Category Archives: Public lectures

May 23, 2014 · 5:29 pm

Freeman Dyson and the Dublin Institute for Advanced Studies

On Monday, I attended the Statutory Lecture of the School of Theoretical Physics of the Dublin Institute for Advanced Studies (DIAS). This is an outreach lecture presented annually by DIAS and this year the lecture took place at University College Dublin. Better known abroad than at home, the Institute has a long and distinguished history of world-class research in fundamental areas of physics (see here), so it was entirely appropriate that the statutory lecture was given by Freeman Dyson, renowned physicist and Professor of Physics at the famous Institute for Advanced Study at Princeton, the college on which DIAS is modeled.

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Freeman Dyson at the DIAS lecture on Monday night  

The title of Freeman’s lecture was  “Are Brains Analog or Digital?” and the abstract is below:

We know that creatures like us have two separate systems for processing information, the genome and the brain. We know that the genome is digital, and we can accurately transcribe our genomes onto digital machines. We cannot transcribe our brains, and the processing of information in our brains is still a great mystery. I will be talking about real brains and real people, asking a question that will have practical consequences when we are able to answer it. I am not able to answer it now. All I can do is to examine the evidence and explain why I consider it probable that the answer will be that brains are analog.

I won’t give more details as Professor Dyson will publish his paper on the subject quite soon. Suffice it to say that tickets for the lecture sold out days in advance and there was quite a buzz on the night. Freeman held the audience spellbound, reading from his paper without the benefit of a single slide.  One could gauge the interest generated from the huge number and variety of questions afterwards. That said, I couldn’t help noticing that the Irish media took no interest whatsoever in the occasion – one wonders if a world-famous  musician or celebrity chef would be similarly ignored.

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Professor Dyson with staff from the School of Theoretical Physics at DIAS: Werner Nahm (Senior Professor and Director ), Arthur Jaffe (Professor of Mathematics at Harvard and Chairman of the board), Freeman Dyson, Vincent Cunnane (Chair of DIAS Council) and Cecil Keaveney (Registrar)

After the lecture, some of us retired to a nearby hotel where Professor Dyson and his wife regaled us with stories from his long and interesting career. Freeman was a close colleague of my late father and was instrumental in bringing Lochlainn and the rest of our family to the Institute for Advanced Study at Princeton many years ago (after this, Lochlainn returned to Ireland to take up a position at DIAS). So it was great to encounter Professor Dyson once again, this time as an adult! Not to mention that Freeman has fascinating and original views on a wide range of topics; from space travel to climate science, he remains a truly deep and original thinker.

Update

The day after the lecture, staff and friends of the Dublin Institute for Advanced Studies were treated to a private recital by the well-known Irish pianist Hugh Tinney. The connection is that Hugh’s late mother, Professor Sheila Tinney, was an accomplished mathematician who spent time at Princeton IAS and studied with Professor Dyson (Hugh himself studied maths at Trinity College Dublin before deciding on a career in music and was in the audience for Freeman’s lecture).

It was an extraordinary occasion. Hugh played beautifully and each piece was prefaced with a short discussion of the interface of mind, memory and music. The intimate setting made for one of the most exciting concerts I have experienced, far more fun than a formal venue such as the National Concert Hall. It didn’t hurt that the programme included three of my all-time favourite works, Beethoven’s ‘Moonlight’ Sonata,  Schubert’s G major Impromptu and *that* Nocturne by John Field (no.5 in B flat). The recital also had a special significance for me as it took place in the Organ Room of the Royal Irish Academy of Music, a venue I spent a great deal of time in as a young music student.

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Each piece was prefaced by a discussion of the role of mind in music

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Hugh Tinney presenting his latest CD to Professor Dyson

After the recital, we retired to dinner in a nearby restaurant. As you can imagine, one subject of conversation was the mysterious connection between maths and music. I have heard one explanation for this strange phenomenon: “People who are good at maths are good at most things!”

P.S. A video of Freeman’s lecture is now available on the DIAS website.

