Category Archives: Public lectures

Science week in Ireland: was Einstein wrong?

This week is Science Week in Ireland, with science events taking place all over the country. There are talks and demonstrations on every aspect of science you can think of, from a demonstration of animal magic at Killaloe in County Limerick to astronomy at the Crawford Observatory of University College Cork.

This evening, I will give a public lecture on the Big Bang in Trinity College, hosted by Astronomy Ireland. We’re still in the International Year of Astronomy, celebrating the 400th anniversary of Galileo’s use of the telescope to establish the heliocentric model of the solar system, so it’s highly appropriate to have a lecture describing another paradigm shift in science brought to us by astronomy: the discovery of the expanding universe and the big bang model that followed. I’m delighted to be giving the lecture as Astronomy Ireland do a fantastic job of promoting astronomy and science around the country, with night-classes in astronomy, public viewings of astronomical events and regular public science lectures. It’s also fun to tell the story of the discovery of the big bang model to people with an interest in astronomy, as many of them already know most of the facts, but from a slightly different perspective. Indeed, much of what we know of cosmology really comes from astronomical observation. You can find a poster, a summary of the lecture and the slides I will use here.

As I write this post, I’m sitting in the RTE canteen having done an interview promoting the lecture on Today with Pat Kenny, the flagship radio show of RTE, the Irish broadcasting corporation. (The last time I was at RTE I was auditioning for deputy work with the  Concert Orchestra but that’s another story!). I think the interview went well, it was certainly good fun. Unlike a lot of scientists I quite enjoy talking to the media, it’s a challenge getting deep ideas across in a short interview without sounding completely incomprehensible! I also find this particular radio show very good and listen in whenever I can.

Astronomy Ireland marketed the lecture as ‘The Big Bang: Was Einstein Wrong? which is quite a good hook, so the interview touched on this quite a bit. Of course the answer is YES, it refers to a famous Einstein gaffe. When E. applied the general theory of relativity, his new theory of space, time and gravity, to the entire universe, it predicted a universe that was changing in time (space and time expanding). No evidence for such a thing existed at the time, so Einstein then introduced an extra term into the equations of relativity to force the universe to be static. Such fudge-factors are always risky in science and sure enough it turned out to be a big mistake. In 1929, the American astronomer Edwin Hubble established unequivocally that faraway galaxies are rushing away from one another and mathematicians realised that the universe is indeed expanding. Einstein immediately dropped the spurious term (known as the cosmological constant), declaring it his ‘greatest blunder’. You can listen to a podcast of the interview here, I hope I got the point across!


Einstein: right about relativity, but missed the prediction of the expanding universe

On Tuesday evening, I’ll give a repeat of the lecture in Waterford,in the main Auditorium of our college. On Wednesday, there is a talk on on the legacy of Charles Darwin at Waterford City Hall, which should be very good, I hope to attend myself. Both these lectures have been organised by CALMAST, the science communication group at WIT. All in all, it’s going be a busy week.

Update: I can see why media interviews are important, we had to change venue to the largest lecture theatre in trinity last night as we got a turnout of about 500! I think the lecture went well, I certainly enjoyed it.







Filed under Cosmology (general), Public lectures, Science and society

Frontiers conference 2009

I spent last weekend at the Frontiers conference of the Irish branch of the Institute of Physics. This is a conference aimed at establishing links with secondary schools all over the country and bringing physics teachers up to date with the latest developments in physics and physics teaching. I attended Frontiers for the first time at University College Dublin last year and enjoyed it immensely (see September 2008 post). This year it was WIT’s turn to host the conference and I think it went very well, thanks to the superb organisational skills of Paul Nugent, David Keenahan, Alison Hackett and Eilish Mc Loughlin of the Institute of Physics and WIT physicist Gabriel Gallagher.

The weekend started with a dinner for the conference speakers and organisers in the Tower Hotel on the Friday night. It’s always great to catch up with other physicists in an informal setting and the occasion didn’t disappoint. In particular, I was amazed to discover that well-known science communicator and Northern Ireland Space Office director Robert Hill and I share a colourful past: many years ago Robert used to play 1st trumpet with the National Youth Orchestra of Ireland while I scraped away in the 1st violins!

Saturday morning kicked off with a series of three lectures: you can see the conference program here.

