> At its most sensitive state, LIGO will be able to detect a change in distance between its mirrors 1/10,000th the width of a proton! This is equivalent to measuring the distance to the nearest star (some 4.2 light years away) to an accuracy smaller than the width of a human hair.
A nitpick: You are greatly underestimating the precision in gravitational-wave astronomy.
ASML's atomic scale corrections are approximately one billion times larger than the fraction-of-a-proton's width displacements measured by LIGO.
From https://www.ligo.caltech.edu/page/facts:
> At its most sensitive state, LIGO will be able to detect a change in distance between its mirrors 1/10,000th the width of a proton! This is equivalent to measuring the distance to the nearest star (some 4.2 light years away) to an accuracy smaller than the width of a human hair.