 Black holes are called black for a reason. It's because they don't emit any light. Almost everything that we know about the universe around us, we know because of light. But light can't always paint the full picture. You can't see everything. In 2015, for the first time ever, we detected a collision between two black holes. But we didn't see it. Instead, it was the first time that we heard the music of gravity, small ripples in the fabric of space and time, called gravitational waves. Albert Einstein predicted the existence of gravitational waves a hundred years ago. They are created whenever masses accelerate through space. Gravitational wave astronomy has opened up a new window into the universe, allowing us to detect things that we cannot see. And in the future, may help us learn about things in our universe that we don't understand very well yet. Gravitational wave observatories combine state-of-the-art technology along with the most precise measurement techniques ever developed to measure these tiny ripples in space and time. As an experimental physicist, I always want to measure things more accurately. I have created a sensor which will help improve the performance of these gravitational wave observatories. My sensor uses a set of torsion pendulums which move and respond to changes in gravity. I use lasers to accurately measure this motion down to less than the diameter of an atom. My sensor is used to characterize changes in gravity here on Earth which show up as unwanted noise in the gravitational wave observatories looking out into space. By removing the effects of these noise, these observatories become more sensitive, allowing them to see new types of events and to see further into our universe. This fundamental science actually has real-world applications as well. I've done modeling to show that my sensor can be used to measure the gravitational signals that are produced during the course of an earthquake before the ground begins to shake. This means that my sensor can be used as an early warning system for oncoming earthquakes, providing up to a couple of minutes extra warning before the arrival of seismic waves. In these extra minutes, you can switch off important and potentially dangerous infrastructure like a nuclear reactor. You can tell people to take cover or stop a high-speed train. In this way, my sensor can be used to help protect important assets and save lives. When there are things that we cannot see, we have to open our ears. We can complete our picture of the universe by listening to the music of gravity.