First up to the podium was Prof David Hughes, a highly distinguished astronomer and science communicator from the University of Sheffield, with a talk entitled ‘Telescopes: their history, development and future’. This was a masterly presentation on the evolution of the telescope over the centuries and its effect on science. The seminar covered the whole gamut – from Galileo’s use of a primitive telescope to observe the moons of Jupiter and the phases of Venus, and its impact on the geocentric model of the solar system, to Hubble’s use of the 100-inch Hooker telescope on Mt Wilson to establish the existence of distant galaxies and the subsequent discovery of the expanding universe (the first plank of evidence for the Big Bang model). I really liked the way the speaker emphasised the impact of each technological step in the development of the telescope: from refracting lenses to reflecting pyrex mirrors, from simple drawing to photographic images, from cumbersome mechanical mountings to computer-controlled giants, from simple photography to the modern CCD camera. (Interesting stat: for the last four centuries, the physical size of telescopes has doubled every 50 years). This was a masterclass in science communication and the audience was enthralled.


David Hughes with an image of the Hooker telescope in the background

David Hughes2

It’s astonishing how astronomy still revolutionizes cosmology from time to time: throughout David’s talk I kept thinking of the recent measurements of distant supernovae that led to the discovery of a universe expansion that is currently acclerating (see post on dark energy here). Interestingly, David was quite cautious about this result in discussion, pointing out that it depends critically on our understanding of Type 1 supernovae – it’s just possible that the effect arises from a lack of understanding of these stars, although there is some coobborating evidence of dark energy from recent measurements of the cosmic microwave background.

In the second talk of the day, Eoin Gill of the WIT science communication group CALMAST gave a talk on ‘The life and legacy of Robert Boyle’. It’s often forgotten just how important the work of this Irish scientist was, from his theory of ‘corpuscules’ to his famous work on gases. Eoin gave a great talk on Boyle, giving an overview of his life and times and the impact of his scientific discoveries. As regards the former, many were surprised to hear that the Irish have a mixed view of one their most famous scientists because of his family background. Robert Boyle was able to indulge his passion for science due to vast wealth inherited from his father, the Earl of Boyle: unfortunately the latter was a notorious Englishman who made his fortune by stealing land from the Irish and redistributing it to English nobility!


Robert Boyle (aka Eoin Gill) in action

Robert Boyle 2

The high points of the talk were the simple but effective demonstrations. Taking his cue from the famous demonstrations employed by Boyle himself at Royal Society lectures, Eoin showed several neat demonstrations of the vacuum that could be done in the classroom – snuffing out candles in a sealed container attached to a simple pump, the elimination of noise from a bell in the same container, the impossibility of pulling apart spheres separated by a vacuum and many others.

The third talk of the morning was my own presentation on ‘Walton, the LHC and the Higgs boson’. This was a 40-min overview of the forthcoming experiments at the Large Hadron Collider at CERN and their importance in the study of the elementary particles, along with a few words on the role of the Waterford-born scientist Ernest Walton in the evolution of accelerator physics.



Ronan McNulty of University College Dublin gave an excellent short talk on his group’s involvement in the LHCb experiment at last year’s conference, so this was an attempt at a more general overview of experimental particle physics. Part one dealt with the how, what and why of the LHC: how particles are created and detected, the relevence of such experiments for particle physics and cosmology and a few specifics on the proton beams and the detectors. (I also tried to emphasise the fact that relativistic effects such as mass-energy equivalence, time dilation and length contraction are routinely measured in particle experiments as I feel this point is often forgotten). The second part consisted of a whirlwind introduction to the Standard Model, from the discovery of quarks to electroweak unification. In the 3rd part, I sketched the role of the Higgs boson in the model and the difficulties of detection. I touched on the possiblity of physics beyond the standard model at the LHC (supersymmetric particles and the implication for grand unified theories) before finishing up with a few words on cosmology – the search for dark matter particles and the study of matter/antimatter decay in the LHCb experiment.

You can find the slides from the talk here and a video will be available on the conference website next week. My only regret is that the conference had been running 15 minutes late all morning so there was no time for questions  – the best part of any talk. Also,  I never got time to show Kate McAlpine’s LHC rap, it would have gone down a bomb!


