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Pop-culture mathematics

By Tushna Commissariat

Earlier this week I went to hear a talk about mathematics…and The Simpsons. That’s right, I am indeed referring to the long-running animated TV show that is a satirical parody of middle-class American life and its unexpected but concrete mathematical vein. Surprising as it may sound, some of show’s scriptwriters have degrees in maths and physics, meaning that some very advanced concepts, problems and ideas from all of 20th-century mathematics and physics are littered around many of the show’s 535 episodes. Regular Physics World readers will have already seen that we have released the shortlist for our Book of the Year 2013 and that physicist and science communicator Simon Singh’s latest offering – The Simpsons and their Mathematical Secrets – is one of 10 books on the list. I had the happy job of reading and reviewing Singh’s book for our “Between the lines: Christmas special” section in the December issue of the magazine.

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Nanomechanical FM transmitter is smallest yet

Researchers at Columbia University in the US have built the smallest frequency-modulated (FM) radio transmitter ever. Based on a graphene nanomechanical system (NEMS), the device oscillates at a frequency of 100 MHz. It could find use in a variety of applications, including sensing tiny masses and on-chip signal processing. It also represents an important first step towards the development of advanced wireless technology and the design of ultrathin mobile phones, says team co-leader James Hone.

“Our device is much smaller than any other radio-signal source ever made and, importantly, can be put on the same chip that is used for data processing,” he explains.

Graphene is a sheet of carbon atoms arranged in a honeycomb-like lattice that is just one atom thick. Since its discovery in 2004, this “wonder material” has continued to amaze scientists with its growing list of unique electronic and mechanical properties, which include high electrical conductivity and exceptional strength. Indeed, some researchers believe that graphene might even replace silicon as the electronic industry’s material of choice in the future.

Ideal for making NEMS

Graphene is ideal for making NEMS – which are scaled-down versions of the microelectromechanical systems (MEMS) that are routinely employed in vibration-sensing applications. The new device made by Hone and colleagues is a NEMS version of a common electronic component known as a voltage-controlled oscillator (VCO) and generates a frequency-modulated (FM) signal of about 100 MHz. This frequency lies exactly in the middle of the FM radio band (87.7–108 MHz) and the researchers say that they have already succeeded in using low-frequency music signals to modulate the 100 MHz carrier signal from their graphene NEMS and recover the signals again using an ordinary FM receiver.

While graphene NEMS might not replace conventional radio transmitters yet, they will certainly be used in many other wireless signal-processing applications. Although electrical circuits have been continuously shrinking over the last few decades (as described by Moore’s law), there are still some types of devices – especially those involved in creating and processing radio-frequency (RF) signals – that are notoriously difficult to miniaturize, explains team co-leader Kenneth Shepard. Called off-chip components because they cannot be integrated with miniaturized devices, they require a lot of space and electrical power, and their frequency cannot be easily tuned.

Graphene NEMS offer a solution to this problem because they are very small – the active area is only a few microns across – and they can potentially be integrated directly onto conventional CMOS chips. Most importantly, it is easy to tune their frequency thanks to graphene’s exceptional strength.

Adjusting the tension

The Columbia researchers made their devices by contacting graphene sheets to source and drain electrodes and freely suspending the sheets over metal gates. In this configuration, the graphene functions like the skin of a drum. A DC gate voltage pulls the graphene down towards the gate and this adjusts the tension and, therefore, the mechanical resonance frequency, explains Hone. A radio-frequency signal on the gate drives sheet vibrations. “Finally, we apply a DC bias across the graphene and when the graphene vibrates it acts as a transistor whose gate capacitance is constantly changing – and it is this that creates an RF source–drain current,” he says.

The team studied the vibrational properties of the device at room temperature in a vacuum chamber. “To make an oscillator, we first adjust the signal gain to just above unity (using a variable amplifier) and the phase to zero (using a phase shifter) at the resonance frequency,” says Hone. “We then connect the output to the gate. This creates a closed loop that amplifies random thermal vibrations and makes the device oscillate.”

The researchers say they are now busy looking at how to put their devices directly onto integrated circuits that already contain all the necessary drive and readout circuitry. They also hope to improve the performance of their oscillators and reduce device noise.

The oscillator is described in Nature Nanotechnology.

Postcard from Rio – a paradise for physics?

Photo of Sugar Loaf Mountain

By Matin Durrani in Rio de Janeiro

Having flown almost half-way round the world from Bristol to Rio, you might think there is little in common between Physics World‘s home city and the Brazilian metropolis.

But on my trip to the Brazilian Centre for Physics Research (CBPF) in Rio today, it soon became clear from the statistical physicist Constantino Tsallis, who hosted my visit, that there is indeed a link between the two cities. That connection lies with the Brazilian physicist César Lattes, who was the founding director of the CBPF.

