The discovery of the gravitational waves have tremendous incept on the scientific community. Not only a confirmation of the creation of black hole, but also give the humanity's ability to observe the universe in a totally new way. So great the impact has on the scientific field that gravitational waves have the potential to show scientists totally new features of cosmic objects.
First of all, To split a beam of laser light LIGO team uses a special mirror and the beams was sent down to two 4-kilometer-long arms, at a 90 degree angle to each other. The normal situation of this designed experiment suppose to be the light waves interfere distractively to cancel out each other. However, as far as LIGO team dectected, as the same tiem as the gravatational wave squeezing the others, it also straches at the same time, altering the distance the two beams travel relative to each other