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The dangerous vagary in 'geoengineering'

Climate engineering — why not just call it that?

By James Dacey

Ok, maybe I’m being a bit pedantic here but am I the only one to be slightly confused and a little concerned by the vagary of the term “geoengineering”?

I raise this question now because yesterday the UK’s most prestigious scientific academy, the Royal Society, released a major report on the topic with the aim of clarifying the technical issues to better-inform climate policy. Politicians, however, like things to be spelt out veeerry cleeaarrly. Therefore, any confusion surrounding the central term in this policy document could stall the debate on what may become a key component of the fight against climate change.

So, let’s consult the Chambers English Dictionary, which just happens to be the only dictionary within grabbing distance at the time of writing:

“Geo” is the prefix — taken from Greek — for “Earth”; and engineer means “to put to practical use, engines or machinery of any type”.

I think you’ll agree that both of these words hold a broad range of meanings and a combination of the two makes for a very wide semantic field indeed. Use your own imagination here but I can picture all sorts of ways in which the naked Earth could be engineered — from spectacular agricultural terraces like those in the Andes to the idea of a giant Eiffel Tower replica carved into the Antarctic ice.

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Fires threaten historic Mount Wilson Observatory

Image of the Californian wildfires from NASA’s Terra satellite (credit: NASA/GSFC/LaRC/JPL)

By Michael Banks

The enormous wildfires in California are still threatening the Mount Wilson observatory sat 1742 m high in the San Gabriel Mountains near Pasadena, northeast of Los Angeles.

Yesterday, the fires crept nearer and the observatory’s website as well as the live webcam went down.

There was some hope, however, as Reuters reported that cooler weather as well as increased humidity had hampered the fires and firefighters hoped they could drive the fire away from the observatory.

Founded in 1904 by the US astronomer George Ellery Hale, the observatory still performs astronomical research via its 1.5 m Hale telescope and 2.5 m Hooker telescope, which was used by Edwin Hubble to discover that galaxies were moving away from us.

Regular updates on the wildfires are being provided by the Los Angeles Times and Georgia State University, which operates the Center for High Angular Resolution Astronomy at Mount Wilson.

A physicist’s life-cycle

Illustration of figures rising up — **On the up?** Charting the progress of physicists’ careers. (Credit: Photolibrary)

What can we learn when we follow people over the years and across the course of their professional lives? This is the question that I have tried to answer by examining one particular group of professionals – namely academic physicists – during their careers at a variety of universities across the US. I chose to study physicists because in the wider culture physics is the scientific discipline par excellence. Physicists possess a recognizable genealogy of immortals – the likes of Kepler, Newton and Einstein – who promote a sense of scientific heroism and define a “model” career for those who follow. Thus, if one is interested in seeing how careers play out against a backdrop of this kind of company, then physics departments are a good place to visit.

In my research as a sociologist, I tracked 55 physicists through different stages of their working lives. The questions I posed were aimed at exploring physicists’ shifting perceptions of their jobs in order to uncover the meanings they invest in their work, when and where they find satisfaction, how they succeed and fail, and how the rhythms of work change as they age. Based on interviews with the subjects, my study examined the consequences of career goals (both met and unmet); the frustrations of scientific careers, universities and the academic profession; and the way in which highly trained professionals deal with boredom and stagnation, as well as with renown.

Under the microscope

Physicists in the study were originally interviewed between 1994 and 1995. At that time, the subjects were sampled according to early, middle and late career stages, with average ages of 37.0, 48.3 and 61.4 years, respectively. They were also grouped by one of three types of university – termed elite, pluralist and communitarian – at which they were employed. Elite universities, such as Harvard and the University of California, Berkeley, are those that stress research in the presence of teaching and other roles. Those that place roughly equal emphasis on teaching and research, such as the University of Maryland, the University of Kansas and Purdue University, are termed pluralist; while those that place the greatest emphasis on teaching, such as the University of Tulsa and the University of Louisville are termed communitarian. Such labels are, of necessity, ideal types; in reality, both universities and individuals exist on a continuum.

The same physicists were interviewed again between 2004 and 2005, thereby creating a longitudinal study – the first of its kind – of how academics, working in a variety of institutions, age in relation to their work. The follow-up study thus reveals how physicists’ perceptions of work evolve with perceived costs and rewards, from early to mid career, from mid to late career, and from late to post career.

The questions I asked in the second study addressed physicists’ attitudes to work; their most prominent work concerns; whether they would seek an academic career again, and, if so, what they would do differently. The study also examined perceptions of peak satisfaction, the objects of their satisfaction and estimations of their overall career satisfaction; and their perceptions of whether the reward system in science is “fair” or not. A few of their responses appear in the box right; note that the study is based on over 1700 pages of transcript, so the passages presented are merely illustrations.

How careers progress

The results of the study reveal striking differences between the attitudes that elites, pluralists and communitarians have to their careers. In passing from early to mid career, elites – who in the earlier interviews had frequently described their situation (especially during the tenure process) as “a burden” – tended to stabilize and rededicate themselves to academia. In other words, they had found a renewed interest in fulfilling the institutional goals of higher education by continuing in their research productivity.

In contrast, pluralists – who had previously been highly satisfied in their work, and felt they had achieved a “happy medium” – experienced a reversal at the middle stage of their careers. They questioned their interest in and commitment to the profession, and they grew disillusioned with academic research. Early-career communitarians, for their part, had already expressed considerable disillusionment in the earlier study; by mid-career, most had ceased to do research entirely. For communitarians in mid-career, cumulative disadvantages had accrued to the point of shutting down interest and motivation to continue with scientific research. Their career pattern may best be described as succumbing to a stasis – there was no forward progress.

