European plan for gigantic new gravitational wave detector passes milestone with its novel underground triangular design, Europa’s Einstein telescope will be a gravitational wave observatory like no other. It’s far from a closed deal, but European physicists’ plans to build a new giant gravitational-wave observatory with a radical design got a boost this week.
The European Strategic Forum on Research Infrastructure (ESFRI), which advises European governments on research priorities, added the € 1.9 billion observatory, called the Einstein Telescope (European plan), to a roadmap of large scientific projects ready to progress. The developers hope the move will give them the political recognition they need to turn the idea of an Einstein telescope into a project.
“It is not a promise of funding, but it shows a clear intention to achieve it,” says Harald Luck, a gravitational wave physicist at Hannover Leibniz University and co-chair of the Max Planck Institute for Gravitational Physics and the Directorate of the Einstein Telescope Committee (European plan). “It is more than a political commitment.”
new gravitational wave detector
American gravitational wave physicists also welcomed the announcement, believing it could bolster their plans to build a pair of detectors even larger than the Einstein Telescope in a project called the Cosmic Explorer. “In the US, I think the momentum will start to build,” says David Reitz, executive director of the Laser Interferometer Gravitational Wave Observatory (LIGO) and a physicist at the California Institute of Technology.
Gravitational wave detectors detect tiny evanescent waves in space itself when massive celestial bodies, such as black holes, rotate and collide with each other. Over the past 5 years, scientists have observed dozens of pairs of merging black holes, the ghostly superintense gravitational fields left behind when massive stars spiraling together collapse into an infinite number of points.
They have also observed gravitational waves, and spectacular explosions, set up by the merger of a pair of tiny neutron stars, the ultra-dense corpses of medium-weight stars that burn up and fly away. This week, the researchers announced that they had twice felt gravitational waves from a black hole swallowing a neutron star.
To understand gravitational waves, physicists use giant L-shaped optical instruments called interferometers. They use laser light to compare the arm length of an interferometer with excellent precision and look for evidence that space is expanding more in one direction than the other. In the United States, LIGO consists of twin interferometers in the states of Louisiana and Washington, each with a 4-kilometer long armament. Europe’s Virgo detector in Italy has arms that are 3 kilometers long.
But scientists want even bigger and more sensitive interferometers. The merger of the LIGO and Virgo black holes can be understood more than 10 billion light years away. But if scientists had detectors 10 times more sensitive, they could detect black hole mergers 45 billion light-years away, from the edge of the observable universe.
To achieve such sensitivity, the Cosmic Explorer would include one or more L-shaped interferometers with 40-kilometer arms. In contrast, Einstein’s telescope would be an underground equilateral triangle with a total of six V-shaped interferometers (two at each corner) with 10-kilometer arms.
The ESFRI roadmap
Physicists in the United States and Europe expect the detectors to be built in the mid-2030s. Inclusion in the ESFRI roadmap is an important first step toward realizing the Einstein Telescope, says Michele Punturo, physicist and director. of the National Institute of Nuclear Physics of Italy and co-chair of the Steering Committee of the Einstein Telescope.
Over the next 3-4 years, the Einstein Telescope developers will develop their current conceptual design for the observatory into a more detailed technical design brief, says Panturo. More importantly, they say, they will begin the process of expanding international cooperation to support the project. Currently, the Einstein telescope team is supported by Belgium, Italy, the Netherlands, Poland and Spain.
unique organizational structures
In fact, Punturo says, ESFRI exists because the European Central Government, the European Commission, does not have a predetermined mechanism to organize and finance such large international projects. (The European Space Agency, the European Southern Observatory, and CERN, the European particle physics laboratory, have their own unique organizational structures, but none of them have the scientific expertise to build a gravitational wave observatory.)
Therefore, ESFRI, which is led by the European Council and includes representatives of national scientific funding agencies, aims to help set priorities for large international facilities in Europe. However, it is up to the Einstein Telescope team to develop the organization backing the project, Punturo says.
technical, legal and financial measures
For example, he says, the organization can adapt to CERN. He says ESFRI will have an important role to play in obtaining support and funding from individual nations. The ESFRI roadmap is opening the initial phase in which all technical, legal and financial measures must be taken so that we can get to the point where we can say: ‘Okay, we are ready to move on.
“The building community is definitely a big part of the facility design,” says Jocelyn Reid, a gravitational wave physicist at California State University, Fullerton and a member of LIGO. She points out that there is less competition than a collaboration to build the next generation of gravitational wave detectors: “The Cosmic Explorer and the Einstein Telescope will do the best science working together.”