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Book of the Year shortlist for 2013

By Margaret Harris
PW-TOP10-books-2013

As the year draws to a close, it’s time for Physics World to dig into its cabinet full of popular-physics volumes, pore over the reviews and decide which of the 59 books we covered in 2013 deserves to be our pick for the year’s best.

As we did last year, we’ve begun by selecting a shortlist of the 10 books that most closely meet our award criteria, which are that the winning book must be novel, scientifically interesting and (of course) well written. This required us to make some tough choices: although many books fulfilled two of our requirements, fewer could claim high marks in all three areas.

The books on the 2013 shortlist are an eclectic group, reflecting the “big tent” nature of physics in recent times. They include popular-science works on biophysics, bombs and a seriously important boson, plus vivid biographies of two very different figures from the history of physics. And we are fairly certain that ours is the only “best books” list you’ll ever see that pits a scholarly argument about the nature of time up against a fan-friendly look at mathematics in the animated TV show The Simpsons.

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A romantic scientist

While giving a lecture on electricity, electrochemistry and magnetism in the spring of 1820, the Danish scientist Hans Christian Ørsted noticed something remarkable: the magnetic needle he was using for one of his demonstrations was deflected by an electric current in a nearby wire. The discovery of this (at first sight) simple and feeble phenomenon came as a great surprise to the scientific community. According to established beliefs among leading scientists in Paris (then the centre of physics and chemistry research), an interaction between electricity and magnetism was not to be expected. Therefore, nobody in Paris was looking for such a connection. But as soon as its existence was realized, electromagnetism sparked a new and extremely fruitful area of physics research. Its discovery was a key step towards understanding the unification of the forces of nature, and it is hard to imagine what life would look like today were it not for the countless telecommunication inventions based on electromagnetism.

The discovery of electromagnetism made Ørsted’s name, ensuring him instant immortality and a place in the history of science. But what is the story behind this important finding, and who was this great Dane whom the renowned British chemist, Humphry Davy, described as “a man of simple manners, of no pretensions and not of extensive resources; but ingenious, and a little of a German metaphysician”? The answers are provided in Reading Nature’s Mind, Dan Charly Christensen’s excellent biography of Ørsted and his times. It is the first complete biography of Ørsted ever written and will probably be the most comprehensive ever to appear.

The picture of Ørsted that emerges in Christensen’s book is of an enterprising and innovative scientific polymath who had been engaged in such diverse intellectual ventures as science, philosophy, art and poetry long before his career-making discovery. Unlike his French colleagues, Ørsted expected a connection between electricity and magnetism to exist and had been looking for one for years. His research involved seeking connections between such phenomena as electricity, magnetism, chemical affinity, heat and light. In his view, the invention of the first chemical battery, the Voltaic pile, in 1800 and the fruitful field of electrochemistry that developed from it were the first important steps in this new programme. For Ørsted, the discovery of electromagnetism was therefore a culmination of his research project.

As citizens of a tiny country on the periphery of the European cultural, scientific and intellectual spheres, Danish intellectuals and scientists have always travelled abroad in order to enhance their qualifications, establish scientific liaisons and learn about research at the forefront of their fields. Ørsted was no exception: he undertook three major journeys around Europe and met and corresponded avidly with most of the leading scientists and scholars of the time. The international flavour of his life lends something extra to his biography, making it a revealing snapshot of the European scientific community and cultural life in the first half of the 19th century.

The narrative of Ørsted’s life in the small but charming Copenhagen bourgeois scene is compellingly written, and Christensen deals with the personal aspects of his life as well as the scientific ones. For the first time Ørsted’s rather innocent love life is analysed, thanks to Christensen’s scrutinizing of Ørsted’s original travel letters. During Ørsted’s first journey abroad in 1801–1803, his fiancée Sophie Probsthein got tired of waiting for him and broke off their engagement, and in 1814 he married his father’s housekeeper, Birgitte Ballum. We share Ørsted’s happiness when he makes his famous discovery and his sorrow when he loses first his beloved sister-in-law Sophie and then, less than a year later, Ørsted’s own daughter, Sophie’s namesake. We follow the lifelong, close alliance between Ørsted and his brother Anders Sandøe Ørsted; although they moved in different intellectual spheres, both men became extremely influential in Copenhagen society, with Anders Sandøe eventually serving as the Danish prime minister. (Two of Ørsted’s younger brothers led more dubious lifestyles, and there are stories about them as well.) We also learn about Ørsted’s friendship with the fairytale writer Hans Christian Andersen and the tribulations experienced by the latter when he first settled in the Danish capital. Ørsted became a patron for the ambitious and vain young writer, and a close filial relationship developed between the “big and little Hans Christian”, as Andersen called them. Ørsted’s scientific epistemology is echoed in some of Andersen’s fairy-tales, such as “The bell”.