In their transitions from mid to late career, elites remained consistent in their identification with science and in their scientific productivity. Their publication productivity continued to accelerate, far eclipsing those of their contemporaries in other types of institutions. Pluralists either attempted to revitalize their careers following earlier fallow periods (largely without success) or continued with the research that they had been doing. Communitarians entered into a kind of scientific demise. They identified less and less with research, and became increasingly disaffected with their departments and universities, which they saw as having crippled their research aspirations.

Given these patterns, it is perhaps not surprising that in moving from late to post career phases, the pluralists characteristically withdrew from work, while communitarians separated themselves completely from it, usually severing all ties with work and their employing organizations. Intriguingly, elites in this stage for the first time lessened their intensity and embrace of research. This effect was associated with a decline in their overall career satisfaction.

The bottom line is that among elites, satisfaction begins high and rises through the career, but it then drops at the end as attitudes turn ambivalent – about what they have done, how much they have achieved, and where they stand professionally. For pluralists and communitarians, however, this pattern is reversed. Among pluralists, satisfaction starts out on a high, drops and then levels off before rising at the end, coinciding with a time when they withdraw from work. Communitarians experience low satisfaction throughout their careers – until the end, when, for the first time, they experience the greatest satisfaction of all the groups. They also, for the first time, regard the system of rewards in science as “fair”.

The role of organizations

Over time, physicists in the three prototypical academic organizations show evidence of reversals – in terms of career orientation, outlook and attitude. Elites may be most dedicated throughout their careers, but most devastated at the end, when they realize that their lofty (and often unrealistic) ambitions remain unfulfilled. Communitarians may be less dedicated during their careers, but most satisfied and positive in their outlooks at the end. Pluralists exemplify the greatest variability in their careers, but in the end find a satisfaction that overcomes a previous ambivalence. It is important to recognize that none of these shifts are taking place in isolation. Academic organizations – both universities and departments – script the courses of careers, and also influence changes in attitude, commitment and motivation to work. These career patterns have implications for the advancement of physics, for the welfare and functioning of academic departments and universities, and for the cohesiveness of the profession.

The telling of contemporary lives in science also prompts questions about what types of people, and with what levels of talent, science will be able to attract. One scenario is that academia will attract less-talented individuals, while more-talented people, seeing the conditions under which academic careers are experienced, will increasingly enter other professions. Perhaps the best answer to the question “What can we learn when we follow people in their careers?” is, simply, “much about the institutions that shape them”. Conditions have developed in modern universities that create an enduring problem of meaning and satisfaction in the academic profession.

In their own words

The following are excerpts from interviews with physicists about their academic careers.

“My attitudes about the job, about me and about the university have undergone tremendous changes in the past 10 years…I’m not sure I want to even submit things to published journals anymore…I’m disgusted by the whole thing…I got tired of getting referee reports…that spend a page talking about the bibliography; they were entirely concerned with whether I cited their work or their friends’ work, and they hadn’t read the paper…I’m in a setting where the last thing people want is honesty…You guys play your game, it’s fine. There are more important things in life than getting grants from the National Science Foundation, getting Nobel prizes even or any of that stuff. That’s all just a game…”
Pluralist at mid career

“Maybe there is some self-delusion in feeling that you’re being a significant contributor to science. It’s just [pause] you have been trained, you know this field, when you’re an expert in something, you tend to take pride in it, and you tend to continue doing it. But I don’t think it’s always very significant in the grand scheme of things…I could have worked harder to become a better professional physicist…At some stages of my career, I could have easily done better. It would have made a difference. It might well have been a significant difference…If I had worked harder, it would have given me a little more status. I would have accomplished more in the field…”
Elite at post career

“There really wasn’t much else to look forward to. [Right now, I’m] not working as hard. I’m not doing research anymore. I had two or three pretty good ideas during the course of my career, and I haven’t had any since. I really don’t keep up with the literature…I think that early on, even though I did some fairly decent work, both as a graduate student and in the beginning of my career, I never was satisfied. I always thought that I could have done better or sooner or more. In more recent years [near and in retirement], I have become content, not only with what I was doing, but also how much. I think this is a reflection of my coming to like myself more.”
Communitarian at post career

Do your experiences match the patterns found in this study? Or has your career as an academic physicist been completely different? Send us your thoughts at pwld@ioppublishing.org

Dreams of a quantum pioneer

Born in 1900, Wolfgang Pauli’s debut as a physicist came in 1921 with the publication of a review paper on relativity so thorough and incisive that Einstein wrote of it “No one studying this mature, grandly conceived work would believe the author is a man of twenty-one”. Three years later, Pauli formulated the exclusion principle that bears his name, and that forms the basis of atomic and molecular structure; this work earned him the 1945 Nobel Prize for Physics. In 1930 he introduced the concept of the neutrino, which is central to modern elementary particle physics. By then, he had already become the key arbiter in the year-long discussions held in Copenhagen between Werner Heisenberg and Niels Bohr that had led to the modern formulation of quantum mechanics. He was also the holder of a prestigious professorship in Zurich, Switzerland, where young physicists from around the world – including Felix Bloch, Max Delbruck, Lev Landau, J Robert Oppenheimer, Rudolf Peierls and Victor Weisskopf – were flocking to work with him. Hence, by the age of just 30, Pauli had already established himself as one of the 20th century’s great physicists.

And yet all was far from well. Although Pauli continued to flourish professionally, his personal life was a shambles. His father, a talented scientist but also a womanizer, had fallen in love with a sculptor who was Pauli’s age and had left his wife, Pauli’s mother. In a fit of despondency, she committed suicide in November 1927. Pauli – never a picture of health and athleticism – began drinking and smoking more heavily. He had always been a night owl, a frequenter of bars and cabarets, and these tendencies also increased. In 1929 he married a dancer, but their union lasted less than a year; his wife left him for another man.

In crisis, Pauli decided to consult a psychiatrist. In 1930s Zurich the obvious choice was Carl Gustav Jung, a pioneer in psychiatry and its broad ramifications in other areas, including religion and mythology. What happened next is the subject of Arthur I Miller’s Deciphering the Cosmic Number, which charts the unexpected friendship that developed between the troubled young physicist and the eminent psychiatrist.

