Subject Grouping: Praxis

By Peter Deák
Wiley–VCH

The most recent and upcoming developments of electronic devices for information technology are increasingly being based on physical phenomena that cannot be understood without some knowledge of quantum mechanics (QM). In the new hardware, switching happens at the level of single electrons and tunnelling effects are frequently used; in addition, the superposition of electron states is the foundation of quantum information processing. As a consequence, the study of QM, as well as informatics, is now being introduced in undergraduate electric and electronic engineering courses. However, there is still a lack of textbooks on this subject written specifically for such courses.

The aim of the author was to fill this gap and provide a concise book in which both the basic concepts of QM and its most relevant applications to electronics and information technologies are covered, making use of only the very essential mathematics.

The book starts off with classical electromagnetism and shows its limitations when it comes to describing the phenomena involved in modern electronics. More advanced concepts are then gradually introduced, from wave–particle duality to the mathematical construction used to describe the state of a particle and to predict its properties. The quantum well and tunnelling through a potential barrier are explained, followed by a few applications, including light-emitting diodes, infrared detectors, quantum cascade lasers, Zener diodes, flash memories and the scanning tunnelling microscope. Finally, the author discusses some of the consequences of QM for the chemical properties of atoms and other many-electron systems, such as semiconductors, as well as the potential hardware for quantum information processing.

Even though the mathematical formulation of basic concepts is introduced when required, the author’s approach is oriented at limiting calculations and abstraction in favour of practical applications. Applets, accessible on the internet, are also used as a support, to ease the computational work and quickly visualise the results.

By Steven Weinberg
The Belknap Press of Harvard University Press

When Nobel laureates offer their point of view, people generally are curious to listen. Self-described rationalist, realist, reductionist and devoutly secular, Steven Weinberg has published a new book reflecting on current affairs in science and beyond. In Third Thoughts, he addresses themes that are of interest for both laypeople and researchers, such as the public funding of science.

Weinberg shared the Nobel Prize in Physics in 1979 for unifying the weak interaction and electromagnetism into the electroweak theory, the core of the Standard Model, and has made many other significant contributions to physics. At the same time, Weinberg has been and remains a keen science populariser. Probably his most famous work is the popular-science book The First Three Minutes, where he recounts the evolution of the universe immediately following the Big Bang.

Third Thoughts is his third collection of essays for non-specialist readers, following Lake Views (2009) and Facing Up (2001). In it are 25 essays divided into four themes: science history, physics and cosmology, public matters, and personal matters. Some are the texts of speeches, some were published previously in The New York Review of Books, and others are released for the first time.

The essays span subjects from quantum mechanics to climate change, from broken symmetry to cemeteries in Texas, and are pleasantly interspersed with his personal life stories. Like his previous collections, Weinberg deals with topics that are dear to him: the history of science, science spending, and the big questions about the future of science and humanity.

The author defines himself as an enthusiastic amateur in the history of science, albeit a “Whig interpreter” (meaning that he evaluates past scientific discoveries by comparing them to the current advancements – a method that irks some historians). Beyond that, his taste for controversy encourages him to cogitate over Einstein’s lapses, Hawking’s views, the weaknesses of quantum mechanics and the US government’s financing choices, among others.

Readers who are interested in US politics will find the section “Public matters” very thought-provoking. In particular, the essay “The crisis of big science” is based on a talk he gave at the World Science Festival in 2011 and later published in the New York Review of Books. He explains the need for big scientific projects, and describes how both cosmology and particle physics are struggling for governmental support. Though still disappointed by the cut of the Superconducting Super Collider (SSC) in the early 1990s, he is excited by the new endeavours at CERN. He reiterates his frank opinions against manned space flight, and emphasises how some scientific obstacles are intertwined in the historical panorama. In this way, Weinberg sets the cancellation of the SSC in a wider problematic context, where education, healthcare, transportation and law enforcement are under threat.

The author condenses the essence of what physicists have learnt so far about the laws of nature and why science is important. This is a book about asking the right questions, when time is ripened to look for the answers. He explains that the question “What is the world made of?” needed to wait for chemistry advances at the end of the 18th century. “What is the structure of the electron?” needed to wait for quantum mechanics. While “What is an elementary particle?” is still waiting for an answer.

