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It’s September 14th, 2015 and students are meandering across campus towards their first class of the year. Finding someone to sit with at the crowded dining hall for lunch will be their biggest discovery of the day. But for a small group of Carleton professors, students and alumni, the day holds something greater. At 5:51 a.m., the two Laser Interferometer Gravitational-Wave Observatories (LIGO) in Louisiana and Washington directly recorded a gravitational wave from the merger of two black holes for the first time. Caltech and MIT operate the LIGO observatories, but the research is part of a transnational collaborative effort that includes Carleton physics Professors Nelson Christensen and Joel Weisberg.
For many, the news of Carleton’s involvement in a scientific discovery is welcome, but not necessarily understood. Why the big gap between the discovery and the announcement? What is a gravitational wave? Why does it matter?
Nathaniel Strauss ’16 and Jialun Luo ’16, two co-authors on the gravitational wave paper, along with Emily Longley ’16, another student researcher, have the answers to these common questions about the research.
According to these three students, the delay in the announcement of the discovery was to preserve the scientific process.
“If people analyzing the data are feeling a lot of pressure to produce something statistically significant, the results may not honor the data that is there,” Longley said.
Luo also explained that “we were almost certain we had recorded a gravitational wave, but you don’t want to make the announcement without very high confidence.” This process of triple checking requires heavy data analysis and computational time running complicated code to make sure the results are statistically significant.
To the importance of this discovery, the students said you first need to understand the difference between gravitational waves and light waves.
Strauss explains that electromagnetic radiation – from a light bulb, x-ray, or radio wave – is what scientists usually use to look up at the sky, although it cannot pass through matter. Gravitational waves, on the other hand, pass straight through matter unperturbed, meaning we can get an “unobstructed look at the sky without worrying about it encountering matter along the way,” Strauss says.
The difference in what the two kinds of waves allow us to see is what makes the discovery so important. “Gravitational waves allow us to see things that don’t emit electromagnetic radiation, like black holes,” Luo explained. The detection of gravitational waves means we have a new tool to view the universe.
What are the implications of this discovery on the scientific community? “Absolutely huge,” according to Strauss. He compared the importance of this discovery to Galileo first using the telescope to look up at the sky.
“Think about everything we learned after Galileo. This discovery is going to have a similar impact. We are getting a whole new way of looking up at the sky,” Strauss said.
Longley added that “we have telescopes that can detect radio waves that come from space, and we have telescopes that can detect optical. This is a whole new realm of information that we can garner from the universe.”
What is it like to be a 20-something-year-old student and already have your name on a huge scientific research paper? “It’s very rewarding,” Luo said.
Strauss seconded this, saying, “I feel very lucky that I ended up at Carleton working with Nelson at such a critical period in this research.”
Langley recalled how emotional learning about the discovery was. “There are so many people who put in so much of their life effort on this discovery and I feel lucky to be a part of it.”