The Pauli–Jung friendship is an ideal subject for Miller, who trained as a physicist but has had a long-time interest in the boundary between science and art, particularly in imagery and questions of creativity. He has explored these topics in previous works, including a joint study of Einstein and Picasso. In this book, he first introduces Pauli, then Jung before beginning to weave their story together. He focuses in particular on Jung’s analysis of Pauli’s dreams – several of which Jung later published along with their interpretation, but without identifying their source other than as “a distinguished scientist”. It makes for a fascinating and an unlikely story, one that Miller follows exceedingly well through its twists and turns. His style is both brisk and accessible, making the book exciting to read as well as informative.

In 1930 Jung had already become an icon in 20th-century intellectual thought. Some 25 years older than Pauli, he placed great emphasis on integrating the analytical, scientific mind with the emotional and the unconscious self. He wrote voluminously, but also had an extended clinical practice. Though interested in Pauli’s condition, he initially felt that his new patient’s analysis would be more successful if he did not carry it out himself. Instead he directed Pauli to Erna Rosenbaum, a young woman whom Jung had trained, feeling that her presence would not threaten or intimidate Pauli in any way. She would act as a conduit, encouraging Pauli to record his dreams and free his unconscious.

Two years later, Pauli began consulting Jung directly, gradually forming an association that had elements of simple friendship and collaboration in addition to the expected doctor–patient relationship. By 1934 Pauli felt himself cured of his neurosis. He remarried, this time happily. His scientific productivity continued unabated, but he seldom mentioned his explorations of the unconscious to his colleagues, although such topics continued to interest him. Indeed, the connection between Pauli and Jung lasted for nearly 25 years, ending only with Pauli’s early death from cancer in 1958. During this period, Pauli sent Jung more than a thousand dreams, transcribed for his own benefit and for Jung to study. The two also carried on a voluminous correspondence, much of which has been published; see, for example, C A Meier’s Atom and Archetype: The Pauli–Jung Letters (1992, Princeton University Press).

The relationship clearly stretched both men and must have been strained at times. Jung’s pursuits of phenomena such as extrasensory perception, unidentified flying objects and astrology were not to Pauli’s liking. However, their bond continued unabated, focusing on issues such as synchronicity and the potential deeper meaning of numbers. In exploring such issues, Pauli also began to study the works of Kepler and his contemporaries, looking for the origins of the so-called scientific mind and what may have been lost in its adaptation to a modern world – both topics of great interest to Jung.

In exploring all these aspects of Pauli and Jung’s relationship, this book also includes a number of visual illustrations that clarify the questions being discussed. Among the most interesting of these are a series of drawings that represent graphic interpretations of important Pauli dreams. The book concludes with a chapter on Pauli and Jung’s interest in the significance of the fine-structure constant, which specifies the coupling of charged particles to the electromagnetic field. Was it really equal to 1/137 and, if so, what did that mean? Was there some deep explanation for that value? As of 2009 the answer is no; the latest value for the inverse of the fine-structure constant is 137.035999070. Nevertheless, the ideas of both Pauli and Jung remain very much part of our intellectual heritage, even if they do not apply to the fine-structure constant as we understand it today. The interaction between the two men, very well told in this book, remains one of the 20th century’s most interesting links between two thinkers who were apparently so different.

Illuminating physics for students

My parents were professors (history and zoology), and they firmly believed that the purpose of education is to show students “how to think”. When I began teaching, I quickly discovered that many of my students could think much better – or at any rate much faster – than I could. What distinguished me from them was that I knew things that they did not, things they had been led to believe they ought to want to learn. I adopted a less-exalted goal: I think the purpose of education is to pass along to the next generation the accumulated knowledge and wisdom of humankind, and my role as a teacher is to make that process as efficient and palatable as possible.

Physics teachers are fortunate (I am among friends, so I can speak frankly): ours is a subject the relevance and importance of which are beyond question, and which is intrinsically fascinating to anyone whose mind has not been corrupted by bad teaching or poisoned by dogma and superstition. I have never felt the need to “sell” physics, and efforts to do so under the banner “physics is fun” seem to me demeaning. Lay out our wares attractively in the marketplace of ideas and eager buyers will flock to us.

What we have on offer is nothing less than an explanation of how matter behaves on the most fundamental level. It is a story that is magnificent (by good fortune or divine benevolence), coherent (at least that is the goal), plausible (though far from obvious) and true (that is the most remarkable thing about it). It is imperfect and unfinished (of course), but always improving. It is, moreover, amazingly powerful and extraordinarily useful. Our job is to tell this story – even, if we are lucky, to add a sentence or a paragraph to it. And why not tell it with style and grace?

Teaching concerns

If our subject were modern poetry, or French philosophy, then clarity would not necessarily be a virtue: part of the fun is figuring out what on earth the author is trying to say in such an obscure and convoluted way; and the actual content, once deciphered, turns out to be pretty trivial. A literature teacher who explains every simile and metaphor has robbed the subject of its interest.

But in physics there is no valid excuse for anything short of crystal clarity (unless the topic is so new that it is not yet fully understood). If a student who is reasonably competent, attentive and sober cannot understand an argument, then it is the teacher’s fault. I have known people who are in some sense too smart to be clear; they cannot remember what it was like not to understand something, because, I suppose, they never had this experience. They may be outstanding physicists, but they do not belong in the classroom. (There are exceptions: the most brilliant physicist I ever encountered, the late Sidney Coleman, was also – by far – the best and clearest teacher.)

