Category Archives: Institute of Physics

Frontiers of Physics 2012 at Trinity College Dublin

I spent last weekend at the Frontiers of Physics conference at Trinity College Dublin. This is an annual meeting hosted by the Institute of Physics in Ireland; the aim is to establish links with secondary schools all over the country and to present the latest developments in physics and physics teaching. This year it was Trinity’s turn to host the conference and it was excellent, not least due to the superb organisation of IoP teaching coordinators Paul Nugent and David Keenahan.

Saturday morning featured some great lectures in the historic Schrödinger lecture theatre, located in the Fitzgerald building of Trinity’s School of Physics. Visiting this building always feels like coming home for me, as I did my PhD in one of the labs downstairs and gave tutorials in the Schrödinger theatre as a postgrad. The library on the second floor of the Fitzgerald building is becoming a notable science museum, with exhibits for many great scientists associated with Trinity such as Preston, Joly, Fitzgerald and Walton. (Schrödinger himself was a Professor at the Dublin Institute for Advanced Studies, not Trinity, but the theatre is named after the famous ‘What is Life? ‘ series of public lectures he gave there there).

The Schrödinger lecture theatre on the top floor of the Fitzgerald building

The Fitzgerald building, home to the physics department at TCD. The bubbles are a mockup of a sculpture that will honour the department’s Nobel laureate Ernest Walton

I won’t describe the lectures in detail, but three stood out for me:  ‘Tuning in the radio sun’, a description of solar astronomy at Birr Castle by Prof Peter Gallagher, head of the solar physics group at Trinity: ‘Tiny but mighty’ , a superb introductory lecture on nanotechnology by Prof Jonathan Coleman, head of the low-dimensional nanostructures group at Trinity: and ‘CERN, the LHC and the Higgs boson’  by Steve Myers, director of accelerators and technology at CERN.

Yes, that Steve Myers, the Belfast-born director of accelerators at CERN. Steve gives great talks on the nuts-and-bolts of the Large Hadron Collider and this was the main reason I was at the meeting. I’m scheduled to give yet another talk on the Higgs boson next month, so it’s important to catch lectures like this whenever I can. There’s nothing like hearing details of the experiment from the horse’s mouth and Steve certainly didn’t disappoint.

Steve Myers in action at the conference

On the teaching of physics, Dr Karen Bultitude of University College London gave an interesting lecture on ‘Gender Aware Teaching Practice’. As everyone in the discipline knows, a marked gender imbalance persists amongst students choosing physics; Karen’s main point was that all of the research done in this area indicates that making physics more ‘girly’ simply does not work, and she had some important tips for making physics more approachable for both genders. (Once more, it raises the question how a certain video at the European Comission ever saw the light of day, but let’s not go there).

After the lectures, we were treated to lunch in Trinity Dining Hall;  I think those who had not visited the college before were blown away by the Hall and by the walk across Front Square. Maybe I notice this sort of thing more after another trip to the US (see previous post), but the best was yet to come..

The Dining Hall at Trinity

Front Square at Trinity College

After lunch, we were treated to an exhibition of Walton memorabilia by  Dr Eric Finch. (Ernest Walton, a former Head of Physics at Trinity, won a Nobel prize for splitting the atomic nucleus with Cockroft in 1932). Eric had many fascinating things to show us, not least the famous letter where the brilliant young scientist describes his ‘red-letter day’ to his fiancee. Best of all, the exhibition is currently situated in Trinity’s Long Room, one of the most famous libraries in the world and a sight well worth seeing in it’s own right.

Dr Eric Finch at the Walton exhibit in the Long Room

The Long Room at TCD – it really is like this

Finally, we all trooped back to the physics department to see the Monck observatory. Since my time at the college, an observatory has been installed on the roof of the Fitzgerald building, consisting of an Atmospheric and Space Weather Monitor (outside radio antenna) and a Schmitt reflecting telescope (inside the dome, see below). Brian Espey, Professor of astrophysics at TCD,  described the operation of the telescope and we each had a peep. The observatory must be one of the most centrally located telescopes anywhere in the world- however, apparently the light pollution is not as bad as you might expect because the college is a quiet island in the centre of the city at night. I’m told the main problem is the use of floodlights for rugby practice!

