Praxis Archives – Page 91 of 179

The incurable attraction of physics

A noble gas, a missing scientist and an underground laboratory. It could be the starting point for a classic detective story. But a love story? It seems unlikely. However, add in a back-story set in Spain during General Franco’s rule, plus a “eureka” moment in California, and the ingredients are there for a real romance – all of it rooted firmly in physics.

CCgom1_01_13 — JJ Gómez Cadenas: a passion for CERN, neutrinos – and writing.
Image credit: Jorge Quiñoa & Jot Down.

When Spanish particle-physicist Juan José Gómez Cadenas arrived at CERN as a summer student, the passion that he already had for physics turned into an infatuation. Thirty years later and back in his home country, Gómez Cadenas is pursuing one of nature’s most elusive particles, the neutrino, by looking where it is expected not to appear at all – in neutrinoless double-beta decay. Moreover, fiction has become entwined with fact, as he was recently invited to write a novel set at CERN. The result, Materia Extraña (Strange matter), is a scientific thriller that has already been translated into Italian.

Critical point

“Particle physicists were a rare commodity in Spain when the country first joined CERN in 1961,” Cecilia Jarlskog noted 10 years ago after a visit to “a young and rapidly expanding community” of Spanish particle physicists. Indeed, the country left CERN in 1969, when Juan was only nine years old and Spain was still under the Franco regime. Young Juan – or “JJ” as he later became known – initially wanted to become a naval officer, like his father, but in 1975 he was introduced to the wonders of physics by his cousin; Bernardo Llanas had just completed his studies with the Junta de Energía Nuclear (the forerunner of CIEMAT, the Spanish research centre for energy, the environment and technology) at the same time as Juan Antonio Rubio, who was to do so much to re-establish particle physics in Spain. The young JJ set his sights on the subject – “Suddenly the world became magic,” he recalls, “I was lost to physics” – and so began the love affair that was to take him to CERN and, in a strange twist, to write his first novel.

The critical point came in 1983. JJ was one of the first Spanish students to gain a place in CERN’s summer student programme when his country rejoined the organization. It was an amazing time to be at the laboratory: the W and Z bosons had just been discovered and the place was buzzing. “I couldn’t believe this place, it was the beginning of an absolute infatuation,” he says. That summer he met two people who were to influence his career: “My supervisor, Peter Sonderegger, with whom I learnt the ropes as an experimental physicist, and Luis Álvarez-Gaume, a rising star who took pity on the poor, hungry fellow-Spaniard hanging around at night in the CERN canteen.” After graduating from Valencia University, JJ’s PhD studies took him to the DELPHI experiment at CERN’s Large Electron–Positron collider. With the aid of a Fulbright scholarship, he then set off for America to work on the Mark II experiment at SLAC. From there it was back to CERN and DELPHI again, but in 1994 he left once more for the US, this time following his wife, Pilar Hernandez, to Harvard. An accomplished particle-physics theorist, she converted her husband to her speciality, neutrino physics, thus setting him on the trail that would lead him through the NOMAD, HARP and K2K experiments to the challenge of neutrinoless double-beta decay.

The neutrinoless challenge

Established for 15 years as professor of physics at the Institute of Nuclear and Particle Physics (IFIC), a joint venture between the University of Valencia and the Spanish research council (CSIC), he is currently leading NEXT – the Neutrino Experiment with a Xenon TPC. The aim is to search for neutrinoless double-beta decay using a high-pressure xenon time-projection chamber (TPC) in the Canfranc Underground Laboratory in the Spanish Pyrenees. JJ believes that the experiment has several advantages in the hunt for this decay mode, which would demonstrate that the neutrino must be its own antiparticle, as first proposed by Ettore Majorana (whose own life ended shrouded in mystery). The experiment uses xenon, which is relatively cheap and also cheap to enrich because it is a nobel gas. Moreover, NEXT uses gaseous xenon, which gives 10 times better energy resolution for the decay electrons than the liquid form. By using a TPC, it also provides a topological signature for the double-beta decay.