The essays vary in difficulty, and some concepts and views are repeated in several essays, thus each of them can be read independently. While most are digestible for readers without any background knowledge in particle physics, a general understanding of the Standard Model would help with grasping the content of some of the paragraphs. Having said that, the general reader can still follow the big picture and logically-argued thoughts.

Several essays talk about CERN. More specifically, the “The Higgs, and beyond” article was written before the announcement of the Higgs boson discovery in 2011, and briefly presents the possibility of technicolour forces. The following essay, “Why the Higgs?”, was commissioned just after the announcement in 2012 to explain “what all the fuss is about”.

One of the most curious essays to explore is number 24. Citing Weinberg: “Essay 24 has not been published until now because everyone who read it disagreed with it, but I am fond of it so bring it out here.” There, he draws parallels between his job as a theoretical physicist and the one of creative artists.

Not all scientists are able to write in such an unconstrained and accessible way. Despair, sorrow, frustration, doubt, uneasiness and wishes all emerge page after page, offering the reader the privilege of coming closer to one of the sharpest scientific minds of our era.

By Thierry Courvoisier
Springer

This book is a curiosity, but like many curiosities, well worth stumbling across. It is the product of a curious, roving mind with a long and illustrious career dedicated to the exploration of nature and the betterment of society. Pieced together with cool scientific logic, it takes the reader from a whistle-stop tour of modern astronomy through the poetry collection of Jocelyn Bell-Burnell, to a science-inspired manifesto for the future of our planet. After an opening chapter tracing the development of astronomy from the 1950s to now, subsequent chapters show how gazing at the stars, and learning from doing so, has brought benefit to people from antiquity to modern times across a wide range of disciplines.

Astronomy helped our ancestors to master time, plant crops at the right moment, and navigate their way across wide oceans. There’s humour in the form of speculation about the powers of persuasion of those who convinced the authorities of the day to build the great stone circles that dot the ancient world, allowing people to take time down from the heavens. These were perhaps the Large Hadron Colliders of their time, and, in Courvoisier’s view, probably took up a considerably larger fraction of ancient GDP (gross domestic product) than modern scientific instruments. John Harrison’s remarkable clocks are given pride of place in the author’s discussion of time, though the perhaps even more remarkable Antikythera mechanism is strangely absent.

By the time we reach chapter three, the beginnings of a virtuous circle linking basic science to technology and society are beginning to appear, and we can start to guess where Courvoisier is taking us. The author is not only an emeritus professor of astronomy at the University of Geneva, but also a former president of the Swiss Academy of Sciences and current president of EASAC, the European Academies Science Advisory Council. For good measure, he is also president of the H Dudley Wright Foundation, a charitable organisation that supports science communication activities, mainly in French-speaking Switzerland. He is, in short, a living, breathing link between science and society.

In chapter four, we enjoy the cultural benefits of science and the pleasure of knowledge for its own sake. We have a glimpse of what in Swiss German is delightfully referred to as Aha Erlebnis – that eureka moment when ideas just fall into place. It reminded me of the passage in another curious book, Kary Mullis’s Dancing Naked in the Mindfield, in which Mullis describes the Aha Erlebnis that led to him receiving the Nobel Prize in Chemistry in 1993. It apparently came to him so strongly out of the blue on a night drive along a California freeway that he had to pull off the road and write it down. Einstein’s famous 1% inspiration may be rare, but what a wonderful thing it is when it happens.

Chapter five begins the call to action for scientists to take up the role that their field demands of them in society. “We still need to generate the culture required to […] bring existing knowledge to places where it can and must contribute to actions fashioning the world.” Courvoisier examines the gulf between the rational world of science and the rather different world of policy – a gulf once memorably described by Lew Korwarski in his description of the alliance between scientists and diplomats that led to the creation of CERN. “It was a pleasure to watch the diplomats grapple with the difference between a cyclotron and a plutonium atom,” he said. “We had to compensate by learning how to tell a subcommittee from a working party, and how – in the heat of a discussion – to address people by their titles rather than their names. Each side began to understand the other’s problems and techniques; a mutual respect grew in place of the traditional mistrust between egg-headed pedants and pettifogging hair-splitters.” CERN is the resulting evidence for the good that comes when science and policy come together.

