Celebrating Gravitational Waves: A Decade of LIGO Breakthroughs

The world of astrophysics took a giant leap forward on September 14, 2015, when the Laser Interferometer Gravitational-Wave Observatory (LIGO) successfully detected gravitational waves for the first time. This groundbreaking discovery confirmed a crucial aspect of Albert Einstein‘s general theory of relativity, which had predicted the existence of these ripples in the fabric of space-time over a century earlier. Since then, LIGO has been joined by other observatories, such as Virgo in Italy and the Kamioka Gravitational Wave Detector (KAGRA) in Japan, further enhancing our ability to observe these cosmic phenomena.

Over the last eight years, the LIGO-Virgo-KAGRA collaboration has recorded more than 300 gravitational wave signals, providing insights into the most extreme events in the universe. Here, we highlight some of the most significant breakthroughs since that historic first detection.

1. Confirming Einstein’s Predictions: The First Detection

The initial detection, known as GW150914, arose from the merger of two black holes approximately 1.4 billion years in transit to Earth. This event validated Einstein’s theory that massive objects warp space-time, producing gravitational waves detectable by sensitive instruments. Announced publicly on February 11, 2016, this achievement represented a monumental milestone in physics and earned the 2017 Nobel Prize in Physics for Rainer Weiss, Kip Thorne, and Barry Barish.

2. The Heaviest Black Hole Merger

On November 23, 2023, LIGO-Virgo-KAGRA detected GW231123, the merger of two black holes with masses of 100 and 140 times that of the sun. This merger resulted in a daughter black hole approximately 225 times the mass of the sun, setting a new record for black hole mergers. As Cardiff University researcher Mark Hannam noted, this discovery challenges existing models of black hole formation, suggesting that these massive black holes may have formed through earlier mergers.

3. The First Neutron Star Merger

On August 17, 2017, LIGO and Virgo recorded gravitational waves from GW170817, resulting from the collision of neutron stars located about 130 million light-years away. This event was groundbreaking not only as the first detection of neutron star mergers but also for its implications on the creation of heavy elements like gold and platinum.

David Shoemaker, spokesperson for the LIGO Scientific Collaboration, described this event as a rich source of information that has advanced our understanding of both neutron stars and fundamental physics.

4. Multimessenger Astronomy Takes Flight

The merger event detected in GW170817 also marked the birth of multimessenger astronomy. While LIGO detected gravitational waves, astronomers simultaneously observed light from the event, leading to a breakthrough in understanding cosmic phenomena. This collaboration resulted in the identification of a gamma-ray burst, GRB 170817A, allowing scientists to study the merger in unprecedented detail.

National Science Foundation Director France Cordova hailed this achievement, emphasizing its significance for observing rare cosmic events through multiple forms of detection.

5. The Sound of Black Hole Mergers

Gravitational waves emitted during black hole mergers follow a defined pattern, transitioning through three distinct phases. Research published in 2023 provided strong evidence for detecting multiple frequencies in a single merger event, specifically in the case of GW190521. This finding validated the theory that black holes are characterized by just three properties: mass, spin, and electric charge.

6. The Discovery of Mixed Mergers

On January 5, 2020, LIGO and Virgo detected a mixed merger event, GW200105_162426, involving a neutron star colliding with a black hole. This discovery confirmed the existence of neutron star-black hole mergers, expanding our understanding of stellar remnant interactions. Astrid Lamberts from the French national research agency CNRS highlighted the implications of this finding in furthering our knowledge of binary systems.

7. A Mysterious Merger

The gravitational wave signal GW190814, detected on August 14, 2019, came from a merger where one object was a black hole of 22 to 24 solar masses, while the other had a mass of 2.6 times that of the sun. This ambiguity raises questions about whether the second object is a light black hole or a heavy neutron star, highlighting the complexities of stellar evolution and the life cycles of massive stars.

8. The Loudest Gravitational Wave

In a recent announcement on September 10, 2025, the LIGO-Virgo-KAGRA collaboration reported the detection of GW250114, the loudest gravitational wave signal to date. This event involved two black holes merging, providing a clear signal that not only confirmed general relativity but also validated theories proposed by physicists like Stephen Hawking regarding black hole behavior.

9. A Cosmic Symphony

In an unrelated but significant discovery, the North American Nanohertz Observatory for Gravitational Waves (NANOGrav) reported low-frequency gravitational waves on June 28, 2023. This breakthrough allows scientists to study the background noise of gravitational waves, providing insights into the behavior of supermassive black holes and the evolution of galaxies.

10. A Complex Legacy

While gravitational wave discoveries have continuously validated Einstein’s general relativity, they have also challenged some of his assumptions about the detectability of these waves. Notably, LIGO’s success in detecting gravitational waves has proven that they are indeed observable, contrary to Einstein’s initial beliefs.

As the LIGO-Virgo-KAGRA collaboration continues its work, the future of gravitational wave astronomy looks promising. Each detection not only enhances our understanding of the universe but also opens new avenues for research, ultimately reshaping our comprehension of cosmic phenomena.