Nobel laureate Steven Chu has announced he is to resign as US energy secretary. (Courtesy: DOE)
The Nobel laureate Steven Chu has announced he is to resign as US energy secretary. When Chu departs, most likely at the end of February, he will have served in the post for four years – longer than any of the 14 previous heads of the Department of Energy (DOE). Chu now plans to return to “an academic life of teaching and research” in California.
Politically independent, Chu received plaudits from Democrats and environmentalists during his time in office, which spanned the whole of US President Barack Obama’s first term in office beginning in 2008. “Steve helped my administration move America towards real energy independence,” Obama said in a statement. “Over the past four years we have doubled the use of renewable energy, reduced our dependence on foreign oil and put our country on a path to win the global race for clean-energy jobs.”
In a letter to DOE staff, Chu noted his successes in office, such as funding the Advanced Research Projects Agency-Energy (ARPA-E) – a programme to promote and fund research and development into advanced energy technologies. The agency’s work in areas such as improving batteries for electric vehicles and developing manufacturing technologies for solar cells has drawn plaudits across the board.
Chu also played a key role in overseeing efforts to cap the oil spill from BP’s Macondo well in the Gulf of Mexico, while the physicist’s “SunShot initiative” – an effort to increase US use of renewable-energy technologies – began progress towards a goal of reducing the cost of solar power to $1 per watt. “Secretary Chu has led the energy department at a time when our nation made the single largest investment ever in clean energy and doubled our use of renewables,” stated Gene Karpinski, president of the League of Conservation Voters.
In his stint as energy secretary, Chu also worked hard to break down the traditional walls between basic and applied science. “He had a substantial impact on changing research in the department, although mainly in terms of applied research,” Robert McKeown, deputy director for science at the Thomas Jefferson National Accelerator Facility, told physicsworld.com.
Facing the critics
Yet Chu also became a controversial figure, facing heavy criticism from Republicans, deniers of climate change and some members of the business community. Critics focused on occasional failures of Chu’s initiatives, such as Solyndra – a solar-cell manufacturer that went bankrupt after receiving $535m in DOE loan guarantees – as well as A-123 Systems, an innovative battery maker that went bust before being rescued by a Chinese conglomerate.
Daniel Kish, senior vice-president of the Institute for Energy Research, a Washington DC-based non-profit corporation, asserted that the emphasis on renewables has cost jobs. “The policies and priorities of Chu’s energy department have benefited our global competitors and intensified the economic pain felt by millions of unemployed Americans,” he says.
Chu responded to those criticisms in his letter to DOE’s employees. “The truth is that only 1% of the companies we funded went bankrupt,” he noted. “The test for America’s policy makers will be whether they are willing to accept a few failures in exchange for many successes.”
Early speculation on the Obama administration’s nomination of Chu’s successor focuses on former governors, including the Democrats Bill Ritter of Colorado, Jennifer Granholm of Michigan and Chris Gregoire of Washington state. Yet there is a possibility that Chu’s successor will be another scientist: theoretical physicist Ernest Moniz of the Massachusetts Institute of Technology, who served as undersecretary of energy for former US president Bill Clinton.
Magnetic-resonance-imaging technology has been shrunk to the nanoscale by two independent teams of researchers, so that molecular samples just a few cubic nanometres in volume can now be detected and imaged at room temperature. Both groups used nitrogen-vacancy defects in diamonds as magnetic-field sensors to probe such minute samples. The research could be the first step towards complete 3D molecular-scale magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR).
Classic images
Classical MRI and its related chemical-diagnostic technique NMR are useful tools as they can be used to study samples and even living organisms non-invasively. However, once a sample is smaller than, say, a few microns, the technique does not have the required sensitivity to work well. This is because a part of the apparatus – the antenna or the magnetic induction coil – that collects the magnetic signal from the sample being measured cannot be made any smaller than a few microns, and so it cannot pick up a signal from tiny volumes. Other methods, such as magnetic resonance force microscopy (MRFM), have been developed to image on very small scales but these only work at ultralow temperatures and so cannot be used outside the lab in an ambient environment.
The new method uses nitrogen vacancy (NV) defects, which occur when two neighbouring carbon atoms in diamonds are replaced by a nitrogen atom and an empty lattice site. NV sites are capable of detecting the very weak oscillatory magnetic fields that come from the spins of protons in a sample.
Defects and vacancies
Tobias Staudacher and Friedemann Reinhard of the University of Stuttgart, Germany, and colleagues used these NV defects to record the NMR spectra of various materials that they placed on the surface of a diamond. First the team embedded a single NV defect 7 nm under the surface of the diamond. “On a quantum level, our NV is in a two-spin state – a bright and dark fluorescence. So we set up a very basic quantum algorithm or protocol – the spin flips from bright to dark only if it detects the proton’s oscillations, and we can detect this with a photodiode or camera,” explains Reinhard. The team used this method to detect the proton spins of a number of liquid and solid samples placed on the diamond’s surface.
