Gravitational waves astronomy: the ultimate test for Einstein's General Relativity

It is well known that Einstein's General Relativity (GR) achieved a great success and overcame lots of experimental tests. On the other hand, GR also showed some shortcomings and flaws which today advise theorists to ask if it is the definitive theory of gravity. In this review we show that, if advanced projects on the detection of Gravitational Waves (GWs) will improve their sensitivity, allowing to perform a GWs astronomy, understanding if Einstein's GR is the correct and definitive theory of gravity will be possible. For this goal, accurate angular and frequency dependent response functions of interferometers for GWs arising from various Theories of Gravity, i.e. GR and Extended Theories of Gravity will have to be used. This review is founded on the Essay which won an Honorable Mention at the the 2009 Gravity Research Foundation Awards.