Gravitational waves are ripples in the fabric of space and time. They were originally predicted by Albert Einstein in 1916 and the confirmation supports Einstein’s notion that space and time are interwoven and continually shifting. The waves are ripples in the fabric of space-time generated by violent events. Here accelerating masses produce gravitational waves that propagate at the speed of light. This is part 1 of a 2 part series on gravitational waves, you can find part 2 here.
The third wave activity was detected by instruments located at the Laser Interferometer Gravitational-wave Observatory (LIGO). The first waves were detected in September 2015.
What are gravitational waves?
The way that gravitational waves are detected is through the waves passing through Earth. The waves are ‘heard’ through the use of highly-sensitive detectors. The recent detection of waves is thought to arise from the merging of two black holes to form a larger black hole.
The black holes were a long way away, some 3 billion light-years from Earth. It appears that two black holes, of different sizes, merged into a black hole larger than the smallest one but smaller than the largest one. The two original black holes had solar masses of 62 (first detection) and 21 (second detection). The newly formed black hole is coded GW170104, a single object of a little under 49 solar masses. Given how far the gravitational waves spread, the merger will have been tremendously energetic. The recent detection is the farthest yet recorded.
Commenting on the discovery, Dr. Vicky Kalogera, of Northwestern University, said in a communication to Digital Journal: “Our handful of detections so far is revealing an intriguing black hole population we did not know existed until now.”
She added: “Now we have three pairs of black holes, each pair ending their death spiral dance over millions or billions of years in some of the most powerful explosions in the universe. In astronomy, we say with three objects of the same type you have a class. We have a population, and we can do analysis.”
READ MORE: Citizen scientists help look for gravitational waves
There are two theories as to how black holes merge. One theory is that black holes twin after they sink to the center of a star cluster. The second theory is that black holes are born in the same binary system, always remaining closely aligned.
Through the gravitational wave detection, astrophysicists can measure and weigh black holes, asses their density and determine how fast they are spinning around their own axes. The new black hole appears to be heavier than any previously known.
The third detection is described in the journal Physical Review Letters. The paper is titled “GW170104: Observation of a 50-Solar-Mass Binary Black Hole Coalescence at Redshift 0.2.”