To build up an actual 3D image on the nanoscale, however, the sample would somehow need to be moved; but as the current method involves placing it on the diamond surface, this is not possible. Instead, Reinhard and his team are currently developing a diamond (with an NV defect) atomic force microscope (AFM) tip that could be used like a scanning device to image a sample in full 3D. “We are quite optimistic about this method and have been building this device for a while now,” says Reinhard.
He also points out that while being able to carry out the procedure at room temperature is a huge advantage, the team will also build some units of the diamond AFM device for low-temperature studies. He tells physicsworld.com that many samples, such as proteins, need low temperatures during imaging as they “move and shake too much at room temperature, so freezing them would give a more accurate image”.
Diverse applications
Reinhard claims that apart from the most basic application – being able to resolve a single atom at room temperature – in the future the method could have many other applications. He claims that the technique could help solid-state researchers and the nanotechnology community image their tiny devices, where “each atom in a device matters”. Currently, nanotechnology researchers can only image the surface of their devices. “Using this technique, they could selectively and chemically image below the surface,” says Reinhard.
Another potential application of the method includes using it as a polarizing agent for traditional NMR. This would involve polarizing the NV defect and transferring this polarization from the defect to the sample.
The method could also be applied to quantum information storage – single spins have been stored and then recovered from an NV, providing a way to store information in a quantum computer.
Manipulative measurements
The other group included Dan Rugar and John Mamin of the IBM Research Division in California, US, and colleagues. The researchers also used NVs in a diamond, just under its surface; however, their sample was not on the diamond surface itself but placed next to it. Their sample was an organic polymer. They manipulate the electron-spin echoes on the NV defects as well as the sample’s spin with an additional radio-frequency field to manipulate the electrons in the hydrogen atoms in the sample. The team believes that the sensitivity of the technique could, someday, even allow single protons to be resolved.
Bubbles are wonderful things – as well as giving children hours of fun, they provide physicists with a number of fascinating phenomena to study and genuine mysteries to solve.
One curious effect that physicists have known about for some time is that tiny air bubbles in water will last much longer when they are stuck on a surface – rather than floating freely. A free bubble with a diameter of 100 nm or less will only survive a few microseconds, while a bubble of similar size on a surface can endure for days.
Why is this interesting, you might wonder? For one thing, controlling nanobubbles can be very important when designing tiny machines that shift fluids about. A coating of nanobubbles could make it easier for a fluid to flow along a tiny channel. Conversely, bubbles in the wrong place could gum up the works. Nanobubbles could someday be designed to carry drugs to specific places in the body, popping on arrival.
It’s the first of the month so – as if by clockwork – the February issue of Physics World is now ready for your enjoyment, in print, online and through our apps.
Our lead news story this month is about how Barack Obama, who was sworn in for a second term as US president last month, deals with the US “fiscal cliff” and what impact any resolution has on funding for science.
Elsewhere, we examine the lasting impact of two famous astronomers – Fred Hoyle and Sir Bernard Lovell. The former’s impact is felt most acutely in the “Hoyle state” – a short-lived excited form of carbon-12 that holds the clue to life in the universe but is still baffling today’s best nuclear physicists. As for Lovell, his notorious visits to the Soviet Union in the 1960s at the height of the Cold War might have been frowned upon by authorities in the West, but they set the tone for international collaboration and helped to pave the way to today’s ITER fusion experiment.
There’s also a great feature on how researchers are gaining valuable information about the black hole Cygnus X-1. Plus don’t miss Peter Kenny’s lateral thoughts about the mysteries of mathematical subtraction and find out why friends hold the key to career success.
Physics for leisure: Just how many popcorn kernels would it take to fill a cinema? Lawrence Weinstein’s Guesstimation 2.0 has the answer to this and dozens more factoid challenges. (Courtesy: iStockphoto/Gustaf Brundin)
Go on – guess!
For many of us in the Physics World office, the chief attraction of stumbling across an intriguing numerical factoid – the total energy required to air-freight a tonne of oranges across the US, say – is that it immediately turns into a guessing game, as we invite colleagues and friends to estimate the correct answer. If you are also partial to this kind of quick calculation, then you will surely enjoy Guesstimation 2.0: Solving Today’s Problems on the Back of a Napkin. Written by Lawrence Weinstein, an experimental nuclear physicist from Old Dominion University in Virginia, it treads the same path as his earlier book Guesstimation (see July 2008 p43). In the current volume, Weinstein poses a series of 70 or so numerical questions and invites the reader to make an educated guess at the answer – with help, if needed, from some gentle hints. Questions range from the simple (What is the total length of toilet roll used in the US each year? How many popcorn kernels would it take to fill a cinema?) to the complex, such as comparing the energy efficiencies of different forms of lighting. Weinstein does an admirable job of giving full and clear answers, always concentrating on making sensible estimates rather than striving for absolute precision. The final chapters of the book contain some quite advanced questions that will test even seasoned physicists. How closely, for example, could we safely orbit a neutron star if we considered only gravitational effects? (About 1000 km.) And what must the minimum possible lifetime of the proton be, such that radiation from proton decay will not kill us? (Some 1017 years.) Weinstein’s strong US-centrism and fondness for footnotes aside, this book will be perfect for all physicists wanting to give their minds a good workout.
