Gravitational waves discovery creates opportunity for further study
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On Feb. 11, the Laser Interferometer Gravitational Wave Observatory (LIGO) made a historic announcement at the National Science Foundation. For the first time ever, humans have managed to detect the the presence of gravitational waves, reinforcing the principles of Einstein’s Theory of General Relativity and breaking open the door to an entirely new area of scientific discovery.
Ironically, the achievement would have been something of a shock to Einstein, who actually wrote a paper arguing that gravitational waves don’t exist, 20 years after becoming the first person to propose them.
“It’s like Galileo pointing the telescope for the first time at the sky”, said LIGO team member and professor Vassiliki Kalogera at the announcement ceremony. “You’re opening your eyes–in this case, our ears–to a new set of signals from the universe that our previous technologies did not allow us to receive, study, and learn from.”
Scientific efforts to measure and detect the presence of gravitational waves predicted in Einstein’s famous theory have been underway for over 30 years, and according to Assistant Professor in the Particle/Astrophysics Group Andrew Tolley, this discovery was previously not possible.
“When people started this project, essentially for the first twenty years, there was no way that the technology was sufficiently advanced in order to allow gravitational waves to be seen,” said Tolley.
The LIGO test facility works using two perpendicular tunnels, each 2.5 miles long. Laser beams are directed down each of the tunnels and deflected back. In normal conditions, both lasers would return at the exact same moment (because both are traveling at the speed of light across an equal distance), but gravitational waves distort space-time and actually alter the distance that the laser signals travel, slightly altering the time that it takes for each beam to travel to the end of its tunnel and return back relative to the other and allowing for a measurement to be taken.
The gravitational waves are believed to have been the result of two black holes circling each other, moving closer together until eventually merging in a massive collision over 1.3 billion years ago. The black holes were 29 and 36 times the mass of the sun, respectively.
“Just think about how much we have obtained, just looking at light,” said Tolley. “We’ve never visited any of these stars that we observe, yet we know the chemical composition of those stars, and we know the nuclear reactions that go on in the sun. We can see the light reflected and look at the spectrum produced. With gravitational waves, we can detect other things, like the mass and the spin of black holes. This is information that will then tell us about how black holes form, the density of different parts of the universe, and more. So there’s really a wealth of information to be had.”
Additionally, the study of gravitational waves is expected to generate data that will be important to the fields of astrophysics and cosmology, allowing for theories to be tested more stringently, against more real-world data than before. The data from this first finding alone has already been used to provide clear evidence for General Relativity and the Kerr Solution. It also represents the first ever direct evidence of the existence of black holes themselves. Information gained from gravitational waves could potentially provide evidence of cosmic strings, measure inflation and even assist in the mapping of the universe.
According to Tolley, this discovery opens up a huge array of new avenues for study and possible discoveries.
“The wave may take longer to reach us, coming from one way then another way, and so ultimately, then there’s going to be a way to provide an independent map of the universe, the distribution of matter in the universe, the dogmatic distribution of the universe,” said Tolley.
Undergraduate physics student Josh Zeigler also shared a longer-term outlook.
“I feel like it’s a promising start to something, and we’ll just have to see what happens in the next ten years, fifteen years, however long it takes,” he said. “We already expected it, but it’s a proof, a direct observation. It’s a really impressive discovery and technical achievement.”
While Tolley feels that this discovery was important, he says that the most interesting results may be yet to come.
“The best possible thing to see [from new data on gravitational waves] is something you didn’t expect,” said Tolley. “That’s when things get really exciting.”
With more advanced and sensitive measurement systems in the works, it remains to be seen what additional gravitational wave research will bring to our understanding of the universe.