Christensen’s aim is to make Ørsted visible in the history of science outside Denmark, and with this new English version (a more or less literal translation from the Danish original, published in 2009) his book seems likely to achieve that goal. The author’s insight into the time period and Danish and European culture – as well as his sensitive description of the characters involved – are unmatched and his love for the topic permeates the text. The inclusion of many striking illustrations makes it a very beautiful book as well, although it is a somewhat heavy one; the Danish version was published in two volumes, but the author chose to squeeze the translation into just one, containing no less than 61 chapters in seven parts.

The title of the book, Reading Nature’s Mind, is well chosen because it captures the essence of Ørsted’s philosophy of nature. Throughout his career, he strove to develop qualitative explanations of phenomena in terms of opposing polar forces that balance each other through a “conflict,” and in his scientific approach and belief he took inspiration from German idealist philosophy. This world-view may have made him more open to discovering electromagnetism, and many scholars (including myself) would call the way the intersection between art, poetry, philosophy and science guided his life “romantic”. However, Christensen makes it clear throughout the book, and particularly in the last chapter, that he does not consider Romanticism an appropriate epithet for Ørsted’s ideas. I disagree with the author on this point, but this did not impair my enjoyment of the book, which is overall a magnificent and superior biography of one of Denmark’s most notable scientists.

  • 2013 Oxford University Press £39.99hb 768pp

Between the lines: Christmas special

Mmm…mathematics

For most people, mathematics and the animated TV show The Simpsons are not exactly synonymous. Yet as the British science communicator Simon Singh shows in his book The Simpsons and their Mathematical Secrets, the show’s writers have stealthily inserted almost an entire PhD’s worth of mathematics into its 500+ episodes. This is partly a reflection of the writers’ backgrounds, since several of the show’s most prolific contributors acquired advanced mathematical degrees before changing careers. Writers David Cohen and Jeff Westbrook, for example, have degrees in physics and computer science, while Al Jean has a BSc in mathematics and was described as a “maths whizz” while a student at Harvard University. The popularity of The Simpsons has spawned a number of books that purport to examine the show’s psychology, politics, popular culture or religion; indeed, there is even a book devoted to the sometimes-impossible science of The Simpsons (What’s Science Ever Done for Us?: What the Simpsons Can Teach Us About Physics, Robots, Life, and the Universe by Paul Halpern). But as Singh shows, the show’s mathematical vein is actually quite deep. Its second episode, “Bart the genius”, features some clever calculus jokes at Bart Simpson’s expense, and from the offset the writers seemed keen to include high-brow hilarity in amongst the silliness and sight gags. Take, for example, the episode “The wizard of Evergreen Terrace”, in which Homer Simpson has a mid-life crisis and is inspired by Thomas Edison to become an inventor. It would be easy to miss the four equations that appear scribbled on a blackboard in this episode, but Singh – who must have worn out the “pause” button on his remote control while researching this book – shows that they include the equation that predicts the mass of the Higgs boson, a (near-miss) solution of Fermat’s last theorem and an equation for the expansion of the universe. Singh explains all of these concepts simply but clearly, and he also incorporates a set of five clever examinations so that you can test yourself. Undoubtedly, his book is the perfect Christmas present for both mathematical savants and Simpsons aficionados – not to mention anyone with a healthy interest in humour and maths.

  • 2013 Bloomsbury Publishing £18.99/$26.00hb 272pp

No more starry nights

View of a cloudy and starry night sky

On a clear night, how many stars can you see in the sky above where you live? For most residents of developed countries (and cities everywhere), the answer is likely to be less than 100 – a far cry from the thousands that our ancestors saw 150 years ago, and that people who live in the world’s remaining dark-sky areas still experience today. Paul Bogard’s book The End of Night: Searching for Natural Darkness in an Age of Artificial Light is both a lament for those vanished starry nights and a tirade against the things that have caused their disappearance, including unshielded street lights, billboards lit from below and even squid-fishing boats, which use daylight-imitating spotlights to attract their prey. Bogard, a journalist at James Madison University in the US, has travelled around the world speaking to people with an interest in darkness, including astronomers, park rangers, philosophers and lighting engineers. Astronomers, in particular, have long been in the vanguard of the fight against light pollution, but Bogard shows that their concerns are only a small part of the big picture. As one of his interviewees puts it, “The presence of an astronomer [is] the sign of a healthy ecosystem…when the sky grows too bright for astronomy and the astronomers go away, you know you have a polluted sky, and whatever has polluted that sky will eventually pollute other resources, given time.” Accordingly, Bogard’s argument goes well beyond astronomy and aesthetics, taking in elements of ecology (light pollution is bad for animals), public health (people are animals too) and even social justice (poorer people are disproportionately affected). The book never quite decides whether it wants to be a poetic lament or a practical call to arms, but its mixture of lyricism and activism still makes for fascinating reading.