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January 21, 2013 · 6:12 pm

RTE, NASA and a WARP drive

On Friday, I got a call from Mooney Goes Wild , the daily science programme on Irish national radio, asking me to participate in an interview concerning NASA’s recent interest in creating a WARP drive for space travel. I’d heard this interesting story over Christmas and I like science on the radio, so it was fun to look up a few details and take part in the discussion.

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Starship Enterprise of Star Trek uses a warp drive to traverse the immense distances of outer space

The live interview took place that very afternoon, right in the middle of our College Exam Boards (those weighty meetings when lecturers come together with external examiners to decide which students pass and which don’t). Our current physics extern, Professor Peter Mitchell of UCD, taught me as a student, so we had fun discussing the NASA project over lunch.

In the event, the interview was very interesting; I thought the RTE panel of Olan Mc Gowan, Eanna ni Lamhna, Richard Collins and Terry Flanagan asked great questions and we all enjoyed ourselves. Below is the Q&A script I prepared in advance (I always run up a draft script as it helps me organize my thoughts and it provides interviewers with a jumping-off point). The panel’s questions went a good deal further, you can hear a podcast of the interview here.

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Artist’s impression of the NASA experiment; the vacuum ring causes space behind the object to expand, propelling it forwards

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Script

We recently came across a story that NASA has begun work on the development of a WARP drive, a device that would allow spaceships to travel faster than light. Such an engine could in principle transport a spacecraft to the most distant stars in a matter of weeks, but seems the stuff of science fiction.  We contacted Dr Cormac O Raifeartaigh, a physicist at Waterford Institute of Technology, to get his opinion on this story…

PANEL: First of all, what is a warp drive?

 COR: It’s the word used for a hypothetical engine that could drive a spacecraft by distorting or ‘warping’ space. In principle, this could allow  the ship to travel faster than the speed of light, taking a shortcut to reach remote galaxies in hours instead of millions of years! (The device turns up in science fiction in order to enable people to get from one galaxy to another without dying of old age on the way…even travelling to a nearby planet  takes several years).

PANEL: How is it supposed to work? I thought faster-than-light travel was supposed to be impossible?

COR: That’s right. According to Einstein’s theory of relativity, no material body can reach the speed of light. If it comes close to this speed, the body gets bigger, and heavier, and it cannot match the speed of something with no mass (light). There is a lot of evidence to suggest that this is exactly what happens, it’s amazing to see particles like  protons accelerated at facilities like the Large Hadron Collider  up to speeds like 99.99% of the speed of light, but never quite reaching nature’s speed limit.

PANEL: So, how does the warp drive work then ?

 COR: Another prediction of relativity is that space and time are not fixed, but affected by motion and by gravity. For example, there is a huge amount of evidence that the space of our universe is continually expanding. In principle, a patch of space can move at any speed; if you could somehow  warp a bubble of space around an object ( or spaceship), then that object would travel at the speed set by the distortion..

PANEL: Has this mad idea been around for a while?

COR: Yes,in principle. The problem is that the energy required to make that bubble of warped space is far greater than any energy available. What’s new is that physicist Harold White at NASA thinks he can reduce the energy required, with a clever design; the object (spaceship) is surrounded by a thin vacuum ring of a special shape that causes the space just behind the spaceship to expand, and just in front to contract; the difference propels the spaceship very fast indeed! Of course that’s just the theory..

PANEL: Do you think it will work?

COR: No, I doubt it, even with objects on the atomic scale. However, we will learn a lot by trying, there’s nothing wrong with the principle. For example,  many cosmologists believe that our whole universe expanded at speeds far greater than light during the first instant (the theory of cosmic inflation), before settling down to today’s more sedate expansion. But as regards investment, I wouldn’t put any money in ‘warp drive’ shares just yet!

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October 9, 2012 · 8:18 pm

The God particle at Trinity College

On Monday evening, I gave a public lecture on the Higgs boson at Trinity College Dublin. The talk was organised by Astronomy Ireland and I think it was quite a success; 200 tickets were sold and quite a few people had to be turned away.

