Gravitational waves and the unheard broadcast of the violent universe

Posted on Monday 10th February 2014

Following his Inaugural Lecture, Ros Dodd met Professor Alberto Vecchio to find out more about the pioneering Birmingham research that could change our understanding of the universe.

There are very few people ever to have been born who can expect to ‘see’ what happened a fraction of a second after the Big Bang – but Birmingham’s Professor Alberto Vecchio is one of them.

The Italian-born astrophysicist is part of a team of international experts on the brink of revolutionising our understanding of the universe – by tuning into its ‘gravity channel’. This has been broadcasting since the dawn of time through the incredibly weak form of radiation known as gravitational waves, but until now no one has been able to hear it directly.

That is about to change dramatically: In a major international project – on a par with the (successful) search for the Higgs bosun – the Laser Interferometer Gravitational-wave Observatory (LIGO) in Livingston, Louisiana is to start using ground-based laser interferometers to listen in to the unheard broadcast of our violent universe.

In just a few years’ time, there is the possibility of witnessing what happens when two black holes collide. It may only take a few decades longer for astrophysicists to push aside the ‘cosmic curtain’ to unearth some of the secrets about the very beginning of time.

Alberto, who arrived at the University as a lecturer in 2001 and was promoted to a Chair in 2010, recently delivered his inaugural lecture on the subject of ‘gravitational waves and the unheard broadcast of the violent universe’.

That he is on the brink of an out-of-this-world discovery is, he says, little more than a happy coincidence.

‘I’m not one of those people who always wanted to be an astrophysicist: when I was at secondary school, there were very many subjects that interested me, but I had an inspirational physics teacher and as a result decided to study physics at university. Of course, physics is very broad, but I remember one of my professors talking about astrophysics and describing it as “the area in which we apply all the interesting physics for the most interesting place we have, the universe, and where we will make the most interesting discoveries”, and I was convinced!’

While studying for a PhD in astronomy at the University of Milan in the mid-1990s, Alberto spent a year at the University of Cardiff.

‘The idea was to spend a few years abroad and then return to Italy, but of course life takes different turns.’

After five years as a research scientist at the Max Planck Institute for Gravitational Physics (Albert Einstein Institute) in Potsdam, Alberto returned to Britain – this time to Birmingham, where he has been ever since.

His research interests include general relativity, the astrophysics of compact objects – black holes and neutron stars – and cosmology, but his focus is the gravitational-wave science and the effort to directly observe gravitational radiation.

‘Scientists have observed the universe using electro-magnetic radiation, such as visible light, radio waves, gamma and X-rays, and learned a lot of fantastic things. However, we know that the universe and most extreme objects are actually shaped by gravity – for example black holes, which are some of the most exciting things out there.’

Gravitational waves, predicted by Einstein's theory of general relativity nearly 100 years ago, are ripples of the fabric of space-time that propagate at the speed of light and are produced by some of the most violent events in the universe, such as the collision of two neutron stars or black holes.

‘These gravitational waves carry information about gravitational fields. The very early universe and black holes are forged by gravity. So through this form of radiation, we could see up close and personal those objects, using the information coming from their very nature. But in order to do this, we needed to develop a new way to capture it.

‘It’s extremely hard to observe these waves: what they do is stretch and squeeze space (and time), producing very, very tiny fluctuations – for example, they would change the separation of two objects a kilometre apart by less than 1,000th of the size of the nucleus of an atom. But if we had a way of measuring them, we would have a way of reconstructing what happened when two black holes collided or a fraction of a second after the Big Bang.’

After decades of dedicated work, new kinds of ‘telescopes’, such as those at the LIGOs in Livingston and Hanford, Washington, are sophisticated enough to tune into the universe’s gravity channel.

‘We have carried out a major upgrade of LIGO, to be completed this year, and from next year we will start our observations,’ says Alberto. ‘In the next few years we hope to be able to map directly what happens when two black holes hit each other.’

Even though this will be a major discovery in itself, it will be ‘just the beginning’. The next stage will be to put instruments in space.

‘The ultimate holy grail is to get as close as possible to the Big Bang. In principle, we could “see” through the gravitational wave channel the universe when it was a fraction of a second old. So far, we haven’t been able to get beyond 300,000 years because there’s a sort of cosmic curtain.’

For Alberto, his ‘calculated gamble’ to go into this research field is paying off even sooner than he dared to hope.

‘People told me I was crazy to work in this area,’ he recalls. ‘No one doubted the importance of it, but there was enormous scepticism that it could be done within a reasonable timescale. One of the reasons I came to Birmingham was because there was the opportunity to put together a group focused on this area of astrophysics, and now we are recognised globally as a strong group.

‘I still get a thrill out of my work, and I’m lucky that there is the possibility of making discoveries. It is very exciting to be at the centre of the action in terms of hearing the sound of the universe directly for the very first time.’

For more information, please contact Samantha Williams, Communications Officer for the College of Engineering and Physical Sciences