As we reach the business end of the book, we find a rallying call for strengthening our global institutions, and here another of Courvoisier’s influences comes to the fore. He’s Swiss, and a scientist. Scientists have long understood the benefits of collaboration, and if there is one country in the world that has managed to reconcile the nationalism of its regions with the greater need of the supra-cantonal entity of the country as a whole, it is Switzerland. It would be a gross oversimplification to say that Courvoisier’s manifesto is to apply the Swiss model to global governance, but you get the idea.

Originally published in French by the Geneva publisher Georg, if there’s one criticism I have of the book, it’s the translation. It made Catherine Bréchignac, who speaks with fluidity in French, come across as rather clunky in her introduction, and on more than one occasion I found myself wondering if the words I was reading were really expressing what the author wanted to say. Springer and the Swiss Academy of Sciences are to be lauded for bringing this manifesto to an Anglophone audience, but for those who read French, I’d recommend the original.

By Joel Franklin
Cambridge University Press

This book provides a comprehensive introduction to classic field theory, which concerns the generation and interaction of fields and is the logical precursor of quantum field theory. But, while in most university physics programmes students are taught classical mechanics first and then quantum mechanics, quantum field theory is normally not preceded by dedicated classic field theory classes. The author, though, claims that it would be worth giving more room to classical field theory, since it can offer a good way to think about modern physical model building.

The focus is on the relativistic structural elements of field theories, which enable a deeper understanding of Maxwell’s equations and of the electromagnetic field theory. The same also stands for other areas of physics, such as gravity.

The book comprises four chapters and is completed by three appendices. The first chapter provides a review of special relativity, with some in-depth discussion of transformations and invariants. Chapter two focuses on Green’s functions and their role as integral building blocks, offering as examples static problems in electricity and the full wave equation of electromagnetism. In chapter three, Lagrangian mechanics is introduced, together with the notions of a field Lagrangian and of action. The last chapter is dedicated to gravity, another classic field theory. The appendices include mathematical and numerical methods useful for field theories and a short essay on how one can take a compact action and from it develop all the physics known from EM.

Written for advanced-undergraduate and graduate students, this book is meant for dedicated courses on classical field theory, but could also be used in combination with other texts for advanced classes on EM or a course on quantum field theory. It could also be used as a reference text for self-study.

By Philip Nelson
Princeton University Press 2017

This book is as elegant as it is deep. A masterful tour of the science of light and vision. It goes beyond artificial boundaries between disciplines and presents all aspects of light as it appears in physics, chemistry, biology and the neural sciences.

The text is addressed to undergraduate students, an added challenge to the author, which is met brilliantly. Since many of the biological phenomena involved in our perception of light (in photosynthesis, image formation and image interpretation) happen ultimately at the molecular level, one is introduced rather early to the quantum treatment of the particles that form light: photons. And when they are complemented with the particle-wave duality characteristic of quantum mechanics, it is much easier to understand a large palette of natural phenomena without relying on the classical theory of light, embodied by Maxwell’s equations, whose mathematical structure is far more advanced than what is required. This classical approach has the problem that eventually one needs the quantisation of the electromagnetic field to bring photons into the picture. This would make the text rather unwieldly, and not accessible to a majority of undergraduates or biologists working in the field.

In the same way that the author instructs non-physics students in some basic physics concepts and tools, he also provides physicists with accessible and very clear presentations of many biological phenomena involving light. This is a textbook, not an encyclopaedia, hence a selection of such phenomena is necessary to illustrate the concepts and methods needed to develop the material. There are sections at the end of most chapters containing more advanced topics, and also suggestions for further reading to gain additional insight, or to follow some of the threads left open in the main text of the chapter.

A cursory perusal of the table of contents at the beginning will give the reader an idea of the breadth and depth of material covered. There is a very accessible presentation of the theory of colour, from a physical and biological point of view, and its psychophysical effects. The evolution of the eye and of vision at different stages of animal complexity, imaging, the mechanism of visual transduction and many more topics are elegantly covered in this remarkable book.

The final chapters contain some advanced topics in physics, namely, the treatment of light in the theory of quantum electrodynamics. This is our bread and butter in particle physics, but the presentation is more demanding on the reader than any of the previous chapters.