In the Joly lecture theatre at Trinity College Dublin

How to explain the basics of particle physics to a public audience? As always, I presented the material as a short history of discovery: from the atom to the nucleus,  from protons and neutrons to Gell-mann’s quarks. I also included some theory on the fundamental interactions, right up to the Standard Model,  electro-weak unification and the role of the Higgs field in electro-weak symmetry breaking. Not for the first time, I came away with the impression that the Standard Model isn’t as intimidating for the uninitiated as you might expect. As for physics beyond the Standard Model, the audience seemed to take the hypothesis of grand unification in their stride, and the connection between particle experiments and the early universe struck a chord, as always.

The results  It was a pleasure to present the fantastic results of the ATLAS and CMS teams, first announced at CERN last July. Giving such talks is a lot easier now that the data are publicly available in two beautiful papers on the ArXiv here and here. I gave an overview of the main findings in the context of previous experiments at CERN and at the Tevatron,  and I think the audience got a feel for the historic importance of the result. Certainly, there were plenty of questions afterwards, which continued in the pub afterwards.

The famous bumps ( excess decay events) seen by both ATLAS and CMS at around 125 GeV in the di-photon decay channel

Combined signal (all decay channels) for both ATLAS and CMS

So what about that title? Yes, I did agree to the title ‘The God particle at last’? I am aware that most physicists have a major problem with the moniker; it is sensationalist, inaccurate and incurs a completely gratuitous connection with religion. (Some religious folk consider it blasphemous,  while others misunderstand the term as evidence for their beliefs).

A poster for the talk; naughty

All of this is true, yet I must admit I’ve got to like the nickname; it is catchy and just mysterious enough to cause one to think. I imagine a tired lawyer catching sight of the poster as she walks home after work;  ‘God particle’ might cause a moment of reflection, where ‘Higgs boson’ will not. At least the former expression contains the word ‘particle’, giving the reader some chance to guess the subject. Of course the ‘God’ part is hubris, but is hubris so bad if it gets people thinking about science? Also, I disagree with commentators who insist that the Higgs is ‘no more important than any other particle’. Since all massive particles are thought to interact with the Higgs field, finding the particle associated with that quantum field is of great importance.

So is it found?  CERN Director General Rolf Heuer stated in Dublin, “As far as the layman is concerned with have it. As far as the physicist is concerned, we have to characterize it”. Such characterization has been going on since July. Without question, a new particle of integer spin (boson) and mass 125 +- 0.5 GeV has been discovered. So far, the branching ratios (the ratio of various decay channels to lighter particles) match the prediction of a Standard Model Higgs boson very well. So it looks and smells like a Higgs, and we are all getting used to the idea of the Higgs field as reality rather than hypothesis. (That said, there is still the possibility of spin 1 or 2 for the new particle, but this is not very likely).

All in all, a very enjoyable evening. The slides and poster I used for the talk are available here.  No doubt, some Trinity professors may have been none too pleased to see ‘God particle’ posters in the Hamilton building. Me, I’ve decided I can live with the name if that’s what it takes to get the public excited about particle physics…

Update

Some bloke called Zephyr is upset and accuses me of misleading the public (comments). His point is that I refer to the Higgs as a particle, instead of a quantum field. There is a valid point here; what were once thought of as elementary ‘particles’ of matter are now considered to be manifestations of quantum fields. However, in the business of communicating physics to the public, each physicist must find their own balance between what is accurate and what is comprehensible. My own experience is that people grasp the idea of the Standard Model reasonably well if it’s told as a story of particle discovery (phenomenology). A small amount on quantum theory is ok, but too much soon leaves ’em bewildered. For this reason, I much prefer books like Particle physics: A Very Brief Introduction by Frank Close to books like Higgs: The Invention and Discovery of a Particle  (Jim Baggot)

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March 16, 2012 · 3:46 pm

Neutrino lecture at University College Cork

I gave another talk on the OPERA ‘faster-than-light’ neutrino experiment on Wednesday evening at University College Cork (UCC). I was booked months ago to give the talk as part of the UCC Public Lecture Series and it’s always a pleasure to visit the beautiful campus at UCC.

