Dr. Josh Willis and a couple of physics students were involved in scientific research that supports Einstein’s 1915 general theory of relativity, opening new windows for astronomy.
Every year since 2011, Willis, associate professor of the engineering and physics department, spent several months in Hannover, Germany as a visiting scientist and senior lead developer on the PyCBC pipeline in the data analysis group of the Max Planck Institute for Gravitational Physics. Willis worked on developing, testing, and running software while also analyzing data that was detected by Laser Interferometer Gravitational-wave Observatory (LIGO) detectors.
For the first time, scientists observed gravitational waves, ripples in the fabric of space-time from two black holes that are each about 30 times the mass of the sun, colliding with each other. The waves were detected on September of 2015 by both of the twin (LIGO) detectors.
“When we look through the data, we perform different searches, partly to look at different signals and partly to look into different methods,” Willis said. “There are at least two searches that take the specific prediction of general relativity for two objects around each other, spiraling into each other and use that template.”
Gravitational waves carry information about their origins and the nature of gravity, which otherwise cannot be obtained.
“We know what the wave signal from that must look like if general relativity is correct and go and compare that to each stretch of data.”
When you drop a book and it falls to the floor, gravity is pulling it down. You can’t see it or feel it, but you know it’s there. In space, black holes have a stronger gravity than Earth’s, and they are constantly moving around. When they crash into each other, huge gravitational waves are sent out, telling the universe what happened.
A century ago, Einstein said these occurrences happen all the time. Scientists weren’t sure that this was true until the LIGO detectors were built and scientists were able to test that theory.
“We have been able to see the universe, but not yet hear it, and now we can,” Willis said. “This will allow us to observe dramatic events in the universe that may not be visible to telescopes, and to learn directly properties of such events that can be hard to measure.”
Hannah Hamilton, senior physics major from Abilene, said that even though she started working on the research after the discovery, she helped run data analysis.
“Data analyzing is basically outputting the data the detectors see that is coherent,” Hamilton said. “I also went back and looked over what they already analyzed to see what was going on.”
Other students who were also involved were Marissa Walker, a 2011 graduate who is now working on her Ph.D at Louisiana State University under the advising of Dr. Gabriela Gonzalez, LIGO Scientific Collaboration spokesperson, as well as Andrew Miller, a 2014 graduate who worked on the development of the PyCBC code in Germany with Willis in the summer through the ACU Pursuit program. Hamilton will also be going to Germany this summer to visit the institution with Willis.
“I feel like I’m bragging when I say that,” Hamilton said.
Even with national recognition, the research is still ongoing, with four months of data left to analyze along with any incoming data in the next couple of months.
“It’s kind of a tedious process to cross check everything, but the experiment is down for a slight upgrade,” Willis said.
A third detector is expected in Italy later this year, which will improve the sensitivity and produce more data.
“About the time we finish analyzing this first chunk of data, it would probably be time to turn right around and think about what improvements we want to make to our analysis technique and be more confident in our findings.”
For more information or to stay updated, visit www.ligo.caltech.edu.