I’d heard about her when helping to make the English version of a film about Cascina. She’s the Gravitational wave Interferometer, called VIRGO, which will tell us so much more about how and when things began. Einstein posited, as part of his theory of general relativity in 1916, the existence of gravitational waves in addition to electromagnetic ones.
Marconi had famously discovered how to use the electromagnetic ones and his experiments at Poldu, Cornwall produced the first wireless signal across the Atlantic.
Yet even with powerful telescopes of both the optical and radio variety we can ‘see’ just five per cent of the universe. The remaining 95% consists of dark matter and black holes. How could anyone possibly measure and observe them? Precisely through the interferometer which picks up any gravitational wave produced by spectacular events, including the collision of binary pulsar stars and, indeed, the original ‘big bang’ itself. How does it do this? A laser beam is divided into two, each one fired through separate vacuum sealed tubes, 3 kilometres long and set in an L shape on the flat alluvial plain of the Arno near Cascina The two separate beams are then returned to a finishing point and if there is any unphasing or discrepancy in their return then this signifies that they have been ‘interfered with’ by a gravitational wave. Or have they? That’s the question. Much of the research at Virgo is spent on filtering out redundant vibrations caused by traffic, earth tremors etc.
(Virgo as seen from the air)
What happens when a gravitational wave hits our planet’s space-time continuum? There’s an infinitesimal change in our appearance and the appearance of objects. We and they oscillate the width of a hair’s breadth in length and breadth – such is the sensitivity of the measurements to be recorded. Fortunately I have yet to meet a person who confesses they know how it feels to be hit by a gravitational wave.
With the mind pulsating with space-time and waves I was privileged to join a specialist group last Saturday at Virgo.
First, we were treated to a seminar where Prof Dattilo introduced us to the concepts involved. It was nice to have two of his children participating in the event and there was plenty of time for questions afterwards.
We then ventured into the control room where scientists work out the data received from the interferometer. As the visit was after working hours the room was empty but there was some evidence of the hard work involved here.
Finally, we were given an exclusive entry into the actual instrument itself. It seemed a bit like a set from Doctor Who, I thought. Here are kept the mirrors used to divide and reflect the laser beams lengthening them from 3 to 120 kilometres in length. It’s all done by mirrors as they say. The price of setting up and maintaining this equipment, originally set up in 2002 and updated this year, goes into the millions of Euros
(Virgo’s main control room where the reflecting and dividing mirrors are kept)
(The north tunnel of Cascina’s gravitational wave interferometer showing the three-kilometre-long tube through which the laser beams travel)
Italy isn’t just about frescoes, food, fashion and fabulous scenery. It’s about a leading cutting edge in astronomy and astrophysics. The Italian VIRGO (so called because it particularly concentrates on the Virgo constellation with its dense array of binary pulsar and neutron stars) forms part of the international team which includes EGO (European Gravitational Observatory involving five EU countries including France) and LIGO (the US Laser Interferometer Gravitational-Wave Observatory which, exactly one hundred years after Einstein’s prophetic theory, has discovered positive evidence for the presence of gravitational waves. As Prof David Reitze, executive director of the LIGO project stated “We have detected gravitational waves. It’s the first time the Universe has spoken to us through gravitational waves. Up until now, we’ve been deaf.”) I
To rephrase the great poet Alexander Pope’s epitaph on Newton:
Nature and nature’s Laws lay hid in Night.
God said, “Let LIGO be!” and all was light.
Except, of course that we are talking about the darkest of matter, black holes themselves.
Let us trust that gravitational waves will in the future help not only to understand the universe in greater depth but ourselves too. For that’s where the true origin of all our species lies: in the deepest mystery of the cosmos. Research carries on apace in this field and in 2034 we shall see LISA space gravitational wave interferometer launched. The principles are the same as those of VIRGO except that the ‘tunnels’ here are not three kilometres long but five million instead! What discoveries shall be made then I wonder. Hope you can wait that long…
Thinking about which I imagined a journey to an exo-planet and came up with this:
Gigantic cliffs stand peaked like wings of gulls
and cut through sky of indigo. Two moons
lie hung upon translucent pregnancy:
this is the planet where there is no sound.
At dusk spiced crimson rocks drum granite chords
which penetrate hard entrails of stilled earth,
bronze sands vibrate with fluent overtones,
ionosphere drops ultrasonic waves.
Here is the summit and below hot seas
of sapphire circle coastlines, solarized
and drawn towards cerise-soaked longitudes:
the night is stretched out like a waking cat.
PS Cascina itself is a delightful place to visit. See my post at https://longoio2.wordpress.com/2016/02/12/something-about-cascina/ for more details.