University College Cork – the nicest campus in Ireland?

Of course, I was concerned the topic might be a bit of damp squib. As everyone in physics knows, a technical fault associated with the OPERA experiment was recently uncovered. Specifically, a connector cable for GPS clock synchronisation was found to be faulty. Between this and other problems, the ‘faster-than-light’ result has been withdrawn (see here for details).

The neutrino detector at Gran Sasso

In fact, the lecture was great fun. We got a good turnout and I made a point of using exactly the same slides I used when the OPERA result was first announced (see here for details). I thought the parts of the talk where I explained the grounds for scepticism from the viewpoint of both special and general relativity (theory and experiment) looked well in retrospect, though I tried hard not to say We told you so. In conclusion, I introduced a few new slides where I discussed what lessons could be learnt from the incident e.g.

1. If your result is in conflict with well-known theory, check, check and check again before you publish (anywhere).

2. If your result is in conflict with decades of experiments, check even more carefully.

3. Never underestimate the media appetite for  ‘Einstein wrong’  stories. Everyone has heard of Einstein and everyone has heard of the speed of light –  this story was always going to be huge.

4. ‘Einstein not wrong after all’ is not such a great media story. In consequence, many members of the public will never get to hear of the correction. Bear this in mind before you go public with a result that may later have to be corrected.

Check your cables – all of them!

The slides I used for the UCC talk are here and I will upload the video in a day or two.

Update

This just in: a group working on an extremely similar neutrino experiment at Gran Sasso have announced the observation of neutrinos obeying the speed limit, as normal. This pretty much refutes the OPERA result completely. See here for details.

Update II

April 3: The head of the OPERA collaboration has resigned over the weekend, see here for details

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January 31, 2012 · 10:06 pm

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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November 21, 2011 · 8:37 pm

Neutrinos and string theory at Trinity College Dublin

I gave a few more talks on the Gran Sasso neutrino experiments last week, in Waterford on Wednesday and in Trinity College Dublin on Saturday. I really enjoy giving these talks; it’s not often one gets an excuse to present the theory of relativity to the hapless public. Journalists talk about the ‘hook’ – well this is a hook from heaven. I even got a 20-minute interview on Ireland’s premier radio show Today with Pat Kenny . You can find the podcast and the slides I used for the lecture here.

There was a real buzz in the air at Saturday’s lecture, thanks to the latest results from OPERA. As you probably know, the team announced on Friday that the superluminal result has passed its first major test: a repeat experiment using a much shorter proton pulse. This time they used pulses only 3 nanoseconds long, separated by by gaps ten time larger. This is vastly shorter than before (10 microseconds) and obviates the statistical approach used for matching transmitted and received pulses used in the original experiment. Like most physicists, I am still pretty certain the result will eventually turn out to be an anomaly, but I certainly hope it survives for another few months! See here for the new OPERA paper.

The lecture was hosted by Astronomy Ireland,a very interested audience that always turn out in droves. The theatre was jammers, quite a few audience members had to stand throughout. As always, I particularly enjoyed the questions and answers afterwards. It’s also fun to be come home; as a postgraduate student, I spent many long years in the magnetic resonance lab next door!

David Moore of Astronomy Ireland presents me with something (?)

Afterwards, some of us all legged it over to another Trinity lecture theatre, to hear the annual statutory lecture of the School of Theoretical Physics of the Dublin Institute for Advanced Studies. This year, the speaker was well-known string theorist Cumrun Vafa from Harvard. Titled ‘Geometric Physics’, the lecture was an excellent introduction to string theory today.

