Teachers, students and graduation

I took time out from exam preparation to catch the end of the college conferring ceremony yesterday and I’m glad I did. As well as the great atmosphere, the beautiful chapel, the students and their proud parents, there was a nice surprise – one of the first students I ever taught at WIT was conferred with a PhD (help I’m getting old).

Venet Osmani arrived at WIT from Kosovo at about the same time I arrived from Trinity – he was among the first of our fulltime students from abroad and I remember there was a certain amount of anxiety as to how the program would roll out! In the event, Venet turned out to be one of the best students we ever had. It’s such a privilege to teach good students – more like a sharing of knowledge than a chore. Venet went on to do his PhD research with the TSSG, the highly respected telecommunications software research group at WIT, and is now continuing research in the same area with renowned international research center CREATE-NET in Italy. Definitely one of our success stories…

Last year’s conferring at WIT

Today, its back to earth and back to work on those pesky exam questions. However, 24 hours from now, I’ll be airborne – en route to Portugal for a few days break with The Surf Experience, hurrah!

Me and my laptop, that is. There’s plenty of work to be done, but it’s as easy to do in the peace and quiet of lazy evenings in the surf lodge as in a busy office in rainy Ireland. Plus, one of the chief instructors at the lodge is doing an Open University course in fundamental physics – we always have great discussions on particle physics, string theory and the mysteries of the universe!

Town, gown and college life

There is a nice atmosphere around the college this week as conferrings get underway. A curious aspect of the Institute of Technology system is that many students get conferred while still at the undergraduate stage! This is due to the stepwise nature of some of our courses, with a Certificate after two years, a Diploma after three and a Degree after four (of course we also have ab initio and postgraduate degrees).

The conferring ceremony is always lovely as it takes place in the beautiful Pugin Chapel in the College St campus, the part of our college that houses the humanities and the performing arts.

The  2007 graduation ceremony at WIT

Some academics dislike the pomp and ceremony of conferrings, but I enjoy them on the rare occasion I get to attend. There is a great sense of achievement among the students and their proud parents, and of the role of the college in the wider community among the staff. Makes it all worthwhile, somehow. There is also a nice atmosphere around town in the evenings as the students and their parents converge on the pubs and cafes – I wouldn’t be surprised if quite a few students decided to go to college as a result of the atmosphere they observed around town during commencements.

Unfortunately, this week is also one of the busiest of the year for lecturers, as it is the midpoint of the semester and exams must be submitted by the end of the week. This can be quite a tough prospect if one is lecturing new modules as it involves setting questions and answers on topics not yet covered. Setting a paper for 1st yr engineering didn’t take long, but I’ve spent all week trying to think up challenging but doable questions in the quantum physics of solids (3rd yr) and the physics of semiconductor devices (4th yr) . Sigh.

Still, no lectures next week yipee!

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

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!

Chamber music and Einstein

This weekend I’m off to play chamber music in Termonfechin, a tiny village on the eastern coast of Ireland. The event is is organised by the Dublin Chamber Music Group, a group of amateur players who organise chamber music weekends twice a year (this particular weekend is the 50th anniversary of the group). They’re great weekends, with up to 20 string quartets and other groups playing away in different rooms in a great country house – with lessons, practice and a concert on the Sunday!

Chamber music in An Grianan, Termonfeckin

I had no plans to be there, but I Got The Call last week…

-  Our violin player is ill, could you lead a piano quartet next weekend ?
- Yes
- It involves an entire weekend’s playing, you may may need to think about it
- No, I’m free
-Sure?
-Yes

It’s not often I get such opportunities these days. The downside is that I’ve had to practice after work every evening this week, trying to coax my fingers out of retirement (I should be practicising now). Two problems have emerged:
1. I don’t like the chosen piece (piano quartet no. 1 by Charles Stanford )
2. I can’t play it for nuts.
So I have a plan – as soon as we meet up, I’ll get the others to play through one of the Mozart piano quartets. They’re both beautiful and I suspect no-one will be bothered looking any  further…

(Technical note for philstines: a paino quartet is not four pianos, it’ s a quartet consisting of piano, violin, viola and cello)

Of course, it’s impossible to discuss violin-playing physicists without thinking of Einstein. One of the things I admire most about E. is that despite his huge contributions to so many areas of physics, his constant travels, and his many changes of job, he found time to keep up his music throughout his life. In fact, he once remarked that the only tangible benefit of fame was that he became much in demand as a chamber musician. Just how good a violin Einstein was is hard to gauge from the biographies (lines such as ‘a better scientist’ or ‘more musical than technically skilled’ can mean just about anything), but my guess is that he must have been pretty good. You don’t get away with much in a chamber group (it’s not like an orchestra) and it takes a certain level to play the lead violin part in groups with musicians like Rubenstein, charity event or not….

Another clue comes from a rare review of one of Einstein’s concerts  – apparently a music critic stated that ” Herr Einstein played very well enough….but hardly world-class”. Of all the plaudits Einstein received during his lifetime, I suspect this was one of his favourites (only a music critic could fail to recognize the world’s most famous scientist).

