Sir Jim

Arise!

Today my good friend and colleague Jim Hough (otherwise known as Professor James Hough FRS of the University of Glasgow) goes to Buckingham Palace to be knighted for his immense contributions to gravitational wave research, and of course to the first detection that LIGO made in 2015. I thought I would permit myself to ramble on a bit here about how deserving he is of this award, how his life and work essentially trace out the whole story of gravitational wave detection so far, and how we really need more Jims in science! 

Jim Hough
Jim Hough (credit: Glasgow University)

Jim won’t like this post, because he is one of the most modest people you could meet. Give him a compliment on what he has done, and he is always at pains to remind you how important the contribution of his students, collaborators, and other colleagues has been. And how it was not that great anyway, since we still have much more to do.

At the same time, Jim’s standards for himself and others are extremely high. His research group at the University of Glasgow, now known as the Institute for Gravitational Research (IGR), pioneered many of the key technologies that made the LIGO and Virgo detectors the most sensitive displacement-measuring instruments ever built and allowed LIGO to make the Nobel-Prize-winning first detection of gravitational waves. 

Big science needs a special kind of leadership

Watching Jim guide others’ research has always been a pleasure for me. He’s invariably full of praise for a good step forward. Should a correction be needed, he will offer advice almost with diffidence, yet in a way that allows everyone to understand immediately why he must be right: “Well, I’m not so sure that is the right way to go about it …” he will say, thoughtfully and slowly, as if he needs to think it through himself (even though of course he knows exactly what is wrong right away); and then “Why not think about it this way …” He has mentored several of the top people in our field, and they all seem to inherit his exacting standards for their own work alongside a wonderfully cooperative approach to working with others. 

Working together is a key aim. If you work for him in his group, you soon get to feel you work with him. There is mutual respect, teamwork rather than internal competition. This, I think, partly explains another striking feature of Jim’s group: he has succeeded in training many talented women scientists, and he was doing this long before achieving gender balance became a priority in physics. An outstanding example is Prof Sheila Rowan FRS, an international leader in our field (she chairs, for example, the Gravitational Wave International Committee), who is currently Scotland’s Chief Scientific Advisor.

Too often, the public image of physicists is of either the ego-driven ruthlessly competitive scientist (name your favourite!) or the nerd (as in television’s “Big Bang Theory”). But big science, such as LIGO, works best when people work together with mutual respect and constant communication, sharing the ego rewards when they come, and using their social skills as much as their mathematical and technical ones in order to move the project forward. Jim provides a great example of this kind of leadership, and so by the way do the three LIGO Nobelists of 2017: Rai Weiss, Kip Thorne, and Barry Barish

One of the founders of GW physics

Jim was in gravitational wave detection from the start. He got his PhD under the supervision of Ron Drever, then a professor at Glasgow, and later one of the founders of LIGO. It was just at the time (1970) that Joe Weber in the USA was claiming to have made the first detections of gravitational waves with his bar antennas. This was exciting, but Joe’s claim looked extravagant — he said he was detecting events roughly once a day, and the sensitivity of his detector meant that each one had to be carrying a huge energy flux, at least 105 times brighter (for a few milliseconds) than the Sun. So Ron asked Jim (and a handful of other young Glasgow scientists, most still in the field today) to work with him to build their own pair of antennas, to check the claim. Several other groups around the world, including in Munich and Rome, embarked on similar experiments.

Remarkably, Ron and Jim’s twin detectors registered one significant coincident event that could not be explained away, but because it could also not be checked against any other detectors – they were the only ones on the air at the time – it remains an historical enigma. (I am reminded of Blas Cabrera’s 1982 magnetic monopole, another unverifiable one-off.) On the whole, however, the ensemble of new bar detectors registered nothing else of significance, certainly nothing like once a day, and this led the physics community to reject Weber’s claims.

So then the question for all these physicists who had just made their bar detectors irrelevant was: what next? 

