Precision Measuring Wins Pair a Share of Nobel Physics Prize

Measuring a meter precisely and keeping time to 15 digits' accuracy are just some of the contributions to science from the winners of the 2005 Nobel prize for physics, announced in Sweden yesterday.

Roy Glauber, a professor of physics at Harvard University in the US was awarded one half of the award for his theoretical description of the behavior of light particles. The other half is shared between John Hall, a physicist at the University of Colorado and National Institute of Standards and Technology at Boulder, in the US, and Theodor Hänsch, a physicist at the Max-Plank institute of quantum optics in Munich, Germany, for contributions to laser-based precision spectroscopy.

Professor Glauber will receive half the 10m Swedish kronor (£730,000) prize money, while professors Hall and Hänsch will receive a quarter each. Prof Glauber is credited with applying quantum mechanics, or particle science, to the interactions between light and matter. In 1963 he developed a method to describe the behavior of photons by observing the disturbance of electrons in the light-detecting material. This gave birth to the field of quantum optics, which has enabled physicists to quantify the differences between thermal light sources, such as a light bulb, and coherent light sources, such as a laser beam.

Profs Hall and Hänsch receive their half of the prize for research into the use of lasers for precise measurements. Five years ago they developed the optical frequency comb, which uses light interference to generate laser pulses that can be used to measure unknown frequencies. Measuring frequencies to 15 digits has been used to develop extremely accurate clocks and GPS technology.