February 11, 2016

expert reaction to announcement on gravitational waves

It has been announced that, for the first time, scientists have detected gravitational waves which would confirm the theory of general relativity.

Prof. Marielle Chartier, University of Liverpool, said:

“Understanding the nature of bulk strongly interacting matter is a major aim in modern nuclear physics. To achieve this, we (physicists) must develop our knowledge of the equation of state and phase diagram of nuclear, hadronic and partonic matter as a function of density, temperature and isospin asymmetry. Such research is highly interdisciplinary and requires input from nuclear physics, particle physics and astrophysics. For example, astrophysical observations of isolated and merging neutron stars, using X-ray, gravitational wave or radio emission must be used to provide information on cold dense nuclear matter and its phases and structures, information that cannot be studied using laboratory experiments.”

Prof. Andrew Coates, Professor of Physics at UCL, said:

“This is a huge discovery in physics – up there with the Higgs boson, the mass of the neutrino, discovery of the electron, electromagnetism, the Copernican revolution and Newton’s laws. It confirms what has only been theory before – that gravity affects space and time. The really new thing it will allow is to peer back towards the beginning of the Universe itself – up to now we have not been able to do that. In planetary science, a similar level of discovery would be that there is indeed life beyond Earth – this may be within our reach with ExoMars and other future missions.”

Prof. Brian Cox, Royal Society Professor for Public Engagement in Science, said:

“This is a very exciting discovery for two reasons. Firstly, it confirms yet again that Einstein’s theory of General Relativity, published 101 years ago, is a supremely precise description of space and time, gravity and the evolution of the Universe. This result is a highly non-trivial prediction, and it is a triumph of high-precision experimental physics that such subtle shifts in spacetime at the level of a millionth of the size of an atom have been detected.

“Secondly, and even more excitingly, this opens up an entirely new way of observing the Universe. We can now observe collisions between black holes, probing gravity in ever more exotic and extreme situations, and look back in time far closer to the big bang than ever before. Gravitational wave astronomy opens up an entirely new window on nature.”

Prof. Alex Halliday FRS, Vice President and  Physical Secretary of the Royal Society, said:

“100 years ago Albert Einstein, a foreign member of the Royal Society, predicted the existence of gravitational waves. It’s a brilliant example of science in action that a century on scientists at Caltech and MIT have now found the evidence to support Einstein’s hypothesis.

“Being able to see these ripples in space-time, which are the signature of massive collisions in space, will advance our understanding of fundamental physics in new directions and could give us more clues about the birth of the universe at the big bang.

“This exciting news is a breakthrough in our knowledge about the universe. It shows just how much more there is left for the next generation of cosmologists to discover.”

Prof. Tom McLeish, FRS, Chair of the Education Committee at The Royal Society and Professor of Physics at Durham University, said:

“The last time anything like this happened was in 1888 when Heinrich Hertz detected the radio waves that had been predicted by James Clerk Maxwell’s field-equations of electromagnetism in 1865. But this time it has taken over a century of waiting from Einstein’s field equations of gravity, and their prediction of waves, to detecting them at last. But the wonderful connectivity of physics is shown by more than history: both Maxwell’s and Einstein’s waves travel at the speed of light. This news has sent my head spinning with delight.”

Dr David Clements, Astrophysicist at Imperial College London, said:

“Firstly this is great news for physics – direct detection of gravitational waves is like discovering the Higgs boson – there’s been plentiful evidence for them in the past, but we weren’t able to detect them. Now we have and, as with the Higgs, the physics side of this operation will now look at the detailed properties of gravitational waves, providing better and better tests of General Relativity.

“But the second side of the equation for me, as an astrophysicist, makes this even more important than the discovery of the Higgs, because today marks the day when gravitational wave astronomy starts. It gives us a whole new tool with which to look at the universe, allowing us to look at some of the most energetic events imaginable – collisions of black holes and neutron stars – in ways that just were not possible before. We now have a whole new spectrum of radiation with which to study the universe.

“It’s as if we were blind and today eLIGO has opened our eyes.”

Dr Tony Padilla, Royal Society University Research Fellow in the School of Physics & Astronomy, University of Nottingham, said:

“Every year I tell my Gravity class about the three classics successes of General Relativity: the perihelion precession of Mercury, light bending and gravitational redshift. Next year, I’ll be adding a fourth: gravitational waves! Their detection is a stunning triumph for experiment, for theory, and most notably, for Einstein. And the source of these waves is rumoured to be a merger of two black holes. Wow! Just wow! Black holes really exist. No more arguments. Looking further ahead we can look forward to a whole new era for astronomy, listening out for these remarkable signals that will teach us so much about the fundamental nature of gravity and the Universe. It’s almost as if we have grown a new set of ears, and there could be so much to hear!”