  • 2013 Fourth Estate/Little, Brown £16.99/$27.00hb 366pp

A medical history lesson

Most physicists are familiar with the role that physics-based techniques such as magnetic resonance imaging, endoscopy and radiotherapy play in healthcare, but the story of how physics came to be an integral part of medicine is perhaps less well known. In Physicists and Physicians: a History of Medical Physics from the Renaissance to Röntgen, retired medical physicist Francis Duck describes the birth of his discipline via the life stories of the scientists and physicians who brought physics out of laboratories and into clinical practice and medical training. Duck has packed his book with interesting facts, quotes and illustrations from an array of pre-20th-century archive sources, some of which were previously unpublished. The medical content is simple enough for non-specialists to understand, although some descriptions of early medical physics experiments are rather stomach-churning. In one particularly gruesome 19th-century example, the vocal functions of the human larynx were probed with the deceased’s face still attached. Modern readers may also be startled by the many 18th-century attempts to use mild electric shocks for treating a wide range of conditions, including constipation, sprains and deafness – with varying degrees of success. Some of the medical-physics pioneers wrote popular-science books and, it seems, had a way with words; for example, an explanation of inertia in a book by the 19th-century British physician Neil Arnott included this delightful quote: “A horse at speed, stopping suddenly, often sends his cavalier over his ears.” The book contains several unnecessarily repeated quotes and a handful of rather jarring jumps from one topic to another, while most of the non-English book titles and institution names are left frustratingly un-translated. But Duck has an engaging writing tone, and physicists keen on history will not be disappointed by the depth of research or wealth of fascinating material presented.

  • 2013 IPEM Books £35.00pb 306pp

Pondering the big stuff

An incandescent light bulb bathed in green light

What is the universe made of? Will we ever cure cancer? And where should we put all the carbon we are generating? These are just a few of the queries that feature in The Big Questions in Science: the Quest to Solve the Great Unknowns. The subject matter of this beautifully illustrated book reflects the diverse interests of its three authors; while all are British-based science writers, Hayley Birch specializes in writing about energy and the environment, while Mun Keat Looi and Colin Stuart focus on biomedicine and astronomy, respectively. The book’s 20 essays are written with clarity and verve, and the authors’ decision to include occasional sub-sections written by active researchers lends them extra gravitas. On the down side, the essays are too short to cover everything, and a few of the expert-penned sub-sections give a rather one-sided view of topics (such as string theory) that are still the subject of active scientific debate. In most cases, though, both the authors and their contributors are unafraid to say “we don’t know”, and the result is a fine introduction to important questions from across the scientific spectrum.

  • 2013 Andre Deutsch £14.99hb 192pp

The weirdness starts here

An artist's impression of life on another planet, showing strange-looking orbs covered in seaweed

Since the turn of the new millennium, planets orbiting stars other than our own have been discovered at an astounding rate: about one per fortnight, on average. This proliferation of new exoplanets has sparked renewed speculation about what, if anything, might be living on them. David Toomey’s book Weird Life: the Search for Life That Is Very, Very Different from Our Own offers an accessible and engaging survey of recent developments in the burgeoning field of exobiology. Toomey, a writer at the University of Massachusetts Amherst, US, begins by considering life that is “weird” in a biological sense. Our own planet, he explains, is home to numerous organisms that thrive in extremes of temperature, pressure, acidity or saltiness. So far, none of these so-called “extremophiles” has been shown to be truly weird (in the sense of having evolved independently from other terrestrial life), but research on them has nevertheless broadened our view of what constitutes a habitable planet. Next, Toomey contemplates the possibility of life that is based on substances other than carbon and liquid water – chemically weird life, in other words. This sort of life is extremely unlikely on Earth, but it might exist elsewhere in our solar system; in particular the icy worlds of Titan, moon of Saturn, and Triton, moon of Neptune, are regarded as good candidates for hosting it. With readers’ imaginations thus primed, Toomey moves on to more speculative notions about physically weird life, such as Freeman Dyson’s idea that life in the extremely distant future might exist in diffuse clouds of molecules, or in the atmospheres of white dwarf stars. In the latter, Toomey suggests, energy would be at such a premium that a sentient being “might take a thousand years to complete a single thought”. Sounds like some of us after a big holiday dinner…

  • 2013 W W Norton £16.99/$25.95hb 288pp

Solar cells get down to pop music

It is not just humans who respond to motivational music. Researchers in the UK have discovered that blasting beats at zinc-oxide solar cells makes them perform up to 50% better. According to the researchers, pop and rock music gets the cells going more than classical music, but they suggest that any noise with a broad range of frequencies will produce similar effects. The discovery might be exploited by placing the devices on top of buses, air-conditioning units and in other noisy spots.