Nobel and DIAS

It’s not every day one finds a connection between a physics Institute in Ireland and the current Noble prize in physics.

I was delighted to see this year’s Nobel go for gauge symmetry (see post below), not only because it gives recognition to a difficult field that has been so important in the evolution of modern particle physics, but because it is exactly the field Lochlainn used to work in. It was also great to see the prize going to three Japanese physicists (Nambu, Kobayashi and Maskawa) as the contribution of the Japanese to gauge theory has been overlooked in the past (it was not realised until recently that gauge theory developed independently in Japan around the same time as its emergence in the west, see here for a reference ).

Kobayashi, Maskawa and Nambu

What I didn’t know is that there is a connection – one of the last scholars to work with Dad at the Dublin Institute of Advanced Studies (DIAS) was the brilliant young physicist Izumi Tsutsui, now at KEK (the Japanese CERN), and a colleague of Maskawa. In fact, Izumi was appointed Professor at Tokyo University by Maskawa directly after his stint at DIAS, which gives us a hint that the quality of work at DIAS can’t be too bad. Since then, they have collaborated extensively. It’s lucky Izumi isn’t the type to rest on his laurels…

Izumi Tsutsui: youngets professor in Tokyo U?

Emcouraged by all this, I had a look to see if I could find any Maskawa-Kobayashi-O’Raifeartaigh papers on the web. I couldn’t, but the very first hit on google is a recent paper by Kobayashi that heavily cites the O’Raifeartaigh model. It’s a small world, especially in high energy physics! Who knows, maybe supersmmetry will actually be seen at the LHC, in which case those of us who can’t really understand Lochlainn’s work will at least be able to appreciate its importance….

Correction; Oops, my mistake. Izumi tells me that the author of the paper is a different Kobayashi, a common name in Japan! Still, the DIAS connection with Maskawa via Izumi still stands, and we in Ireland should be proud of this association..

Nobel for symmetry breaking

Great news for particle physics -  the 2008 Nobel Prize in Physics has been awarded for hidden gauge symmetry.

This year’s prize has been awarded to three particle theorists – one half to Yoichiro Nambu“for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics”, and the other half to Makoto Kobayashi and Toshihide Maskawa “for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature”

While I was betting on a prize for neutrino oscillation (experimental), most would agree that the Nambu prize is long overdue. He was the first to introduce the concept of spontaneous symmetry breaking to particle physics, having studied the phenomenon in superconductivity. The idea caught hold rapidly and was a seminal step in the construction of the Standard Model of particle physics (for example, symmetry breaking is an integral part of the theory of the electro-weak interaction, and the process by which particles acquire mass via the Higgs field is thought to be an example of symmetry breaking).

There’s more: among theoreticians, Nambu is most revered for his discovery of the gauge theory of the strong interaction  – in other words as the grandfather of quantum chromodynamics. And if that weren’t enough, he is also a godfather of string theory, so some may see this prize as a nod towards string theory.

Nambu: pioneer of gauge symmetry, QCD and string theory

Spontaneous symmetry breaking : symmetry is broken as the ball rolls down the hill

I know less about the others, but Kobayashi and Maskawa developed the mechanism of CP violation in the weak force, and how CP violation is reflected in the interactions of quarks – this work led to the prediction of  three generations of quarks (the last of the 3rd generation of quarks was found in the 1990s).  CP violation is crucial to our understanding of the asymmetry of matter and antimatter, and was experimentally demonstrated in some famous k -meson experiments in the 1960s (more recent experiments at the BaBar detector at Stanford and the Belle detector at KEK in Japan have also demonstrated CP violation). Next year, matter/antimatter asymmetry and CP violation and will be examined in further detail at the LHCb experiment.

You can find more details and the official announcement on the Nobel site here.

All in all, a good day for particle physics, as spontaneous symmetry breaking is a crucial component of the modern theory of elementary particles. I do have my reservations about Nobel prizes in general, but I’ll leave that discussion for another day..

Postscript

A couple of people hinted darkly at political timing over lunch – is it a coincidence that the prize should be awarded to particle physics in this year, the year of the LHC?

I think it is, and even if not so what. The prize is decades overdue, in all three cases. The importance of hidden gauge symmetry in particle physics may not be as obvious as the latest measurements of the Cosmic Microwave Background (say), but it is a vital piece of our understanding of the subatomic world. Plus, the relevant experiments have been done decades ago.

P.P.S.

For a more technical discussion of the issues above, see today’s postings on blogs such as Symmetry Factor and Not Even Wrong.  An important point being made is that the third (and original) physicist of the Cabibbo-Kobayashi-Maskawa matrix was overlooked – Cabibbo is yet another victim of the silly Nobel rule that the prize can only be awarded to three. This is also true of Goldstone, a gauge theorist who even has a famous particle named after him- in an ideal world one Nobel prize should go to Nambu and Goldstone, and another to C,K and W. There is a good discussion of this on T. Dorigo’s blog  A Quantum Diaries Survivor

100 years of atoms

Quite a few people have pointed out that this month marks the hundreth anniversary of Minkowski space-time (see Backreaction for a good post on this). However, another anniversary occurs this year that has received less attention although it is highly relevant to the LHC.