Professor Sheila Rowan, Director of the University of Glasgow’s Institute for Gravitational Research, said:

“It’s amazing to realise that we turned on our detectors on the centenary of the year Einstein’s general theory of relativity was published and at exactly the right time to receive this signal coming to us from 1.5 billion years ago – when far out in the Universe two black holes spiralled in to collide”.

“This detection marks not only a confirmation of Einstein’s theories but most exciting is that it is marks the birth of gravitational astronomy. This expands hugely the way we can observe the cosmos, and the kinds of physics and astrophysics we can do – with more discoveries to come!”

“To make this possible took a global collaboration of scientists – in Glasgow we are proud to have led a UK team that created and delivered the heart of the advanced LIGO gravitational wave detectors – the ultra-low noise suspended mirrors that a passing gravitational wave moves. These were critical to making the detection – technology is the key to enabling progress in science.”

Professor Kenneth Strain is deputy director of the Institute for Gravitational Research at the University of Glasgow and principal investigator of the Advanced LIGO project team in the UK, said:

“We’ve been involved with the LIGO and aLIGO initiatives from the beginning, and the simultaneous discovery of both evidence of gravitational waves and the collision of black holes is more than we ever could have hoped for. Many significant discoveries will be made as the field continues, which is enormously exciting. aLIGO’s discoveries will be immensely important in expanding our understanding of the universe, and we’re pleased and proud to be involved in this historic project”

Professor Jim Hough, associate director of the University of Glasgow’s Institute for Gravitational Research, said:

“I began looking for evidence of gravitational waves in 1971, and I’ve spent my career since then involved in projects aiming to discover experimental proof of their existence. My immediate reaction when we heard about the first detection was a certain amount of delighted surprise, followed by great excitement when it became clear that the evidence was solid.”

Professor Martin Hendry, Professor of Gravitational Astrophysics and Cosmology and Head of the School of Physics and Astronomy at the University of Glasgow, said:

“Einstein’s General Theory of Relativity is regarded as one of the most impressive scientific achievements of all time and the existence of black holes is one of the theory’s most startling predictions. To see such clear and direct confirmation of this prediction, and moreover that the merger of two black holes converts enormous amounts of mass into the energy of gravitational waves, is a wonderful vindication of Einstein’s masterwork a century after it was written.”

Dr Giles Hammond who led the installation of the fused silica suspensions for aLIGO at the University of Glasgow, said:

“The detection of gravitational waves is a truly international project, requiring coordination and collaboration of over 700 researchers. The UK gravitational wave community has been responsible for designing, installing and characterising the monolithic suspensions in aLIGO. The suspensions are built from fused silica and support the 40kg interferometer mirrors. Their goal is to reduce noise sources due to ground motion and thermal fluctuations, essential to produce the quiet reference frame necessary to detect gravitational waves.”

”To support the 40kg test masses of aLIGO in the quietest possible way, we are continually pushing the boundaries of our technology via fundamental research. This work has direct spin-offs into applied physics and engineering. Some examples include techniques to joint materials for space-based application and high power lasers, in addition to the development of hardware to make precision gravity measurements with sensors similar to those found in everyday mobile phones, but 10,000 times more sensitive”.

Dr Ik Siong Heng, from the University of Glasgow and co-chair of the LSC-Virgo collaborations’ Burst analysis group, said: “This fantastic discovery is a reminder of the virtues of exploring the unknown. We can now listen to the symphony of the cosmic orchestra played to us from the darkest, densest regions of the universe and eagerly anticipate the new science that the gravitational wave universe will reveal to us. This magnificent achievement was made possible by an international collaboration of researchers with strong contributions from UK research and leadership.”

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.

“The Advanced LIGO detectors are a masterpiece of experimental physics. They are the most sensitive gravitational wave detectors ever built, and they have now for the first time done what they were built to do: there was a ‘disturbance in the gravitational force’, and the LIGO detectors have felt it! We started with a well-known concept, a light interferometer, but it required new technologies that we have developed over several decades to create these extremely sensitive listening devices for gravity signals from the universe.

“This is a fantastic time for us, being on the verge of receiving completely new signals from elusive cosmological objects such as black holes.

“I started to work in the LIGO collaboration as a PhD student 1998, my work always focused on building the instruments, because I like to make things work. I am delighted that LIGO now has shown us how spectacularly it does work.”

Professor Alberto Vecchio, from the University of Birmingham’s School of Physics and Astronomy, said:

“I feel quite humble in thinking that we have just watched the last few orbits of two stellar-mass black holes moving at a third of the speed of light smashing into each other at a billion of light years from us. And we have captured the last whisper from the black hole produced by this collision.