Crystalline-silicon photovoltaic cells have been around for more than 50 years but they are fragile and expensive, and producing them is labour intensive. Much attention has been focused on investigating alternative materials, such as flexible, transparent and cheap zinc-oxide devices, but these remain woefully inefficient compared with silicon. In an attempt to stretch its limits, functional-nanomaterials expert Steve Dunn of Queen Mary University of London and Imperial College photochemist James Durrant wondered whether they could combine two of zinc-oxide’s special physical properties to make solar cells more efficient.

Extracting excitons

“One of the biggest problems with polymer or organic materials when they’re used in solar cells is recombination,” explains Dunn. When a photon of light interacts with a solar cell, it generates an exciton – an electron–hole pair. To harvest the photon’s energy, the electron and hole must be extracted into an external circuit before they manage to recombine and waste the energy as light or heat within the cell. Zinc oxide – a semiconductor – is known to hinder recombination, and nanorods of the material can be embedded in photovoltaic cells to funnel electrons out of the active layer.

Zinc oxide is also piezoelectronic (piezo comes from the Greek “to squeeze”), meaning that when it is subject to mechanical strain, the symmetry of its component crystals is distorted and a polarization charge appears along the length of the structure. Dunn and Durrant hypothesized that by using acoustic vibrations to wobble – and induce tiny piezoelectric currents in – zinc-oxide nanorods, they could boost their photovoltaic cells’ electricity output. To test their idea, the researchers used computer speakers to play the device music from their mobile phones and individual frequencies from a signal generator at volumes of about 75 dB – equivalent to a lively office.

AC from AC/DC

The team found that the device was 40–50% more efficient when particular types of music were played. “It quite liked Adele and AC/DC,” says Dunn, “but then Safa [Shoaee] played some Persian funk at it and it was really loving that!” Classical music apparently did little for the device though, having almost no effect on its power-conversion efficiency. “[In classical music] there’s a lot less going on in terms of all the additional overtones that come from synthesized or rock music…The device responds to the larger variety of frequencies in the rock music, and also to the fact that there’s just a lot more energy available in it,” says Dunn.

The more energy delivered by the sound, the more the pressure wave deforms the rods as it ploughs through the device, and the more polarized the rods become. As they deform and relax with each successive wave, an oscillating electric field is generated within them, dragging the free electrons and holes back and forth at the zinc-oxide–polymer interface and hampering their chances of recombining before they can be harvested.

Absolute numbers

If playing music to solar cells sounds like a somewhat inefficient way to produce electricity, the researchers suggest that a similarly broad range of frequencies arise from myriad types of everyday noise, marking the devices out for use on laptops, public transport and near airports. That is a long way off yet, though. Even with the 50% increase, this type of cell only achieves 1.8% power-conversion efficiency and lags way behind crystalline silicon’s 10–20% standard.

Jenny Nelson, a physicist at Imperial College who was not involved with the research, calls it a “nice example of how nanomaterials can do things better than bulk materials, and in this case without needing an expensive fabrication processes”. But she points out that the effect is especially impressive partly because zinc-oxide cells are currently so inefficient: “In a very efficient device, the losses to recombination would be less and the relative advantage of the acoustic waves would be less.”

To find out more, take a look at the video above presented by Dunn and his colleague Joe Briscoe.

The research is published in Advanced Materials.

How to watch a Bose–Einstein condensate for a very long time

A new way of making measurements on Bose–Einstein condensates (BECs) has been proposed by physicists in the UK and Australia. Calculations made by the team suggest that the technique could allow researchers to monitor BECs over much longer timescales than the several seconds possible today. If successfully implemented in the lab, the process could increase the use of BECs in practical applications such as atomic clocks and accelerometers.

A BEC is created by holding atomic gas in a magnetic trap and cooling the gas to nanokelvin temperatures. This causes all of the atoms (sometimes tens of thousands) to settle into a single coherent quantum state. When this occurs, the condensate is a macroscopic system that is described by the same wavefunction. BECs can then be studied to gain further insights into quantum mechanics or be used to create practical devices such as atomic clocks or extremely sensitive accelerometers that could be used for navigation and other applications.

An important challenge facing anyone trying to create and use a BEC is that quantum coherence extending over thousands of ultracold atoms is extremely fragile and the tiniest disturbance can destroy the BEC. This makes it difficult to monitor the properties of a condensate once it has been made. Indeed, most experiments involve taking just one image of a BEC, which destroys it. Other methods do allow the BEC to be monitored for a few seconds, but developing techniques to monitor a BEC over longer periods of time has proven elusive.

Unexpected evaporation

A promising way of imaging a BEC is to use “off-resonance” light – light at a frequency that does not correspond to any atomic transitions in the condensate. Because this light will not be strongly absorbed by the BEC, it should not cause much disruption – at least in principle. In practice, however, physicists have found that BECs quickly evaporate when exposed to off-resonance light.