The big challenge was to find a way to amplify the charge in the xenon gas without inducing sparks. The solution came when JJ talked to David Nygren, inventor of the TPC at Berkeley. “It was one of those eureka moments,” he recalls. “Nygren proposed using electroluminescence, where you detect light emitted by ionization in a strong field near the anode. You can get 1000 UV photons for each electron. He immediately realized that we could get the resolution that way.” JJ then came up with an innovative scheme to detect those electrons in the tracking plane using light-detecting pixels (the silicon photomultiplier) – and the idea for NEXT was born. “It is hard for me not to believe in the goddess of physics,” says JJ. “Every time that I need help, she sends me an angel. It was Abe Seiden in California, Gary Feldman in Boston, Luigi di Lella and Ormundur Runolfson at CERN, Juan Antonio Rubio in Spain … and then Dave. Without him, I doubt NEXT would have ever materialized.” The collaboration now involves not only Spain and the US but also Colombia, Portugal and Russia. The generous help of a special Spanish funding programme, called CONSOLIDER-INGENIO, provided the necessary funds to get it going. “More angels came to help here,” he explains, “all of them theorists: José Manuel Labastida, at the time at the ministry of science, Álvaro de Rújula, my close friend Concepción González-García … really, the goddess gave us a good hand there.”

Despite the financial problems in Spain, JJ says that “there is a lot of good will” in MINECO, the Ministry of Economy, which currently handles science in Spain. He points out that there has already been a big investment in the experiment and that there is full support from the Canfranc Laboratory. He is particularly grateful for the “huge support and experience” of Alessandro Bettini, the former director of the Gran Sasso National Laboratory in Italy, who is now in charge at Canfranc. JJ finds Bettini and Nygren – both in their mid-seventies – inspirational characters, calling them the “Bob Dylans” of particle physics. Indeed, he set up an interview with both of them for the online cultural magazine, Jotdown – where he regularly contributes with a blog called “Faster than light”.

In many ways, JJ’s trajectory through particle physics is similar to that of any talented, energetic particle physicist pursuing his passion. So what about the novel? When did an interest in writing begin? JJ says that it goes back to when his family eventually settled in the town of Sagunto, near Valencia, when he was 15. An ancient city where modern steel-making stands alongside Roman ruins, he found it “a crucible of ideas”, where writers and artists mingled with the steel-workers, who wanted a more intellectual lifestyle for their children – especially after the return of democracy with the new constitution in 1978, following Franco’s death. JJ started writing poetry while studying physics in Sagunto, and when physics took him to SLAC in 1986, as a member of Stanford University, he was allowed to sit in on the creative-writing workshop. “I was not only the only non-native American but also the only physicist,” he recalls. “I’m not sure that they knew what to make of me.” Years later, he continued his formal education as a writer at the prestigious Escuela de Letras in Madrid.

A novel look at CERN

Around 2003, CERN was starting to become bigger news, with the construction of the LHC, experiments on antimatter and an appearance in Dan Brown’s mystery-thriller Angels & Demons. Having already written a book of short stories, La agonía de las libélulas (Agony of the dragonflies), published in 2000, JJ was approached by the Spanish publisher Espasa to write a novel that would involve CERN. Of course, the story would require action but it would also be a personal story, imbued with JJ’s love for the place. Materia Extraña, published in 2008, “deals with how someone from outside tries to come to grips with CERN,” he explains, “and also with the way that you do science.” It gives little away to say that at one and the same time it is CERN – but not CERN. For example, the director-general is a woman, with an amalgam of the characteristics that he observes to be necessary for women to succeed in physics. “The novel was presented in Madrid by Rubio,” says JJ. “At the time, we couldn’t guess he had not much time left.” (Rubio was to pass away in 2010.)