The new dome on top of the Fitzgerald building

The Schmitt reflector inside the dome

The radio antenna for atmospheric measurements

All in all, a great meeting in a superb setting. The Frontiers conference takes place in a different venue each year, but it’s hard to compete with 400 years of history…

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The Royal College of Surgeons and the Institute of Physics

I attended a very enjoyable blacktie dinner at the posh Royal College of Surgeons in Dublin on Friday. The occasion was the annual meeting of the Institute of Physics in Ireland, the Irish branch of the umbrella group for physics in the UK in Ireland. I always enjoy these occasions, it’s a great way to catch up with colleagues from schools and colleges around the country. This year was no exception and the evening also featured a very enjoyable pre-dinner lecture by Nobel laureate Bill Phillips.

The Royal College of Surgeons on Stephen’s Green in Dublin

In previous years, the IoP meeting stretched over a weekend but we decided to try a single-day meeting this year. Events included an overview of current research in the different colleges, the Rosse poster competition for postgraduate students, and a ‘physicist in the chair’ interview with Bill Phillips. The meeting went on all day but I only caught the dinner and talk due to teaching commitments.

Bill’s lecture was very entertaining. Entitled ‘Time, Einstein and the coolest stuff in the universe’, he gave a simple overview of the hows and whys of laser cooling (the cooling of atoms to extremely low temperature in order to study them in slow motion). From a description of the Heisenberg Uncertainty Principle to Bose -Einstein condensates, the talk was clearly accessible to students yet worked well with a roomful of professionals. I have often noticed this before; people love being told what they already know (and we are all on the lookout for tips in science communication). My only complaint was that the lights were too bright during the during the lecture and too dim during the meal, wrong way round!

Cool atoms: a Bose-Einstein condensate

At dinner, my nearest neighbour turned out to be a climate skeptic. I was intrigued as one rarely encounters skeptics of the theory of man-made global warming amongst professional physicists nowadays. However, I didn’t hear any new arguments, merely a discussion of our ignorance of the role of cloud formation in weather. (A valid point, but hardly a reason to disregard the well-established correlation between greenhouse gas emissions and temperature rise). Indeed, my neighbour seemed unaware of the excellent research being done in this area by several physicists in his own department.

After dinner, a few of us retired to a nearby hotel bar to catch up on the latest in physics, not least, the breaking news of the resignation of the head of the OPERA neutrino experiment. All in all, an interesting night out for a nerdy physicist..

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A tour of Irish universities

This week I’m on tour, giving the annual Tyndall lecture of the Institute of Physics to secondary school students. Yesterday I gave two lectures at University College Cork, today I was in the University of Limerick, tomorrow I’ll be at NUI Galway and on Friday I’ll be talking in Queen’s University Belfast. The biggest event is a set of twin lectures in the main hall of the RDS in Dublin on Thursday.

I decided to give a talk titled ‘The big bang – is it true?’ because this is the question I am most frequently asked. It is also the title of my book-in-progress so the tour is a good dummy run (I gave a similar talk to the Graduate School of Arts and Sciences at Harvard last year).  The abstract can be found on the poster below and the slides are on my Seminars Page.

Tyndall 2012 poster

So far, the lectures are good fun. I address the question by giving a brief overview of the main experimental discoveries that underpin the big bang model, with a little bit of theory along the way. I also explain the main flaws of the model, not least the problem of the singularity (while we have a highly successful model of the evolving universe from its first moments, we have no knowledge of the bang itself, or even know if there was a bang. Nor will we, until we learn how gravity, space and time behave on the quantum scale). I am constantly amazed by the number of scientists who are unaware of this problem.

Lecturing at the Royal Dublin Society

There are always plenty of questions afterwards. I enjoy this part the most, it’s astonishing how the same questions come up agin and again. What happened before the bang? What is outside the universe? How will it end? All in all, the tour is great fun if a little tiring – a lot of traveling and searching for lecture rooms and hotels.

