By announcing, on February 11, 2016, the first discovery of a new type of extraterrestrial signal, observed in two detectors in the United States, the thousand physicists responsible for the feat claimed to be opening a new window on the cosmos. Promise kept.
We know the wide range of electromagnetic radiation: X-rays, visible light, ultraviolet, infrared, radio, gamma, etc. which reveal stars, galaxies or planets, and also dissect their compositions and evolutions. We also know about neutrinos, fleeting particles coming from the heart of violent reactions of stars or other violent cataclysms. From now on, alongside them, we will have to count on new waves, called “gravitational”.
They witness deformations of space-time caused by movements of very massive and compact objects such as black holes, by definition invisible, due to lack of electromagnetic radiation. These waves are crucial messengers for understanding the history of galaxies. They provide information on their sources or on the importance of the process of fusion-destruction-creation which gives rise to them. They also provide information on the beginnings of the Universe as much as on its future, that is to say its speed of expansion. They also make it possible to test the robustness of general relativity in extreme situations.
Also read (2015) | How Einstein’s theory of relativity changed our lives
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“It’s fantastic astronomy. One hundred years after the prediction of[Albert] Einstein [qui a eu lieu, en réalité, en 1916] of the existence of these waves within the framework of general relativity, we have made these invisible things visible, greets Marica Branchesi, professor at the Gran Sasso Science Institute, in Italy. These waves do not interact with almost anything and are therefore difficult to detect. But if we can do this, then it means that we are sensitive to things that have traveled a long time. » “We are like Galileo with his telescope. We have new instruments to discover new objects”adds Simone Mastrogiovanni, researcher at the Italian National Institute of Nuclear Physics.
“Building a new discipline”
The enthusiasm is not overplayed. By the time you read this, nearly 250 gravitational waves will have been detected. There were 90 during the first three campaigns carried out since 2015. And nearly 160 “candidates” during the fourth campaign, which began in May 2023. It is only in the summer of 2025 that these observations will be confirmed, during the publication of the new catalog, but it is likely that few will disappear between now and then.
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