Rai Weiss at M.I.T. was telling people that laser interferometers would do better than Weber-like bars at catching these weaker signals, and Ron and Jim had been led by their own thinking in a similar direction. The Munich Max Planck group, led by the great Heinz Billing, also agreed with Rai and also embarked on this route. Out of these small beginnings in the 1970s, out of just three groups with a few people in each, grew today’s mammoth 1000+ LIGO-Virgo collaboration.

Time to think big

I won’t go into the whole history, but a few facts are important here. Ron accepted Kip’s invitation to go to Caltech in 1979, leaving Jim in charge at Glasgow. Kip wanted Ron because he had already made several creative innovations, which have since proven their worth as standard features of today’s interferometers. Jim was of course determined keep up this innovative tradition in Glasgow after Ron left.

The field rapidly began thinking big. In the mid-1980s the Munich group made the first proposal, for a 3-kilometre-scale detector. Ron and Kip got together with Rai to propose what is now the 4-km LIGO. Groups in Italy and France new to the field formed Virgo and got their 3-km proposal out.  And Jim decided to put in a UK proposal for a more modest, but easier and faster to build, one-kilometre detector in Scotland, not far from St Andrews. 

This proposal got me into the field, and gave me the pleasure of working with Jim. In order to write a convincing proposal to the UK science funding body (then called SERC), Jim needed a science case: what could such a detector observe, what could be learned from observations? I was in Cardiff (University of Wales, Cardiff, as it was then known), and I had worked on the theory of neutron stars and binary systems, so Jim invited me to write that part of the proposal. I wasn’t sure I wanted to get into big science. He was persuasive! I joined.

That first proposal in 1986 wasn’t successful, but it led SERC to suggest we cooperate with the Munich group and propose something bigger that could be funded jointly by Germany and the UK. This was a far-sighted idea and it led to what we call the GEO collaboration, which is still going strong, now as a part of LIGO. 

The 1989 joint GEO 3-km proposal initially got plenty of positive reaction in both countries, but in the end it did not get funded, partly because of UK science politics and partly because German reunification happened in 1990 and shifted the spending priorities in Germany. It was hard to argue against the German agency’s point of view: reunification had to be done right if Europe was to remain peaceful after the Berlin Wall came down.

A setback leads to a brilliant recovery

But for us this was an immense and unexpected setback. To my mind, the measure of Jim Hough is how he held his research group and research aims steady despite this. It was clear by this time that the LIGO and Virgo collaborations were soon likely to get approval for their detectors, so how could Glasgow survive in this field?

Some group leaders would have given up and done something else; the leader of our German partner group did just that. But Jim kept his group together, and kept morale up, by deciding that they were going to stay at the leading edge of gravitational wave technology. Gravitational wave science was going to have a long future, marked by successive generations of more and more sensitive detectors, and Glasgow was going to invent the technologies they required.

Jim’s reasoning was that building these big detectors — something nobody really knew how to do yet at the level of detail that was going to be needed — would absorb so much of the effort of the US, French, and Italian scientists in our field that they would not have much spare effort to devote to looking ahead at the technologies that would be needed to keep improving the detectors, after their first versions had been built and operated.

We knew enough in 1990 about likely gravitational wave sources to know that the expected sensitivities of these first big detectors were not guaranteed to yield detections, and indeed history proved this to be correct. The LIGO proposal had explicitly envisaged a second, advanced stage of sensitivity, which would all but guarantee detections. Again, history proved this to be correct. But much of the technology for Advanced LIGO existed only on paper. Or not at all. 

So Jim saw the opportunity and went for it. The Max Planck Society also showed resolution and vision: they kept our German partner group together by inviting a young Stanford scientist, Karsten Danzmann, to take over the Munich group and move it to the Leibniz University, Hanover.

Karsten immediately began thinking creatively about the future himself, and he secured funding for an intermediate-scale instrument: a 600-m interferometer that would be an excellent development platform for moving the new technologies out of the laboratory and getting them ready for the advanced versions of the 4-km detectors. And as a bonus, GEO600 (as we call it) would employ the advanced technologies that would be created in Glasgow and Hanover to become a kind of mini-advanced detector, able to compete with first-stage LIGO in sensitivity.