I’m also becoming an expert on university campuses in Ireland. My favourite so far is University College Cork. Beautiful, old and tiny, it is nicer again than Trinity College Dublin. On the other hand, the University of Limerick is very like University College Dublin with its fantastic grounds and playing fields.

Meanwhile, the future of my own college (Waterford Institute of Technology) remains uncertain. Local interests have been campaigning for many years for a regional university and it is true that the city and surrounding regions have suffered by not having a university. (The best and the brightest school-leavers head to college in Cork and Dublin and don’t come back – not to mention the problems in attracting industry to the region). As WIT is respected academically for its research output, there is now a strong political wind to upgrade the college to university status. However, the proposed upgrade has triggered a campaign to amalgamate and upgrade all the Institutes of Technology to university status. Like many academics, I think this would be a pity because the binary system of universities and Institutes has served Ireland very well (the latter are of slightly lower standard and more practical bent). So it’s a tricky situation, hard to know what the best solution is..

Update

Galway was fun, but the lectures in the Royal Dublin Society were hard work. A huge venue, there was a great buzz but it was a little difficult to keep the students focused and not easy for them to ask questions afterwards. They seemed to enjoy the talk all the same. Belfast was the opposite; a much more intimate venue and the quietest students so far. The campus was stunning but my fancy new iphone doesn’t seem to have saved my photographs. Tomorrow it’s Carlow and then back to Waterford at last…

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Institute of Physics (Ireland) Spring Weekend

The teaching term ended with the Spring Meeting of the Institute of Physics in Ireland. These annual IoP weekends are quite unique as they are more relaxing than a technical conference and a great way of keeping in touch with physicists from all over Ireland. At the same time, there are usually plenty of good talks on general topics and this year was no exception. As ever, as well as the seminars, there was a physics pub quiz on Friday night, an enjoyable conference dinner on Saturday and a highly competitive postgraduate poster competition throughout the weekend (the winners are listed on the meeting website above).

The theme of the 2010 meeting was particle physics and a strong program of talks was offered on Saturday: a brief history of 20th century particle physics (by Peter Kalmus of UCL), a description of last year’s accident at the LHC (by Steve Myers, director of accelerators at CERN), a description of the upcoming experiments at the LHC (by Ronan McNulty of UCD and the LHCb experiment), an overview of recent developments in measurements of the cosmic microwave background (by Hiranya Peiris of UCL), and a brief summary of applications of particle physics in medicine (by Lynn Gaynor of the Mater Misercordiae University Hospital). You can see the full programme on the IoP website.

Lecture Summaries

I thought it was a really good idea to start with a general overview of particle physics and Peter Kalmus didn’t certainly didn’t disappoint. Starting with a slide on Rutherford’s discovery of the nucleus, Peter traced the evolution of particle physics from 1911 to the 1970s. From the beginning, he placed great emphasis on the relation between theory and experiment, and between the fundamental forces and particles, explaining how neutrinos were ‘invented’ (predicted) by Pauli and pions by Yukawa, and describing the subsequent experimental discovery of these particles. Then it was on to the particle zoo of the 1950s, where unexpected and unwanted new particles were suddenly being discovered regularly and experimentalists ‘faced the prospect of paying a fine”! The simplification of the new particle physics by the development of quark theory by Gellman and Zweig was explained and the discovery of evidence for quarks in the famous scattering experiments at SLAC described. Finally, Peter explained the prediction of new heavy particles (W and Z bosons) from the elecro-weak unificaton program of Salaam, Glashow and Weinberg and went on to decribe his own role in the discovery of these particles in the famous CERN experiments.

Steve Myers stared his talk with one of my favourite slides (below), explaining succintly the importance of the TeV energy range for both particle physics and cosmology. He gave a brief overview of the engineering challenges involved in achieving beam collisions at that energy, touching on almost every aspect of engineering technology imaginable, from the civil engineering projects in the tunnel build to the use of superconducting magnets for beam bending, and the challenges of maintaining the extremely low temperatures and extremely high vacuum necessary for the experiments. He then gave an overview of last year’s accident and the steps taken to repair the damage and ensure such an event does not re-occur  (and yes, it did come down to one joint that was simply not soldered, although other faults were subsequently found). All in all, Steve’s talk was a salutary reminder that the LHC is not just a large scale experiment, but a whole industry.