When asked by Espasa to write another book, JJ turned from fiction to fact and the issue of energy. Here he encountered “a kind of Taliban of environmentalism” and became determined to argue a more rational case. The result was El ecologista nuclear (The Nuclear Environmentalist, now published in English) in which he sets down the issues surrounding the various sources of energy. Comparing renewables, fossil fuels and nuclear power, he puts forward the case for an approach based on diversity and a mixture of sources. “The book created a lot of interest in intellectual circles in Spain,” he says. “For example, Carlos Martínez, who was president of CSIC and then secretary of state (second to the minister) liked it quite a bit. Cayetano López, now director of CIEMAT, and an authority in the field, was kind enough to present it in Madrid. It has made some impact in trying to put nuclear energy into perspective.”

So how does JJ manage to do all of this while also developing and promoting the NEXT experiment? “The trick is to find time,” he reveals. ‘We have no TV and I take no lunch, although I go for a swim.” He is also one of those lucky people who can manage with little sleep. “I write generally between 11 p.m. and 2 a.m.,” he explains, “but it is not like a mill. I’m very explosive and sometimes I go at it for 12 hours, non-stop.”

He is now considering writing about nuclear energy, along the lines of the widely acclaimed Sustainable Energy – without the hot air by Cambridge University physicist David MacKay, who is currently the chief scientific adviser at the UK’s Department of Energy and Climate Change. “The idea would be to give the facts without the polemic,” says JJ, “to really step back.” He has also been asked to write another novel, this time aimed at young adults, a group where publisher Espasa is finding new readers. While his son is only eight years old, his daughter is 12 and approaching this age group. This means that he is in touch with young-adult literature, although he finds that at present “there are too many vampires” and admits that he will be “trying to do better”. That he is a great admirer of the writing of Philip Pullman, the author of the bestselling trilogy for young people, His Dark Materials, can only bode well.

• For more about the NEXT experiment see the recent CERN Colloquium by JJ Gómez Cadenas at http://indico.cern.ch/conferenceDisplay.py?confId=225995. For a review of El ecologista nuclear see the Bookshelf section of this issue.

The incomprehensibility principle

Educators and psychologists invented the term “attention span” to describe the length of time anyone can concentrate on a particular task before becoming distracted. It is a useful term but span, or duration, is only one aspect of attention. Attention must also have an intensity – and the two variables are independent of each other. Perhaps one can postulate an analogue of the Heisenberg uncertainty principle, in which the intensity of attention multiplied by its span cannot exceed some fixed value. I call this the “incomprehensibility principle” and I have had plenty of opportunities to observe its consequences.

In the hands of skilled presenters, information can be carefully packaged as entertainment so that the attention needed to digest it is minimal. The trick is to mask the effort with compelling emotional appeal and a floppy boy-band haircut. However, the need to pay attention is still there; in fact, absorbing even the most trivial information demands a modicum of attention. How many of us, when leaving a cinema, have had the nagging feeling that although the film made great entertainment some details of the plot remained less than crystal clear?

The existence of a minimum level of attention suggests that it is, in some sense, a quantum substance. This means that under close examination, any apparently continuous or sustained effort at paying attention will be revealed as a series of discrete micro-efforts. However, while attention can be chopped up and interleaved with other activities, even tiny pulses of attention demand full concentration, to the exclusion of all other voluntary activities. Any attempt at multitasking, such as using a mobile phone while driving a car, is counterproductive.

The incomprehensibility principle plays a major role in education, where it is closely linked to the learning process. Because of the subject matter and/or the teacher, some school lessons require more time to assimilate than others. This trend accelerates in higher education. In my case, a hint of what was to come appeared during my third year of undergraduate physics, when I attended additional lectures on quantum mechanics in the mathematics department at Imperial College London.

My teacher was Abdus Salam, who went on to share the Nobel Prize for Physics in 1979. Salam’s lectures were exquisitely incomprehensible; as I look back, I realize he was probably echoing his own experiences at Cambridge some 15 years earlier at the hands of Paul Dirac. But he quickly referred us to Dirac’s book, The Principles of Quantum Mechanics. At a first and even a second glance, this book shone no light at all but after intense study, a rewarding glimmer of illumination appeared out of the darkness.

