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Nuclear power – the road ahead

By Louise Mayor

Until recently, the phrase “nuclear power” conjured for me a hazy and somewhat ignorant vision, comprising images of cooling towers, diagrams of fission and a sense of subdued controversy, in which proponents from neither the pro- nor anti-nuclear lobbies seem to know more about the subject that I do from high-school days.

But for the past few months I have been immersed in the landscape of modern nuclear power in preparation for a special issue of Physics World, which should land on readers’ doorsteps any day now. It is also available as a free PDF download.

Something I really wanted to get to grips with, when it comes to nuclear power, is who has what, and where? Well, if you do too, check out our colour-coded nuclear power world map, based on data from the International Atomic Energy Agency. It’s on pages 38 and 39 of the “special issue”.

But where do we go from here? In the long term, newly built reactors could be based on the six designs that the Generation-IV International Forum – consisting of 13 Members including the Russian Federation, the US, China and the UK – identified to meet its goals. Physics World’s Rome correspondent Edwin Cartlidge writes about these in the feature “Nuclear’s new generation”.

We also review four concepts for radically different reactor designs, including the travelling-wave reactor endorsed by Bill Gates; and accelerator-driven sub-critical reactors, which we quiz Nobel-prize-winning physicist Carlo Rubbia about in a Q&A.

Not only are there new designs, but new fuel. Elsewhere in the special issue, award-winning science writer Matthew Chalmers looks at how India is seeking to exploit its vast reserves of thorium as an alternative to uranium.

As well as fission, nuclear power also covers the realm of fusion. In the feature “Hot fusion”, Steve Cowley, chief executive of the UK’s Atomic Energy Authority, looks at the challenges facing the ITER facility being built in southern France. He says that with predictions of net power gain at ITER, we should act now to reduce the time to commercial fusion.

Attitudes are key in an energy future with nuclear power in the mix – a future that is only feasible if it has support. With that in mind, check out the debate between climate scientists who go head to head on the merits of nuclear power. You’ll find this, and much more, in the October issue of Physics World.

Between the lines

A lump of uranium ore — Shock and ore: The story of the impact of uranium on humankind.

History of an uneasy element

Among the Bemba people of central Africa, the word “shinkolobwe” is slang for “a man who is easy-going on the surface but who becomes angry when provoked”. It is also the name of the Congolese uranium mine that yielded raw material for the atomic bomb that flattened Hiroshima. As historical coincidences go, this one seems almost too good to be true. Still, one can hardly blame author Tom Zoellner for seizing upon it in Uranium: War, Energy and the Rock that Shaped the World, a very readable (if somewhat chaotic) history of how this normally easy-going element has provoked anger on five continents. After a scene-setting visit to the Shinkolobwe mine, Zoellner’s description of the Manhattan Project will contain few surprises for anyone who has read more comprehensive histories. One notable exception is his explanation of how the scientists got the uranium for the bomb. This tale of costly enrichment programmes, dubious middlemen and colonial skulduggery has important ramifications for the entire subsequent history of uranium. In chasing this history, Zoellner goes to an impressive amount of trouble to tell some of the less-heralded stories of the uranium age, talking to prospectors from Darwin, Australia, to Moab, Utah, and to one of the last survivors of an East German uranium gulag, where political prisoners dug the ore that built the Soviet nuclear arsenal. The price they paid was high – thousands died from radiation, non-existent safety precautions and maltreatment – but it was scarcely lower for miners in the West, where labour was unforced but just as hazardous. The universally cavalier attitudes to radiation during this period are sobering to contemplate. The book’s final chapters cover a grab-bag of topics from endemic fraud in Canadian uranium stocks to the question of whether terrorists could get enough uranium to build a bomb. It is not a question Zoellner cares to answer directly, but some may feel that the facts speak for themselves: on his visit to Shinkolobwe, he found the still-productive mine almost completely unguarded.

