These waves can change our understanding of the Universe

 The Gravitational Waves

Gravitational waves are 'ripples' in space-time caused by some of the most violent and energetic processes in the Universe. Albert Einstein predicted the existence of these waves in 1916 in his general theory of relativity. Einstein's mathematics showed that massive accelerating objects (such as neutron stars or black holes orbiting each other) would disrupt space-time in such a way that 'waves' of undulating space-time would propagate in all directions away from the source. Gravitational waves are invisible but incredibly fast. These cosmic ripples would travel at the speed of light, carrying with them information about their origins, as well as clues to the nature of gravity itself. They squeeze and stretch anything in their path as they pass by. The strongest gravitational waves are produced by catastrophic events such as:

• When a star explodes asymmetrically (supernova)
• When two big stars or neutron stars orbit each other 
• When two black holes orbit each other and merge

Other waves are predicted to be caused by the rotation of neutron stars that are not perfect spheres, and possibly even the remnants of gravitational radiation created by the Big Bang. Though Einstein predicted the existence of gravitational waves in 1916, the first proof of their existence didn't arrive until 1974, 20 years after his death. In that year, two astronomers discovered a binary pulsar that was likely emitting gravitational waves. They researched the pulsar for 8 years are finally confirmed the existence of gravitational waves. Since then, many astronomers have studied pulsar radio emissions (pulsars and neutron stars emit beams of radio waves) and found similar effects, further confirming the existence of gravitational waves. But these confirmations had always come indirectly or mathematically and not through direct contact. The objects that create gravitational waves are far away. And sometimes, these events only cause small, weak gravitational waves. The waves are then very fragile by the time they reach Earth. This makes gravitational waves hard to detect. 

All this changed on September 14, 2015, when LIGO (Laser Interferometer Gravitational-wave Observatory) physically sensed the undulations in space-time caused by gravitational waves. But where did these waves come from? What is the magnitude of these waves? And why are they so important to us? In 2015, LIGO detected the first gravitational waves from a black hole merger that was 1.3 billion light-years away. This also means that the merger actually took place 1.3 billion years ago and the waves traveling at the speed of light reached is in 2015. As these waves pass by anything, they will stretch and compress it. So our Earth is constantly being stretched and compressed by these waves. But this stretching and compressing is extremely small. How small you ask? It is equivalent to the 1000th power of the diameter of a proton. And this is what we detected using state-of-the-art scientific equipment. Detecting these waves is a very challenging task.

The LIGO facility consists of two identical L-shaped detectors in Washington state and Louisiana, each of which employs lasers and mirrors to measure the tiny changes in space-time made by passing gravitational radiation. The goal is to record the change in distance between mirrors parked at each end of two perpendicular, 4-kilometer long tunnel arms. A laser bouncing back and forth between the mirrors keeps track of how apart they are to an almost impossibly precise degree. Crucially, the detectors are sensitive to things such as passing trucks, lightning strikes, ocean waves, and earthquakes. For a signal to be real, it should show up in both detectors. There is one more detector, similar to LIGO, in Europe. Having detectors all over the world will further help to precisely identify the region of the sky where gravitational waves' source is located. Soon, similar experiments are anticipated to come in Japan and India.

Since LIGO's first detection, we've gained insight into the cosmos. That's because gravitational waves are a new way of 'seeing' what happens in space. We can now detect events that would otherwise leave little to no observable light, like black hole collisions. And with this latest detection, astronomers were able to combine gravitational waves with more traditional ways of seeing the universe, helping to untangle mysteries about the dense, dead objects known as neutron stars.