Motivated by Salam’s unintelligibility, I began postgraduate studies in physics only to find that my previous exposure to incomprehensibility had been merely an introduction. By then, there were no longer any textbooks to fall back on and journal papers were impressively baffling. With time, though, I realized that – like Dirac’s book – they could be painfully decrypted at “leisure”, line by line, with help from enlightened colleagues.

The real problem with the incomprehensibility principle came when I had to absorb information in real time, during seminars and talks. The most impenetrable of these talks always came from American speakers because they were, at the time, wielding the heavy cutting tools at the face of physics research. Consequently, I developed an association between incomprehensibility and accent. This reached a climax when I visited the US, where I always had the feeling that dubious characters hanging out at bus stations and rest stops must somehow be experts in S-matrix theory and the like, travelling from one seminar to the next. Several years later, when I was at CERN, seminars were instead delivered in thick European accents and concepts such as “muon punch-through” became more of an obstacle when pointed out in a heavy German accent.

Nevertheless, I persevered and slowly developed new skills. The incomprehensibility principle cannot be bypassed but even taking into account added difficulties such as the speaker’s accent or speed of delivery – not to mention bad acoustics or poor visual “aids” – it is still possible to optimize one’s absorption of information.

One way of doing this is to monitor difficult presentations in “background mode”, paying just enough attention to follow the gist of the argument until a key point is about to be reached. At that moment, a concerted effort can be made to grab a vital piece of information as it whistles past, before it disappears into the obscurity of the intellectual stratosphere. The trick is to do this at just the right time, so that each concentrated effort is not fruitless. “Only cross your bridges when you come to them”, as the old adage goes.

By adopting this technique, I was able to cover frontier meetings on subjects of which I was supremely ignorant, including microprocessors, cosmology and medical imaging, among others. Journalists who find themselves baffled at scientific press conferences would do well to follow my example, for the truth is that there will always be a fresh supply of incomprehensibility in physics. Don’t be disappointed!

• Gordon Fraser. Gordon, who was editor of CERN Courier for many years, wrote this as a ‘Lateral Thought’ for Physics World magazine but died before the article could be revised (see obituary). It was completed by staff at Physics World and is published in both magazines this month as a tribute.

CERN becomes UN observer

CCnew2_01_13 — Image credit: Evan Schneider/UN.

On 14 December, the UN General Assembly adopted a resolution to allow CERN to participate in the work of the General Assembly and to attend its sessions as an observer. With this new status, the laboratory can promote the essential role of basic science in development.

In a meeting with UN secretary-general, Ban Ki-moon, on 17 December, CERN’s director-general, Rolf Heuer, pledged that CERN was willing to contribute actively to the UN’s efforts to promote science, in particular UNESCO’s initiative “Science for sustainable development”. Ban Ki-moon, left, with Rolf Heuer.

Europe launches consortium for astroparticle physics

At the end of November, European funding agencies for astroparticle physics launched a new sustainable entity, the Astroparticle Physics European Consortium (APPEC). This will build on the successful work of the European-funded network, the AStroParticle European Research Area (ASPERA).

Over the past six years, ASPERA has brought together funding agencies and the physics community to set up European co-ordination for astroparticle physics. It has developed common R&D calls and created closer relationships to industry and other research fields. Above all, ASPERA has developed a European strategy for astroparticle physics to prioritize the large infrastructures needed to solve universal mysteries in concerning, for example, neutrinos, gravitational waves, dark matter and dark energy.

APPEC now plans to develop a European common action plan to fund the upcoming large astroparticle-physics infrastructures as defined in ASPERA’s road map. Ten countries have already joined the new APPEC consortium, with nine others following the accession process. APPEC’s activities will be organized through three functional centres, located at DESY, the Astronomy, Particle Physics and Cosmology laboratory of the French CNRS/CEA, and the INFN’s Gran Sasso National Laboratory. Stavros Katsanevas of CNRS has been elected as chair of APPEC and Thomas Berghoefer of DESY as general secretary.