In the US there is a movement inspired by physics education research (PER) to promote “active engagement” in the classroom. I applaud this – though it is hard for me to imagine any good teacher since Socrates who is not already practising it. But taken to extremes it can be destructive. When it is claimed, for example, that students learn nothing from lectures (because, apparently, they are not “actively engaged”) I demur. It goes without saying that there are bad lectures, but there are also very good ones, in which students are totally engaged. Nobody’s mind wandered during Coleman’s lectures. In despair over the ineffectiveness and unpopularity of traditional methods, some PER people advocate “learning by discovery” in the lab. It is a nice idea, but stultifying slow and inefficient – how are we to rediscover 500 years of physics in a semester? I can explain the conservation of momentum in 15 minutes, but three hours in the lab would only convince an honest student that the law is false.

The Harvard University physicist Eric Mazur and others have introduced flash cards (now – inevitably – replaced by electronic “clickers”) to enforce student engagement at lectures. They can be powerfully effective in the hands of an inspired expert like Mazur, but I have seen them reduced to distracting gimmicks by less-capable instructors. What concerns me, however, is the unspoken message reliance on such devices may convey: (1) this stuff is boring; and (2) I cannot rely on you to pay attention. Now, point (2) may be valid, but point (1) is so utterly and perniciously false that one should, in my view, avoid anything that is even remotely open to such an interpretation.

How often have we heard colleagues say, with a sigh and a roll of the eyes, “Today I have to teach about balls on inclined planes; what could be more tedious and dull?”. This attitude, of course, is communicated loud and clear to the students, who are promised, in compensation, “Next year you will get to the interesting stuff”. But rolling a ball down an incline is emphatically not tedious and dull. I am sure there exist genuinely boring subjects – accounting comes to mind – but physics is not one of them.

Take a closer look at the classical theory of rolling: why does a sphere roll faster than a hoop, and exactly how much faster? I think this analysis is one of the truly great products of the human mind – vastly greater (for all its simplicity) than the Born approximation or the Higgs mechanism. My job as a teacher is to call attention to its beauty – not to disparage it.

Ever since it was founded a century ago, all final-year undergraduates at Reed College have been required to write a thesis. We have been delighted (and, truth be told, smugly amused) at the recent enthusiasm at other institutions for undergraduate research – as though this were some extraordinary new invention. But let us be honest about what we are calling “research”. Is it merely an activity that is conducted in a lab or a library, or is it a way of learning – a protocol for discovery? If a student walks into an established lab, is told how to operate an instrument, records some data and enters them into an existing computer program, is this really “research”?

At Reed we try to involve students in all aspects of the project: choosing the question; designing the mode of attack; mastering the background literature; carrying out the experiment (or the calculation); presenting the results in a seminar; and (in some cases) writing it up for publication. It is true that such a project tends to be more modest than most professional research, but the student emerges with a real sense of ownership and understanding.

Abstraction is the enemy of learning – it is the end, not the beginning, of understanding. Mathematicians cannot comprehend this, and I suppose it is conceivable that their brains are wired differently. But most physics students learn by proceeding from the concrete to the abstract, not the other way around. It is the universal blunder of lecturers just starting out in their careers to go straight for the most sophisticated formulation – the one they recently learned in graduate school, and to which they are still in thrall. They want to start every problem with a Lagrangian, even if Newton’s laws would do it much more simply. This is like trying to potty-train a two year old on a full-sized toilet: exciting to the parent, perhaps, but frightening to the child, and potentially dangerous. Our business is to empower students, not to impress them; to instil confidence (“I could have done that!”), not awe (“How did they do that?”). The simplest tool is almost always the best one.

Educating physicists

I have been lucky. I spent most of my career at an institution where the students are reasonably bright and extraordinarily motivated, where effective teaching is genuinely encouraged and appreciated, and where I have enjoyed the freedom to pursue whatever strikes me as interesting and important. I have never suffered the interference of a brainless dean concerned only with grants and publications, and as a consequence I have been more productive than would have been possible in the usual academic straitjacket. I do not know what makes good teaching, beyond the obvious things: absolute command of the subject; organization; preparation (I write out every lecture verbatim the night before, though I never bring my notes to the lecture hall); clarity; enthusiasm; and a story-teller’s instinct for structure, pacing and drama. I personally never use transparencies or PowerPoint – these things are fine for scientific talks, but not in the classroom. I want my students to know that something is happening in real time: I am thinking through each argument as I present it, not merely reciting something they might just as well have read in a book.

Learning physics is hard, and it can be frustrating; there is no point in concealing this or (far worse) watering it down in a futile at_tempt to make the subject more marketable. Serious students relish a genuine challenge; they do not like being coddled, patronized or made to feel stupid, and they resent meaningless hurdles – tedious lab sessions, plug-in problems, trick questions, unfair examinations and confusing explanations. Studying physics is often represented as a brutal and unforgiving ascent whose main reward is a sense of snide superiority over those who struggle below. To my mind the worst aspect of this culture is that it tends to select for nasty childish temperaments, and in particular to drive women out of the field.

This is a terrible shame. I believe every educated person should study physics. Why? Because it is interesting – the natural world is a remarkable and fascinating place; because it is liberating – the universe is not arbitrary, but rational and comprehensible; and because physics is unequivocally the most powerful and profound system of thought ever devised. Perhaps, after all, I do agree with my parents. My purpose is to teach students how to think, by exposing them to the most brilliant and successful example of human thought: physics.

Once a physicist: Subramaniam Ramadorai

Why did you choose to study physics?

I come from a traditional South Indian family, where the culture typically emphasizes science education. My upbringing reflected these same influences, and my father in particular had a great love for mathematics and physics. I remember going on long walks with him in the countryside, where he shared with me his unfulfilled dreams of becoming an engineer. He felt that he had a talent for engineering, but parental advice steered him towards studying mathematics instead. Perhaps I imbibed his passion, because I always loved fixing things and figuring how they worked through experimentation. All of these developed in me a growing interest in physics, and so my major at Delhi University was physics, with maths and chemistry as subsidiary subjects.

What did you do next?