BB time/energy line: note how the LHC energy is only slightly higher than the Tevatron, while cosmic ray collisions are much more energetic

Ronan Mc Nulty then gave a brief overview of the how and why of the experiments that will be done at the LHC. Central to this talk was an explanation of the role of symmetry in particle physics. By slid three, Ronan was talking about Noether’s theorem – a theorem of fundamental importance in physics that states that for every observed symmetry in physics, there is a corresponding law of conservation. He then moved on to the difference between local and global symmetries and how the masses of the W and Z bosons suggest an extra field in nature – the famous Higgs field. In the second part of his talk, Ronan explained the experimental approach of the four experiments at the LHC and how the LHCb experiment differs by talking a tangential slice of the beam rather than the cross-sectional ”cathedral’ approach of the larger detectors. He finished with an overview of possible discoveries at the LHC, including candidates for dark matter. I couldn’t do justice to Ronan’s succinct talk,  but you can find the slides on the IoP website.

Dr Hiranya Peiris then gave a talk on current measurements of the cosmic background radiation and how they constrain models of cosmic inflation. This was a timely reminder of the connection between cosmology and the world of particle physics. As particle accelerators reach higher and higher energies, we can create and study particles that have not existed since shortly after the Big Bang; similarily, there is much information for particle physicists in the study of the cosmic background radiation. It is often forgotten that the basic idea of inflation was first postulated by particle physicist Alan Guth in order to address a problem in grand unified theory (the lack of obsevation of magnetic monopoles). Dr Hiranya’s talk was extremely clear and to the point;I won’t say more on it here but you can find the slides on the IoP website.

The final talk of the day was a seminar on applications of particle physics in medicine. Medical application is often quoted as one of the major spinoffs of particle physics, so it was good to hear a full talk on the subject. Dr Lynn Gaynor brought us up to date with a description of advances in X-ray imaging, radiotherapy, nuclear medicine and positron emission tomography. She finished the talk by pointing out that medical physics is a very exciting career opportunity for a physicist, with a workload including the administration of physics-based therapies for patients, the teaching of radiation physics courses to medics and the involvement in innovative research projects.

Physicist in the Chair

On Sunday morning, the ‘Physicist in the Chair‘ session featured Prof Alex Montwill, Ireland’s best known particle physicist. It was a highly appropriate choice as Alex was one of the very first Irish scientists to work at CERN and led a particle physics group at UCD for many years. It was a fascinating interview, with the legendary Tony Scott of UCD giving Alex the ‘This Is Your Life’ treatment, from his flight from Latvia after the war to Ireland, to his career at UCD. This was also another mini-talk on the history of particle physics, as Alex described the role of his group in the discovery of kaons. [The direct successor of that UCD particle group is the current group led by Ronan Mc Nulty that has a major involvement in the LHCb experiment, see above]. Alex taught legendendary 4th year courses in quantum theory and particle physics at UCD for many years and his thoughful approach spawned a whole generation of students interested in the philosophy of quantum physics. The interview also touched on Alex’s activities in the communication of science; an expert chess and international bridge player, he became very well known as a communicator of science through the radio series ‘The Laboratory of the Mind’ on RTE Radio 1. Alex also recently published the popular science book ‘Let there be light’ with Anne Breslin (more on this here).

Panel discussion

The weekend finished with a panel discussion on Irish membership of large scale scientific instruments, chaired by IoP President Dame Jocelyn Bell-Burnell (Ireland is not a member of CERN or of the ESO). The panel comprised four physicists: Dr Sheila Gilheany of the IoP, Dr Paul Callanan of University College Cork, Dr Kevin McGuigan of the Royal College of Surgeons and myself. Each of us gave a 5 min presentation of reasons for and against and questions were then taken from the floor. Of course, you might expect a roomful of physicists to be broadly supportive of the idea and so it transpired (although Kevin made some cogent arguments against, which I won’t describe here). My own argument was that Ireland cannot afford not to join such facilities for four reasons:

1. Experimental – small countries simply don’t have the facilities for big science, so this is our only way to do it

2. People – it is very important that our best young scientists get to train and work with the very best

3. Knowledge industry – large scale contracts in advanced technology (software and hardware) are awarded primarily to members

4. Politics – CERN and ESO are examples of historic and successful co-operation between different European nations that Ireland should not snub

All in all, it was a super weekend, courtesy of the Institute of Physics. Next day, I flew to Geneva for a ski holiday: on the same flight were Ronan and Tara of the UCD group and Steve Myers (above), all on their way back to CERN for Tuesday’s switch-on! I was delighted to see the event got frontpage coverage in the French, Swiss and German press the next day (if not the British, see post below).