• APPEC is the Astroparticle Physics European Consortium. It currently comprises 10 countries represented by their Ministries, funding agencies or their designated institution: Belgium (FWO), Croatia (HRZZ), France (CEA, CNRS), Germany (DESY), Ireland (RIA), Italy (INFN), The Netherlands (FOM), Poland (NCN), Romania (IFIN) and the UK (STFC).

Quantum Gravity (Third Edition)

By Claus Kiefer
Oxford University Press
Hardback: £65 $117

The search for a quantum theory of the gravitational field is one of the great open problems in theoretical physics. This book covers the two main approaches to its construction – the direct quantization of Einstein’s general theory of relativity and string theory. There is a detailed presentation of the main approaches used in quantum general relativity: path-integral quantization, the background-field method and canonical quantum gravity in the metric, connection and loop formulations.

Writing Science: How to Write Papers That Get Cited and Proposals That Get Funded

By Joshua Schimel
Oxford University Press
Hardback: £60 $99
Paperback: £22.50 $35

Success is not necessarily defined by getting papers into print but by getting them into the reader’s consciousness. Writing Science is built on the idea that successful science writing tells a story. It shows scientists and students how to present their research in a way that is clear and that will maximize reader comprehension. This book takes an integrated approach, using the principles of story structure to discuss every aspect of successful science writing, explaining how to write clear and professional sections, paragraphs and sentences. The final section deals with challenges such as how to discuss research limitations and write for the public.

Relativistic Cosmology

By George F R Ellis, Roy Maartens and Malcolm A H MacCallum
Cambridge University Press
Hardback: £80 $130
E-book: $104

Using a relativistic geometric approach, this book focuses on the general concepts and relations that underpin the standard model of the universe. Part I covers foundations of relativistic cosmology. Part II develops the dynamical and observational relations for all models of the universe based on general relativity. Part III focuses on the standard model of cosmology, including inflation, dark matter, dark energy, perturbation theory, the cosmic microwave background, structure formation and gravitational lensing. It also examines modified gravity and inhomogeneity as possible alternatives to dark energy. Anisotropic and inhomogeneous models are described in Part IV, and Part V reviews deeper issues, such as quantum cosmology, the start of the universe and the multiverse.

LHC Physics

By T Binoth, C Buttar, P J Clark and E W N Glover (eds.)
Taylor & Francis
Hardback: £76.99

LHC Physics collects the written versions of lectures delivered at the Scottish Universities Summer School in Physics that took place in August 2009, in St Andrews, and covers many relevant issues for people working on the analysis of LHC data. The first nine chapters include discussions about QCD, the Higgs, B physics, forward physics, quark–gluon plasma and physics beyond the Standard Model, complemented by lectures on the LHC accelerator and detectors. The last three chapters cover Monte Carlo event-generators, statistics for high-energy-physics data analyses, and Grid computing. The lecturers are top-level experts and the book provides a nice introduction to many topics in high-energy physics, making it a valuable addition to many libraries around the world, including those of the hundreds of universities and institutes that participate in the LHC experiments.

The chapter on statistics is particularly useful as an introduction for the PhD students and postdocs who are heavily involved in data analyses. It addresses the relevance of Bayesian approaches and of the Markov-chain Monte Carlo tool, as well as the importance of providing results in the form of posterior probability distributions and how to deal properly with systematic uncertainties. It also overviews the topic of multivariate classifiers (with emphasis on “boosted decision trees”) and readers will probably appreciate the concluding remark that “while their use will no doubt increase as the LHC experiments mature, one should keep in mind that a simple analysis also has its advantages”.

Despite the book being published in 2012, it already seems somewhat old – a clear testimony to the amazing speed at which LHC results are being produced. Since the school took place, around 500 physics papers have been published by the LHC collaborations (a really impressive achievement), including many results that have significantly improved our understanding of most of the topics addressed in this book. While holding such summer schools is obviously important, one might wonder about the usefulness of the corresponding proceedings, especially when published more than two years after the school took place.

