Physicist here.  You&#x27;re off base.<p>a) Saying &quot;gravitational waves don&#x27;t shake the mirrors, it&#x27;s length contraction&quot; is as confused as saying &quot;the Sun doesn&#x27;t pull on the Earth, it bends spacetime around it&quot;.  In each case, you&#x27;re describing the same mechanism with different words.  The whole point of the equivalence principle is that gravitational forces are equivalent to changing the local inertial frame.  Ultimately, the Einstein field equations are what they are, but both types of description in words are correct (and inexact).<p>b) Virgo and GEO600 didn&#x27;t detect gravitational waves. LIGO did.