2012 Princeton University Press £13.95/$19.95pb 377pp
A celebration of physics
So you want a popular-science book that encompasses our entire state of knowledge of fundamental physics, is technically correct yet also short and easy to read? Then The Universe Within by Neil Turok, director of the Perimeter Institute for Theoretical Physics in Waterloo, Canada, is for you. Based on the Massey Lectures that Turok gave in November 2012 on CBC Radio, the book races through the “standard history” of physics – from ancient Greek scholars to Einstein – before romping through quantum theory, cosmology and recent attempts to unify physics. It is all familiar territory, but whereas lesser authors might have got bogged down in details, Turok stays lucidly on track, drawing on his own experiences at Princeton University, Imperial College London and the University of Cambridge, collaborating with the likes of Stephen Hawking. The technical level is nicely consistent – there are no wild lurches up or down – and Turok’s prose is measured and even. However, the final chapter, which seeks to remind us of the power of scientific thought in tackling society’s ills, is a rather curious affair. Its strange conclusion – if there is one – is that we face a bright future because humans will derive “great mutual benefit” from quantum computers as both are analogue devices. (Classical computers, in contrast, provide digital information – which, Turok claims, is “evolutionarily regressive” for some reason.) The last chapter also has a few silly errors – South Africa didn’t “win the competition” to host the Square Kilometre Array (it will host the radio telescope jointly with Australia), while Paul Dirac studied engineering at the University of Bristol, not Cambridge. Unfocused ending aside, the rest of the book is first rate and highly recommended.
2012 Anansi £9.96/$15.95pb 294pp
Rolling in the deep
Most of us have been to the beach and seen waves rolling up the shore line. We may even have idly wondered where such waves come from, how they form and how they travel. But how much do we really know of the science behind their evolution? In Waves, author Fredric Raichlen takes an in-depth look at all of these topics, flowing easily from the mechanics of how water waves are born, through the way currents travel across the Earth, to the effects of wind, astronomical tides and the formation of tsunamis and hurricanes. An expert on coastal engineering and wave mechanics at the California Institute of Technology, Raichlen was inspired to write the book after recalling the questions his sons asked him about waves as they sat on a beach many years ago. A compilation of the answers would, he decided, help others with similar queries. The book is interspersed with interesting titbits, such as the fact that tsunami waves – the lengths of which are typically about 100 times their depth – travel at average speeds of “about 700 km per hour – the speed of a jet plane”, which is a neat way of conveying their might and destructive power. Later in the book, Raichlen also explains how a ship 300 m in length can be displaced by the action of waves that may be less than 1 m high – even to the point where the lines mooring it to a dock can be snapped by the wave action. However, the book is quite technical in its content, with a fair number of formulae and graphs. The language is also rather formal, making Waves feel like a textbook despite its slick cover and handy “pocket book” size. But if you want a quick reference guide to the nitty-gritty of water waves rather than a casual beachside read, this could be a handy addition to your bookshelf.
People can simultaneously identify the pitch and timing of a sound signal much more precisely than allowed by conventional linear analysis. That is the conclusion of a study of human subjects done by physicists in the US. The findings are not just of theoretical interest but could potentially lead to better software for speech recognition and sonar.
Human hearing is remarkably good at isolating sounds, allowing us to pick out individual voices in a crowded room, for example. However, the neural algorithms that our brains use to analyse sound are still not properly understood. Most researchers had assumed that the brain decomposes the signals and treats them as the sum of their parts – a process that can be likened to Fourier analysis, which decomposes an arbitrary waveform into pure sine waves.
However, the information available from Fourier analysis is bound by an uncertainty relation called the Gabor limit. This says that you cannot know the timing of a sound and its frequency – or pitch – beyond a certain degree of accuracy. The more accurate the measurement of the timing of a sound, the less accurate the measurement of its pitch and vice versa.
Getting around Gabor
Unlike the Heisenberg uncertainty principle, the Gabor limit is not an intrinsic property of the signal but is a result of the method used to analyse it. If you can find a way to analyse a complex waveform without decomposing it into sine waves, you can in theory track the frequency at a particular time to much greater accuracy. However, whatever analytical technique you choose must be nonlinear because any technique that represents the waveform as a sum of simpler waveforms will be bound by the Gabor limit.
Researchers such as Brian Moore at the University of Cambridge first showed, in the 1970s, that the human auditory system could beat the Gabor limit, implying the brain could perform some kind of nonlinear analysis of the signals that it received from the ear. However, this work was not picked up by the broader scientific community, partly because cochlear processes were not then understood.