2008 marks the centenary of the experimental discovery of atoms i.e. Perrin’s seminal work on Brownian motion. This series of experiments verified Einstein’s conjecture that the presence of molecules in a liquid could be demonstrated by a careful study of the ‘random’ motion of small particles suspended in the liquid. Up to this point, many scientists still doubted the reality of atoms, despite pointers from the kinetic behaviour of gases and Dalton’s work in chemical reactions. Einstein’s statistical analysis of the expected ‘random walk’ of suspended particles (1905) coupled with Perrin’s subsequent experiments (1908) effectively settled the debate in favour of the reality of atoms – a seminal moment in science which also pointed to the role of probability in the laws of physics for the first time (since it was realised that the laws of thermodynamics describe large assemblies of molecles and are therefore statistical in nature).

Einstein, Perrin and Brownian motion: settled the atomic debate

Settled the issue for scientists, I should say: to this day, one comes across philosophers who write that ‘no-one has seen an atom’. I find this a bit of a stretch – there are lots of things in nature we observe indirectly. Besides, this viewpoint ignores the advent of technologies such as Scanning Tunneling Microscopy, Atomic Force Microscopy and modern experiments with single atoms!

Below is an extract from an article on Brownian motion I wrote for Spin Science magazine during Einstein year:

******************************************************

….Einstein and the Atomic Theory

Greatly interested in the atomic view of matter, the young Einstein devised a mathematical method of calculating the size of atoms and molecules in early 1905. From an analysis of sugar molecules dissolved in water, he calculated both the diameter of the sugar molecule and Avogadro’s number (the number of molecules per unit volume under standard conditions) from the known viscosity of the liquid and the diffusion rate of sugar. His calculations were in good agreement with previous theoretical estimates and were well-received. However, the very existence of atoms and molecules had still to be demonstrated in convincing fashion, and the 26-year old Einstein applied himself to this task.

Einstein and Statistics

According to the atomic view of matter, a liquid is made up of a huge number of molecules in random, ceaseless motion, the properties of the liquid arising from the average behaviour of its constituent molecules. Working from first principles, Einstein made a careful study of the statistics of such an assembly and, in May 1905, he made a key proposal concerning its behaviour. He proposed that any such system would experience statistical fluctuations, during which random elements depart from their average behaviour (just as a dice player can occasionally throw several sixes in a row). Applying this concept of statistical fluctuation to the case of molecules in liquids, Einstein proposed that a small group of neighbouring molecules could momentarily move in the same direction – a fluctuation that would cause a body immersed in the liquid to experience a tiny push in that direction. Another group of molecules could cause the same body to experience a tiny push in a different direction moments later and the immersed body would therefore experience a zigzag motion in the liquid – a motion that might be observable. Hence, while the molecules of a liquid were far too small to be observed directly by microscope, their motion might be detectable by its effect on a larger particle suspended in the liquid!

Brownian Motion

Excitingly, a zigzag motion of particles suspended in a liquid had long been known to scientists (named ‘Brownian Motion’ after the English botanist who studied the effect in detail). The cause of this motion had been a great mystery – and accurate measurement of the 3-D random motion of an immersed particle had proved extremely difficult. Here, Einstein made a second vital contribution. Starting with the assumption that the motion was indeed due to a buffeting of the immersed particle by the molecules of the liquid, he calculated the average horizontal distance an immersed particle would travel in a given time. Hence, from his own statistical analysis, Einstein delivered a well-defined, measurable estimate that could be easily tested by experimentalists.

The Experiment

The French scientist Jean Perrin rose to Einstein’s challenge with a series of experiments in 1908. Equipped with nothing but a microscope and a stopwatch, Perrin and his team measured the horizontal displacement of gum extract particles suspended in water as a function of time. The data were in exact accord with Einstein’s predictions, giving the world the first unequivocal evidence of the reality of molecules. Einstein was delighted, as was Perrin – the Frenchman was later awarded the Nobel Prize for this work!

Implications

Einstein’s ‘Brownian-motion’ paper facilitated the first real glimpse of the atomic nature of matter, an advance that underpins almost all of modern science. Another consequence of the paper was that, since the properties of matter were now known to be determined by the behaviour of huge numbers of atoms, it was realized that the laws of thermodynamics were valid only in a statistical sense. For the first time, the role of probability in the laws of physics was established, a defining moment in the philosophy of science.

Modern Applications

Today, Einstein’s notion of statistical fluctuations has found application throughout the sciences. From the study of cell membranes to our view of evolution, from the analysis of weather systems to the study of the stock market, it underpins our understanding of all complex systems. Perhaps the ‘Brownian–motion’ paper did not have quite the dramatic impact of the Special Theory of Relativity, or indeed of Einstein’s quantum view of light – but it resulted in a quiet revolution that has had an lasting influence on modern science.