el with MIT, Glasgow, and Garching. Caltech then brought Drever on board in 1979 to lead the new experimental effort, because, as Thorne says, they knew his inventiveness would prove crucial to LIGO's success. Soon thereafter, in 1980, Caltech hired a young Chicago astrophysicist, Whitcomb, to assist in the leadership.
"What a pleasure it was to have this brilliant, budding experimental group working alongside my theory group at Caltech," says Thorne. "Those were heady days."
Together, Drever and Whitcomb led the design and construction of a 40-meter interferometer at Caltech—a prototype to test and perfect the ideas of Weiss, Drever, and others, including the teams at Glasgow and Garching.
Meanwhile, Thorne and his theory students—in collaboration with the late Vladimir Braginsky of Moscow State University, a regular Caltech visitor over three decades—were analyzing various sources of noise that the big interferometers would face, especially "quantum noise," or random fluctuations of the mirrors' positions predicted by quantum theory. They were coming up with ways to deal with those fluctuations.
In 1984, all of this parallel work came together. Caltech and MIT, with encouragement from the NSF, formed a collaboration to design and build LIGO. Rochus E. (Robbie) Vogt, Caltech's R. Stanton Avery Distinguished Service Professor and Professor of Physics, Emeritus, was recruited in 1987 as LIGO's first director. Vogt led the merging of the Caltech and MIT experimental groups; the early planning for LIGO; the writing of a proposal to NSF to fund the project; and the education of Congress about this high-risk project with a potentially exceedingly high payoff. In 1992, Congress allocated the first major funding. "NSF and Congress have backed LIGO unwaveringly ever since," says Thorne.
Scaling up LIGO
Building LIGO was a tremendous challenge—logistically and technically. To meet this challenge, Caltech and MIT later recruited, as LIGO's second director, Barry Barish, who at that time had been the leader of several very large high-energy physics projects. Barish developed the first high-energy neutrino beam experiment at Fermilab near Chicago and was one of the leaders of a large international collaboration that performed a search for magnetic monopoles—magnetic analogs of single electric charges that, if found, would help confirm the Grand Unified Theory that seeks to unify the electromagnetic, weak, and strong forces. The experiment, called MACRO (Monopole, Astrophysics and Cosmic Ray Observatory), did not find magnetic monopoles but set the most stringent limits on their existence. Barish then led the design of one of the two detectors planned for another big science project, the Superconducting Super Collider—a particle accelerator to be built in Waxahachie, Texas. The accelerator was canceled during construction in 1993, after which Barish took on the challenge of LIGO, becoming its principal investigator in 1994, and then its director in 1997.
"I always wanted to be an experimental physicist and was attracted to the idea of using continuing advances in technology to carry out fundamental science experiments that could not be done otherwise," says Barish. "LIGO is a prime example of what couldn't be done before. Although it was a very large-scale project, the challenges were very different from the way we build a bridge or carry out other large engineering projects. For LIGO, the challenge was and is how to develop and design advanced instrumentation on a large scale, even as the project evolves."
"Barish, in my opinion, is the most brilliant leader of large science projects that physics has ever seen," says Thorne.
Barish ushered LIGO through its final design stages and secured funding through NSF's National Science Board. He oversaw construction of the two LIGO facilities from 1994 to 1999, and then the installation and commissioning of the initial LIGO interferometers from 1999 to 2005. The scaling up from Caltech's 40-meter prototype to LIGO's 4-kilometer interferometers was such a huge undertaking that it was carried o