String theorist Cumrun Vafa from Harvard

And after all that, there was a reception to celebrate the fact that Werner Nahm, the director of the DIAS School, was recently made a fellow of the Royal Society. What a weekend

Update

On Sunday, Werner gave a fascinating talk on ancient astronomy at the Dublin Institute of Advanced Studies. After the seminar, many of us remained in the fading light in that famous seminar room, discussing the neutrino result and other experiments at CERN. As so often, I was struck by the depth and detail of knowledge the theorists had of particle experiments. I also enjoyed the way the discussion wandered into German for a while, then seamlessly back to English – only at DIAS!

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October 20, 2011 · 4:46 pm

Faster than light and the public misunderstanding of science

Yesterday evening, I gave a public lecture in Dublin on the Gran Sasso neutrino experiment, hosted by the Irish Skeptics Society. The event formed part of Maths Week Ireland, an initiative co-ordinated by CALMAST, the science outreach group at our college. We had a great audience turnout and I enjoyed the Q&A afterwards immensely. Below is the abstract and you can find the slides for the talk here.

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In September 2011, a group of scientists announced that they had detected subatomic particles travelling at speeds greater than the speed of light in vacuum. The finding is in conflict with Einstein’s theory of relativity and has been met with great skepticism by mathematicians and physicists around the world. This lecture will examine the grounds for that skepticism and consider the role of skepticism in general in science and mathematics

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       The Gran Sasso experiment

I suspect I was invited to speak because of a letter I had published on the subject in The Irish Times (below). Although the Gran Sasso experiment has certainly raised awareness of physics, I think the way the media are portraying this experiment as an  ‘Einstein wrong’ story is most unfortunate. It is far too soon to reach that conclusion and the overall effect is to make science seem very uncertain. It is more Public Misunderstanding of Science than PUS, in my view.

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Sir, – Margaret Moore (September 29th) asks what word will be used to describe a speed faster than the speed of light. The technical term is superluminal speed. However, much of the media coverage of recent experiments at Gran Sasso has been very misleading. Almost all professional physicists (including the experimenters) consider the Gran Sasso result a curious anomaly almost certainly due to some unknown error in measurement, for several reasons:

1. Light is carried by particles of zero mass and it follows that there are fundamental theoretical reasons for supposing that the speed of light in vacuum represents a natural speed limit for particles of non-zero mass.

2. Thousands of experiments have verified that the tiniest particles of matter can be accelerated up to speeds close to, but not equal to, this limiting speed.

3. The recent Gran Sasso experiment involves measurements of time and distance of unprecedented precision, yet it was not designed for this specific purpose; thus there are many potential sources of systematic error.

It’s true that science sometimes progresses by upsetting the status quo, but scientists are a sceptical lot and extraordinary claims require extraordinary evidence! –Yours, etc,

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Does it matter how the experiment has been portrayed in the media? I think it does. A few years from now, journalists will be say ‘ but didn’t you guys think in 2011 that Einstein was wrong’? In fact, there has already been one editorial in the Wall St Journal urging inaction on climate change, on the basis that science is never certain, given the neutrino result (see point 5 of this article ). Exactly the wrong conclusion to draw…

Update

I see my lecture got a short review in today’s Irish Times. It’s not a bad overview, considering the writer wasn’t at the lecture. The last sentence doesn’t make sense, however – I suspect she meant supernovae instead of black holes!

Udate II

Just caught  BBC program on the experiment (Marcus du Sautoy). Superb, superb program. Nothing like the players themselves for conveying the concepts of science..

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March 23, 2011 · 3:34 pm

The big bang: is it true?

On Monday evening, I gave a big bang talk to the Harvard Graduate School of Arts and Sciences. I really like the way there is a single graduate school for both arts and science at Harvard, what a great interdisciplinary mix. The school has its own activity center, Dudley House ; the house is non-residential but modeled on the residential houses at Harvard, with its own building (Lehman Hall) complete with coffee shop, canteen, senior common room, games room, and a beautiful and quiet library with a fantastic view of Harvard Square.  It is served by two faculty masters, an administrative staff and graduate student fellows who organize activities for the School’s 4,000 Masters and PhD candidates. In truth, I spend a good deal of time at Dudley House – perhaps it’s the wide variety of disciplines that makes for such interesting conversations.

