Gravitational Waves
Then: An Impossible Dream?
Now: Nobel Prize
An artist's rendering of the merger of two black holes and the resultant gravitational waves rippling outward from it, as the black holes spiral toward each other. (Image courtesy: R.Hurt/Caltech/LIGO)
Over the past 25 years, gravitational-wave astrophysics has seen monumental discoveries. A key milestone was in 2015, when Syracuse University faculty, including Professor Stefan Ballmer, played a leading role in the first detection of gravitational waves from colliding black holes. Ballmer, who directs Syracuse’s Center for Gravitational Wave Astronomy and Astrophysics, focuses his research on optimizing observatories like Cosmic Explorer, which is set to come online in the next decade and aims to detect every black hole and neutron star collision in the visible universe. By studying these waves, researchers gain insights into the early universe and the creation of heavy elements like gold and platinum. In the following Q&A, Ballmer highlights the incredible discoveries by Syracuse researchers and shares his predictions for the future.
How was the field of gravitational-wave detection perceived in the early 2000s, and what was the environment like for researchers?
Stefan Ballmer (SB): In the year 2000, when I started my professional career, the entire field was definitively not considered mainstream, and considered a hopeless endeavor by many. The Laser Interferometer Gravitational-Wave Observatory (LIGO) team was held together by the desire to make this seemingly impossible dream – using lasers to measure fluctuations in space-time – a reality. The first 15 years of my research career were spent in this environment.
What were the significant milestones in gravitational-wave detection over the last 25 years?
SB: The most notable was the Nobel Prize-winning first observation of Gravitational-Waves in 2015, which we celebrate the 10-year anniversary of this year. That first detection was followed by five months of radio silence during which the entire LIGO team triple-checked that everything was okay, followed by the official announcement. LIGO was front-page news.
Fast-forward ten years: While the novelty of the first discovery has worn off, the LIGO observatories keep delivering. By now, we have seen on the order of 200 black hole collisions, adding several every week of observation. We have also made significant progress in the design of LIGO’s successor observatory, Cosmic Explorer, which is what I spend most of my research time on today. Cosmic Explorer’s goal is to observe black hole and neutron star collisions throughout cosmic time, right back to the colliding remnants of the very first stars.
In his research, Stefan Ballmer, left, is working to improve the sensitivity of gravitational-wave detectors of the future.
Considering projects like Cosmic Explorer, what do you predict for the future of gravitational-wave detection by 2050, and how will Syracuse play a role in that work?
SB: The Syracuse Center for Gravitational Wave Astronomy and Astrophysics, together with a handful of groups at other universities, took the lead in defining what the next generation of gravitational-wave observatory in the U.S. (now named Cosmic Explorer) should look like. The center now has National Science Foundation design awards covering multiple aspects of Cosmic Explorer, including site selection (PI Joshua Russel), optical design (PI Georgia Mansell), optical mode control (myself as PI) and data infrastructure (PI Duncan Brown). As the project grows, we intend to take hardware design tasks for Cosmic Explorer and ultimately help with its installation and commissioning.
In the meantime, our group also supports improvements at the current Advanced LIGO Observatories, and we keep an active research program improving aspects of the detector technology, including quantum squeezing, optical coatings and laser stabilization.