After I graduated, I learned that the Indian Institute of Science (IISc) in Bangalore offered a Bachelor of Engineering degree in electronics and telecoms in three years, which meant that I could get two undergraduate degrees in a matter of six years. After studying both science and then technology, applied computer science was, to me, a natural progression. At that time the US was the top destination for someone keen to learn from the world’s best, so I went on to earn a Masters degree in computer science from the University of California. I was the first in my family to study abroad.

How did you become involved in TCS?

After I finished my Masters degree, I was at a crossroads in my life, weighing up a career in the US against the opportunity to join TCS. Back in the 1960s, an opportunity with Tata was considered better than a job in the US, and second best only to a job with the Indian government, which in those days was extremely prestigious. Still, it was a very difficult decision. In the end I opted for TCS, and I have never regretted it.

What do you see as the “next big thing” for the IT industry?

There is no single “next big thing” but I believe that innovation and R&D are going to be the big game-changers. The rapid growth of new technologies is making us question traditional models of doing business. There are many opportunities for IT in emerging growth areas such as energy, healthcare, life sciences and mobile technologies. Furthermore, all these developments are driven by intellectual property, which means investment in R&D.

How has your physics training helped you in your career?

Initially, it helped enormously in my understanding of the fundamentals of scientific thought. Later in my career, it helped me develop a healthy respect for R&D, and for the algorithm-based research so crucial for software development. The animation and visualization technologies we have now have helped me understand abstractions so much better; today, a Stephen Hawking book and the theories it propounds could well be translated into a fascinating film. I also believe that experimentation is akin to risk-taking. At TCS, we took several risks; we were the earliest IT services company in India, with no previous precedents or points of reference to learn from. It helped us become pioneers of Indian IT.

Do you have any advice for physics students interested in IT?

In my view, the combination of physics and mathematics is very powerful, because it provides you with a springboard to several avenues, including IT. Information technology is not the sole preserve of engineers. There are science, social-science and arts graduates who are helping shape the future of technology services on different continents, bringing their own special talents to this melting pot. At TCS we have tried to bring the IT growth story to science and maths graduates through a programme called Ignite, which aims to train them for the software industry. In a changing world, programmes such as Ignite will help ensure that an individual wishing to pursue a career in IT has a range of paths to choose from; Ignite provides a direct way, but there is also an R&D route and a technology route. Each of these are great entry points. Eventually, however, one’s ability to constantly learn and grow is the path to success.

Plan B for climate change

Ever thought about tackling climate change by spraying aerosols into the upper atmosphere to act as a giant sunblock? Or how about placing trillions of tiny parasols in space to divert solar radiation? Or perhaps fertilizing the oceans with iron to promote artificial blooms of phytoplankton that can soak up carbon dioxide? The problem with these and other proposed “geoengineering” techniques is that they sound so crazy, expensive and dangerous that many mainstream climate scientists have refused to take such solutions seriously. Indeed, some fear that even discussing geoengineering is enough to scupper climate negotiations, such as those that are due to take place in Copenhagen in December, by implying that we do not need to bother cutting greenhouse-gas emissions.

Thankfully, however, geoengineering has slowly been entering the mainstream in recent years. This month marks a watershed in that process with the publication by the Royal Society of a study – the first by a major scientific academy – into whether planetary-scale geoengineering schemes could help to prevent the worst aspects of climate change. Although Physics World was not able to obtain an advance copy of the report before going to press, the main issues are described in a feature elsewhere in this issue by physicist Peter Cox from the University of Exeter – one of the report’s co-authors – and Hazel Jeffery from the UK’s Natural Environment Research Council (“Engineering the climate”).

Geoengineering techniques basically fall into two main camps: removing carbon dioxide directly from the air or reflecting more sunlight back into space. The former is a pricey, long-term but relatively low-risk solution, while the latter could be implemented quickly and cheaply but does nothing to stop the rising acidity of the world’s oceans. The technique that appears to bring the biggest benefit for the least cost involves using a fleet of ships to suck up seawater and spray it into the atmosphere. The sea salt would provide extra cloud-condensation nuclei that would brighten lower-altitude stratocumulus clouds lying over oceans and coastal regions, and so reflect more short-wave solar radiation back into space.

Indeed, a report published last month by the Copenhagen Consensus Center – a Danish think tank led by Bjørn Lomborg, author of the controversial book The Skeptical Environmentalist – suggests that the current century’s global warming could be avoided by spending just $9bn on a fleet of unmanned cloud-brightening ships. However, no less a figure than Steven Koonin – former chief scientist at energy giant BP and now under-secretary of science at the US Department of Energy – has co-authored a new report for the California-based Novim think tank suggesting that our best approach would instead be to pump sulphates into the upper atmosphere to mimic the effects of volcanic eruptions.

The problem with geoengineering is that it is laced with too many scientific, economic and political uncertainties. There are also ethical concerns about modifying the Earth’s climate: a technique that cools one region could actually raise temperatures, or slash rainfall, in another. If that is the case, who then would decide how we should act? Geoengineering may only ever be a plan B for dealing with climate change, but unless we do more research, we will never know for sure if it could work and, if so, what the best approach should be.

Web life: Sixty Symbols

Sixty Symbols

So what is the site about?

If you enjoyed The Periodic Table of Videos we profiled earlier this year (see “Web life: The Periodic Table of Videos“), but found it a bit too…well…chemical, then this is the website for you. Physics does not really have a periodic table, so a handful of scientists from Nottingham University in the UK worked with video-journalist Brady Haran to create one. The result is a 6 × 10 matrix of important symbols in physics and astronomy, each linked to a 5–10 min video describing the symbol’s significance.

What symbols are included?

