Billions of years ago, two black holes collided, releasing a massive amount of energy.
The power of that collision caused a massive energy wave to ripple through space and time until in 2015, it was captured by detectors at the Laser Interferometer Gravitational-Waves Observatory (LIGO) here on Earth.
The observatory, consisting of thousands of researchers from twenty countries, had successfully observed what are considered gravitational waves. For their discovery, the leaders of LIGO (Rainer Weiss, Kip Thorne, and Barry Barish) received the Nobel Prize in Physics in October 2017.
What Are Gravitational Waves?
We know gravity as the force of attraction between two objects. Gravity is what pulls us down to the Earth, and the lack of gravity allows astronauts to float in space. Gravity is what keeps the Moon orbiting around the Earth, the Earth around the Sun and so on. The more mass an object has, the stronger its gravitational pull.
Albert Einstein, in his theory of relativity, imagines gravity as an object making a depression or dent on the “surface” of space-time. To help understand this better, imagine space-time as a rubber sheet stretched at its four corners. Dropping a heavy bowling ball in the middle of this sheet will cause a depression to form. If you place a smaller ball near the larger one, it will fall into the depression. Einstein compared this to the larger ball attracting the smaller one.
As objects move along space-time or collide with others because of gravitational pull, the movement causes ripples through space. These ripples spread out just like ripples in pond do when you drop a stone in. These waves, known as gravitational waves, travel outwards at the speed of light. As they travel, they stretch and squeeze objects along their path, losing energy and becoming smaller as they do so.
What Gravitational Waves Tell Us
Gravitational waves are too small to be felt by humans, and it takes special observatories like LIGO, to detect them. LIGO detectors, installed in Hanford, Washington and Livingston, Louisiana capture the ripples in space-time using finely tuned mirrors and light beams.
Gravitational waves that travel over large distances can only be produced by a supernova (explosions of stars) or a collision of massive black holes. The 2015 signals were created by the collision of black holes around 1.3 billion years ago. The information collected from this and many other similar collisions can help scientists determine an object’s orbit, an object’s mass, and dark matter in general.
The detection of gravitational waves may just tell us a lot more about our solar system and possibly, the Big Bang theory itself. Our solar system was born through a supernova explosion, and slowly gravity pulled several masses of gas and dust together to form the planets and their orbits around a nearby star, our Sun. Gravitational waves may help us figure out where and why the objects formed in our solar system.