Now, Michael Hush of the University of Nottingham together with colleagues at the University of Queensland and the Australian National University have developed new computer-modelling techniques that provide fresh insights into how a BEC interacts with the light used to image it. This new information has inspired the team to create with a new protocol that – if it works in the lab – could allow multiple images to be taken over several minutes or even indefinitely.

The simulations allow us to see heating effects that others had not predicted
Michael Hush, University of Nottingham

To gain a better insight into how BECs interact with light, Hush and colleagues used a simulation technique called the “number-phase Wigner (NPW) particle filter”. The NPW aspect of the technique refers to the phase-space representation of the BEC used in the calculations, while the particle filter is a numerical technique that provides an optimal estimate of the quantum state of the BEC. “The simulations allow us to see heating effects that others had not predicted,” says Hush. “These effects could be the cause of atom loss when a BEC is imaged,” he adds.

Dampening vibrations

Armed with this new knowledge, the researchers developed a feedback scheme to remove this heat (see figure). In their system, the BEC would be bathed in a standing wave of off-resonant light, which would be used to monitor its density. Heat absorbed from the light will cause the atoms in the BEC to vibrate and these vibrations would be detected by the light. A feedback system would use this information to adjust the parameters of the magnetic trap so that these vibrations are dampened. While the scheme has not yet been tested, Hush is hopeful that it could be implemented in the lab.

Jacob Sherson of Aarhus University in Denmark, who was not involved in the research, described the work as “a great contribution to the field”, saying that as an experimentalist he would love to implement the ideas in the lab. While Sherson points out that certain experimental challenges would have to be overcome to implement the scheme, he adds that he is “convinced that the ideas put forth [by Hush and colleagues] can help extend the duration over which BECs can be monitored”.

The research is reported in New Journal of Physics.

In search of the real Stephen Hawking

Stephen Hawking is famous for three reasons. The first is his reputation as a cosmologist. Back in the 1960s, when Hawking began studying singularities in black holes and the early universe, the field of general relativity was more or less in the doldrums. Hawking’s work helped change that, and he deserves a substantial part (though by no means all) of the credit for the field’s revival.

The second source of Hawking’s fame is his role as a science communicator. Some people are sniffy about his first popular book, A Brief History of Time, calling it “the least-read bestseller in history”, but I am not one of them. As a teenager, I lapped up every challenging word of it, and together with one of his later books, Black Holes and Baby Universes, it helped persuade me (and many other like-minded people) to study physics at university.

Like it or not, though, these achievements are overshadowed by the third component of Hawking’s fame: his public image as the stereotypical disabled genius. Cut off from most human interaction by the effects of motor neurone disease, which have rendered him almost immobile and unable to speak except through a computer, Hawking – so the story goes – chooses instead to concentrate on loftier matters. Even as his body remains confined to a wheelchair, his mind is free to journey to the furthest reaches of space and time.

In his memoir My Brief History, Hawking strikes a balance between scientific contributions, communication and image. Writing in his characteristic clear, concise style, he describes how, after an idyllic childhood and some rather lazy undergraduate years, his devastating diagnosis spurred him to make something of his life using whatever abilities remained to him. What follows are short sketches of his research career, interspersed with accounts of his travels, his two marriages and his role as an advocate for people with disabilities.

Readers with no previous knowledge of Hawking will find these stories interesting. For everyone else, though, the book will feel disappointingly superficial, and perhaps also strangely familiar (more on that later). The tales from his childhood are pleasant enough, but unlike the biologist Edward O Wilson, whose memoir Letters to a Young Scientist seems sure to become a classic, Hawking mostly declines to draw the sort of connections to his later career that would give weight to these reminisces. There are also some curious inclusions, and one even more curious absence. Hawking devotes nearly a whole paragraph to the Roman heritage of St Albans, his boyhood home, but nary a word to Jacob Bekenstein, whose ideas about black holes and entropy helped precipitate some of Hawking’s best work.

My Brief History is not entirely colourless, though. It does contain some moments of waspish humour, as when Hawking relates how his doctor told his then wife that he was coming home to die (“I have since changed my doctor,” he adds drily). Less pleasant are the book’s occasional brushes with sexism, as when he quips that “scientists and prostitutes get paid for doing what they enjoy” or grouses that the title of the television series The Ascent of Man would “not be allowed today” because it is not politically correct. And there is real heat in his gibes at particle physicists (“falling over themselves to latch on to the latest idea”) and his repeated digs at the widely held view that theoretical physics can only progress with the help of experimental data.

