Sitting in his garden when an apple hit his head, it was on that fateful day for science and the world that Sir Isaac Newton came up with his theory of gravity. Over the next few centuries, science made full use of his genius, discovering the concept of gravitational pull and why the moon orbits the earth, to name a few. But even after all those years, have we truly achieved a full understanding of how gravity really works?

       Gargantuan objects like the earth and our sun each have their own gravitational pull, but why would they possess gravity in the first place? In 1915, Einstein’s theory of general relativity predicted that gravity is carried out in waves, but he had no way of proving their actual existence. However, this all changed on September 14th, 2015 when LIGO — Laser Interferometer Gravitational-Wave Observatory — detected the mergence of two black holes 1.3 billion light years away. Interestingly enough, this collision did not happen on September 14th, or on any date remotely close. Noting that the merge was 1.3 billion light years away and that gravitational waves travel at the same speed as light, we can deduce that this event actually occurred 1.3 billion years ago.


       Essentially, we’ve detected waves that date back long before the existence of dinosaurs. They are currently defined as “ripples” in the fabric of space-time, and are created by extremely disruptive events like black hole collisions or supernovas. Much like how a stone is dropped into water and creates ripples, these events release huge amounts of gravitational energy which radiate and create ripples throughout the universe. These ripples are what LIGO picked up during its September discovery, and it is the first time we have confirmed both the observation of merging black holes and the existence of gravitational waves. What’s even more fascinating is that unlike light waves, which can be refracted and affected by a myriad of different factors, gravitational waves are not affected by any of these. Therefore, they can reveal valuable, unaltered information about the event, like distance and magnitude. The nature of these waves also provides us important clues, specifically about how two black holes actually merge.

       Given that gravity is an important force in our universe, understanding things like planetary orbits and black holes, to name a few, may pave the way for a better understanding of our universe. Although time and inter-galactic travel are still far outside our reach, this discovery is at the very least an important step forward.

March 5, 2016

Author: Jerry Jiao

Editor: Wennie Wei

Sources:

“Gravitational Wave.”Wikipedia. Wikimedia Foundation, n.d. Web. 23 Feb. 2016.

“What Are Gravitational Waves?”LIGO Lab. N.p., n.d. Web. 23 Feb. 2016.

“Einstein’s Gravitational Waves ‘seen’ from Black Holes – BBC News.”BBC News. N.p., n.d. Web. 23 Feb. 2016.

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