Gravitational Waves: Why are They Such a Big Deal?

Fagjun | Published 2017-10-20 23:33

There’s been quite a bit of buzz around gravitational waves lately. However, many of us may not get the hype since we don’t know what these things even are. Thus, here are the basics of gravitational waves to catch all of us up.


What are gravitational waves?



Rau Weiss, Kip Thorne, and Barry Barish, the founders of the Laser Interferometer Gravitational-Wave Observatory (LIGO) Laboratory, won the 2017 Nobel Peace Prize for their work on detecting gravitational waves. Scientists have been trying to detect this phenomena for decades, and the technology to make this possible eventually improved over time. There are now four confirmed detections of gravitational waves.

Ripples in the Pond, Ripples in Space-Time

Perhaps koi fish can help us understand what gravitational waves are.



Albert Einstein was the first to suggest the existence of gravitational waves way back in 1916. According to him, this phenomena may be the natural consequence of the general theory of relativity. This theory states that objects with very high mass distort the fabric of space-time. This is something that we experience as gravity. When massive objects move toward one another, they cause wrinkles in space-time.


Imagine two koi fish circling each other near the surface of a pond. Their movements send ripples spreading throughout the surface of the water. Now, imagine those ripples moving at the speed of light. That’s what the distortions in space-time are like. These are gravitational waves.


An illustration of binary neutron stars causing gravitational waves. [Image by NASA]



Einstein himself wasn’t entirely convinced by his own theory, and even refuted his own findings in later papers. However, other scientists saw the merit in the possibility of gravitational fields, and more recently, Einstein was proven right all along.


If these waves did exist, however, why were they so hard to detect? Let’s get back to the koi pond. When ripples appear on the surface of the water, they grow smaller as they go farther away from their source, until they eventually disappear. Something similar happens to gravitational waves from a faraway source as well. When the gravitational waves get closer to us but farther away from their source, they distort space-time by only a small amount. In fact, by the time the distortion reaches us, it’s many times smaller than a miniscule proton. Most instruments haven’t been able to pick up on distortions that small.

Expanding the Observable Universe

What will gravitational waves allow us to discover about the universe?



In 2015, however, the LIGO team was able to directly observe gravitational waves. This feat came a century after Einstein first postulated the existence of gravitational waves.


But, you may be asking, if you take this history out of the equation, what else is so special about gravitational waves?


Because of the first direct observation of gravitational waves, we now have a new perspective from which to view the universe. For example, we can now observe phenomena that would otherwise go undetected because they emit little to no light, like the collision of black holes. LIGO’s Rau Weiss says that the detection of gravitational waves can open up a new science, since they can enable us to observe phenomena that we may simply know of but haven’t really observed--phenomena much like gravitational waves themselves.

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