For insights on Hawking the man, and especially Hawking the scientist, you would be much better off reading Hélène Mialet’s book Hawking Incorporated. Mialet is an anthropologist, and her book is a densely-written “ethnographic study” of Hawking and the network of people and technologies that assist him. The existence of such a network, Mialet observes, is at odds with Hawking’s public image, an entity she calls HAWKING. How, she asks, has “this man who cannot move a finger without his nurse’s help…come to represent the mythical figure of the lone genius who can grasp the ultimate laws of the universe with nothing more than the strength of his reasoning”?

To find out, Mialet interviewed a dozen or so people, including her subject’s nurses, personal assistants and students as well as several of his colleagues. These are the people who enable Hawking not only to travel and give talks, but also to do the research and writing for which he is famous. Mialet refers to them as Hawking’s “extended body” and she reveals, in painstaking detail, how they transform Stephen Hawking – a 71-year-old man with a debilitating illness – into HAWKING, the world’s most famous physicist.

In his memoir (which came out after Mialet’s book was completed), Hawking writes that he is glad he became a theorist, because his disabilities would have prevented him from succeeding in experiment. Even so, his illness has profoundly affected the way he works. Hawking alludes to this briefly when he writes that he thinks in pictorial terms instead of equations “partly because it is difficult for me to write them [equations] down”. But Mialet, characteristically, probes deeper. For most people, she observes, doing mathematics is a very tactile process, and “one needs not only a head but also 10 fingers to write equations, draw diagrams and use a computer”. Moreover, “far from being a discipline in which one can devote oneself to the joys of solitary thought, theoretical physics requires intense collaborative work”. But Hawking cannot do any of these things easily, and some he cannot do at all. How has he managed it?

The answer, in a nutshell, is through his students. Because communication is so difficult for Hawking, his students learn to present their questions to him in such a way that he can give them maximum information with minimum effort. They also learn to translate his tiniest facial gestures and most cryptic comments into useful feedback. But this is an art, not a science. Although his students insist to Mialet that Hawking does help them, they often struggle to explain how. One is left with the impression that Hawking, even more than most senior scientists, relies on his students to do the intellectual grunt work.

More unsettling is the chapter on how the media and Hawking have collaborated to create HAWKING. In his public utterances, Hawking has repeated most anecdotes about himself many times; his assistants even keep an archive so he can call up previous comments as required. When he does this in interviews, journalists dutifully repeat his answers, treating each as a new revelation. But on the rare occasions when he deviates from the “script” – by, for example, expressing opposition to the Iraq war – Mialet shows that he is often ignored. Hence, regardless of whether he “plays the game and lets the media exploit his writings, or rebels and intervenes in the construction of his own myth”, the result is much the same. The public gets the version of Hawking it expects, and maybe the version it deserves.

As an anthropologist, Mialet is interested in this process because each repetition helps to standardize HAWKING, the public image. As a reviewer, I am interested because it explains why Hawking’s memoir gave me such a sense of déjà vu. Hawking is hardly the only prominent figure to engage in “recycling”, and since he can only write a few words per minute, he has a better excuse than most. Even so, the extent of his repetition is annoying. Why should anyone buy Hawking’s memoir when some of the most interesting stories in it have already been published – sometimes nearly word for word – in A Brief History of Time, Black Holes and Baby Universes or even, for heaven’s sake, an interview he once gave to Playboy magazine? And does the identity he constructs by such recapitulation have anything in common with what Mialet calls “the real, unique Mr Hawking, the flesh-and-blood person”? These are good questions, but neither Hawking nor HAWKING seem prepared to answer them.

  • My Brief History: a Memoir by Stephen Hawking 2013 Bantam Press £12.99hb 144pp
  • Hawking Incorporated: Stephen Hawking and the Anthropology of the Knowing Subject by Hélène Mialet 2012 University of Chicago Press $31.00pb 272pp

Making sense of Oppenheimer

J Robert Oppenheimer has proven all but unfathomable to his biographers. It is not easy to craft a convincing portrait of someone who was alternately brilliant and obtuse, eloquent and shallow, arrogant and insecure, robust and fragile. Handsome and charismatic, the head of the Manhattan Project to build the atomic bomb cultivated friends in high places, but he could also be callous and even vicious toward friends and intimates. The range of reactions he inspired is as discordant as his character. Some people called him a secular saint, a “Gandhi stretched up to six feet”, while others saw him as treacherous – a brutal, petty and often pretentious colleague.

Moreover, Oppenheimer was notoriously guarded. He left no personal diary, no autobiography. He repeatedly and deliberately frustrated efforts by interviewers to elicit personal feeling and reflections. A biographer has little to go on in figuring out what drove this driven man, despite the existence of years of now-public wiretaps and FBI surveillance. As Ray Monk puts it in his masterful new book Robert Oppenheimer: a Life Inside the Center, “Not revealing things about himself was something he was extraordinarily good at.”

