Scientific project

The Einstein telescope on its way to Europe!

In Research

The consortium of more than 40 European universities, including the University of Liège (STAR Institute, A&M and UEE), has just officially applied for inclusion in the European planning for the construction of one of the most ambitious scientific projects in the coming years: the Einstein telescope. Located in Europe, this infrastructure will study the gravitational waves that enable us to understand better the otherwise invisible side of our universe. The construction of a prototype has been entrusted to the Centre Spatial de Liège (CSL).


he proposal to include the Einstein Telescope, an innovative third-generation gravitational-wave observatory project, in the roadmap of the European Strategic Forum for Research Infrastructures (ESFRI) was submitted last week. The ESFRI roadmap supports major projects for future research infrastructures in Europe. The Einstein Telescope (ET) is the most ambitious gravitational wave observatory project on Earth. The incredible scientific success of the collaborations Advanced Virgo (Europe) and Advanced LIGO (mostly USA) over the last five years marks the advent of the era of gravitational astronomy. This adventure began in September 2015 with the first direct detection of gravitational waves. It continued in August 2017 when Advanced Virgo and Advanced LIGO observed the gravitational waves emitted by the fusion of neutron stars. Simultaneously, signals from this fusion were observed by several traditional telescopes (on Earth and in space), over the entire electromagnetic spectrum, from radio waves to gamma rays.

The recent detection by Advanced Virgo and Advanced LIGO of the fusion of two black holes into a black hole 142 times more massive than the Sun (in the class of intermediate-mass black holes) has uncovered the unexpected existence of such objects in the Universe. In order to exploit fully the potential of this emerging scientific discipline, a new generation of observatories is needed. The Einstein telescope should enable scientists to detect the merging of intermediate black holes throughout the history of the Universe and provide a better understanding of its evolution. These observations will lift the veil on the dark Universe and lead to a better understanding of the role of dark energy and dark matter in the evolution of the large-scale structures of the Cosmos.

The Einstein telescope will explore the physics of black holes with unparalleled precision. These extreme celestial bodies, predicted by Albert Einstein's Theory of General Relativity, are ideal candidates to test the possible flaws of the theory, thanks to their extreme gravitational field. ET is also expected to detect thousands of neutron star mergers each year, improving our understanding of the behaviour of matter under extreme conditions of density and pressure, which cannot be reproduced in the laboratory. It will also be a chance to explore the nuclear physics that controls the explosion of stars in supernovae. 

However, in order to achieve these ambitious objectives, scientists need an observatory capable of detecting gravitational waves with a sensitivity at least ten times greater than that of current (known as second-generation) detectors. ET will consist of a new infrastructure and will require the development of much more advanced technologies than those available today.

The design phase of the ET was financed by a fund of the European Commission. This week, a consortium of universities and research institutes in Europe, together with the political support of five European countries — Belgium, the Netherlands, Spain, Poland and Italy, the latter currently taking the lead in the project — officially submitted the proposal to build such an infrastructure on European soil. The European Gravitational Observatory (EGO) in Italy will host the temporary headquarters of the ET. The consortium brings together 40 universities and institutes from several European countries, including, in addition to the five countries mentioned above, France, Germany, Hungary, Norway, Switzerland and the United Kingdom. A similar project, the Cosmic Explorer, could also be launched in the United States. At the University of Liège, researchers from the STAR Institute (Sciences), A&M and UEE (School of Engineering) research units are involved in the project in close collaboration with the CSL.

At present, two possible sites for the ET construction are being evaluated: one in the Euregio-Meuse-Rhine, on the border between Belgium, the Netherlands and Germany, and the other in Sardinia in Italy. The study of these sites is ongoing and the decision on the location of ET will be taken within five years.

Enstein telescope ESFRI 

Artist's view of the Einstein Telescope (ET) underground gravitational wave observatory project, illustrating the triangular arrangement of 3x10km at 150 metres underground. ET could be built in the Euregio-Meuse-Rhine region (Belgium-Netherlands-Germany) or in Sardinia (Italy). Each end includes a "measurement station" in an underground laboratory equipped with state-of-the-art optics and laser technology. The various optical components are cooled to a temperature close to absolute zero and suspended at the end of a complex apparatus about 15 metres high. (courtesy: NIKHEF, Amsterdam)

In Belgium, all the universities support the Einstein Telescope project. Seven of them (UCLouvain, ULB, ULiège, KULeuven, UAntwerpen, UGent and VUB) are currently members of the Advanced Virgo collaboration.

Together with UHasselt, UMONS, UNamur and other partners in the Netherlands and Germany, they are also involved in two ambitious projects. On the one hand, the construction of the ET-Pathfinder laboratory in Maastricht and on the other, the E-TEST project, the aim of which is to develop an underground observatory in the Euregio-Meuse-Rhine region, and to build a prototype — under construction at the Liege Space Centre (CSL) — which will enable certain elements of the future Einstein telescope to be validated experimentally.

More generally, since 2015, Belgium has seen the construction of a strong community of scientists involved in the field of gravitational waves, both from a theoretical and instrumental point of view, or in connection with data analysis.


Prof. Christophe Collette, ULB/ULiège
Prof. Jean-René Cudell, ULiège
Prof. Giacomo Bruno, UCLouvain
Prof. Nicolas Boulanger, UMons,
Prof. Sebastien Clesse, ULB/UCLouvain/UNamur
Prof. André Füzfa, UNamur

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