Unlike chapter zero, which explains the rudiments of probability theory in the standard frequentist and Bayesian approaches that can be understood basically by anyone familiar with high-school mathematics, chapters 12 and 13 require a more substantial background in advanced physics and mathematics.

The gestalt approach advocated by this book provides one of the most insightful, cross-disciplinary texts I have read in many years. It is mesmerising and highly recommendable, and will become a landmark in rigorous, but highly accessible interdisciplinary literature.

By Joseph Boudreau and Eric Swanson
Oxford University Press

This book aims to provide physical sciences students with the computational skills that they will need in their careers and expose them to applications of programming to problems relevant to their field of study. The authors, who are professors of physics at the University of Pittsburgh, decided to write this text to fill a gap in the current scientific literature that they noticed while teaching and training young researchers. Often, graduate students have only basic knowledge of coding, so they have to learn on the fly when asked to solve “real world” problems, like those involved in physics research. Since this way of learning is not optimal and sometimes slow, the authors propose this guide for a more structured study.

Over almost 900 pages, this book introduces readers to modern computational environments, starting from the foundation of object-oriented computing. Parallel computation concepts, protocols and methods are also discussed early in the text, as they are considered essential tools.

The book covers various important topics, including Monte Carlo methods, simulations, graphics for physicists and data modelling, and gives large space to algorithmic techniques. Many chapters are also dedicated to specific physics applications, such as Hamiltonian systems, chaotic systems, percolation, critical phenomena, few-body and multi-body quantum systems, quantum field theory, etc. Nearly 400 exercises of varying difficulty complete the text.

Even though most of the examples come from experimental and theoretical physics, this book could also be very useful for students in chemistry, biology, atmospheric science and engineering. Since the numerical methods and applications are sometimes technical, it is particularly appropriate for graduate students.

By Eduardo C Marino
Cambridge University Press

This book provides an excellent overview of the state of the art of quantum field theory (QFT) applications to condensed-matter physics (CMP). Nevertheless, it is probably not the best choice for a first approach to this wonderful discipline.

QFT is used to describe particles in the relativistic (high-energy intensity) regime, but, as is well known, its methods can also be applied to problems involving many interacting particles – typically electrons. The conventional way of studying solid-state physics and, in particular, silicon devices does not make use of QFT methods due to the success of models in which independent electrons move in a crystalline substrate. Currently, though, we deal with various condensed-matter systems that are impervious to that simple model and could instead profit from QFT tools. Among them: superconductivity beyond the Bardeen–Cooper–Schrieffer approach (high-temperature superconducting cuprates and iron-based superconductors), the quantum Hall effect, conducting polymers, graphene
and silicene.

The author, as he himself states, aims to offer a unified picture of condensed-matter theory and QFT. Thus, he highlights the interplay between these two theories in many examples to show how similar mechanisms operate in different systems, despite being separated by several orders of magnitude in energy. He discusses, for example, the comparison between the Landau–Ginzburg field of a superconductor with the Anderson–Higgs field in the Standard Model. He also explains the not-so-well-known relation between the Yukawa mechanism for mass generation of leptons and quarks, and the Peierls mechanism of gap generation in polyacetylene: the same trilinear interaction between a Dirac field, its conjugate and a scalar field that explains why polyacetylene is an insulator, is responsible for the mass of elementary particles.

The book is structured into three parts. The first covers conventional CMP (at advanced undergraduate level). The second provides a brief review of QFT, with emphasis on the mathematical analysis and methods appropriate for non-trivial many-body systems (as, in particular, in chapters eight and nine, where a classical and a quantum description of topological excitations are given). I found the pages devoted to renormalisation remarkable, in which the author clearly exposes that the renormalisation procedure is a necessity due to the presence of interactions in any QFT, not to that of divergences in a perturbative approach. The heart of the book is part three, composed of 18 chapters where the author discusses the state of the art of condensed-matter systems, such as topological insulators and even quantum computation.

