How LIGO Works

Detector Structure

LIGO's structure is a marvel of engineering, featuring two 4 km long arms set at 90 degrees to each other, forming a half-square shape. Each arm contains a tube with a near-complete vacuum and highly reflective mirrors cooled to just above absolute zero. Gary Arndt explains that a laser is shot down these tubes, splitting at a partial mirror, and any phase changes in the light beams indicate a gravitational wave 1.

The ability to measure a change of one 1000th the diameter of a proton is what makes LIGO the most accurate measuring device ever made.

--- Gary Arndt

The observatories in Washington and Louisiana minimize outside interference, ensuring accurate detections by requiring both to observe the same event simultaneously.

   

Technological Advancements

Technological advancements have significantly enhanced LIGO's sensitivity and accuracy. Initially turned on in 2002, LIGO underwent major upgrades between 2010 and 2015, resulting in a fourfold increase in sensitivity. Gary Arndt notes that within two days of the enhanced LIGO's activation, it detected its first gravitational wave from merging black holes 1.4 billion light-years away 1.

The signal, which both observatories found, was almost a perfect fit for what was predicted from the theory of relativity.

--- Gary Arndt

Future plans include additional observatories worldwide and further improvements to LIGO, promising even more discoveries in gravitational wave astronomy.