Dudley House, home of the Harvard Graduate School of Arts and Sciences

The talk was titled The Big Bang; Is It True? and it was great fun, with a drinks reception, a really nice dinner, a 40-min spiel from me and then almost an hour of questions from the audience. There were postgrads there from history, literature, psychology, philosophy, astronomy and other fields. Apparently, tickets sold out within hours of the posters going up, it shows the interest in the subject.

Of course, no scientist can give a definitive answer to the question I posed. Instead, I laid out a brief history of the discovery of the evidence supporting the big bang model (the expanding universe, the composition of the elements and the cosmic microwave background), followed by an outline of recent puzzles that have arisen from modern studies of the microwave background. I like a quasi-chronological approach to such talks, I think it makes the discoveries and concepts easier to understand, and at the same time it gives the audience a great feel for the surprises nature has in store for scientists. As for truth, the audience can decide for themselves.

You can see the full slideshow at https://coraifeartaigh.wordpress.com/my-seminars/

I really enjoyed the questions and discussion afterward; not for the first time, it struck me that you get very interesting questions and comments from a wide interdisciplinary audience (it doesn’t hurt if they are Harvard PhD candidates). There was also plenty of time to touch on one of my favourite themes; that a great many scientific discoveries come as a complete surprise to the discoverers. Far from being ‘constructed’ in order to support pet theories, scientific findings are often undesirable, unexpected data that no-one knows what to make of  at first – an aspect of science that proponents of the social construction of scientific knowledge often fail to address, in my view.

All in all, it was great to interact with postgrads from so many different disciplines, I wish I could do this more often.

Questions

One of the most challenging questions came from Prof Sam Schweber, a well-known Harvard physicist and historian of science. Sam couldn’t make the talk, but he emailed me his question: What happened before the bang?

I think the answer is twofold:
1. The standard answer is that the big bang model is situated within the context of general relativity, the modern theory of gravity. Since relativity predicts that space and time form part of the universe (and are affected by motion and by mass for example), we expect that time is born at the bang along with everything else – there is no ‘before’ just as there is no north of the north pole.

2. However, cosmologists are less cocksure of this answer nowadays. This is because fundamental problems in describing the moment of the bang (the singularity) have, far from going away, got worse. The problem is due to the inapplicability of the modern theory of gravity to phenomena on the atomic or quantum scale i.e. due to the absence of a successful theory of quantum gravity. Since we have no real way of modeling the singularity, we cannot rule out the prospect of exotic phenomena such as multiple bangs. The problem is compounded by the fact that, while recent observational evidence offers support for some type of cosmic inflation close to the birth of the universe, there is (so far) no way of selecting a particular model of inflation – which leaves the door open for models such as the cyclic universe. In other words, we cannot rule out the possibility of a ‘before’ until we have a clearer picture of what happened at the bang itself.

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June 16, 2010 · 3:15 pm

‘Black Holes, the Hadron Collider and the God Particle’

We got a massive turnout on Monday evening for a public lecture I gave on the Large Hadron Collider at Trinity College Dublin. I was invited to give the talk by Astronomy Ireland and it was a great time to give it as there is still plenty of interest in the Collider because of the black hole ‘controversy’, and because last week saw the first offical conference on results from the LHC. Indeed, there has been very little media attention given to the fact that, in the space of a few months,  all four detectors at the LHC have been busily rediscovering the elementary particles of the Standard Model that took so many years to first detect, from pions, muons and kaons right up to W and Z bosons.

