In the end, science could peacefully resolve the tight political competition for the Einstein Telescope between Italy and the Netherlands, and adopt a win-win solution in which everyone emerges victorious and happy. The hypothesis that is gaining ground is in fact that of building not just one interferometer - the large gravitational wave detector - but two, in the candidate sites currently in the competition, in Lula and near Maastricht.
The hypothesis
«The first idea was to build a triangle, but it dates back to the 2000s, at a time when we were thinking of a single infrastructure of this kind on earth, which would do everything. Subsequently, with observations and experiments also on the functioning of the current Ligo and Virgo detectors, the alternative of two L-shaped instruments made its way", explains Alessandro Cardini, director of the National Institute of Nuclear Physics section of Cagliari, head of the team of researchers from the island committed to characterizing Sos Enattos as an ideal place.
In short, now the international group of experts studying and managing the mega project, after a detailed analysis, has decided to consider a double configuration, that is, two L-shaped interferometers with 15 kilometer arms, a thousand kilometers apart. 'from each other, one in Barbagia the other in Limburg.
«We found that doing two would be substantially better from a scientific point of view, and this is obviously the objective, to create the best possible work for research and studies on the subject», continues Cardini, «then, of course, under a another aspect would also offer a solution to this "dispute", because both governments have invested funds and made a promise to the communities, who care very much about hosting the Einstein Telescope".
The experts
The issue was discussed in a recent article published in "Nature". For Marica Branchesi, astronomer at the Gran Sasso Science Institute, «two L-shaped detectors would be able to observe two to three times the number of events that the triangle would see, and this configuration would also allow us to better localize the source of each wave gravitational force in the sky, which is essential for pointing optical telescopes in the right direction and observing the light emitted by neutron stars during fusion."
Regarding the costs, according to the physicist co-director of the ET organization Fernando Ferroni, «they would be more or less equal in the two configurations, and certainly the Italian government and the Sardinia Region, which have allocated around 1 billion euros, would not withdraw their support if Italy ends up hosting only one of the two detectors."
Times
When will it be decided? «To have all the elements it is necessary for the pre-feasibility study – which the Rocksoil consortium of companies is carrying out – to be completed», says Alessandro Cardini, «we will have all the inputs between the middle and the end of 2025. Then, the final decision will be made by the Einstein Telescope Board of Government . In one case or another, everything that has been done so far in Sardinia and imagined around the work remains unchanged. The quality of our site, to create the detector (both triangle and L-shaped) is exceptional."
Cristina Cossu