After lunch, Robert Hill , the director of the Northern Ireland Space Office, gave a workshop on useful astronomy software and website resources for teachers. As the former science communicator for the Armagh Planetarium and founder of the Astrogazers Ireland Schools Network, Robert knows a thing or two about getting young people interested in astronomy and science and this was a highly useful workshop, fnishing with a great 3-D show on the universe. I won’t give more details, but examples of the sort of invaluable web resources he gave are

Astronomy Ireland

Armagh Planetarium

The Hubble Site

The Faulkes Telescope Project


Finally, there was a workshop on making videos for educational proposes by Jonathan Sanderson. Jonathan is a highly experienced producer of TV science shows (he has produced series on science for the BBC, ITV and RTE) and he gave us an overview of the SciCast project: this is a nationwide effort in the UK to get students to discover the wonder of science by making short films of simple scientific demonstrations. Jonathan had some great tips on how to get the students to work in teams for the production of such films and then showed us some classic examples from the existing SciCast collection. So far, there are more than three hundred films in the SciCast collection, you can view the collection here!

Video workshop2

A masterclass in science film directing

All in all, it was a great conference, with plenty of items of interest for any science educator. There were also plenty of useful freebies such as astronomy posters, polarising sheets, SPIN science magazine, flash memory sticks and a DVD on the universe produced by the ESA. Professional photos of the event and videos of the talks will be available on the conference website in a few days.


Filed under Particle physics, Public lectures, Teaching

The Alchemist Cafe

I gave a talk on Wednesday evening at the Science Gallery in Trinity College Dublin, as part of the Alchemist Cafe series. It was great to be back at the Gallery, I’ve fond memories of participating in the RAW debates there last year (see blog posts on the debates here).

The Alchemist Cafe is the Irish branch of the international Cafe Scientifique movement: the idea is to get a scientist or engineer to give an informal talk on a scientific topic in a cafe/bar setting, with plenty of questions and discussion afterwards. You can find abstracts and videos of previous talks on their website above.

I gave a short spiel titled ‘The Big Bang: Fact or Fiction?”. I thought it would be fun to go over the three basic planks of evidence for the model and then discuss some modern results (from the accelerating universe to WMAP measurements of the cosmicrowave background). The rest of the session was given over to questions and discussion.

It seemed to work well, I thought the Science Gallery cafe a particularly good setting. One whole side of the cafe is a glass window onto the street and we projected the images I used onto the opposite wall, with the audience in between. It made for a nice relaxed atmosphere.

The Naughton Institute and the Science Gallery at Trinity College Dublin

al caf 1

Photos courtesy of The Alchemist Cafe

There were plenty of good questions, on topics as diverse as unified field theory and dark energy. I wish I’d taken note of the questions, must check with the organisers if someone did. Turnout was a big surprise – a few friends turned up at 8.05 and couldn’t get in! It’s amazing the public interest in cosmology, I guess everyone has heard of the Big Bang and Hawking’s A Brief History of Time.

All in all, it was a great experience. There will be a video of the event on the Alchemist Cafe site in a few days and I’ve uploaded the slides I used on the My Seminars page.

P.S. The Gallery is currently exhibiting INFECTIOUS, an excellent show on the spread of infectious diseases: well worth seeing and highly relevant given the news on swine flu…


Filed under Public lectures, Science and society

Angels, demons and antimatter

I’m re-reading Dan Brown’s Angels and Demons in preparation for the film release later this month. I’m quite enjoying it – if you’re going to write a fast-paced thriller, why not have lots of science and religion in it? Not many thrillers feature antimatter as a core part of the plot. Also, it’s great to see CERN feature in a book aimed primarily at an American market. In fact, the first 150 pages or so of the book are set in CERN.

However, it has to be said that much of the science is disappointing. First, there are the usual stereotypes – the CERN director is portrayed as a cold scientific type with few morals or empathy. The lab is full of all sorts of gadgetry incomprehensible to the hero Langton, a Harvard professor of religious iconology. More seriously, some of the science is poorly researched and inaccurate.

For example, a very basic component of the plot makes no sense. An anti-religious group is suspected of murdering a CERN scientist because he has discovered that ‘‘matter can be created out of pure energy, contradicting modern science and giving support for creationism”. Except that the creation of matter from pure energy is a standard prediction of both relativity and quantum physics (E = mc2) and we have been producing it in accelerator experiments for years. There are no implications for religion!