This insight, that the future of the field needed technology labs, that there were advantages to being a group that wasn’t building a big detector, was brilliant. It led Jim to Buckingham Palace today. 

GEO600 optical components.
GEO600 optical components (AEI).
Getting ready for tomorrow’s detectors

Jim’s group in Glasgow and Karsten’s in Hanover certainly had more fun than anyone else in the field during the 1990s. Experimental physicists typically enjoy time in the lab more than anything else in their jobs. Building the immense LIGO and Virgo detectors, by contrast, was disciplined hard work, where ground-breaking, ultra-high-precision engineering was followed by painstaking and often tedious trouble-shooting.

Getting the big instruments to work as designed pushed the limits of what was possible, technically and organisationally. After 8 difficult years, Barry Barish took charge of LIGO in 1994 and made the project work. Along the way, LIGO lost Ron Drever, the creative genius who simply couldn’t leave the lab, couldn’t fit into the business suit needed to build a big detector. (Ron still deserved, and received, huge credit for the success of LIGO. Sadly he died before the Nobel Prize was decided, and that gave Barry a chance to receive his due recognition. The restriction of the Nobel Prize in Physics to three individuals produces strange anomalies for big-science projects.)

Out of Glasgow came, among other advances, the technique of signal recycling, devised by the late Brian Meers, followed by the monolithic suspension system, a project led by Sheila Rowan. Barry Barish, understanding the importance of these technologies and others developed by Glasgow and Hanover to LIGO’s future, brought the GEO collaboration into LIGO before the end of the 1990s.

Signal recycling was tested in GEO600 in the period 2005-10 and then implemented in Advanced LIGO, ready for the first detection, GW150914. Sheila Rowan’s suspension system uses glass fiber suspensions for mirrors and other optical components rather than wire, and it was also demonstrated in GEO600 during the 2000s and then implemented in Advanced LIGO. It contributed to the first detection by helping reduce the amount of noise in the frequency band where that signal had most of its power. Both technologies will be standard in all big detectors for a long time to come. 

GEO600 monolithic suspension close-up.
Monolithic suspension: close-up of the glass fiber bonded to the glass “ear”, which is bonded to the body of the GEO600 mirror. The bonding is glass directly to glass, with no intermediary layer of glue, which would create friction and make the mirrors noisier at observation frequencies. (AEI, H. Lück)

And while on the subject of key technologies, let’s note Glasgow’s important contribution to the optical measurement package that was part of the LISA Pathfinder mission (LPF). Launched by ESA soon after GW150914, LPF was designed to test the new technologies needed for the future LISA space-based gravitational wave detector, and it did so with flying colours, beating not only the performance goals set by ESA but also the much more stringent nominal measurement accuracy required for the individual LISA spacecraft themselves. The Glasgow group’s contribution was led by Harry Ward, who has been part of the Glasgow gravitational wave effort since the 1970s.

LISA is scheduled for launch in 2034, so here again Glasgow is developing the technologies of the future. And it is worth remarking that Jim was part of the early LISA proposal team back in 1995; so was the equally visionary Karsten, who has led the LISA project ever since. 

Vision

Seeing ahead, far ahead, is one of Jim’s most notable characteristics. Another is that he sees both the wood and the trees. Jim placed Glasgow at the core of the LIGO experimental effort by combining his people skills with his vision of the future. He has the ability to understand what is needed long-term, and the amiability to motivate his team with this vision. His knighthood is a splendid recognition of this, and I hope that younger scientists will be inspired by the honour to study his example and emulate it. It can lead, after all, to the very top.

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P.S. If you would like to see the man himself talking about his science, and besides that driving his red sports car, he gave a very interesting interview in the Scienceface series. It was filmed before LIGO was converted to Advanced LIGO using new technologies, key ones from his group. He predicts here that the first detection will happen in 2016 or 2017, so he was a little (but not much) on the conservative side. Also on the same webpage is an interview with Sheila Rowan explaining in simple terms the monolithic suspensions.

Jim being interviewed in the Scienceface series.
Jim being interviewed by Annalie Schutz in the Scienceface series (AEI)

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