By Patricia Daukantas

2008 is shaping up to be a really long year – especially with the addition of a “leap second” to the last day of the year, as announced by the U.S. Naval Observatory (USNO) in Washington, D.C. But how do the world’s timekeepers know that our calendars, already tweaked by a leap day every four years, need such a small adjustment?

As it turns out, the Naval Observatory and its colleagues in the international scientific community increasingly rely on optical technology to distinguish between the time based on the rotation of the Earth and the time based on the atomic standard. (After all, the second is defined as exactly 9,192,631,770 times the period of a certain hyperfine transition of the cesium-133 atom.) The leap second will keep the two kinds of time synchronized.

USNO is responsible for monitoring the variations in Earth’s rotation. Its time scale is governed by a combination of 52 atomic clocks – 16 hydrogen masers and 36 cesium clocks. The observatory’s Time Service, a member of the International Earth Rotation and Reference Systems Service, has provided data on past leap seconds, ongoing variability of the Earth's rotation and other cool facts about time measurement.

The observatory has been working on cesium fountain clocks and rubidium fountain clocks and recently dedicated a new Master Clock Facility building for its present and future time technology.

2008-12 December, Applied optics, Lasers, Miscellaneous Optics atomic clock, lasers, timekeeping

By Patricia Daukantas

OSA Honorary Member Steven Chu, director of the Lawrence Berkeley National Laboratory in California, is President-elect Barack Obama’s choice to lead the U.S. Department of Energy.

Democratic officials announced Obama’s environmental team to the media last night, according to the Washington Post, the New York Times and CNN.

Chu, Claude Cohen-Tannoudji and William D. Phillips shared the 1997 Nobel Prize in physics for their work in laser cooling and trapping atoms. OSA named Chu a Fellow in 1991 and an Honorary Member in 2003. In 1994, he received OSA’s William F. Meggers Award for outstanding work in spectroscopy.

At Frontiers in Optics 2006, OSA’s 90^th annual meeting, Chu gave a plenary talk devoted to energy efficiency and the search for alternative fuels, including solar energy.

2008-12 December, Energy, OSA steven chu, fio, osa, energy, energy policy