I saw an article last night about gravitational waves, that a black hole merger was detected by not just the Laser Interferometer Gravitational Wave Observatory (LIGO), but by another project altogether, the Virgo collaboration. This is the first gravitational wave detection confirmed by two separate groups, and it marks the beginning of a new era of experimental science, the first in astronomy in over two decades.
Around 1.8 Billion years ago, to black holes merged in a faroff galaxy. They had masses of 31 and 25 times that of the Sun, though with their incredible density they would each be less than 200km in diameter. The resulting collision formed a black hole was 53 solar masses, converting the three extra solar masses to pure energy in the form of gravitational waves, which travelled outward in every direction, like the ringing of a giant bell. After travelling through space for 1.8 billion years, growing gradually weaker, the gravitational waves passed by a planet who developed amazing technology in just a few hundred short years. The waves caused a beam of light to contract a tiny bit, around 1/10,000th the width of a proton. Yet this tiny detection revealed the information contained in the ancient gravitational waves, the imprint of the incredible event that bore them.
But this detection was captured more than once. Both LIGO detectors caught the event, and for the first time it was captured by a second major gravitational wave observatory, the Virgo collaboration in Piza, Italy. Not only does this allow researchers to pinpoint the precise origin of the collision, it gives more data about the collision, confirming it from multiple independent sources.
More importantly, it marks the beginning of a new era of experimentation, the first in two decades, the study of gravitational waves. One could argue that the last great leap in scientific experimentation was the moment the Large Hadron Collider came online at CERN, but that was more a brute force method that we knew would reveal answers. We knew that building a higher energy collider would reveal higher energy particle interactions and give new insights into particle physics and the conditions of the very early universe. Yes we were looking for the Higgs boson and needed to reach the energy to find it, but even if we didn’t discover the Higgs, the LHC would produce valuable data.
The difference with gravitational waves is that they were purely theoretical. We didn’t know they even existed until LIGO’s first detection. We could have spent millions of dollars to build these massive detectors, and find absolutely nothing. Instead, we open the door on a new tool for discovering the deeper laws of Physics.
I liken it to the discovery of exoplanets. The first few were accidental, even though it seems logical that planets would exist around other stars. In the decades since the discovery of 51 Pegasi b, thousands of exoplanets have been discovered, studied, and even directly imaged. Now we are working on finding Earth sized planets with more finely tuned detectors, and the idea that there are more planets than stars in the Milky Way galaxy is common knowledge in the scientific community.
As gravitational wave detectors improve, and we break into the lower-energy realm, they could reveal the beginnings of our universe, uncovering the electromagnetic veil of the cosmic microwave background radiation, and letting us peek in on the first 325,000 years of the universe’s existence. That’s the goal, and although we are only finding the ‘loudest’ of the gravitational waves right now, it may take as little as 20 years to get there.