Such misconceptions run throughout the book. Elsewhere, it is explicitly stated that particle physics is about smashing things together in order to see what’s inside. This is completely wrong – in experimental particle physics, exotic new particles are created out of the energy of reaction (e.g. antiquarks do not exist inside protons, they are created out of the energy of proton-proton collisions). Much of the discussion of antimatter also contains errors – for example the ‘antimatter bomb’ of the plot makes little sense. While antimatter can and is created in accelerator experiments, only the tiniest amounts have ever been successfully stored (i.e. atoms of antimatter, not micrograms). Statements like ‘‘the electron is the antiparticle of the proton” don’t help either.

That said, I like the idea of a bestselling novel featuring antimatter heavily. Also, the ‘struggle’ between science and religion, a central theme of the book, is an interesting theme for a bestseller – although it’s a pity that the emphasis is on the extreme views on either side of the debate.

As you know, the film is about to be released, with the usual heavy promotion. Sadly, I hear that the science in the film version is cut quite drastically – the CERN angle is limited to a few shots at the very beginning, Langton never visits the facility, and the CERN director, a central character of the novel, doesn’t feature in the film. Almost all scientists in the film are show wearing white coats, reducing their role to that of lab technicians..oh dear.

In summary, it’s easy to take potshots at science in novels like this. Overall, I’m glad to see science mentioned at all. Pity much of it is left out in the film..

Update: The particle physics community in the US have organised a series of public lectures on the science behind Angels&Demons in order to coincide with the release of the film. You can read more about this here and see the lecture timetable here.

I’m hoping to get involved in a similar lecture at the Science Gallery in Trinity College Dublin. I think it’s a good idea to tap into the anticipated public interest in antimatter. That said, I think such a lecture should also include a certain amount of discussion of science and religion, as this is a major theme of the book. More on this later…

Update II:

I just read that The Irish Times and the Royal Irish Academy are hosting a public a panel discussion on Angels, Demons and Antimatter at the RIA on June 2nd. The panel includes some very good particle physicists like Alex Montwill and Ronan Mc Nulty of UCD, well worth a visit for anyone in Dublin. You can find details of the event and book tickets on the RIA website.


Filed under Public lectures, Science and society

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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Filed under Institute of Physics, Public lectures

ESA Mission to Mars

This week is Engineering Week in Ireland and it got off to a great start at WIT with a talk on space exploration at the European Space Agency (ESA) by Micheal McKay, the Belfast-born engineer who has acted as Flight Operations Director for ESA lunar and Mars missions. (The seminar was presented by CALMAST, the Centre for the Advancement of Learning of Mathematics, Science and Technology at WIT, see here for other science/engineering events this week).

Dr McKay started with a superb outline of space exploration in general and of the work of the European Space Agency in particular. He put great emphasis on practical applications such as:

– the monitoring of the earth’s climate via the ESA ERS satellites:

– the forthcoming ESA Galileo GPS network, an independent European satellite telecommuncations network, vital for air traffic contol and for air/sea rescue:

– the SOHO mission, a study of the interaction of solar output with the earth’s magnetic field with the ESA SOHO satellite:

– observations of the most distant galaxies using Far Object Cameras mounted on ESA satellities:

– the study of the atmosphere of Venus using an ESA satellite, gathering vital information on the greenhouse effect and its implications for the earth.

One of the ESA’s earth-monitoring satellites

A schematic of the ESA’s Galileo GPS system

McKay then went on to talk about the ESA’s greatest success – the Mars Express Orbiter. He gave a superb overview of the information got from the orbiter, despite the loss of the Beagle II Lander. Indeed, McKay spent a good deal of time on the Mars mission, explaining carefully that it was the Mars Express that established the first firm evidence for substantial ice/water at the south pole. At this point, the speaker described two great examples of the sort of thinking-outside-the box engineering solutions  necessary in his  job  – the slow rotation of the Mars orbiter into sunlight to free up a jammed hinge on one of the antennae, and a software ‘sunglasses’ patch to protect a sensitive detector from excess sun…both successfully completed from hundreds of millions of miles away!

