Two weeks ago, the Laser Interferometer Gravitational-Wave Observatory (LIGO) collaboration announced the first direct observation of gravitational waves. The signal was emitted by two black holes colliding together 1.3 billion years ago forming a single black hole 62 times more massive than our Sun. The collision created gravitational energy ripples that travelled through the Universe. The two multi-kilometer-scale LIGO detectors located in Hanford, Washington, USA and in Livingston, Louisiana, USA, have now detected these ripples in the fabric of spacetime. Check out more about the detection principle!

LIGO observatory in Livingston
image credit: Caltech/MIT/LIGO Lab

The existence of gravitational waves was predicted by Albert Einstein in 1916, exactly a century ago. According to his theory of general relativity, the presence of large amounts of mass distorts the space-time. As a consequence of this theory, the merging of two black holes should radiate waves of distorted space that propagate through the Universe. More explanations here and here.

For centuries, all we knew about our Universe was coming from optical light observation. The 20th century has seen the birth of X-ray, radio and gamma-ray astronomy, increasing our understanding of the many astrophysical events happening around us. Each wavelength has taught us a bit more about the phenomena that took place in our Universe since its formation. In 2013, the IceCube neutrino observatory announced the first detection of very high energy astrophysical neutrinos. Neutrinos are an ideal cosmic messenger since they could bring us information from the most energetic phenomena occurring in our Universe.  The first observation of these cosmic neutrinos opened a new window to study our Universe.


” The detection of gravitational waves adds yet another observational band. As of now, we can hear our Universe and try to understand what it is telling us. “


This discovery opens a new era in astrophysics: the multimessenger exploration of our Universe can start!

The Discovery of Gravitational Waves – The Sound of Black Holes

In order to celebrate the first observation of Gravitational Waves the Interuniversity Institute for High Energies IIHE(ULB-VUB) is hosting a seminar in English for the general public.

This event will take place at VUB, March 8th, 6:30 pm.