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Glasgow scientists are taking part in an international search for gravitational waves – ripples in the fabric of spacetime thought to have been created by the Big Bang.

The University is one of a number of UK collaborators, including the Universities of Strathclyde, Cardiff and Birmingham, working on the production of 25 new assemblies for the Laser Interferometer Gravitational-Wave Observatory (LIGO) facility in the United States – a network of detectors designed to search for these elusive waves.

The LIGO project is funded by the US National Science Foundation (NSF), LIGO also allows scientists to look inside the most violent events in the Universe such as black-holes. By increasing the sensitivity of the LIGO detectors by a factor of ten, the upgrades will greatly increase the chances of finding gravitational waves and open a new observational window on the Universe to test current theories and models.

The UK’s Science and Technology Facilities Council (STFC) is contributing £8.5m to the multimillion-dollar upgrade project, named Advanced LIGO, and is managing the UK’s overall involvement.

The UK teams will provide suspension systems which help to ensure that the ultra-sensitive silica mirrors at the heart of the upgraded detector will not be influenced by ground-borne noise.

The detector is sensitive to movements a hundred million times smaller than an atom so it is vital to ensure that stray noise sources are eliminated. Technology developed in the European GEO-600 project (a gravitational wave detector in Hannover, Germany) forms the basis of the systems being supplied for Advanced LIGO. Shipping of the new parts to the US is currently underway.

The completion of the UK-made upgrades comes as the LIGO Scientific Collaboration (of which the UK-German GEO600 group is a founding member) and the Virgo Collaboration announce new results that have significantly advanced our understanding of the early evolution of the Universe.

In a paper published in Nature today (20th August) the scientists explain how LIGO observations have set the most stringent limits yet on the amount of gravitational waves that could have come from the Big Bang in the gravitational wave frequency band where LIGO can observe. In doing so, they have narrowed down the possibilities of how the Universe looked in its earliest moments.

Prof Jim Hough, UK Principal Investigator for the GEO600 project and Professor of Physics at the University of Glasgow, said: “The Institute for Gravitational Research at Glasgow has strong participation in both the data analysis and instrument design activities within the LIGO Scientific Collaboration.

“This paper helps demonstrate the real excitement and potential of the field of gravitational wave studies to further our understanding of the Universe.”

The Big Bang is believed to have created a flood of gravitational waves when the universe was very young. These waves still fill the universe today as background ‘noise’, similar to random ripples on a pond on a windy day. The strength of this gravitational wave background is directly related to the way the Universe was in the first minute after the Big Bang, and the fact that researchers have not found any signal so far already tells them the maximum strength which this background could have.

This information builds on what has been learnt from studying the cosmic microwave background – heat radiation that tells us the way the universe was when it was about 380,000 years old.  This is still very young compared with its present 14-billion year age, but much older than the time period probed by gravitational waves.

"Since we have not observed the gravitational waves from the Big Bang, some of these early-universe models that predict a relatively large background of waves have been ruled out," said Vuk Mandic, assistant professor at the University of Minnesota.

"We now know a bit more about parameters that describe the evolution of the universe when it was less than one minute old," Mandic added.

Justin Greenhalgh, from the STFC Rutherford Appleton Laboratory, said: “Once it goes online, Advanced LIGO will allow us to further advance this research into the evolution of the early Universe. It will be able to detect cataclysmic events such as black-holes and neutron-star collisions at 10-times-greater distances and will be sensitive to sources of extragalactic gravitational waves in a volume of the universe 1,000 times larger than we can see at the present time.  The new sensitivity of the instruments will propel our work forward and allow us to reveal more of the hidden mysteries of our Universe.”

Gravitational waves carry with them information about their violent origins and about the nature of gravity that cannot be obtained by conventional astronomical tools. The existence of the waves was predicted by Albert Einstein in 1916 in his general theory of relativity.