LIGO: Their Discovery & Why it Matters

What is LIGO?

LIGO stands for Laser Interferometer Gravitational-wave Observatory. In English, this project measures and captures the movement of gravitational waves: ripples in the fabric of space-time first theorized by Albert Einstein in his theory of relativity. The scientists behind the LIGO project discovered a gravitational wave signal on September 15, 2015.

Scientists believe these ripples were from two colliding black holes approximately 1.3 billion years ago. These ripples come from huge objects colliding into each other, for example, two black holes using their gravity to propel themselves into each other. You can  watch this video which shows an animation of what the collision could look like.  To learn more about black holes, I suggest checking out Kip Thorne’s Black Holes: The Most Luminous Objects in the Universe, But No Light! For the most part, it is an easy read and Thorne does a proficient job to put it in terms that make sense to ordinary people, such as myself,  who don’t know that much about astrophysics.

LIGOObservatory
Picture of LIGO Observatory. Photo credit: http://www.phys.org

Why Does LIGO Matter?

This is not the first detection of gravitational waves; scientists have been able to study them indirectly, but this validates Einstein’s theory of relatively, which is the exciting part. The importance of this information allows scientists to observe the universe in a different way, hopefully leading to more discoveries.

Cool Video: You can check out this video to see what a gravitational wave sounds like. Note, this is not the actual sound, gravitational waves are not a form of sound. Like sound waves, gravitational waves carry vibrations making it possible for us to alter it into an audible sound.

LIGONasas
Picture of rippled gravitational waves. Photo credit: http://www.nasa.gov

How Does LIGO Work?

LIGO works like this: a laser beam is split down two 2.5 mile arm-like containers which have mirrors. This reflection off of the mirror converges at a point of the arm, which cancels each other out. When a gravitational wave passes through this laser beam, it alters the length of the arm and causes the beams to travel different distances. Scientists use light detectors to measure this process. The observatories in Washington and Louisiana collaborate simultaneously as they collect the data which allows them to triangulate the gravitational wave’s source in the sky. I’ve had to re-read the explanations several times to try and grasp the idea; the visualization below helps.

LIGOgraphic
Credit to http://www.ligo.org

References:

http://space.mit.edu/LIGO/more.html
https://www.ligo.caltech.edu/page/what-are-gw
https://www.space.com/33199-why-are-gravitational-waves-important.html
http://www.euronews.com/2017/10/03/why-gravitational-waves-are-key-for-physics
https://www.space.com/25445-how-ligo-lasers-hunt-gravitational-waves-infographic.html

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