“It makes me very proud to look at all the students and post-docs in our group that have spent many sleepless nights teasing out from the data this amazing information using the techniques that we have pioneered in Birmingham over the last ten years.

“The observation of GW150914 is the proof that binary black holes exist: they form, evolve and die. It is also the most convincing evidence to date that the strange mathematical objects predicted by Einstein’s theory correspond to those produced by Nature. This completes our quest for the last elusive experimental validation of Einstein’s theory. More significantly, it is the dawn of a new era for astronomy and astrophysics.

“The observation of GW150914 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.”

Ed Daw is a Reader in Physics at the University of Sheffield, and has been researching gravitational waves with LIGO since 1998.

“Discoveries of this importance in Physics come along about every 30 years. A measure of its significance is that even the source of the wave – two black holes in close orbit, each tens of times heavier than the sun, which then collide violently, has never been observed before, and could not have been observed by any other method. This is just the beginning.

“Imagine that your T.V. had only ever received one channel on which the shows were all rather similar to each other. One day a second one appeared which showed completely different programs, like nothing that had ever been broadcast on the old channel. Wouldn’t you want to switch over? By detecting this signal, LIGO has effectively tuned in to a new channel – a completely new way of observing the Universe.

“Gravitational waves are so completely different from light, we’re probably only just beginning to understand how they reflect and shape our Universe. For example, a gravitational wave will propagate almost completely unaltered through entire planets, star systems, galaxies….how different is that from the radio waves that your mobile phone picks up – even getting too close to a building can disrupt those signals. Light, or more generally electromagnetic waves are so much more vulnerable to interference than gravitational waves.”

Dr Jonathan Gair from the School of Mathematics at the University of Edinburgh, said:

“2015 was a landmark year for gravitational wave science. Not only has LIGO directly detected gravitational waves from a merging black hole binary for the first time, but ESA successfully launched the LISA Pathfinder satellite in December, which will pave the way for a space-based gravitational wave detector within the next two decades. A fantastic way to celebrate the hundredth anniversary of the prediction of the existence of gravitational waves!

This detection is a remarkable achievement of human endeavour, both in terms of the construction and operation of these amazingly sensitive detectors and in the analysis of the data they generate. I feel very privileged to have been involved with this work and the continued development of this new field. I am very excited to see what discoveries the next few years will yield, as we use these new observations to learn about exotic astrophysical systems, to put Einstein’s theory of relativity to the test in a new regime and perhaps also to see something completely unexpected!”

Dr Patrick Sutton, from Cardiff University’s School of Physics and Astronomy, said:

“Every time astronomers have learned how to view the universe in a new way, they’ve found things that were completely unexpected, from Saturn’s rings, to pulsars, to microwave echoes of the Big Bang. Now, on the one-hundredth anniversary of Einstein’s presentation of the general theory of relativity, we have the wonderful surprise of the first direct detection of gravitational waves. This first-ever observation of a pair of black holes, as they spiral into each other, will allow us to put Einstein’s theory to the test in the most extreme event since the Big Bang itself, and will give us insights into how black holes form and grow. The whole community is excited to see what surprises nature has in store for us next.”

Professor B S Sathyaprakash, from Cardiff University’s School of Physics and Astronomy, said:

“With this phenomenal discovery by Advanced LIGO we have opened a new window to observe violent processes in the Universe, such as merging black holes and neutron stars, supernovae, gamma ray bursts and other cosmic phenomena. At Cardiff we not only model the dynamics of these systems, but exploit these observations to understand the nature of space-time near black holes. We also use the observations to test Einstein’s theory of gravity when gravitational fields become inexorably large, and solve riddles of dark matter and dark energy. Our goal is also to motivate the next generation of detectors which will observe these violent processes right out to the edge of the Universe.

“It was nearly 40 years ago I had first heard about black holes in a public talk and it is absolutely incredible that we have today directly detect them. Our students and postdocs over the past 20 years have contributed tremendously to this exciting discovery and I am excited to share this news with all of them wherever they are today.”

Dr Stephen Fairhurst, from Cardiff University’s School of Physics and Astronomy, said:

“We have spent the last decade developing searches to detect the tell-tale signal of merging black holes emerging from the LIGO and Virgo data. With this observation, we have not only made the first detection of gravitational waves but also obtained the best evidence yet for the existence of black holes, and we’ve seen them merging for the first time. This is a spectacular confirmation of many of the predictions of Einstein’s general theory of relativity. Furthermore, this discovery heralds the beginning of gravitational wave astronomy, a brand new way to observe the Universe.”

