The Detection of Gravitational Waves

Nicole Gilbert

Was Einstein right about gravitational waves?

On February 11, physicists with the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) announced that their twin detectors observed a transient gravitational-wave signal.

What are gravitational waves?

In 1916, Albert Einstein first predicted the existence of gravitational waves in his theory of general relativity. This seminal theory redefines gravity as a distortion or curvature in space-time. As he worked on his theory, Einstein realized that massive objects, like celestial bodies, can actually cause space and time, “spacetime,”  to curve. These distortions or ‘ripples’ in spacetime are known as gravitational waves and are caused by some of the most energetic processes in the Universe. Normally, objects follow the most simple path in spacetime. However, massive bodies can cause a curve in spacetime, causing the other objects to naturally be pulled towards the more massive objects. That is what we know as gravity. For the past 100 years, Einstein’s theory has yet to be proven untrue. However, there are still many questions about this theory that remain unanswered. For a very long time, we have not been able to directly detect a theoretical gravitational wave. However, physicists at LIGO have recently documented a “gravitational ringing” from the collision of two black holes, the first detection of gravitational waves.

How/when did LIGO detect them?

The gravitational waves were detected on September 14, 2015 at 5:51 a.m. Eastern Daylight Time (09:51 UTC) by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. (1)” Based on the signals detected, scientists estimate that the cosmic collision was between two black holes, one about 36 times the mass of the sun, and the other about 62 solar masses. “ The ‘loudness’ of the recorded signal also provides a rough measure of when the merger occurred: between 600 million and 1.8 billion years ago. (2)”

What does this mean for science?

A discovery supporting Einstein’s Theory of General Relativity is “making robust theories even stronger. We can now sample the spacetime ripples generated by some of the most energetic events that occur in the universe and, perhaps, use gravitational waves to reveal new physics and discover new astrophysical phenomena.” (3) Not only does this discovery strengthen our knowledge on gravitational waves and how to detect them, the detection is arguably the most direct evidence of the existence of black holes. World renowned physicist and cosmologist, Prof. Stephen Hawking mentions,  “apart from testing general relativity, we could hope to see black holes throughout the history of the universe. We may even see relics of the very early universe during the Big Bang at the most extreme energies possible.”  Mansi Kasliwal, an astronomer at Caltech, adds,“It’s the very real dawn of a new era,”  (1)

 

  An Image Describing LIGO’s Wave Detector, courtesy of nature.com

Want to learn more? Check out these links:

http://www.nature.com/news/the-hundred-year-quest-for-gravitational-waves-in-pictures-1.19340

https://www.newscientist.com/round-up/instant-expert-general-relativity/

http://www.seeker.com/100-years-of-general-relativity-thought-and-action-1770516858.html#news.discovery.com

 

References:

http://www.ncbi.nlm.nih.gov/pubmed/26918975?dopt=Abstract&holding=npg  (1) http://www.nature.com/news/einstein-s-gravitational-waves-found-at-last-1.19361 (2) htttp://news.discovery.com/space/weve-detected-gravitationalwaves-so-what-160213.htm (3)

Leave your thought