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Institute of Physics Spring Weekend

This weekend I was at the annual spring meeting of the Institute of Physics in Ireland in Wexford. I always enjoy these weekends – more relaxing than a technical conference and a great way of keeping in touch with physicists from all over Ireland. As ever, there were good seminars, a physics pub quiz and discussions of science and philosophy over breakfast, lunch and dinner (not to mention a 32-strong Wexford choir who gave superb after-dinner entertainment). At the same time, there was a serious side to the weekend with committee meetings, the Annual General Meeting and a highly competitive poster competition for postgraduates.

The theme of the seminars on Saturday was ‘Physics for Life’ and it mainly concerned advances in medicine/ biology that have resulted from research in fundamental areas of physics such as atomic and molecular physics (Bob McCullough of Queen’s University Belfast), solar physics (Louise Harra of University College London), nano-photonics (Brian MCraith of DCU) and molecule manipulation using ‘optical tweezers’ (Martin Hegner from Trinity). I won’t attempt to describe each talk, but you can find abstracts of the talks here.

My favourite was a general talk on causality in complex systems by world-famous cosmologist George Ellis: ‘Top-down action in the hierarchy of complexity’. This was a fascinating overview of the subject of causation, focusing on the influence of feedback from top-down processes on bottom-up causes. There were lots of great examples and the speaker was fully convincing in his conclusion that ‘no complex system can have a single cause’. I couldn’t help thinking how true this is of climate change. Some media pundits describe global warming phenomenon in terms that too simple; by citing man-made CO2 as the only factor in climate, they give great ammunition to climate skeptics who point to other factors. (The point is that while CO2 is not the only factor in global climate, it is now clear that the man-made increase in CO2 is a significant driver of warming.)

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Top-down causality: George Ellis

Sunday saw a new IoP initiative – instead of more seminars, four well-known physicists were given the ‘This is your Life’ treatment in sequence. It was a great success, with the legendary Tony Scott of UCD interviewing Ronan Mc Nulty (on the LHCb experiment), Sile McCormaic (on her path to the world of cold atoms) and Ray Bates (reknowned Irish climatologist who was one of the first in the area of climate modelling).

Best of all, the very first interviewee was Dame Jocelyn Bell-Burnell, the Belfast-born astrophysicist famed for her discovery of radio pulsars. (She is also President of the Institute of Physics). Professor Bell gave a fascinating overview of her life in physics, from failing the 11-plus exam to Cambridge. Of particular interest was her description of the postgraduate work leading up to the famous discovery: the long build of the radio-telescope from raw materials, perservering to the end as team members drifted off, the discovery of an unknown source, convincing her supervisor she was onto something, the disappearance of the source and the stress of a possible mistake and lost thesis, the re-appearance of the source, the classification of the first pulsars….terrific stuff.

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Tony Scott interviewing Jocelyn Bell-Burnell

Professor Bell’s story was reminiscent of the discovery of the microwave background by Penzias and Wilson (see post here), but with one big difference. Bell was a highly trained astrophysicist, who understood clearly that she might have discovered an important phenomenon. For this reason, it is still highly controversial that, while her supervisor Antony Hewish was awarded the Nobel prize for this work, she was not. Was it because she was still a postgraduate? Because she was a woman? Perhaps we will never know. Apparently, there was a very good BBC documentary on the story a few months ago – I misssed it but I’ll try and track it down.

