Not even a pandemic can hold AS Pisa down!
Many cities in Italy are currently quarantined, and Pisa makes no exception. Nevertheless, last November we had a chance to visit the Virgo Interferometer... without leaving our homes!Researchers Valerio Boschi and Elena Fiori gave us an interesting introduction on gravitational waves and guided us in a virtual trip just outside Pisa, in the very building where the magic happens.
You all certainly remember when, in early 2016, Einstein’s general theory of relativity got an important confirmation with the first observation of gravitational waves produced by the merger of two black holes.
But what made it possible for an imperceptible distortion (we are talking about something in the order of 10-18m!) in the space-time continuum to be recorded? Exactly, an interferometer!
An interferometer allows to measure spatial isotropy through the study of the interference between two controlled rays. And when is spatial isotropy not preserved? When the Earth is invested by a gravitational wave, and the space-time continuum is distorted.
Observing something so small requires a very precise structure to minimise the signal noise. There are only three advanced interferometers in the world and Virgo is the only one in the EU.
Thanks to Virgo and the interferometers taking part to the LIGO Scientific Collaboration scientists were able to observe more and more gravitational waves.
This led to important discoveries such as the fact that neutron stars can cause short-duration gamma ray bursts and produce heavy metals such as gold, and also gave us a direct measurement of the expansion rate of the Universe.
What is more, we can now discover new astronomical object right before they become visible, pointing the telescopes where the waves came from just to see the void lighten up.
Listening to the music of the Universe is a whole new way to study it. Until the past few years we have been deaf, but now we are able to turn the volume up.
AS Pisa, November 2020