Pitch and timing
In this latest study, Jacob Oppenheim and Marcelo Magnasco of Rockefeller University gave volunteers a series of tasks in order to determine precisely how sensitive humans are to the pitch and timing of sounds. One test involved playing two notes widely spaced in time but at the same pitch. In-between the two, they were played a third note, and they were asked to identify whether it was slightly higher or slightly lower than the other two. In another, the subjects were played two notes widely spaced in pitch almost simultaneously: they were then asked whether the higher or the lower one had been played first.
The final test combined the first two tasks: a low note was played followed by a high note. At almost the same time as the high note was played, a third note was played at almost the same pitch as the low note, and the volunteers were asked whether it was pitched above or below the low note and whether it was before or after the high note.
Oppenheim and Magnasco discovered that the accuracy with which the volunteers determined pitch and timing simultaneously was usually much better, on average, than the Gabor limit. In one case, subjects beat the Gabor limit for the product of frequency and time uncertainty by a factor of 50, clearly implying their brains were using a nonlinear algorithm.
Highly nonlinear hearing
“In signal processing, there are a very large number of time–frequency distributions that have been proposed in order to analyse these signals,” says Magnasco. “The question is, since there are very many different ways in which you can do this and only the highly nonlinear ways can offer performance comparable to what humans do, which one of these is in the same family as what the brain does?”
Mike Lewicki, a computational neuroscientist at Case Western Reserve University in Ohio, says the research is “a nice demonstration that our perceptual system is doing complex things – which, of course, people have always known – but this is a nice quantitative demonstration by which, even at the most basic level, using the most straightforward stimuli, you can demonstrate that the auditory system is doing something quite remarkable”.
In their 2010 book The Grand Design, Stephen Hawking and Leonard Mlodinow expressed the opinion that philosophy was dead as a useful vocation – and that it was now scientists who must address the big questions such as “How was the universe created?”.
Of course this is not the first time that scientists – primed by the many triumphs of their craft, particularly in the last few centuries – have put down philosophy, and the debate about its usefulness will continue.
A recent instalment pits the biologist Lewis Wolpert of University College London against Steve Fuller, who is a philosopher at the University of Warwick. It was organized by the Institute of Art and Ideas (IAI) and you can watch it on the IAI’s video website. Also sticking his oar in on the side of philosophy is Jonathan Derbyshire, who is culture editor of the New Statesman. You can watch the debate here.
In this week’s Facebook poll we are asking which side of the fence you sit on – Hawking’s or the philosophers’.
Has today’s science rendered philosophy obsolete?
Yes No
Let us know by visiting our Facebook page, and as always please feel free to post a comment to explain your answer.
In last week’s poll we asked what many would consider a philosophical question: In your interpretation of quantum physics, do objects have their properties well defined prior to and independent of measurement?
64% of you answered no – and when the same question was put in 2011 to professional physicists who study quantum theory, the result was 48%. The most popular response then was “yes in some cases”, which garnered 52% of the vote. In our poll, by contrast, only 18% went for that option.
Aaron Swartz at a Creative Commons event. (CC BY Fred Benenson)
It’s surprising the little nuggets of information that come our way here in the Physics World office.
A couple of weeks back, for example, we received an e-mail from Paul Ginsparg, the Cornell University physicist who set up the now-ubiquitous arXiv preprint server more than 20 years ago.
Ginsparg had written a great article for us back in 2008, when Physics World celebrated its 20th anniversary, in which he reflected on the early days of the Web and examined how it has changed scientific communication.
At one point in that article, Ginsparg discussed the growing influence of blogs, describing how he watched someone at a scientific seminar blogging with seemingly expert ease.
“Glancing over my shoulder”, Ginsparg wrote, “I was struck by how a native laptop-user can navigate text and search windows faster than the eye can follow, and assemble references, photos and graphics from multiple sources, simultaneously replying to comments, and in the end spending far less time to assemble a set of useful pedagogic pages, accessible to the entire world, than I spend writing problem-set solutions for a small class.”
Ginsparg did not realize at the time who the person in question was, but he has now discovered that the mystery blogger was in fact the Internet activist and open-access advocate Aaron Swartz. Swartz had been arrested by US federal authorities in 2011 in connection with systematic downloading of journal papers form the JSTOR database and was tragically found hanged in his Brooklyn apartment on 11 January this year.
Ginsparg had been reading reports about Swartz’s death and realized, from photos of the SciFoo 2007 meeting, that Swartz was the person who had been “sitting next to me…blogging with unforgettable skill”.
“I didn’t know who he was,” Ginsparg wrote in an e-mail to me, “having missed introductions because I was going back and forth between sessions, and never did get to talk to him at all. [It was a] missed opportunity and only now I learn he was not the typical generic 20-something blogger as assumed. Oddly enough, 5.5 years later I see the precise text I’d presumably described him writing preserved here
You can read more about the meeting in this blog entry by the science writer George Dyson.
