Picture a trampoline with a basketball on it. If you stand in the middle of it, the ball rolls towards you – that’s gravity. If you jump up and down, or move side to side, the trampoline stretches or shrinks, and the ball will bounce around a bit. Little ripples in the trampoline will spread out from where you land.
Einstein theorized that when two really fast-moving heavy objects get close to each other, the ‘dents’ they put in the trampoline of space (like in the picture) stretch and shrink the trampoline, creating ripples. These ripples should spread out in space, so we can detect them.
But because we’re so far away from everything else in space, it takes extremely sensitive equipment to detect irregularities consistent with what we think gravitational waves look like. Two receptors with a laser in between them measure how long it takes for light to travel a small distance. If a gravity wave passes through the equipment, the sensors would detect an irregularity, which we now believe to be the result of a gravity waves – like two buoys in the ocean.
You’re probably wondering: “who cares?” Well, not many people. But I think more people should. In 1918, Einstein’s general theory of relativity revolutionized our understanding of gravity and in part predicted the existence of gravity waves. As of 2015, gravity waves remained the final unconfirmed component of general relativity. Now, we have concrete evidence of every component of general relativity. With this new information we have gained further insight into the workings and beginning of our universe.