As always, the most humbling part of the weekend was the postgraduate posters. The level of research made one feel seriously inadequate. You can find the results of the competition on the IoP website; choosing the winners must have been very difficult. I particularly enjoyed two posters from UCD on the LHCb experiment (an indirect measurement of luminosity using muon production rates, and the measurement the cross-section of Z boson -muon decay). Even there, Ronan had to explain to me how antiquarks arise in proton-proton collision; must revise my quark physics!

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Poster session at the meeting

All in all, a super weekend, courtesy of the Institute of Physics. Now it’s back to earth and those corrections…

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The human physics laboratory

Another great lecture at WIT this week was a public lecture on the physics of the human body. (The lecture was presented as the annual Tyndall lecture of the Institute of Physics and also as part of Engineering Week at WIT by CALMAST, see post below).

The lecture was given by Dr Kevin McGuigan, Senior Lecturer in physics at the Royal College of Surgeons of Ireland. Kevin is well-known for his successful research into the solar disinfection of drinking water, but he clearly has a second talent as a natural communicator of science.

The theme of the talk was that if you consider almost any important principle in physics, you will find a great example of its application in the human body. There were dozens of intriuging examples of this, here are just a few:

- Discussing friction, Kevin described the role of saliva in overcoming friction in indigestion. The students weren’t particularly interested until he gave a superb demonstration of the effect by getting two hapless volunteers to stuff themselves quickly with cream crackers without water!

- On Newton’s second law, the speaker explained the concept of impulse, showing clips of the effect on the neck/head of the driver of a car brought to rest from high speed, or struck from behind. He then explained the importance of both the crumple zone and air bags.

- A quick overview of the physics of rotational motion in liquids led to a discussion of the role of fluid in the ear. Kevin then gave a demonstration of the role of this liquid in balance by rotating a hapless volunteer in a chair 10 times!

The human laboratory: IoP Tyndall lecture

The speaker also discussed Bernouille’s equation, discussing what happens during an aneurysm as example. However, I suspect the students enjoyed another example of Bernouille’s equation most – ‘The physics of farts’. Here Kevin gave each member of the audience two sheets of paper and got them to observe what happens when you place them close to the mouth and blow (it behaves like a shutter opening and closing due to the difference in air pressure on the sides of each sheet). He then explained this as the same process that happens as  boys (only boys?)  attempt to release compressed air from their posteriors without making a sound, usually with a resulting brmmmmmpt!!

Another fine example was a demonstration of how sweat cools the body, using the latent heat of vapourization.

All in all, this was a super example of an outreach lecture that got a fantastic reception from a packed auditorium of students and schoolkids. I had to leave early, but I found myself frantically taking note of examples for next year’s 1st science class!

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LHCb, UCD physics and the last symmetry

This weekend I was back at my Alma Mater, the UCD school of physics, for a conference for physics teachers organised by the Institute of Physics.

I arrived late and sneaked into the back row of Theatre E of the UCD science block, just as I used to all those years ago. Such a strange feeling to be back in that same seat in that same lecture hall (one difference is that the grounds of the college are beautiful now). The feeling increased when I was joined by two of my former professors, the best teachers I ever had; Alex Montwill (who taught courses in formal quantum theory and high energy physics) and Ann Breslin (special relativity and experimental high-energy physics). Alex was Ireland’s foremost experimental particle physicist for many years, but is probably best remembered for a well-known series of public lectures on modern physics on national radio.

There were some very nice talks, including one on the discovery of The Antikythera Mechanism by Mike Edmunds of Cardiff University and one on the work of the UCD high-energy astrophysics group by John Quinn. However, I was mainly there to hear Ronan McNulty, the leader of the new experimental particle physics group at UCD (UCD has always been strong in fundamental areas of physics such as astrophysics and particle physics). Ronan’s group has been involved with the DØ experiment at the Tevatron, the L3 experiment at LEP and now with the LHCb detector at the LHC (they got some nice attention recently when they were one of the few groups able to report some preliminary measurements from the September switch-on). The work of the group is very important not just because of its fundamental nature, but because it is the only group in the Republic of Ireland that has an official involvement with the LHC (thanks to our non-membership of CERN, see post below). I’m sure Alex and Ann are very proud to see this large and very successful experimental particle physics group at UCD as they themselves had a successful particle physics group at UCD many years ago, measuring particle tracks in emulsions sent over from CERN (I did my final-year project with their research group, estimating the mass of the muon from pion decay tracks).

