The Einstein Telescope (ET) will be the European Third-Generation Gravitational Wave (3G GW) Observatory, a multi-detector, multiinterferometer designed to observe the whole Universe. Thanks to the unprecedented sensitivity of ET, Europe will take the lead in the newborn multi-messenger astronomy by combining information delivered by ET with optical, IR, UV, gamma, cosmic ray and neutrino telescopes observations. ET, being a unique tool to investigate the spacetime fabric of the Universe, will impact on our fundamental physics knowledge, and our understanding of the fundamental interactions governing the evolution of blackholes and neutron stars. The technologies needed for ET will affect industrial sectors, like lasers, sensors, optics, seismic isolation, and materials.
Entered in the ESFRI Roadmap 2021, ET builds on the success of current, second-generation laser-interferometric detectors Advanced Virgo and Advanced LIGO. The idea of 3G GW observatory was conceived in 2004 with the Design Phase in 2008. Part of the enabling technologies of ET was developed in collaboration with the Japanese project KAGRA and currently through the Interreg ETpathfinder and E-TEST projects and the SarGrav facility. The Preparation Phase towards Implementation will consist in a number of steps including the formalization of the ET collaboration, the selection of the hosting site, the acquisition of the land, the establishment of a legal entity, the organisation of the governance, the delivering of operative TDR and the optimization of the site. Start of operations are expected in 2035.