Here is some more info regarding this subject which may be of interest describing the ultimate precision required to do this "stuff".
"Having found its first signal, LIGO is now gearing up to transform them into routine tools for astronomy.
The twin LIGO stations each pass laser light back and forth between mirrors along perpendicular 4-kilometer-long arms arranged in an L.
An incoming wave would slightly warp these arms so that one became longer or shorter than the other by only a few thousandths the radius of a single proton, altering the flight time of the light and triggering a detection.
Any number of background noises can scuttle the delicate measurement—LIGO can also hear ocean waves pounding distant coastlines, airplanes flying overhead, and even the seismic hum from washing machines.
We’re trying to detect something smaller than the atoms our detector is built of,” says Imre Bartos, a LIGO member and lecturer at Columbia University. “It doesn't sound believable, to be honest with you.”
That LIGO can hear gravitational waves at all over the cacophony of background noise is due to both stations recently receiving a series of noise-cancelling “Advanced LIGO” upgrades that will soon make them ten times more sensitive than they were during a fruitless first-generation search that occurred between 2002 and 2010. All told, the upgrades bring the experiment’s total cost to more than $1 billion, most of it paid by the National Science Foundation. LIGO’s ultra-high-vacuum hermetic perfection, Márka quips, is “the most expensive ‘nothing’ ever made.”
