After publishing the theory of general relativity, Einstein predicted the existence of waves that would create ripples in the curvature of spacetime. Last February, the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration announced the detection of gravitational waves. Spacetime isn’t just a void, but a four dimensional fabric that gets pushed and pulled. Just as a bowling ball on a trampoline bends the canvas, a large object in the universe will bend spacetime. When that object is accelerated, ripples occur. Gravitational waves themselves, although they likely occur frequently, are difficult to detect. Potential sources of detectable waves include binary systems of white dwarfs, neutron stars, and black holes. The first detection in February came from the collision of two black holes. Even with this immense collision, LIGO only detected a minuscule signal indicative of the gravitational waves.

"If you ask me whether there are gravitational waves or not, I must answer that I do not know. But it is a highly interesting problem."


A Second Detection

Now, the same team has published a second gravitational wave observation. Once again, the signal originates from a black hole merger. Each of the black holes weighed about ten times more than the Sun, and collided over a billion light years away. By using two detectors placed at a great distance apart, a technique known as interferometry, researchers can measure the delay in induced motion indicative of a gravitational wave. Despite the emitted energy being enough to destroy the Sun, the LIGO detectors found a shift of less than .01% the size of an atom’s nucleus.

Moving Forward

With a second detection, the hope is now that more detections of gravitational waves will me made in an attempt to better understand their nature, helping to verify Einstein’s theory of relativity, or identify where it goes amiss. This is especially true as technological enhancements to the LIGO detectors are bringing increased sensitivity to observations. By understanding gravitational waves, we can peel off another layer in the attempt to understand the structure of our universe, paving the way towards the creation of a Theory of Everything.