Thursday, 11 February 2016 back

Gravitational waves, GSSI in the discovery of the century

This time it is true. Gravitational waves, predicted 100 years ago by Einstein, do exist. They have been detected by the LIGO experiment, in the US. The “discovery of the century”, as it is already called, has also the signature of the GSSI, which contributed with 8 coauthors, six of which are young researchers from Italy, China, India and Pakistan.

The research, published on Physical Review Letters, accounts for LIGO’s observations of gravitational waves produced by swirling and merging black holes and is expected to revolutionize the study of the Universe. After months of rumors, the official announcement was officially given on Thursday 11th February, in a simultaneous press conference held at the two observatories, LIGO (Washington) and VIRGO (Cascina, Pisa), which merged into one single international collaboration.

The press conference was live broadcast at the Gran Sasso Science Institute, one of the institutions involved in the research, in the crowded main lecture hall hosting not only scientists but also representatives of local institutions.

“This is an exciting and unforgettable moment: I have spent 35 years of my life in this research”, GSSI’s director Eugenio Coccia says. “Detecting gravitational waves and proving the existence of black holes all in once is wonderful. Humanity has now a new sense: from now on we will not only see the cosmos, but also listen to its vibrations, its music.”

So far, we have studied the universe thanks to the “sight”, that is, the photons that come from the stars. Now, the ability to pick up gravitational waves allows us to “listen” to so far unreachable cosmic events. Gravitational waves are indeed ripples in the fabric of spacetime generated by the acceleration of massive objects such as black holes or neutron stars, similarly to the waves produced by throwing a stone into a pond. According to Einstein’s General Relativity, gravitational waves propagate at the speed of light and travel unaltered in the universe.

The observation of these imperceptible vibrations was possible thanks to decades of experimental efforts and extremely advanced machines, laser interferometers. The interferometer LIGO, consisting of two identical 4-km-long legs forming an L, can detect length variations of a billionth of a billionth of meter, a quantity twenty millions times smaller than the size of a hydrogen atom.

The LIGO-VIRGO endeavor involved 1004 researchers belonging to 133 scientific institutions all over the world. The National Institute for Nuclear Physics, which has GSSI as a center for advanced studies, has many among the coauthors. The GSSI contributes with 8 researchers, listed below in alphabetical order, including some of the youngest coauthors of the PRL paper.

Lorenzo Aiello (25 years old, Italy)
Eugenio Coccia (59, Italy)
Viviana Fafone (51, Italy)
Imran Khan (25, Pakistan)
Matteo Lorenzini (38, Italy)
Akshat Singhal (24, India)
Shubhanshu Tiwari (26, India)
Gang Wang (30, China)

Imran Khan, Akshat Singhal, Shubhanshu Tiwari e Gang Wang are supported by the GraWiToN project, an Initial Training Network funded by the European Commission under the FP7 Marie Skłodowska-Curie Actions.

Foto di NASA/Tod Strohmayer (GSFC)/Dana Berry (Chandra X-Ray Observatory)

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