Ronan gave a superb talk, ranging from a basic introducton to particle physics up to the search for asymmetry in matter/antimatter decay and their contribution to the VELO detector of the LHCb experiment – all within the paltry 20 minutes he was allotted on the program. You can find the slides from the talk here. At question time, I asked him his view of the likelihood of seeing supersymmetry at the LHC: like many experimentalists, he seemed pretty sceptical, pointing out that there has been absolutely no hint of supersymmetric particles up until now.

At lunchtime, we all had a great chat, ranging from supersymmetry to ‘progressive’ ideas in university administration, to Ireland’s continued non-membership of CERN. It’s always great to catch up with the people who taught you and to hear their perspective on things as an adult. I particularly enjoy talking to Alex and Ann as they are among the very few people who understand Lochlainn’s work in gauge symmetry and the impact it had at the time. Re CERN, it seems negotiations on the issue are continuing…

In other news, although they are now officially retired, Alex and Ann have just written a book (real academics don’t do retirement): Let there be lightis due to be published by Imperial next month. I got a sneak preview and it looks superb, as you might expect of the culmination of a lifetime’s reflection on physics by two highly respected physicists. The book is pitched at a level somewhere between undergraduate and the layman and is an introduction to pretty much all of modern physics from the perspective of the study of the nature of light – from optics to wave theory, from wave/particle duality to light quanta, from electromagnetism and light to special relativity, etc. The book will be officially launched at UCD next month, so I’ll discuss it in detail then.

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Postscript

Supersymmetry has been in my mind all day today, sparked by a comment Ronan made yesterday. He mentioned that as he understands it, one of the reasons mathematicians are keen on SUSY is that it’s the last remaining symmetry under the Poincare symmetry group. I think that’s right and in fact I once heard Julius Wess comment that he sometimes wished he had used the term ‘ultimate gauge symmetry’ in the original paper (he made the comment at a Memorial Syposium two years ago). Sadly, Julius, one of the last of the supersymmetry pioneers, passed away himself last year.

Julis Wess of the Wess-Zumino model of supersymmetry.

All day I’ve been thinking thatThe Last Symmetry would be a great title for a popular book on particle physics, if supersymmetric particles do turn up – possibly a better title than The Story of Atoms . Either way, I didn’t do too much work on my imaginary book over the summer, must get back to it. On the subject of language, I also wonder about the term super-matter…I’ve never heard the term but it’s a nice word and immediately hints at an analogy with antimatter (if SUSY does exist, it must involve a broken symmetry, just like matter/antimatter decay).

As to whether SUSY really exists, a philosophical point has also been on my mind – as far as I know, there is no path to a unified field theory of the interactions without some sort of symmetry betweenfermions (leptons and quarks, the constituents of matter) and bosons (the force carriers). In the 1960s, the unification program ran into a formidable mathematical wall with the emergence of a series of no-go theorems (McGlynn, O’Raifeartaigh, Coleman and Mandula) that showed that the strong interaction could not be incorporated into a single scheme with the other interactions using the methods that had been so successful in electro-weak theory. Mathematicians were hugely relieved when SUSY, a radical new symmetry between the two most fundamental classes of particles, suggested a possible way around the problem and even hinted at the inclusion of gravity. Without some form of SUSY, it’s not clear whether unification can happen, and without unification, the picture of a single ‘superforce’ in the early universe condensing out into the fundamental interactions we see today can’t happen – a major blow for cosmology as well as for particle physics. So I like to think that either we will see SUSY sometime, or if we don’t, we haven’t got our predictions right because we simply haven’t developed the right model of supersymmetry breaking yet…

Also, there is one famous mathematical clue. When theoreticians plot the magnitude of the coupling constants of the three strongest fundamental interactions as a function of energy, they converge – but not to a single point. That is, unless SUSY is included in the calculation – in which case they converge very nicely. Hmm…

PPS: . Last week was the hundreth anniversary of Minkowski space-time. I completely forgot about this, but Stefan and Bee have a great post on it on Backreaction

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