Monk is hardly the first scholar to try his hand at explaining one of the 20th century’s most enigmatic scientists. Indeed, several biographies appeared around 2005 in the wake of the centennial of Oppenheimer’s birth. These include the Pulitzer-prizewinning American Prometheus (2005) by Kai Bird and Martin J Sherwin; and Abraham Pais’s J Robert Oppenheimer: a Life (2006), to which I contributed after Pais died with the manuscript unfinished. Yet all of these biographies managed to paint their respective portraits by adopting partial perspectives, whether historical, sociological or political.

Monk’s biography improves on them by subtly shifting the focus away from the man to his interactions with his surroundings. It presents Oppenheimer as a man consumed by centres – social, scientific, political. Monk describes the dynamics of Oppenheimer’s life as efforts to move towards these centres, to maintain his unstable presence at them and to avoid falling away from them. In part one, for instance, Monk goes to some lengths to describe the German Jewish community on Manhattan’s Upper West Side in which Oppenheimer was born and raised in the early 1900s. This community was struggling to fit in not only with its adopted country but also with more recent Polish and Russian Jewish immigrants who landed in the “Jewish Ghetto” on the city’s Lower East Side. Monk describes the leaders of this centre-aspiring community and its institutions, including the Ethical Culture School, which Oppenheimer attended. He presents Oppenheimer as a youth whose German and Jewish background propelled him to seek to become a devoted American, and whose patriotism and assimilation into American life were unequivocal.

Monk also dwells on Oppenheimer’s intense and formative personal relationships with classmates and teachers en route to his becoming a promising young theorist, one who managed to show up at the centre of theoretical physics (Göttingen) at a time (1926) of radical change: the quantum revolution. Yet for Oppenheimer, it was not enough merely to be at the centre of theoretical physics. He wanted that centre to be American, and after leaving Europe, he quickly set out to build the US’s first school of theoretical physics.

In succeeding chapters, Monk portrays other kinds of centre-seeking movements, as Oppenheimer became the surprise choice to lead one of the riskiest military ventures ever, the Manhattan Project, and as he afterwards sought to play a key role in shaping US atomic policy, only to be expelled after a gruelling and humiliating series of security hearings. Monk enables us to understand why Oppenheimer was so determined to brave that ordeal, defending himself against charges of disloyalty, when he might have gracefully stepped back.

Strangely, Monk does not go into as much detail about Oppenheimer’s later personal relationships as he does with his earlier ones. A lack of evidence may be partly to blame; Oppenheimer’s wife and children, in particular, seem to have shared his reticence about putting personal feelings on paper. Even so, plenty of people knew his late wife and daughter, and his son is still alive, though elusive. Some sense could have been made of it.

Monk’s care not to overstep the available evidence does pay off later in his treatment of Oppenheimer’s possible Communist Party membership. “The question of whether Oppenheimer was a communist or not is thus rather like the question of whether he was or was not a German Jew,” Monk writes insightfully. “He did not consider himself to be German, Jewish or communist and yet, as those words are commonly used, he was ethnically a German Jew and politically a communist. One does not have to accuse either Oppenheimer or common usage of being wrong here; one just has to be careful in distinguishing the sense in which he was and was not German or Jewish or a communist.”

Only occasionally does Monk falls prey to Oppenheimer-mystique: the temptation to read deep meanings into the man’s verbiage when more mundane explanations are likely. When Oppenheimer named a used car “Ichabod”, Monk proposes that he was thinking of an obscure Old Testament priest – the son of Phinehas in the Book of Samuel – or a figure in an enigmatic Robert Browning poem. Oh, come on. The car’s most probably named after Ichabod Crane, the itinerant schoolteacher famously chased by a headless horseman in Washington Irving’s The Legend of Sleepy Hollow – a tale known to every New York schoolchild.

Unlike most other biographers, Monk takes Oppenheimer’s scientific concerns seriously. Quantum electrodynamics, he notes, had an “extraordinary hold” on Oppenheimer in the 1930s, and he quotes a student’s recollection about Oppenheimer’s determination to make sense of the meson puzzle: “it bothered him, it tore at him”. In her New York Times review of this book, the journalist Janet Maslin chides Monk for wasting so many pages on things like mesons, asking sarcastically: “Would anyone seriously interested in Oppenheimer seek out a biography for this?” Gosh, how small-minded! But Monk appreciates just how captivating science is to the true scientist. “I need physics more than friends,” he cites Oppenheimer as saying.

Isidor Isaac Rabi once said that, while most physicists regard physics as simply a profession, Oppenheimer regarded it as a path to deeper truths; physics for Oppenheimer was therefore a means to the Centre. The towering achievement of Monk’s book is that it finally makes this plausible. J Robert Oppenheimer has never made more sense.

  • 2013 Doubleday/2012 Jonathan Cape $37.50/£30.00hb 832pp
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