Nikhef played an important role in the discovery of gravitational waves

For the first time, scientists have observed ripples in the fabric of spacetime called gravitational waves, arriving at the earth from a cataclysmic event in the distant universe. This confirms a major prediction of Albert Einstein’s 1915 general theory of relativity and opens an unprecedented new window onto the cosmos. Dutch scientists, including those of at Amsterdam Science Park established Nikhef, played an important role in the discovery of gravitational waves

Assembly and testing of the multi-stage seismic attenuation systems in the clean room at Nikhef. Credit: Marco Kraan, Nikhef

Gravitational waves carry information about their dramatic origins and about the nature of gravity that cannot otherwise be obtained. Physicists have concluded that the detected gravitational waves were produced during the final fraction of a second of the merger of two black holes to produce a single, more massive spinning black hole. This collision of two black holes had been predicted but never observed. 

The gravitational waves were detected on September 14, 2015 at 10:51 a.m. Central European Time by both of the twin Laser Interferometer Gravitational-wave Observatory (LIGO) detectors, located in Livingston, Louisiana, and Hanford, Washington, USA. The LIGO Observatories are funded by the National Science Foundation (NSF), and were conceived, built, and are operated by Caltech and MIT. The discovery, accepted for publication in the journal Physical Review Letters, was made by the LIGO Scientific Collaboration (which includes the GEO Collaboration and the Australian Consortium for Interferometric Gravitational Astronomy) and the Virgo Collaboration using data from the two LIGO detectors.

Dutch scientists were closely involved in this groundbreaking discovery. As members of the ‘LIGO Scientific Collaboration - Virgo Collaboration’ (LVC) physicists from the National Institute for Subatomic Physics (Nikhef) and VU University Amsterdam, as well as astronomers from Radboud University made vital contributions to validating the measurement, to the data analysis for these gravitational waves, and they collaborated on the astrophysical interpretation. More details about the Dutch contribution can be found further on in this press release.

Enthusiastic reactions

The Minister of Education, Culture and Science, Jet Bussemaker, and her state secretary Sander Dekker are delighted about this historic scientific discovery: “This demonstrates the importance of fundamental research that forms the basis for our knowledge about life now and about our history and the origin of the universe. The fact that Einstein's prediction has been confirmed 100 years later is a major posthumous compliment to Einstein but most definitely to the scientists of today as well. In particular, we would like to congratulate the physicists from the Dutch institute Nikhef and VU University Amsterdam and the astronomers from Radboud University who have contributed to this outstanding global achievement.”

“Incredible - what a fantastic discovery. I would also like to congratulate the Nikhef scientists involved and their colleagues from LIGO and Virgo. The observation of two black holes merging is where extreme precision in knowledge and instrumentation come together with the most audacious imagination,” says Stan Bentvelsen, director of Nikhef.

Gravitational waves specialist Jo van den Brand, Professor of Subatomic Physics at VU University Amsterdam and initiator and leader of the gravitational physics programme of Nikhef adds: “What we have measured is fantastic. The signal captured is so clear that you can see it in the raw data with the naked eye. A surprise aspect of this discovery is that the black holes that have merged are far heavier than the black holes we know in binary stars in our Milky Way.”

Chris Van Den Broeck, scientist at Nikhef, is one of the two coordinators of all data analysis related to the measurement. For months he worked with his colleagues on the detailed analysis: “The signal agrees exactly with what you would expect according to Einstein's theory. Now we can test the theory in the most extreme situations.”

Astronomer Gijs Nelemans (Radboud University & KU Leuven, and affiliated to Nikhef) is also extremely enthusiastic: "This is the start of a new era for astronomy. We now have a completely new way of looking at the universe and studying the most extreme objects. With the new instruments we can now for the first time accurately pinpoint the end of the complex evolution of massive binary stars."

‘Building blocks of matter, foundations of space and time’ is one of the 16 exemplary routes in the Dutch National Research Agenda. This fundamental curiosity-driven theme is based on questions that the Dutch public posed. “This research is directly related to that theme,” says Bentvelsen. “One of the prominent questions in this theme is: ‘What is the real nature of gravity, space and time and what can you learn from black holes, for example?’ The discovery of gravitational waves is a big step towards answering this question.”