Hunt for gravitational waves to resume after massive upgrade

Each of LIGO’s detectors is designed to measure the deformation of space-time by comparing changes in the paths of laser beams that race down its two perpendicular 4-kilometre-long arms, bounce between mirrors and interfere with each other back at their source (see ‘To catch a wave’). When a gravitational wave passes through, it slightly alters the lengths of the arms, and the observatory can spot such changes with a sensitivity of one part in 1022.That is comparable to a hair’s-width change in the distance from the Sun to Alpha Centauri, its nearest star, says Laura Cadonati, a physicist at the Georgia Institute of Technology in Atlanta who will be coordinating the experiment’s data analysis. Read full story here.