A lot of physicists might have a problem with the populist title ‘Black holes, the Hadron Collider and the God particle’; however the title was worked out with Astronomy Ireland, an organisation that knows a thing or two about attracting a wide audience! Also, I think controversies such as the black hole controversy are best tackled head on i.e. by describing early on in the talk what a black hole is and why one doesn’t expect to create one at the LHC  (in particle physics, one gets only a minute amount of mass  from a very large amount of energy since  m = E/c2 ). I also touched on micro-black holes and Hawking radiation; overall I had the distinct feeling the audience enjoyed this part of the talk no end!

As for the term ‘God particle’, I happen to be one of the few physicists who likes this name for the Higgs boson. Yes, it was probably originally ‘that goddamn particle’ due to its elusiveness,  but I think ‘God particle’ neatly gets across the importance of the particle; after all it is the interaction of the other particles with the Higgs field that is thought to determine their mass, according to the Standard Model.

I divided the talk into three parts; first, an overview of the LHC – how, what, why etc. Then I devoted the central part to a brief history of particle physics, from the discovery of the nucleus to protons and neutrons, from the hypothesis of quarks to the electroweak interaction and the Standard Model. In the third part, I described extensions to the SM such as supersymmetry and Grand Unified Theory and went over our expectations of the LHC experiments, from the possible detection of the Higgs boson to supersymmetric particles, from candidates for dark matter to the search for assymetries in matter/antimatter decay at LHCb.

The LHCb experiment is of particular interest to an Irish audience, as a group at University College Dublin are heavily involved, despite Ireland’s non-membership of CERN.

Finally, I can never resist showing a couple of slides on the basics; not only do experiments at accelerators give us information on the elemental structre of matter and the interaction of the fundamental forces, they also give us supporting evidence for our underlying theories of modern physics, from the observed mass-increase of particles (predicted by special relativity) to the detection of antiparticles (predicted by quantum theory). You can see the full set of slides for the talk here and a video is available here.

All in all, there was a great atmosphere at the talk and I really enjoyed the occasion. There were plenty of questions afterwards, from queries on black holes to the prospect of detecting extra dimensions. I was also asked about a recent study of the cosmic microwave background (CMB) that may cast doubt on the hypothesis of dark matter (based on a revision of measurements of perturbations in the  CMB). I haven’t studied this report yet, but I gave the answer that I always give in public fora: let’s see if other groups replicate the findings before pay too much attention. After all, the postulate of dark matter comes not primarily from measurements of the CMB, but from thousands of measurements of the movement of stars, galaxies, galaxy-clusters and halos. That said, it’s certainly an interesting paper…

Update

I really enjoy giving such talks on particle physics, there are so many fascinating subjects to cover; special relativity, quantum theory, quarks, the fundamental interactions, symmetry breaking, antimatter, dark matter etc. Yet while there are quite a few excellent books for the public on cosmology, there are remarkably few on particles physics… might be fun to try to put one together one day.

Update II

Apparently, U.S. newspapers are full of stories on the discovery of the God particle at the Tevatron. It seems these stories are based on an unpublished paper (see discussion on Not Even Wrong) – I wouldn’t pay too much attention just yet.

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November 22, 2009 · 9:13 pm

Einstein, de Valera and the Institutes for Advanced Study

Is there a collective noun for a roomful of professors? A great many of the most senior figures of Irish academia turned up in Trinity College Dublin on Saturday night to hear the annual statutory lecture of the School of Theoretical Physics of the Dublin Institute of Advanced Studies.

The lecture, titled “No excuses in paradise: the past, present and future of the institutes for advanced studies” (see poster here) was a fascinating talk on the history and purpose of the Institutes for Advanced Study at Princeton, Dublin, Paris and elsewhere. It was given by Professor Peter Goddard, the current director of the famous Institute for Advanced Study at Princeton in the US. This institute, one of the most prestigious research centres in the world, has hosted staff such as Einstein, Godel, Oppenheimer, Freeman Dyson and Ed Witten and became the prototype for similar institutes around the world. Peter Goddard himself is extremely well-known as one of the early pioneers of string theory.