The last chapter is a clear example of the non-conventional approach proposed by the author: going straight to the point, he does not explain the basics of quantum computation, but rather discusses how to preserve the coherence of the quantum states storing information, in order to maintain the unitary evolution of quantum data-processing algorithms. In his words, “the main method of coherence protection involves excitation, having the so-called non-abelian statistics”, which, going back to CMP, takes us to the realm of anyons and Majorana qubits. In my opinion, this book is not suitable for undergraduate or first-year graduate students (for whom I see as more appropriate, the classic Condensed Matter Field Theory by Altland and Simons). Instead, I would keenly recommend this to advanced graduate students and researchers in the field, who will find, in part three, plenty of hot topics that are very well explained and accompanied by complete references.

by Gordon Fraser. Oxford University Press. Hardback ISBN 9780199208463 £25 ($49.95).

The late Abdus Salam – the only Nobel scientist from Pakistan – came from a small place in the Punjab called Jhang. The town is also famous for “Heer-Ranjha”, a legendary love story of the Romeo-and-Juliet style that has a special romantic appeal in the countryside around the town. Salam turned out to be another “Ranjha” from Jhang, whose first love happened to be theoretical physics. Cosmic Anger, Salam’s biography by Gordon Fraser, is a new, refreshing look at the life of this scientific genius from Pakistan.

I have read several articles and books about Salam and also met him several times, but I still found Fraser’s account instructive. What I find intriguing and interesting about Cosmic Anger is first the title, and second that each chapter of the book gives sufficient background and historical settings of the events that took place in the life of Salam. In this regard the first three chapters are especially interesting, in particular the third, where the author talks about Messiahs, Mahdis and Ahmadis. This shows in a definitive way the in-depth knowledge that Fraser has about Islam and the region where Salam was born.

In chapter 10, Fraser discusses the special relationship between Salam and the former President of Pakistan, Ayub Khan. I feel that more emphasis was required about the fact that for 16 years, from 1958 to 1974, Salam had the greatest influence on the scientific policies of Pakistan. On 4 August 1959, while inaugurating the Atomic Energy Commission, President Ayub said: “In the end, I must say how happy I am to see Prof. Abdus Salam in our midst. His attainments in the field of science at such a young age are a source of pride and inspiration for us and I am sure that his association with the commission will help to impart weight and prestige to the recommendations.” Salam was involved in setting up the Atomic Energy Commission and other institutes such as the Pakistan Institute of Nuclear Science and Technology and the Space and Upper Atmosphere Research Commission in Pakistan.

Finally, I find the book to be a well written account of the achievements of a genius who was a citizen of the world, destined to play a memorable role in the global development of science and technology. At the same time, in many ways Salam was very much a Pakistani. In the face of numerous provocations and frustrations, he insisted on keeping his nationality. He loved the Pakistani culture, its language, its customs, its cuisine and its soil where he was born and is buried.

By Vladimir Belinski and Marc Henneaux
Cambridge University Press

This monograph discusses at length the structure of the general solution of the Einstein equations with a cosmological singularity in Einstein-matter systems in four and higher space–time dimensions, starting from the fundamental work of Belinski (the book’s lead author), Khalatnikov and Lifshitz (BKL) – published in 1969.

The text is organised in two parts. The first, comprising chapters one to four, is dedicated to an exhaustive presentation of the BKL analysis. The authors begin deriving the oscillatory, chaotic behaviour of the general solution for pure Einstein gravity in four space–time dimensions by following the original approach of BKL. In chapters two and three, homogeneous cosmological models and the nature of the chaotic behaviour near the cosmological singularity are discussed. In these three chapters, the properties of the general solution of the Einstein equation are studied in the case of empty space in four space–time dimensions. The fourth chapter instead deals with different systems: perfect fluids in four space–time dimensions; gauge fields of the Yang–Mills and electromagnetic types and scalar fields, also in four space–time dimensions; and pure gravity in higher dimensions.

The second part of the book (chapters five to seven) is devoted to a model in which the chaotic oscillations discovered by BKL can be described in terms of a “cosmological billiard” system. In chapter five, the billiard description is provided for pure Einstein gravity in four dimensions, without any simplifying symmetry assumption, while the following chapter extends this analysis to arbitrary higher space–time dimensions and to general systems containing gravity coupled to matter fields. Finally, chapter seven covers the intriguing connection between the BKL asymptotic regime and Coxeter groups of reflections in hyperbolic space. Four appendices complete the treatment.

Quite technical and advanced, this book is meant for theoretical and mathematical physicists working on general relativity, supergravity and cosmology.