There are some self-evident ones, like Planck’s constant h, the speed of light c and the cryptic signs that represent planets in ancient (and modern) astronomy. For other symbols, part of the fun lies in guessing which of several meanings the team has elected to explore. Does µ represent the coefficient of friction? The chemical potential? Or maybe the magnetic moment? Some of the choices are far from obvious; the lower-case Greek letter delta, for example, is a ubiquitous symbol in many areas of physics, but here it signifies chaos theory’s Feigenbaum constant. A handful of entries – like Schrödinger’s cat, represented by a hieroglyphic feline – stretch the definition of “symbol” to breaking point, but it seems churlish to complain when the films supporting them are so intriguing.

Can you describe a typical video?

Since different disciplines within physics often concentrate on different aspects of a particular concept or symbol, many of the videos include contributions from two or more scientists. In the video on magnetic fields, for example, most of the eight minutes are spent following Richard Hill around his magnetic-levitation lab (at a respectful distance from the magnet for the sake of the camera’s magnetic tapes), but astronomer Michael Merrifield also makes a brief appearance to discuss the solar magnetic field. Some of the symbols lend themselves to experiments, while others – like the Schwarzschild radius, R_S, representing the characteristic size of a black hole – are described with equations and diagrams sketched on paper. These sketches are also posted on the site, so if you miss a detail, you can look it up later.

What are some of the highlights?

You could search LaTeX manuals and computer fonts in vain for the symbol in the bottom right-hand corner of the Sixty Symbols grid, which resembles a long-necked bird peering into a small cup. The “drinking bird” toy in the corresponding video has a head made of absorbent felt and a body filled with dichloromethane, and, at first glance, it looks like a perpetual-motion machine. The real explanation presented in the video is surprisingly simple (although apparently it eluded Einstein). Another high note – literally – is the video of a device called a Chladni plate. In one of the most beautiful demonstrations in physics, grains of powder sprinkled on this vibrating plate form patterns that trace out nodal points in the vibrations; the shape of the pattern depends on both the frequency of the sound and the size of the grains. The accompanying noise is annoying, but the video is marvellous.

Why should I visit?

Because this is what online physics should look like. The videos are professional but not too slick. The concepts are explained thoughtfully. The scientists skilfully avoid either confusing or patronizing their audience, and they are obviously keen without drifting into “hyperactive mad scientist” territory. Plus, the site has a sense of humour.

How often is it updated?

The matrix has been slowly filling up with symbols since spring 2009, with fresh videos appearing every few weeks. One recent addition discusses the “spots” that appeared on Jupiter and Venus this summer, and another includes footage of the team’s trip to China to view the solar eclipse in July. If you do not see your favourite symbol, then there is still time to request it (contact details are available on the site), but you had better hurry: as of mid-August, more than 50 of the planned 60 slots were already filled.

Can you give me a sample quote?

“The classic thing to ask at the end of a seminar is ‘Ah yes, but what about magnetic fields?’,” says Merrifield in one video. “The person you’re talking to won’t actually have an answer…but you’ll sound quite clever, because magnetic fields almost certainly affect a lot of things going on in the universe.”

Your best unit

Back in the Old Country, a practice among Jews who had lost a loved one was to light a candle on the “jahrzeit” or anniversary of their death. The candle was supposed to burn for 24 hours, and was placed in a holder called a “jahrzeit glass”. Such items were never thrown away – inexpensive glass is a modern technology – and families kept theirs, often reusing them as drinking cups. The practice continued in the New World. In the title story of Philip Roth’s first book, Goodbye Columbus, the protagonist recalls his grandmother drinking “hot tea from an old jahrzeit glass”, an effective detail in conjuring up a transplanted ancestor.

Most Jewish households had them, and they were all approximately the same size – for they were made to hold the same size candle – so jahrzeit glasses were a natural cooking measure. Your friend would tell you that a recipe called for a certain number of “glasses” of flour or matzoh meal. Such recipes were at first passed on orally, and then written down by a later generation – what a daughter remembered from her mother. They were approximate – Old Country recipes tended to be loose with quantities – but they worked.

The transformation of jahrzeit glasses from memorial to measurement, though odd in some ways, is typical of how objects can become units of measure. This generally occurs when the objects in question are: (1) ready to hand in a community’s environment as an element of daily life; (2) of a standard size that is appropriate for a use; and (3) known to be reliable or trustworthy.

Crusoe’s foot

We even see this in more quirky cases, such as two that were recently discussed in the pages of Physics World: the “football pitch” to describe an area (May p23, print edition only) and the “Sydney Harbour” to describe a volume (July p21, print edition only). (I have no idea how big or small either unit is, not being a member of either relevant community.) Another regional example is the Peruvian cocada, which is a linear measure of how far one can walk with a certain load under the influence of a cocoa-leaf-based stimulant in a little over half an hour (about 3 km on flat ground, a kilometre less uphill).

In the days before SI, even common units could have similar origins. Sometimes the units were anthropomorphic, based on parts of the human body or related to its abilities, and thus standard and reliable because of the relative uniformity of human bodies. Examples are the linear measures finger, foot, pace, hand and mile (from the Latin milia passuum). Other units were motivated by the relative uniformity of non-human organisms, such as the mass measures of grain or carob beans (whence carat).

In Daniel Defoe’s novel Robinson Crusoe (1719), the shipwrecked protagonist must recreate a variety of simple technologies on his own, from baking bread to cutting trees into boards. Crusoe carefully and lovingly describes his tools, stressing how much more valuable they are to him than gold. But while he uses traditional English measures (feet, inches and yards; pecks and bushels; pounds), he never says how he did the measuring. Either he is not telling us about his scales, or he is estimating based on a memory shaped by such equipment. This part of the novel never rang true to me. Why in 28 years did Crusoe never invent his own measures? The sole exception is when he uses his foot to make the terrifying discovery that the strange track on the beach is, as it were, “bigger than a Crusoe foot”. To me, at least, the tale would have rung truer with more ready-to-hand measures of this kind.