The  speaker started by tracing the initial idea by the American educationalist Abraham Flexner in the 1920s to seek funding for an Institute of Advanced Study in the US that could compete with research centres in Germany such as that in Gottingen. The plan was to create an elite American ‘graduate university’ –  a university that did not teach at undergraduate level but focused on research and on the training of researchers. Of course such an institute could only be staffed by the best of the best, and Einstein, already a world figure in science, was approached on one of his periodic visits to Caltech. Worried about the rise of the Nazis, Einstein quickly agreed. You can read more about this story here, but Prof Goddard showed a wonderful slide showing the famous issue of the New York Times with the headline: ‘Einstein to set up new school’.

Einstein in his office at IAS

The speaker then explained how during the war the Irish premier Eamon de Valera, a former mathematician, decided a similar institute would be of benefit in Ireland. Due to economic constraints, it was settled that the institute would deal with theoretical physics (as there were great advances being made in this field and it required no expensive equipment) and with Celtic studies (also not very expensive and of national interest). On the advice of Einstein, de Valera approached Schroedinger, the father of wave mechanics, to persuade him to come to Ireland to direct the institute.

This part of the story was well-known to an Irish audience but the speaker gave a very nice sketch of the history – Schroedinger did come in 1940 and spent many years at the Dublin IAS, followed by other prestigious theoreticians such as Heitler, Lanzcos and Synge. The institute became a great success internationally, attracting regular visits by famous physicists such as Paul Dirac. Indeed, some nice slides concerning Dirac’s visits were shown, not least a menu demonstrating the attraction of Ireland during wartime. Another slide showed a comment by Dirac, expressing surprise that the Irish Prime Minister had time to sit through a whole mathematics conference! All in all, it was a lovely overview of the history of the Dublin IAS and included a nice reference to Lochlainn’s work (it turns out Goddard collaborated quite a bit with Lochlainn in the early days of supersymmetry) .

Nobel laureates Dirac, Heisenberg and Schrodinger in Sweden

The speaker then explained how the American idea was imported back to continental Europe, notably at IHES in Bures-sur-Yvette just outside Paris (set up in 1958). This institute is also highly regarded in the world of academia, thanks to the work of mathematicians such as Alain Connes and the late Louis Michel. There are also informal links between the institutes – many of the professors in the audience had spent time at more than one (in my own family we have fond memories of years spent at both the Princeton and Paris institutes as well as Dublin).

The lecture finished with a brief discussion of the role of such research institutes. In a world dominated by the technological application of science, it is sometimes hard to persuade people of the importance of enquiry for it’s own sake – ‘the usefulness of useless knowledge’. Of course, one answer to this is that we don’t know which part of scientific enquiry will prove technologically useful (look at Boolean algebra or the development of the web at CERN). However, a deeper answer is that knowledge and the pursuit of knowledge will always be important for their own sake. The professor summed up with the best quote of the night: ‘the thing about a scholar’s paradise is that there are no excuses for failing to do something important!’

So have the institutes been a success overall and should they continue? As a student, I often heard certain university staff mutter darkly that precious little work went on there – however such comments rarely came from staff at the highest levels. It’s worth noting that Saturday’s speaker was introduced by Professor Samson Shatashvili, the well-known string theorist who directs the Hamilton Mathematics Institute , a research institute that functions within Trinity College. Prof Goddard didn’t compare the role of such institutes with the institutes for advanced study directly, but I think his historical account demonstrated that the latter still have an important role to play. As regards the Dublin IAS, I should have said that the lecture above took place in the middle of a conference to celebrate the 60th birthday of Professor Werner Nahm, a noted theorist at the Dublin IAS. A measure of the stature of Werner, and of the continuing prestige of DIAS, can be seen from the list of speakers in the conference program here. Another indication of the continuing success of DIAS was the preponderance of well-known international figures on Saturday night such as Shatashvili, Nahm, Goddard and Frohlich – not to mention the mathematician Micheal Atiyah and a quiet man in the back row who I later realised was Peter Higgs (yes, he of the elusive boson).

The school of theoretical physics (DIAS) on Burlington  Road

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