“It was the morning of my hundredth birthday. I shaved the final mirror-disc of old tired face under the merciless glare of the bathroom lighting. It was all very well telling oneself that Humphrey Bogart had that sort of face; but he also had a hairpiece, half a million dollars a year and a stand-in for the rough bits. I dabbed a soda-stick at the razor nicks. In the magnifying mirror it looked like a white rocket landing on the uncharted side of the moon.”
Len Deighton’s classic novel Billion Dollar Brain was written in 1966. It captures perfectly the cloying fug of Cold War paranoia that infected the childhood of anyone older than the age of 40 today. The knowledge that, at any given moment, serried ranks of silos from Sverdlovsk to South Dakota were poised to spew forth missiles that would reduce Europe to a radioactive wasteland was a dreary undercurrent to life in the 1960s.
And then there was television, which featured a steady diet of spy thrillers gleefully highlighting one horror after another: smallpox viruses carried in hen eggs; secret biomedical research complexes in the back-woods of Siberia ready to brainwash kidnapped American soldiers; computers primed to seize control of the nuclear trigger at a second’s notice and cut their human makers out of the decision loop. All of it provided the two subtexts that defined the Cold War: science and technology.
So how close were these fictional accounts to the truth? A fascinating insight into the reality of the situation comes from the diaries of the celebrated astronomer Sir Bernard Lovell, who died last August aged 98. He had transferred most of his papers to the University of Manchester several years before his death, but felt that some parts relating to his scientific links with the Soviet Union in the 1960s were still sensitive and instructed they remain closed during his lifetime. Those sections – now released by the university – reveal Lovell’s deep commitment to international research collaboration, even in the face of stupendous barriers erected by the combatants in the Cold War.
A Lovell playing field
Having worked tirelessly through the late 1940s and 1950s setting up a radio-telescope facility at Jodrell Bank in rural Cheshire, Lovell had spent three weeks in the summer of 1963 travelling in the Soviet Union. While international scientific collaboration is an everyday occurrence in the 21st century, Lovell’s trip beyond the Iron Curtain was an unusual affair at the time of the Cold War. Coming just eight months after the Cuban Missile Crisis – the closest the world has ever got to outright global thermonuclear war – the visit was perhaps an unlikely one for such a leading scientific figure. But Lovell was passionate in his pursuit of scientific understanding and was happy to accept his invitation from the Soviet Academy of Sciences.
Visionary thinker Sir Bernard Lovell, shown here in the control room of the 75 m Mark 1 radio telescope at Jodrell Bank, was for a short while in the front line of the West’s nuclear defence against the Soviet Union, yet he fervently believed in the collaborative nature of science. (Courtesy: Jodrell Bank/Science Photo Library)
Yet Lovell’s visit affected more than just science, for he had played, perhaps rather unexpectedly, a key role in the Cuban crisis. In 1962 Lovell had been told that, according to British intelligence, the Soviets had mobile intercontinental ballistic missile launchers targeted on London and that there was a seven-minute window between launch and the arrival of the missiles. With the Royal Air Force’s primary missile-defence warning system at Fylingdales in Yorkshire over-budget and overdue as a result of strike action, Lovell was asked by military officials if Jodrell Bank was technically able to detect the launch of the missiles. He replied that it was, but after wondering aloud how helpful any such advance notice would be, Lovell was informed that a seven-minute warning would achieve a lot, giving Britain crucial time to launch fighter planes and mount a retaliatory strikeback. “At least a million people in London could be saved and the Bomber Force could be scrambled,” he was told.
And so – throughout much of 1962 and on into 1963 – Jodrell Bank became Britain’s early-warning system in the event of a sneak attack by the Soviet Union. The telescope was simply the only instrument in the West that could detect the launch of nuclear missiles from the USSR and there were good reasons to be optimistic about Jodrell’s far-seeing eye. In April 1957 it had been the only ground-based facility in the world that could locate the rocket that the Soviets had used to launch Sputnik 1. In 1958 it had been the telescope that tracked America’s first satellite, Explorer 1. Such was the importance of the telescope that a special telephone with a distinctively coloured green handset was even installed in Lovell’s home to allow Britain’s Chief of the Air Staff to tell Lovell if an attack was imminent and to hand the telescope over to the RAF officers whom he had personally trained to detect launches.
And yet, Lovell’s posting as point man on the front line of the West’s nuclear defence hid another side of his character – his fervent belief in the collaborative nature of science. Throughout the late 1950s and on into the 1960s, Lovell was a regular host to Soviet guests who would come to work at Jodrell Bank and stay in the nearby family home at Swettenham in Cheshire. Slumbering among the grassy knolls and sleepy copses of north-west England, Jodrell Bank proved to be the unlikely location where western and eastern bloc science met. And contrary to the Cold War techno-thrillers being written at the time, nobody batted an eyelid. If anything, the British government thought Lovell’s planned trip to the USSR might be a good way of extracting information from the Soviets.