The invisible network

When societies began to manufacture unit standards – such as an official yardstick or kilogram – so that the standard was a one-of-a-kind artefact, the standards were made accessible to daily life via a network of copies, scales and instruments. The artefact was at the centre of the network, so to speak, and the standards used in daily life – grocery and postal scales, store-bought measuring sticks – were at the fringes. This network also required inspectors, supervisors and records to operate in an efficient and trustworthy manner. By the 19th century, improving these networks came to be seen, not just as a utilitarian goal for facilitating specific technologies, but as an end in itself.

This network has a strange ontology. The “being” of a measurement standard – the authority of the metal cylinder that today sits in the vault in Sevrès as the kilogram – depends on this network. The network is practically invisible to users and to anyone but the network’s managers. It can briefly become visible – along with our vulnerability and dependence – when there is a disaster, as when, in 1999, a $125m Mars spacecraft crashed when NASA engineers used two different systems, metric and imperial, to programme the rockets.

The critical point

So have units changed since the development of SI? In one sense, almost completely. The SI serves not a local community but a universal one. Its definitions of the metre, and its proposed definitions of the kilogram, involve no artefacts, only sets of recipes that may incorporate things like wavelengths or collections of atoms. The question of reliability and trustworthiness has been transferred from objects to the technologies and traceability of the networks.

In another sense, though, the story is the same. The standard unit is not outside the human environment, but still within it – the product of a network of agreements, conventions and habits. The standard is not an intrinsic or natural foothold that is a gift from nature, but the outcome of recipes involving technologies of human invention. I have mentioned a few non-SI units that arose out of human life. There are many others, of course, “barn” being a favourite in physics lore. But what are your pet units and why do you like them? Let me know and I will report on your responses in a future column.

Hectolitre, decigram, oersted, knot, erg, lux, furlong, league or perhaps the kilderkin? Send your favourite units to Robert P Crease at the address or e-mail below.

Of gluons, atoms and strings

Imagine a bowling ball rolling toward a group of pins. You are an excellent bowler, so the ball is heading for the centre of the group at high speed. Then something strange happens: when the ball reaches the pins, it stops dead. Instead of crashing down, the pins remain frozen in place. What is going on here?

Scientists at the Brookhaven National Laboratory in Upton, New York, are accustomed to unusual collisions. Within the lab’s Relativistic Heavy Ion Collider (RHIC), two beams of gold nuclei moving at 99.99% of the speed of light crash into each other millions of times per second, creating an extraordinarily hot “soup” of particle debris. Two large detectors allow researchers to study this debris (which survives for only 3 × 10^–23 s) and thereby reconstruct the behaviour of matter at temperatures of more than 10¹² K, almost 100,000 times hotter than the centre of the Sun.

But on some occasions, the outcomes of the collisions surprised both theorists and experimentalists. For example, experiments carried out in the early 2000s showed that the “soup” of matter formed at RHIC – known as a quark–gluon plasma – is extremely opaque to energetic quarks and gluons. Any such particles travelling through this plasma are halted in a short distance and become part of the soup. This quenches the characteristic signal used to detect their emission, effectively causing them to go “missing”. Like the hypothetical bowling ball that stops when it hits the pins, heavy particles with a lot of momentum do not make it out of this plasma. To extend the analogy, it is as if someone tied the bowling pins together with extra-strong rope.

A quark–gluon soup

For quarks and gluons, this heavy-duty “rope” is more properly known as the strong interaction. One of the four fundamental interactions in nature (along with gravity, the weak interaction and the electromagnetic interaction), the strong interaction holds together the quarks making up the protons and neutrons inside atomic nuclei. It is mediated by the exchange of gluons, which work much as photons do in the electromagnetic interaction, but with one enormous difference. Unlike photons, which are more or less oblivious to one other, gluons interact with each other as well as with quarks – a process known as gluon self-interaction. This self-interaction causes the potential between quarks to increase with distance, so more and more energy is required to pull them apart. Eventually this energy pops new gluons out of the vacuum. This process confines quarks inside the normal hadrons detected by experiments, which is why lone unbound quarks have never been observed.

Mmm…science

The theory of the strong interaction, known as quantum chromodynamics (QCD), is notoriously complicated (see “Colourful calculations” Physics World December 2006; print edition only). Calculating the properties of matter containing quarks, known as hadronic matter, requires sophisticated mathematical techniques beyond perturbation theory. Still, by solving the QCD equations, we find that the theory predicts that at high energies or temperatures (above 170 MeV or 10¹² K) there are so many quarks and gluons that the strong force is “screened”. When this happens, individual quarks and gluons no longer feel the full impact of the force. (A similar effect occurs in a conventional, electromagnetic, plasma, where the presence of free charges can screen the electromagnetic force.) This screening effect causes hadrons to “melt”, liberating their constituents into a plasma of quarks and gluons. Such a plasma may have existed about 1 s after the Big Bang, so investigating these novel plasmas experimentally is an important way of learning more about the early universe.

Experiments at RHIC have shown that the hot matter behaves more like a liquid soup of quarks and gluons than like a nearly ideal gas. In this liquid system, multiple particles exert forces on one another simultaneously, and the quark-gluon plasma flows in a coordinated way. More precisely, the experiments show that the plasma flows in an elliptic fashion, spreading more rapidly along one axis than the other. Such behaviour can be quantitatively calculated using the laws of hydrodynamics, and the results reproduce the magnitude of the flow quite well – but only if we assume that the system starts in a plasma phase with a very tiny ratio of viscosity η to entropy density s.

The term “viscosity” is best understood as the measure of a fluid’s ability to sustain a wave and transport momentum. Hence, low-viscosity fluids absorb particles and transport disturbances easily. Transport properties of materials are determined by both the viscosity and the density of particles. Consequently, we use the ratio of viscosity to entropy density, which measures the disorder and particle number. For example, the efficient momentum transport observed in quark–gluon plasmas implies that neighbouring fluid elements “talk” to each other; in other words, the coupling between them is strong. Such strong coupling also explains the fluid’s opacity, as the traversing particles collide with more than one gluon or quark at a time.

