On 14 September 2015 at 10.50:45 UK time, an international team of scientists including the University of Birmingham detected gravitational waves for the first time, using the twin LIGO instruments in Louisiana and Washington state in the US. The detection of these waves will help us to understand and explore the mysteries of our universe.
Confirming Einstein's theory
Gravitational waves are generated by some of the most catastrophic, violent motions occurring in the universe, such as the collision of black holes. The gravitational waves detected on 14 September 2015 originated from two black holes, each around 30 times the mass of our Sun and located more than a billion light years from Earth, merging to form a single, more massive black hole. The discovery confirms one of Albert Einstein’s major predictions in his 1915 general theory of relativity.
Professor Alberto Vecchio, from the University of Birmingham, whose team has developed the techniques to extract the properties of the sources from the gravitational wave signatures, and has provided a significant contribution to the analysis of the LIGO data, said: ‘This observation is truly incredible science and marks three milestones for physics: the direct detection of gravitational waves, the first observation of a binary black hole, and the most convincing evidence to-date that Nature's black holes are the objects predicted by Einstein's theory.’
Gravitational waves carry unique information about the origins of our Universe, and studying them is expected to provide important insights into the evolution of stars, supernovae, gamma-ray bursts, neutron stars and black holes.
When a gravitational wave passes by the detector, it stretches and squeezes space-time by a tiny amount. The Advanced LIGO detectors use incredibly sensitive equipment to detect these ripples, indicating a gravitational wave; they have never been directly observed before, until now. The University of Birmingham has been involved in the Advanced LIGO project since its inception. Birmingham physicists have built hardware components now installed in the LIGO instruments, they developed one of the main optical simulation tools, FINESSE, and contributed significantly to the design and commissioning of modern gravitational wave detectors. The Birmingham group has developed the techniques essential to tease out the signatures of gravitational waves from the data and has provided a major contribution to the analysis of the LIGO data.
A better understanding of our universe
This discovery will open a new door on the cosmos and provides us with a better understanding of our universe, and its most violent manifestations. In the future LIGO may even pick up gravitational waves generated just a fraction of a second after the Big Bang.
Professor Andreas Freise, from the University of Birmingham’s School of Physics and Astronomy, said: ‘It is amazing to think that we have been able to measure the echoes from the birth of a new black hole that happened more than a billion years ago… there was a ‘disturbance in the gravitational force’, and the LIGO detectors have felt it!'
The next leap
In the near future, the Advanced LIGO detectors will be increased to full power, boosting their sensitivity to gravitational waves, which will allow more distant events to be discovered. With increasingly sensitive instruments and new detectors to be constructed in other locations around the world, soon we may discover things that above and beyond anything we could have predicted.
A second detection
On 26 December 2015, at 03:38:53 UK time a binary black hole coalescence named GW151226 was observed.
The gravitational waves of the Boxing Day signal were produced by a pair of black holes, of around 14 and 8 solar masses, that travelled for over a billion years before reaching Earth. LIGO observed the final second of this pair of black holes before they collided, at half of the speed of light, to form a new black hole.
The signal was longer and quieter than that observed in September, making it more difficult to detect, but it confirms the existence of a whole population of such events.
Professor Alberto Vecchio "It is the dawn of a new era for astronomy and astrophysics"
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