  Even if Einstein's General Relativity achieved a great success and overcame
lots of experimental tests, it also showed some shortcomings and flaws which
today advise theorists to ask if it is the definitive theory of gravity. In
this essay we show that, if advanced projects on the detection of Gravitational
Waves (GWs) will improve their sensitivity, allowing to perform a GWs
astronomy, accurate angular and frequency dependent response functions of
interferometers for GWs arising from various Theories of Gravity, i.e. General
Relativity and Extended Theories of Gravity, will be the definitive test for
General Relativity. The papers which found this essay have been the world's
most cited in the official Astroparticle Publication Review of ASPERA during
the 2007 with 13 citations.