Professor Mark Hannam, from Cardiff University’s School of Physics and Astronomy, said:

“We’ve spent the last ten years performing large computer simulations of black holes colliding, so we will know what their gravitational wave signals will look like. This helps us to find them and to measure the properties of the black holes. We now know exactly what those signals should look like – but that’s nothing compared to the thrill of observing them for real. This observation has confirmed so many things that we guessed, but didn’t know for sure – that black holes exist with tens of times the mass of the sun, and so do black-hole binaries. This has transformed our understanding of the Universe – and is just the beginning.”

Dr Nicholas Lockerbie, Reader in Physics at the University of Strathclyde, said:

“The direct detection of gravitational waves marks the dawn of a new era in astronomy. I never expected to see this event in my lifetime. Gravity has now spoken to us, across vast tracts of the Universe. For the first time in mankind’s history, we have been able to hear it – and understand what it said.

“This event – known as GW150914 – is evidence of a stunning black-hole-black-hole merger, lasting less than one second. However, its detection is the result of decades of international, scientific and technical collaboration, culminating in the matchless gravitational wave sensitivity of the Advanced LIGO detectors in the USA. I’m personally delighted and honoured that Strathclyde research and technology has also helped create the system behind this incredible discovery of gravitational waves.”

Dr Stuart Reid, from the Institute of Thin Films, Sensors and Imaging at the University of the West of Scotland, said:

“The significance of this discovery by Advanced LIGO is simply staggering. This is the first direct observation of the final (and until now, the most elusive) prediction from Einstein’s theory of General Relativity. In addition, we have the first ever direct observation of black holes, and of two black holes colliding. And finally, this opens a completely new way to observe the Universe, which will possibly change our entire understanding of the cosmos we live in.”

“We await with anticipation for further new discoveries and insight that will almost certainly be made through gravitational wave astronomy. The Universe is speaking, and for the first time, we are listening!”

“At the very point hen these two black holes violently collided and merged, they emitted energy in gravitational waves that is comparable to the total light power being emitted by all the stars in the entire galaxy. This is a staggering discovery – and we wait with excitement as the field of gravitational wave astronomy now begins!”

Prof. Des Gibson, Director of the Institute of Thin Films, Sensors and Imaging at the University of the West of Scotland, said:

“The excitement within the scientific community has been immense since Advanced LIGO moved towards its first observational run in 2015.  This has been a truly international achievement, and yet we are immensely proud of the UK contribution to the core technology. In particular, the mirror suspension technology, developed by our partners in Glasgow, has enabled these laser interferometers to observe black holes colliding, by being capable of measuring tiny distortions in the fabric of space, approaching a millionth of the diameter of a proton.”

Dr Ian Jones, from the University of Southampton’s Mathematical Sciences department, said:

“When I was first shown the black hole signal in the data I could barely believe what I was seeing.  I have been working in the field of gravitational wave astronomy for over 20 years, and it felt as if we had been discussing this sort of signal for a very long time. To then actually be able to see, by eye, the signal in the data, with all its characteristic features, was amazing – all the more so given that it was so strong, and came so early on in the data taking.  It felt as if Nature was not only doing what we predicted, but was, finally, happy to let us take a look.  This makes me even more excited about the prospects of detecting gravitational waves from neutron stars, which form the focus of my own area of research.  While black hole observations help us test physics at the extremes of strong gravity, neutron stars help us test physics at the extremes of high density, and could show us what happens when Nature packs the mass of the Sun into a ball the size of a city.”

Professor John Womersley, physicist and Chief Executive of the UK’s Science and Technology Facilities Council said:

“It has taken 100 years and the combined work of many hundreds of the cleverest scientists, engineers and mathematicians on Earth to prove that this key prediction of Albert Einstein is correct, and show that gravitational waves exist.  Of course Einstein was always the smartest guy in the room. Today’s results also remind us just how important the UK’s contribution to world leading science is — I’d certainly like to think that some of the smartest people on Earth today are living and working in the UK”

Dr Danny Steeghs, Associate Professor and Reader in the Astronomy & Astrophysics group in the Department of Physics, University of Warwick, said:

“This is a fantastic technical achievement by the LIGO team, a highly deserved reward after many years of effort and technology development. A century after Einstein’s theory of General Relativity was presented, we now have a convincing, direct detection of a gravitational wave signal produced by a pair of black holes. It was fortunate that such an event occurred so soon after the detector upgrades, and a long anticipated window on the Universe has now opened.

“I have been collaborating with the LIGO/Virgo consortium, in particular to look for signatures of any gravitational wave events they detect in visible light. Through this collaboration, we have been aware of the possible signal since its discovery. We (Warwick and partners) are about to deploy a robotic telescope (GOTO) that is designed to chase optical signatures of events detected by Advanced LIGO/Virgo and are delighted to see LIGO delivering real detections.”