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  • Remember when the discovery of gravitational waves was first officially announced back in 2016

  • and we were all like, “wow that's wild, I wonder if we'll see more?”

  • Well since then, we have spotted a handful more, but recently our cup runneth over.

  • The latest news from the gravitational wave detectors LIGO and Virgo confirms that the trio of instruments spotted another

  • 39 gravitational wave signals in just the first half of their third observing run,

  • and some of those signals are giving us new insights into black holes.

  • Colliding neutron stars and colliding black holes produce some of the strongest gravitational waves.

  • As they spin around each other the massive objects generate ripples in spacetime that spread across the universe at the speed of light.

  • These ripples carry information about how they were made and offer insights into the nature of gravity itself,

  • but they're not easy to detect. Well, not from far away at least.

  • Near the merging black holes or neutron stars the waves can be very intense,

  • but by the time they reach Earth they are thousands of billions of times smaller.

  • The amount the waves cause space-time to wobble can be one thousand times smaller than the nucleus of an atom.

  • That's where interferometers like LIGO and Virgo come in.

  • Using orthogonal laser beams that bounce off mirrors at the end of multi-kilometer long tunnels,

  • the two detectors in the United States that make up LIGO and their collaborator Virgo in Italy,

  • can pick up that extremely minute wibbly-wobbly of spacetime.

  • During their first two observing runs, the observatories had tallied a total of 11 gravitational wave events.

  • Not too shabby.

  • But before observing run number 3, the detectors underwent several improvements, like getting more powerful lasers and better mirrors.

  • They even addedquantum squeezing devices,” which sound like a made up supervillain invention but I promise they're real.

  • They manipulate the quantum fluctuations in the vacuum in which the instruments operate.

  • If left unsqueezed, these fluctuations can reduce the sensitivity of the detectors by changing the properties of individual photons

  • and affecting their measured travel time.

  • With the upgrades complete, the third observing run began on April 1st, 2019 and the first half concluded October first that same year.

  • Thanks to the buffed detectors and improved algorithms that analyzed the data,

  • a whopping 39 more gravitational wave events were identified, bringing the total to 50.

  • Thanks to the large number of detected signals, we're getting some new insights into black holes and neutron stars.

  • We've learned that large black holes can spin rapidly,

  • which eliminates some theories on how they could form.

  • The 39 signals include the second-ever observation of two merging neutron stars,

  • which not only send out gravitational waves when they collide but also light that can be detected by telescopes.

  • Another signal is the first ever candidate for a merger of a neutron star and a black hole.

  • One particular black hole collision offers an exciting glimpse at a kind of black hole that seemed to be missing from the universe.

  • On May 21, 2019, LIGO and Virgo detected gravitational waves generated by two huge black holes,

  • one at around 66 solar masses and the other at a gigantic 85 solar masses.

  • They combined to form a black hole with a mass around 142 times that of our Sun,

  • making it the first ever directly observed intermediate black hole.

  • It exists in the size range between stellar mass black holes that form when stars collapse

  • and the supermassive black holes found at the center of galaxies.

  • Even the existence of the 85 solar mass black hole is interesting,

  • because scientists think there should be a gap in the spectrum of black holes between 65 and 120 solar masses.

  • A phenomenon called pair-instability should prevent stars from collapsing and forming black holes in this range,

  • so that 85 solar mass black hole could call our understanding of stellar evolution into question.

  • These 39 new gravitational wave events certainly give us a lot to ponder,

  • but remember that's just from the first half of observing run 3.

  • Unfortunately, the second half had to be cut a month short because of COVID-19,

  • but with observing runs 4 and 5 still planned for some time in the near future,

  • and the inclusion of data from detectors in Japan and India,

  • expect to see a lot more interesting discoveries from the laser interferometers of the world.

  • If you're a math geek you may have noticed the masses of those two huge merging black holes added up to more than the final result.

  • Scientists estimate about 8 solar masses were radiated away as energy in the form of gravitational waves during the merger.

  • Wouldn't you know it, right before the first intermediate sized black hole was officially announced,

  • I made a video about how we haven't been able to find them.

  • If you'd like to see my still mostly good video about the size ranges of black holes, check it out here.

  • Thanks for watching, be sure to subscribe and I'll see you next time on Seeker.

Remember when the discovery of gravitational waves was first officially announced back in 2016

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Why We’re Seeing More Gravitational Wave Events Than Ever Before

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    林宜悉 posted on 2020/11/23
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