But one of the most intriguing consequences of the plasma’s low viscosity is that its η/s ratio is near the value that string theorists have calculated must be the lower limit for a liquid: that is, 1/4π. This is about 380 times smaller than the value for water under normal conditions and nine times lower than that for liquid helium. The vanishing viscosity-to-entropy ratio makes the liquid nearly “perfect”, i.e. able to flow with no resistance whatsoever.

Cold cousins

In the aftermath of the discoveries at RHIC (see, for example, K Adcox et al. 2005 Nucl. Phys. A757 184), there has been a raging debate about just what exactly is interacting inside the quark–gluon plasma. It is not clear whether the matter consists of individual gluons, pure gluonic fields or perhaps multi-gluon objects that continually split and re-form. The task at RHIC now is to upgrade the accelerator and experiments to provide new probes of the matter to differentiate between these scenarios.

In the meantime, our efforts to solve this nuclear-physics problem are benefiting from insights gained in other areas of physics. Although a quark–gluon plasma is an exotic substance in many ways, its liquid properties are similar to those of other strongly correlated systems, where one cannot use the behaviour of a few particles to work out how a large number will behave en masse. Such systems include warm, dense electromagnetic plasmas, which have liquid and even crystalline phases even though they are plasmas. Strongly correlated condensed matter such as high-Tc superconductors also display liquid behaviour and phase transitions (see “The strong-correlations puzzle” Physics World June 2009 pp32–37, print edition only) . Most intriguingly of all, so does some of the coldest matter on Earth.

Hot property

At about the same time that the researchers at RHIC began heating nuclei to unprecedentedly high temperatures, atomic physicists at Duke University were cooling lithium atoms down to a fraction of a degree above absolute zero. In these experiments, the atoms were first laser-cooled to about 150 µK, then placed in a “bowl of light” formed at the focus of a carbon-dioxide laser beam. By gradually reducing the depth of the bowl, the researchers allowed more energetic atoms to evaporate away, thus producing a supercooled sample of atoms at 10^–7K.

Among the many beautiful features of these experiments is that, unlike the plasmas created at RHIC, these ultracold atomic systems live for a relatively long time – several tens of seconds under some circumstances. This means that the cloud of atoms can be reproduced and photographed multiple times, and be released from the trap as well as set to rotate. Another major advantage is that experimentalists can control the transformation of the ultracold lithium atoms from a weakly coupled to a strongly coupled system simply by changing the surrounding magnetic field, using a phenomenon known as a Feshbach resonance.

Amazingly, the team at Duke found that when the strongly coupled cloud was released from the trap, the cold atoms flowed with the same kind of elliptical pattern as observed at RHIC. Further experiments allowed the Duke researchers to measure the entropy of the atom cloud and to estimate its viscosity by observing the rotation rate of the lithium gas as it is allowed to expand. This measurement showed that the viscosity-to-entropy ratio is just as small in the ultracold system as it is in the ultrahot quark–gluon plasma. Naively, one would not expect such different systems to exhibit the same behaviour – but they do.

The string connection

While nuclear and atomic physicists were pondering how to reconcile these observations, a third group of researchers – string theorists – weighed in too. The connection came to light when the theorists were investigating what happens to gravity near tiny black holes, where quantum-mechanical effects matter. Understanding these quantum black holes requires combining the theory of general relativity with quantum mechanics, and one important payback for this effort is the ability to compute the minimum possible viscosity-to-entropy ratio in quantum matter.

Since black holes are thought to radiate, they act like bodies possessing temperature and entropy, where their entropy depends on their area. String theory supplies a quantum-gravity description of the black hole’s internal structure – one that allows calculations of the physics of the black hole to be carried out using a theory known as the holographic principle. These calculations involve building a mathematical “box” around the black hole. Our normal world lies on the surface of that box, and our normal four dimensions (time plus the three spatial dimensions) are supplemented by an extra, fifth dimension that dangles inside the box and connects to the black hole. The strong gravitational effects of the black hole manifest themselves in this fifth dimension.

Going with the flow

Remarkably, string theorists were able to connect this esoteric system with our normal 3 + 1 dimensional world and interpret the viscous flow of strongly coupled matter as the motion of the string dangling in the fifth dimension (see, for example, P Kovtun, D T Son and A O Starinets 2005 Phys. Rev. Lett. 94 111601). This analogy provided a new mathematical tool, which was promptly used to compute the value of η/s in matter the constituents of which are too strongly coupled to be calculated using more conventional means.

The interactions among the hot quarks and gluons at RHIC or the cold lithium ions at Duke can be described as strings in the extra dimension. In addition to the very low viscosity/entropy observed, other properties of strongly coupled systems can be calculated. For example, the transport of energy and the propagation of sound waves are currently being studied in both string theory and in experiments at RHIC through correlations of the detected particles.

This development is extremely exciting as it finally allows experimentally testable predictions to be made from string theory. It is also helpful for experimentalists studying very complex novel liquids. Fresh efforts in this field are beginning to exploit the idea that gravity can be seen as a “dual” for such systems, where the term “dual” basically refers to a system or process that can be described equally well by two theories that, despite their differences, predict the same observable result. Such gravity duals are now being investigated for gap-less superconductors, quantum-critical phase transitions between insulators and superfluids, as well as other quantum-critical points of interest in condensed-matter physics.

Such deep and varied links to seemingly unrelated areas of physics were not something researchers expected to find when RHIC began colliding gold ions earlier this decade. Yet perhaps we should not have been surprised. After all, an impenetrable “soup” of quarks and gluons that flows like a liquid is a fairly remarkable thing in itself. The connections between this system and cold atoms, string theory and superconductors are sure to reveal more surprises in the future.

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