxford, Levine used an atomic beam of metastable xenon to investigate whether the electron might have a permanent dipole moment. “I worked on one of the ancient ancestors of Eric Cornell’s dipole moment experiment now underway at JILA,” Levine recalls. He noted that his research included a parity test experiment, which was very different from what Cornell is trying to do now. (To find out about Cornell’s research, see the research highlight Running Backwards.)

The effect Levine and his colleagues were looking for was much too small to be detected with the technology of that era. The researchers tried to compensate with a complex data-acquisition strategy implemented on the largest computer of the day: a full rack-sized PDP-8 with 4,000 words of memory. The machine had no higher-level languages. This was a major step up from the computer Levine had built as a graduate student, which had 400 words of real core memory and was programmed with a soldering iron.

Levine’s second postdoc (1967–1969) was under Jan Hall at JILA. He worked on some of JILA’s first photoelectron detachment experiments in what would become one of Carl Lineberger’s first laboratories at JILA.

Upon completion of his JILA postdoc, Levine was hired by the National Bureau of Standards (NBS) in Boulder to be part of a team to measure the speed of light to facilitate the redefinition of the meter in terms of the standard of frequency. Although he was rostered in the Radio Standards Physics division and not in the NBS division responsible for laboratory astrophysics (JILA’s mission in those days), Levine was to remain at JILA “temporarily” until the speed-of-light project was completed. In his case, temporary has come to mean 40+ years.

After shuttling back and forth between NBS and JILA as part of a team to measure the speed of light, Levine eventually inherited an interferometer that had been built by Jan Hall, Peter Bender, and John Ward to measure the wavelength of light inside the Poorman Mine, just west of Boulder. The interferometer became available when the wavelength measurement was made in JILA by Jan Hall and Richard Barger with one of Hall’s stable lasers.

As a result of getting the interferometer, Levine decided to “go into the geophysics business.” He spent the next 10 years building instruments in eastern Colorado, southern California, and Yellowstone National Park to measure Earth movements, especially in the seismically active zone of Southern California and in the tectonically active area of Yellowstone National Park. Because no one else at NBS was doing geophysics at the time, Levine stayed at JILA. He worked with colleagues in the University of Colorado’s physics department and the Cooperative Institute for Research in Environmental Sciences (CIRES).

To maintain his membership in the “crazy experiments club,” in 1972, Levine and his student Robin Tucker Stebbins tried to use the Poorman Mine interferometer to detect the gravitational radiation from the Crab pulsar. This effect was also far too small to be detected with the technology of the 1970s.

Soon afterward, the Radio Standards Physics division was dissolved. Levine was transferred to the Time and Frequency Division, where he was when NBS changed its name to the National Institute of Standards and Technology (NIST) about 10 years later. Levine soon discovered that many of the technologies he had developed for geophysics (such as computers and software for real-time data acquisition and control) were quite useful for atomic clocks and time transfer.

In the early 1980s, Levine began a project to distribute digital time signals using telephone lines and the Internet that started out small, but soon was growing rapidly. Today, after more than three decades of looking after the nation’s time, Levine has earned the titles of “Time Lord” and the “Nation’s Timekeeper.” As the nation’s timekeeper, his job is to keep and disseminate civilian time and frequency through a computer system that he developed and has maintained for nearly 20 years. His Internet Time Service is now accessed more than 30 billion times each day (348,000 times per second) and is incorporated into all major computer operating systems. The number of requests has increased at a rate of 5% per month compounded for many years. The accurate time and frequency Levine disseminates is vital for synchronizing telecommunications networks, controlling electric power grids, making modern navigation systems work, and providing time stamps for electronic financial transactions. He has supported the exponentially increasing demand for digital time services with increasingly sophisticated software for both the servers and the users. 

Many of these critical functions require timing accuracy to the level of one millionth to one billionth of a second. These functions also rely on NIST’s time scale, which is one of the most accurate in the world, thanks to Levine. One of his first initiatives in the 1970s was to create a better time scale, which now includes 9 atomic clocks in Boulder and 5 at the NIST radio station in Fort Collins, a complex measurement system, and calibration by the NIST-F1 atomic clock, which neither gains nor loses more than one second in 80 million years. Levine now disseminates atomic-clock time over the Internet Time Service from his fourth floor office at JILA. The systems in JILA are also used to monitor time servers at 20 other remote locations. 

Levine received two Department of Commerce Gold Medals (in 1983 and 2007), the Allen V. Astin Measurement Science Award in 1998, a 2009 Time Lord Award, and a 2011 Presidential Rank Award for his support of the nation's time services. In 2013, Levine was awarded the IEEE Ultrasonics, Ferroelectrics, and Frequency Control Society Rabi Award for his outstanding contributions to the field of precise time keeping and time transfer, including pioneering research and development of time transfer, network time services, and the design of better time scales. His award also cited clear tutorial writings that have made these advances open to the world community.

Levine is married to editor and publications consultant Alice Levine, who worked in the late 1960s with NIST Precision Measurement Laboratory Director Katharine Gebbie to publish conference proceedings in camera-ready format. She also edited books written by several JILA Fellows.