The Mars Express Orbiter

McKay also spent some time explaining the next ESA Mars project, a  manned mission to Mars in 2030.  I won’t describe this part in detail, but you can find details of the Aurora mission here;

This ws a fine seminar and there were a few general themes  I liked a lot:

(i) ‘you too can do this’ – like so many at the top, the speaker continually emphasised to the students that they too had the potential for a great career in space exploration

(ii) the outstanding success of a relatively young European space agency (currently accounts for 40% of the global space market) and the fact that European citizens are not always aware of it

(iii) the spectacular benefits of European co-operation, and of the co-operation between ESA and NASA and other space agencies – nations seem to co-operate better in space than down here!

(iv) the importance of space exploration in its own terms for our knowlege of our universe, plus the beneficial spinoffs such as the ERS  earth observation missions

(v) the success of Ireland’s membership of ESA: not just in terms of commercial contracts gained, but the payback in terms of experience and knowledge brought back to Ireland, and the potential for fantastic careers in space exploration for the next generation of Irish science and engineering students

Interesting that many of these themes are precisely the advantages that I, and others, refer to as the potential benefits of Irish membership of CERN – see earlier post on CERN and Ireland.


At question time, I asked the speaker the stock question – given the expense of building the space station necessary for manned expeditions to Mars, what can a manned mission discover that robotics cannot? He answered this in detail, carefully listing the problems of communication and contol of robots. It will be interesting to see what happens in the context of the current recession..

All in all, this was an inspiring seminar for our students given by a top expert in the field.  For me, the highlights were a music video showing the docking of the ESA vessel Columbus to the International Space Station, and the description of the solutions to engineering problems with the Mars Express orbiter – from a software patch to protect a detector from excess sun, to the rotation of the station into sunlight to free up a jammed hinge!


Filed under Astronomy, Public lectures

Atoms of light: Book launch at UCD

I drove up to Dublin yesterday evening for a book launch at University College Dublin. Two of my former professors, Alex Montwill (who taught courses in formal quantum theory and particle physics) and Ann Breslin (special relativity and experimental high-energy physics) have just written a popular science book Let there be light: The Story of Light from Atoms to Galaxies‘ published by Imperial College Press. Both were among the best teachers I ever had, as well as outstanding researchers in the field of particle physics. In fact, Alex was Ireland’s foremost experimental particle physicist for many years, but is probably best known for a series of lectures on modern physics on national radio.

I’ve never been to a physics book launch before, it was great fun. All the great and the good from the world of Irish physics were there, including just about everyone who taught me as an undergraduate! Talk about a trip down memory lane. One big difference – I couldn’t believe how beautiful Belfield campus is now with tons of landscape gardening and new buildings.

The book was launched with great aplomb by Dick Ahlstrom, science editor of The Irish Times. Dick has played a huge role in the communication of science to the public in Ireland, mainly through writing and editing a full page on science every week in The Irish Times (you can see an example here). As far as I know, there is a fairly unique example of a full page on science in a quality newspaper, and is now an integral part of that great paper.

I have yet to have a good read of the book but it looks superb, as you might expect of the culmination of a lifetime’s reflection on physics by two highly respected physicists and teachers. The book is pitched at a level slightly above most popular science books, 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 astronomy to quantum theory, from electromagnetism to special relativity. An unusual feature is the essay-like style of the presentation – you can start reading anywhere (though it’s hard to put down). Another unique feature are the illustrations; a huge number of really helpful small illustrations, from well-known images to sketches and cartoons. A lot of the concepts are illustrated via an owl character, which reminds me of the books of George Gamow, an old hero of mine.

If you want to know more, buy the book. I’m looking forward to reading it at the weekend

Update: You can get it at discount at the World Scientific site, and there is a very nice overview of the book there


Filed under Public lectures

Zeilinger in Ireland

The highlight of Science Week (see below) was a talk on Monday evening at University College Cork by Anton Zeilinger, the world’s foremost quantum experimentalist. The title of the talk was ‘Quantum puzzles and their applications in future information technologies’ and it was sponsored by Science Foundation Ireland, the Institute of Physics and the Tyndall Institute. (The connection is that Sile Nic Chormaic, the leader of the quantum optics group at the Tyndall Institute, is a former member of the Z. group).