The Eupatoria enigma
Lovell’s visit to the USSR in 1963 was not his first journey beyond the Iron Curtain. He had been there five years previously and was to travel there again in 1975 and 1976. It is quite clear from his diaries of these trips that Lovell was well treated when in the hands of his scientific hosts. As Lovell happily confided to his 1963 notebook, “The president [of the Soviet Academy of Sciences] said that a country’s scientific effort was a most significant contribution to the standing of a country in the eyes of other nations. He was good enough to illustrate this by pointing out that Jodrell had enormously contributed and added to the prestige of the UK in the USSR.”
All of Lovell’s trips were devoted to the development of collaborative interactions between the two countries. However, there is an enigma surrounding his 1963 visit to the city of Eupatoria on the Black Sea coast. In a last-minute addition to an already busy scientific tour, Lovell was taken to see the Soviet Union’s new radio-telescope and space-tracking facility in the Crimea. It included a powerful radar transmitter for contacting space probes that was never operated at an elevation of less than 15° because of “the intense beam of radiation being a danger to human beings”, as Lovell later termed it.
Watchful eye In 1962 and 1963 the Lovell Radio Telescope at Jodrell Bank in Cheshire, UK, was the only instrument in the West that could detect the launch of nuclear missiles from the Soviet Union. (Courtesy: Martin Bond/Science Photo Library)
Lovell was deeply impressed by the sophistication of the technology and, on his return to Moscow, was quizzed about his plans for the development of a larger telescope at Jodrell Bank. As Lovell wrote in a 2008 memorandum that was released last year alongside the diaries of his trip, the Soviets made it clear to him that if he elected to stay in the USSR and build the facility there, then they would give him the money. Such an offer was not, however, the flattering trans-national intellectual poaching it would be considered nowadays. After all, there was still a Cold War on. Lovell’s reply was immediate and unambiguous: “I am an Englishman and I wish to remain in England.”
On Monday 15 July 1963 Lovell flew back to Britain. But after arriving back in Swettenham, he became unwell and remained under the weather for some weeks. “It was as though all life had suddenly turned to dust and ashes,” Lovell wrote in his 2008 memorandum. “The family could do nothing for me nor the doctors”. Lovell recovered only after joining his daughter Susan and son-in-law John on a holiday in Ireland, which restored him to his normal robust health. “At dawn with the boat sailing up the river to Cork I suddenly began to feel normal,” he wrote.
So what are we to make of his sudden illness?
When Lovell was debriefed by the Ministry of Defence in the months after his recovery, he was told that the illness might have been caused by a Soviet attempt to remove his memory of the recruitment offer and what he had seen at the Eupatoria facility. The method used, the unnamed official speculated, had been radiation. When this story was originally told in 1984 by Lovell and his biographer Dudley Saward, “radiation” was widely interpreted to mean ionizing radiation. But the Jodrell Bank astronomer Tim O’Brien, who is also the observatory’s public-relations officer, says that what was really meant was simply “electromagnetic radiation”.
Although O’Brien admits that no-one knows whether the Soviets really did try to brainwash Lovell, his son Bryan favours a more mundane explanation. “My father was so tired that his mighty constitution took quite a while to recover; he needed a holiday,” he told Physics World. Referring to the “huge load” his father had borne in completing his telescope, Bryan Lovell thinks that the added responsibility of it playing a key military role, coupled with his Russian visit, had simply taken a toll. “For me the more likely explanation is that father was simply exhausted – and that gels with the account that he wrote in the contemporaneous diary of the 1963 trip, in which you will find nothing untoward, but plenty of fascinating science.”
On 9 August 1963 an important part of Lovell’s secret burden was lifted when he was flown by the RAF to Fylingdales as part of a handover of early-warning responsibilities that took place that autumn. From then on, if he looked east, he could give his undistracted attention to collaboration with his Soviet colleagues and friends – and deal purely with astronomy matters.
Fusing relations
One person who agrees that Lovell was unlikely to have been brainwashed is Mike Forrest, a physicist who collaborated with scientists from the Soviet Union on nuclear fusion during the Cold War. “It just flies in the face of my experience of working with the Russians,” recalls Forrest, who at the time was based at the UK Atomic Energy Authority’s laboratory in Culham, Oxfordshire. In the 1960s the lab led the country’s efforts in studying potential practical applications of fusion power, including its use as a possible source of cheap, plentiful and clean energy – the philosopher’s stone of energy production.
Lovell was impressed by the Soviets’ technology and they made it clear that if he elected to stay in the USSR, they would give him the money to build a larger telescope there
Forrest was a member of a major British post-war experiment called the Zero-Energy Toroidal (or Thermonuclear) Assembly, or ZETA, which was the world’s first large-scale fusion machine when it opened in 1957. It was a doughnut-shaped toroidal device about 3 m in diameter containing a hot plasma, in which a powerful magnet was used to induce an electric current inside the ionized gas. The current generates its own magnetic field that causes the plasma particles to be attracted to each other, effectively making it contract – an effect known as “Z-pinching” (the z referring to the current travelling axially in the z-direction). A series of secondary magnets ringed the torus, with the two external magnetic fields combining to create a helical field that compressed and stabilized the plasma.