Léon Rosenfeld: Physics, Philosophy, and Politics in the Twentieth Century

By Anja Skaar Jacobsen
World Scientific
Hardback: £56
E-book: £69

The life of Léon Rosenfeld (1904–1974) spanned all of the three main epochs of the development of physics during the 20th century, at least according to the classification that Vicky Weisskopf expressed in a colloquium at CERN entitled “The development of science during this century”. So it should not be surprising that, as Anja Skaar Jacobsen of the Niels Bohr Archive demonstrates, the activities of this outstanding Belgian physicist cannot be grouped into a single category. Rosenfeld, who was extremely curious and erudite, contributed substantially to electrodynamics, to the Copenhagen interpretation of quantum mechanics and to the problem of the measurability of quantum fields. He was also a science historian, a tenacious political activist and, last but not least, the founding editor of the journal Nuclear Physics.

The first and second of the six chapters follow Rosenfeld’s life and interests through the 1930s up to the period where he actively participated in the formulation of the so-called Copenhagen interpretation of quantum theory and collaborated with Niels Bohr. The interface between science and politics in this period is specifically addressed in the third chapter. Rosenfeld never joined the communist party but progressively became a convinced leftist intellectual. Prior to the Stalinist purge in the second half of the 1930s, Copenhagen was also at the heart of political debates, hosting many leaders such as Lev Trotsky who visited Denmark in 1932. The fourth chapter describes how Rosenfeld survived the war in Utrecht where he took over the position of George Uhlenbeck, who left for the US in 1939. The final two chapters focus on his political commitment during the Cold War and on heated discussions surrounding the attacks on the Copenhagen interpretation, which Rosenfeld fiercely defended throughout his life.

The interests of Rosenfeld and the second “quantum generation” implicitly encourage debates. In a purely scientific context, there is the broad problem of the interpretation of quantum mechanics. The quantum theory of measurement was perceived as essential in the 1930s and throughout the 1940s. How does a classical object interact with a quantum system? Does it make sense to separate the world into quantum systems (the observables) and classical observers? The discussions leading to the most successful applications of quantum mechanics are a continuous source of reflection, from the early Einstein-Bohr controversy to Bell’s inequalities via the Bohmian interpretation of quantum theory. Quantum mechanics is not reducible either to a successful computational framework or to a philosophical perspective. It is, rather, a complicated mix of ideas that matured in one of the most difficult periods of European history. To understand quantum mechanics also means to understand the history of the first part of the 20th century: this is probably one of the main legacies, among others, of the life of Léon Rosenfeld.

Higgs Discovery: The Power of Empty Space!

By Lisa Randall
Bodley Head
Paperback: £4.99

Readers of CERN Courier need no introduction to Lisa Randall, the well known theoretical physicist. Her previous books, Warped Passages and Knocking on Heaven’s Door, are exceptionally interesting and surprisingly easy to read, especially when considering the complexity of the topics that she addresses. I cannot judge if the fluidity of her writing is a natural talent or the result of much hard work through several editorial iterations – but the result is outstanding. Her new book, Higgs Discovery: The Power of Empty Space, reports her reactions to the announcement by the CMS and ATLAS experiments that “a particle related to the Higgs mechanism had been found” – “I was flabbergasted” – and compiles her answers to the many questions that she has been asked since.

This is a small book of fewer than 50 pages, which can be read in a couple of hours. The writing style is refreshing and informal, with a warped sense of humour that helps to grab the target audience: the people who were fascinated with the discovery without knowing why. Sometimes it is a little repetitive and almost feels like “Higgs for dummies” but this is more a compliment than a criticism. Nowadays, most people forget to explain “the basics”, a challenge that Randall excels at. And she does not forget to wrap her teachings with passages that extend well beyond high-energy physics: “The Higgs boson discovery is more likely to be the beginning of the story than an end.” I wonder if she purposely paraphrased Winston Churchill.

I certainly agree that “the discovery is truly inspirational” and I am also glad that we can avoid the need to explain why not finding the Higgs boson would be even more interesting than actually finding it.

Topics

Reset your password

Registration complete

Critical point

The neutrinoless challenge

A novel look at CERN