Zeiinger started with a brief introduction to quantum theory, from Planck’s quantum of action to the emergence of wave theory. He then focused on the problem of interpretation, starting with Bohr’s double slit experiment. Having explained the ideas of interference and entanglement, the theme of the talk was set at at the difference between Bohr’s spooky-action at a distance and Einsein’s refusal to yield either locality or realism. Z. then gave a clear depiction of Bell’s theorem and described how the experiments of his own group effectively ruled out hidden variable theory, leaving the question of whether locality or realism was violated. He also mentioned recent tests his group have done that point at the latter, you can read a good account of them here.


Quantum interference on the ski slope

In the second part of the talk, Z. gave a masterly overview of the applications of entanglement – teleportation, encryption and quantum computing – and described the astonishing progress of his group on each. Funding agencies should note how experiments concerning the esoteric question of the interpretation of quantum physics turned out to have important practical applications.

Interestingly, Zeilinger returned to the nature of reality in the final part of the talk. After a careful discussion of recent experiments, he discussed the modern philosophy that it is operationally impossible to seprarate reality and information in any meaningful way, finishing with his own view – that information, not reality, is the fundamental aspect of our lives.

At question time, the speaker was as affable as ever. In response to a question from me on the so-called BB problem (who/what was there to observe it), he pointed out that qt does not specify the ordering of space-time – i.e. it doesn’t matter when the observable is observed…

All in all, this was a fabulous talk on cutting edge quantum research and its applications.

The Zeilinger record: entangled photons over the Canary Islands

P.S. Zeilinger has a well-known blog here, but you’ll need to brush up on your German!

P.P.S. There is a super description of the Einstein-Bohr debate and the Zeilinger experiments here, see comment by Zeynel


Filed under Public lectures

Lisa Randall and warped passages at Trinity College

The highlight of Maths Week Ireland (see post below) was the Hamilton lecture, a public lecture at Trinity College presented by the Royal Irish Academy in conjunction withThe Irish Times and Depfa Bank. The lecture was Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions’, by Lisa Randall, Professor of Particle Physics at Harvard. Prof Randall needed no introduction to the physicists in the audience – a particle theorist, comsologist and string theorist, she is currently one of the most cited physicists in the world, not least due to the Randall-Sundrum model of a higher dimensional universe. She has also just published a highly successful book on the RS model for the general public, and this was the topic of the lecture.

It was obvious from the start the lecture was going to be exceptional. The very first point Prof Randall made was her belief in the role of experimental verification in science, citing the role of experimentation in the optics and mechanics of Hamilton as an example (this is an important point for string skeptics, who worry that some aspects of string theory may not be falsifiable/verifiable above the Planck scale). A second point in the introductory remarks concerned her philosophical approach to theoretical physics – that models and theories are avenues to be explored, which may or may not turn out to represent nature.

The lecture proper started with a highly succinct introduction to the world of particle physics (the atom, the nucleus, the proton and the quark were dealt with in one slide). The next slide covered the fundamental forces and the Standard Model. The audience was then treated to an introduction to the rise of string theory as an attempt to reconcile general relativity and quantum physics, with higher dimensions arising naturally from the equations. There was a lovely flashback to the work of Kaluza and his attempt to unify gravity and electromagnetism by writing the equations of general relativity in five dimensions (rather than the four of Minkowski spacetime), and the subsequent proposal of compactification by Einstein and Klein (compactification is the idea that we do not percieve the 5th dimension simply because its rolled up on a tiny scale).

In the second part of the talk, Randall went on to give an outline of modern string theory, from the proposal of eleven dimensions to brane theory. The crux of the talk was a description of how, in her model, branes might provide an a solution to the hierarchy problem (i.e. the relative weakness of gravity relative to the other three fundamental interactions), if we dispense with compactification. As I understand it, the basic idea is that the non-gravitational particles and interactions could be trapped on a 3D brane, with gravity not confined – in which case the familiar particles would experience a reduced gravity due to their separation from it and a warping of that spatial separation by the energy of the universe. In the two-brane model for example, it is proposed that gravity resides on a different brane, its influence on our ‘home’ brane hugely reduced by the warping of space between the two branes.