The idea of the device was that it could heat the plasma to such a high temperature that light elements in it would fuse together and release huge amounts of energy. The holy grail of such technology is that the ratio of output energy to input energy should be greater than one. ZETA, based at Harwell in Oxfordshire, was an experimental device that served, in Forrest’s words, as a “proof-of-principle” experiment. Soon after ZETA was switched on, it produced a burst of neutrons – the most obvious output of nuclear fusion – that amazed and heartened its designers, though the results were hyped (some would say over-hyped) to suggest that Britain was on the cusp of a fusion-technology breakthrough. But when it was discovered that the neutron bursts were not the result of a nascent fusion reaction, spirits slumped at Harwell and the prospect of nuclear fusion seemed as far away as ever.
It was soon thereafter that the Culham researchers began their unusual liaison with Soviet scientists, who had been pursuing their own line of research at the Kurchatov Institute on the outskirts of Moscow. Under the leadership of Igor Tamm and Andrei Sakharov, the Soviets had designed the “tokamak” – a different kind of fusion device in which the high-temperature plasma is confined by magnetic fields in the shape of a torus. But whereas the magnetic field created by the toroidal current in ZETA was smaller than the external magnetic field from solenoidal coils wrapped around it, the reverse is the case in a tokamak. In other words, the applied field is stronger than the magnetic field caused by the current in thetorus.
This may seem a subtle point – but it made all the difference. From early on in their development, it became clear that tokamaks were superior to other fusion devices in their ability to confine the plasma. However, one thing that the Soviets had not been able to do as well as their British counterparts was to accurately measure the temperature of their plasma. Indeed, the Harwell scientists’ ability to do so, which involved the use of lasers and Thomson scattering, was one of many successes that emerged from ZETA in spite of its failure to achieve fusion.
Forrest, who was one of the British researchers involved in developing this laser technique, was therefore sent together with four other colleagues to the Kurchatov Institute in 1969 to help measure plasma temperatures in the Soviets’ new breed of tokamak reactors. The team made four separate trips, each lasting about six weeks, between April and December of that year.
International science ITER director-general Osamu Motojima (left) unveils the foundation stone of the facility with the help of Igor Borovkov, the head of the Russian delegation to the ITER Council. In the background are (from left to right) Robert-Jan Smits, head of the European delegation, William Brinkman from the US Department of Energy and Evgeny Velikhov, chair of the ITER Council. (Courtesy: LESENECHAL/PPV-AIX.COM)
There were many challenges to overcome, not least the differing voltages between the two countries and the notorious instability of the Moscow power supply. Perhaps more so than with Lovell, there were concerns from Forrest’s contacts in the intelligence community about his work in Russia. Forrest had access to sensitive knowledge, which meant that he and his colleagues – like Lovell – had to be careful what they said and to whom. And yet, Forrest insists, the British researchers were handled well. “All scientists, whether Soviet or Western were treated with total respect,” he says.
The path to international collaboration
The temperature measurements were highly successful and led to the world fusion community switching to tokamaks. But just as significant were the strong links forged between British and Soviet fusion researchers in the depths of the Cold War. The collaboration proved that it was possible for science – and scientific research in particular – to diffuse tensions between geopolitical rivals. Getting researchers to work together for a common purpose was a relatively uncontroversial matter that leaders from both sides could easily agree on.
Indeed, the fusion collaboration forged in the 1960s ultimately led to the creation of the International Thermonuclear Experimental Reactor (ITER) project. ITER emerged from the Geneva Summit in November 1985 when the US and Soviet presidents Ronald Reagan and Mikhail Gorbachev agreed that their nations would join forces on fusion science. These were the same unlikely bed-fellows who did so much to initiate the scaling down of the world’s nuclear arsenals. Gorbachev was in a strong position since his country was so far ahead of any other in the tokamak field and it says much for his statesmanship that he was willing to share his country’s technology. In fact, the current ITER instrument, which is being built near Cadarache in the Maritime Alps of southern France, is a tokamak design.
ITER is a practical attempt to prove that ideas from plasma physics can be translated into full-scale electricity-producing fusion power plants, and the project has since expanded to include China, the EU, Japan and South Korea as well as Russia and the US. No tokamak has previously managed to produce more energy than has been put in, but ITER is designed to generate 500 MW of output power from 50 MW of input power. The first plasma is expected to be produced in 2020 with the first real working fusion power plants coming – if all goes well – some 20–30 years after that.
When – and if – that happens, historians will be able to trace that success back to those early collaborations between Britain and the Soviet Union, and, in part, to the legacy of Sir Bernard Lovell’s radio telescope that was used as the earliest of early-warning systems. Its importance in maintaining world peace cannot be underestimated, for a single slip at that time and, as Len Deighton’s laconic hero put it, “every alarm in the whole world will blow, and four minutes later, nobody is going to be around”.
A new compact high-flux source of energetic neutrons has been built by physicists in Germany and the US. The new laser-based device has the potential to be cheaper and more convenient than the large neutron facilities currently used by physicists and other scientists. The inventors say the source could be housed in university laboratories and might also be used to identify illicit nuclear material.
Neutrons are a valuable tool for scientists in many fields, allowing them to probe the structure and dynamics of a range of materials. Today, the main drawback of neutron science is that intense beams of neutrons must be produced in either nuclear reactors or dedicated accelerator facilities – making a laser-based table-top source very attractive.
Low fluxes
Laser-based sources involve creating very brief pulses of high-energy electromagnetic radiation, which ionize a small solid target and then propel the liberated electrons to the back of the target, so creating a very strong electric field that in turn accelerates the ions. The ions – typically deuterons, which comprise one proton and one neutron – then stimulate nuclear reactions in a second target, producing neutrons. Despite a decade of research, however, the resulting neutron fluxes have remained low. This is largely because charged molecules such as water vapour contaminate the target surface and are accelerated at the expense of the ions.
In 2006 Lin Yin and Brian Albright at Los Alamos National Laboratory in the US showed how this problem might be overcome. They used computer simulations to show that an intense laser beam can penetrate a thin solid target. Usually a solid object is opaque because the frequency with which its constituent electrons vibrate exceeds that of the incoming light. But Yin and Albright calculated that a very intense laser beam should be able to boost the speed of electrons in a plasma to such an extent that their relativistic mass significantly reduces the electrons’ frequency to below that of an infrared laser.
Breakout afterburner
Yin and Albright named this effect the “laser breakout afterburner” because in “breaking out” to the far side of the target the laser beam would re-energize electrons that have lost energy in accelerating ions, so allowing those ions to reach higher energies. The beam would also interact with the entire target, rather than just the atoms on the surface, meaning that many more deuterons would be accelerated, so increasing the neutron flux.
This scheme has now been put into practice by Markus Roth of the Technische Universität Darmstadt and colleagues at Los Alamos and Sandia National Laboratories. Roth’s team directed extremely powerful and well defined pulses from the Los Alamos TRIDENT laser onto a 400-nm-thick plastic target doped with deuterium atoms. This was positioned just 5 mm in front of a secondary target made from beryllium.
Even though the pulses delivered less than a quarter of the energy employed in previous experiments, they produced neutrons that were nearly 10 times as energetic – up to 150 MeV – and also nearly 10 times as numerous. In addition, many of these neutrons were emitted in the forward direction, which the researchers attribute to one specific kind of nuclear reaction, the break-up of deuterons.
First radiographs
Roth’s group also took the first radiographs using a laser-driven neutron beam, by placing a series of tungsten, steel and plastic objects between the neutron source and a scintillating fibre array that was linked to a CCD camera.
Hopefully this will make neutron science available to many university students
Markus Roth, Technische Universität Darmstadt
Roth says that although his group’s device produces fewer neutrons than reactors or accelerators do, it packs the neutrons into extremely short pulses – each lasting just a few 10-billionths of a second. This, he explains, makes it suitable for applications that need high temporal resolution, such as pump-probe investigations of neutron damage inside nuclear reactors or monitoring simulations of conditions inside planetary cores. And he claims that, once commercialized, the entire device will fit on a lab bench and that only the target will need shielding. “The really cool thing for me as a university professor is that we replaced an accelerator hundreds of metres long with a laser,” he says. “Hopefully this will make neutron science available to many university students.”
The group will now work on tailoring the device’s energy spectrum – low-energy neutrons being useful for studying matter under extreme conditions, for example, whereas high energies are needed for the inspection of sensitive material inside containers. It is for this counter-terrorism application that the device could find its first customers. “We have started a network with US laboratories and universities to develop a system that can be sold commercially within the next five to six years,” he explains.
Boosting repetition rate
Laser-driven neutron expert Scott Wilks of Lawrence Livermore National Laboratory in the US points out that non-laser based neutron sources small enough to fit in a suitcase can generate comparable numbers of neutrons, but, he says, over a time interval measured in seconds and at much lower energies. This makes them less good at imaging very short-lived phenomena. The next step, Wilks adds, will be to increase the laser’s repetition rate, which, he predicts, “will be no small feat, but, given laser technology’s rapid evolution, inevitable”.
The device is likely to have its limits, cautions Bob Cywinski of the University of Huddersfield in the UK. He agrees it could be useful for applications requiring single shots of neutrons, such as nuclear-materials monitoring or radiation-damage studies, and might, if its time-averaged flux can be made high enough, be suited to nuclear-waste transmutation. However, Cywinski thinks the average flux will be too low to replace reactors and accelerators for conventional neutron-scattering applications.