Image from NYT via Cosmic Variance

The lecture concluded with an overview of testable consequences at the LHC. First, it was suggested that higher dimensions might be detectable as missing energy, as Kaluza-Klein particles produced in high-energy interactions escape into higher dimensions. Even better, KK particles of the RS model should be clearly distinguishable from the compactification model (and from supersymmetric particles) by their decay mechanisms, mass-spectrum and spin. She amplified further on this point in answer to a query of mine – indeed question time was excellent , with clear answers to all questions.

Overall, this was a super talk on an extremely hot topic. The main themes I took out of it were

(i) an emphasis on the possible verification/falsification of modern concepts in string theory at the LHC

(ii) an emphasis on ‘it might be wrong’

(ii) disappointment at the unavailability of energies that could have been seen at the cancelled SCC– often forgotten in Europe.

Two great quotes were

‘I don’t believe in any particular theory – I have often worked simultaneously on theories which are mutually incompatible’

‘When dealing with higher dimensions, a word is worth a thousand pictures’

If you want to more about this topic buy the book. Alternatively, there are some great articles on the topic on the Randall website.

Postscript: On the journey back to Waterford last night, it struck me that the real ‘out-there’ proposal on the dimensions of the universe remains that of Enstein and Minkowski. The idea that time is simply another dimension, equivalent to the three spatial ones was truly extraordinary – evidenced by the interplay between temporal and spatial dimensions for bodies travelling at high speed (special relativity) or in strong gravitational fields (general relativity). I’ve never understood the public amazement at the idea of multi dimensions in space – if anything, I find the idea a bit trivial once compactification is added to the mix. So the RS model is a welcome change from that. But here’s a really shocking proposal – what if we live in a universe with extra dimensions, but the extra dimensions are non-spatial? Imagine if spin (which we don’t really understand) is a dimension rather than a parameter? Or colour, charm, strangeness, parity and all those other quantum properties that are really just labels? Hmm…daft thought for the day


Filed under Public lectures

Hamilton and Maths Week in Ireland

This week is Maths Week in Ireland, an annual celebration of mathematics designed to promote a positive attitude to maths among schoolchildren and adults. All sorts of events are taking place at Universities, Institutes of Technology, museums and schools throughout the country. There are public lectures on topics like maths and magic, the maths in your ipod , statistics in real life, and probability in practice. (Yours truly was down to give a talk on the maths of the LHC experiments, but it didn’t draw a big enough audience…I guess the maths of particle physics isn’t riveting for everyone, I should have chosen a more obvious application of maths in everyday life).

There are also plenty of outside events such as maths in the street and cafe discussions of the maths of betting , not to mention astronomy shows in planetaria. You can find the full program here.

The week will be capped off with the annual Hamilton walk and Hamilton lecture.

William Rowan Hamilton was undoubtably the greatest mathematical genius Ireland has produced – and possibly one of the greatest mathematicians ever. He made many contributions to maths and physics, in optics, dynamics and algebra, but is probably best known in mathematics as the inventor of quaternions. In theoretical physics, his best known (and constantly used) work is of course the Hamiltonian operator – the operator used for energy in quantum physics. As a consequence, the Hamiltonian appears hundreds of times in every textbook on quantum physics!

William Rowan Hamilton: Irish genius

The Hamilton walk, led by Dr. Fiacre O Cairbre of NUI Maynooth, will follow the footsteps of Hamilton from Dunsink Observatory in Dublin along the Royal Canal to Broombridge. On 16th October 1843, Hamilton saw the equations of quaternions in his mind’s eye while out walking with his wife, and scratched them in the wall of the bridge lest he forget them. The markings are still there, and the walk is re-enacted each year by academic staff, students, schoolchildren and the general public.

Broom Bridge: where the quarternion formula was scratched

For me, the highlight of the week will undoubtably be the Hamilton lecture, given this year by Lisa Randall, the renowned cosmologist and particle physicist who is Professor of physics at Harvard. The title and abstract for the lecture are given below:

Warped Passages: Unraveling the Mysteries of the Universe’s Hidden Dimensions

Do we inhabit a three-dimensional universe floating in a four dimensional space? What if the extra dimensions required by string theory were not curled up and unobservably small, but unfurled and vast, extending forever? Could an invisible universe only a tiny fraction of an inch apart in another dimension explain phenomena that we see today in our world?
These are among the questions that we will consider in this lecture about extra dimensions of space.

Defnitely worth a trip up to Dublin, watch this space!

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