2010 Penguin £11.99/$16.00 pb 368pp

Questioning the cosmos

As a means of conveying scientific information, the “question and answer” format has a lot to recommend it: it is simple, straightforward and easy to follow. The downside is that books in this style tend to misjudge their audiences – after all, how do the authors know which questions readers want answered? For this reason, A Question and Answer Guide to Astronomy is a pleasant surprise. Written by engineer Pierre-Yves Bely and astrophysicists Carol Christian and Jean-René Roy (and recently translated from the original French into English), the book claims to give “simple but rigorous explanations” in “non-technical language”, and it does exactly what it says on the tin. Split into 10 sections, it answers hundreds of questions in fields ranging from planetary science (“What is the greenhouse effect?”) to astronomy and cosmology (“How do stars die?”). It also tackles trickier concepts such as “Can anything go faster than the speed of light?” and various big mysteries, including “What was there before the Big Bang?”. All the explanations are well expressed and usually aided by a full-colour illustration or photograph. Within explanations, the authors helpfully have embedded cross-references to other pages that may help to explain common concepts, allowing readers to skim through the questions focusing on the areas that interest them most. Towards the end, the book becomes more specialized, with 30 or so questions on telescopes followed by a propaganda-like section on how to get involved in astronomy. Despite this, the majority of the guide is informative, and by successfully tackling ideas that are often misunderstood, it makes for a worthwhile and enjoyable read.

2010 Cambridge University Press £18.99/$28.99 pb 294pp

First you have to look for them

The ever-expanding catalogue of worlds discovered outside our own solar system contains all sorts of planets: hot, cold, icy, rocky – you name it. But what about watery planets? Or those lovely, not-too-cold, not-too-hot “Goldilocks” ones with an active geology and perhaps a biggish moon nearby, just to keep things interesting? In How to Find a Habitable Planet, James Kasting begins by describing various factors that geophysicists, astrobiologists and others have deemed necessary (or at least desirable) for producing planets capable of supporting life. He then examines the evolutionary histories of the planets we know best – the Earth, Venus and Mars – in an attempt to determine why they developed the way they did. The book’s second half looks at ways of finding new planets using indirect methods (like measuring the tiny gravitational wobble imparted to a star when a planet passes nearby) before moving on to the challenges associated with detecting them directly. Being able to separate the faint reflected light of individual planets from the much brighter light of their parent stars “turns out to be a tall order”, writes Kasting. As a planetary scientist at Pennsylvania State University in the US, Kasting was involved in a design study for a space-based telescope that would have examined light reflected from the surfaces of extrasolar planets for clues about their composition. Unfortunately, the mission was cancelled while it was still in the design phase, and NASA has not yet revived it. How to Find a Habitable Planet offers an eloquent explanation of why such a mission would still be desirable.

2010 Princeton University Press £20.95/$29.95 hb 360pp

Weird science

Tired of biscuits that crumble into a soggy mess at the bottom of your teacup? Uncertain of the best technique for skimming stones across water? If you need answers to these pressing problems – plus advice on how to win at Trivial Pursuit and a rather invasive way to cure hiccups – then Dunk Your Biscuit Horizontally is the place to look. This light-hearted book of bite-sized strange science was compiled by the Dutch journalists Rik Kuiper and Tonie Mudde, and would make a great gift for anyone whose sense of humour encompasses both the scientific and the scatological. It is probably not one for younger children, though: the best cure for intractable hiccups turns out to be either good sex or “digital rectal massage”.

2010 Summersdale Books £7.99 pb 128pp

The Nobel Prize in Timekeeping goes to…

By Hamish Johnston

Forgive me for being a grumpy old man, but there is something on the Nobel Foundation website that is driving me crazy (see right).

The foundation seems to be saying that the physics prize will be announced at 11.45 CET and 9.45 GMT.

But how can this be? There is only one hour difference between CET (Central European Time) and GMT (Greenwich Mean Time).

Furthermore, Stockholm will still be on Central European Summer Time (CEST) next Tuesday.

So did they mean to say that the announcement will be made at 11.45 CEST, which is 9.45 GMT?

I sent an e-mail to the foundation asking as much, I’ll keep you posted.

Royal Society releases new guide to climate change

By Hamish Johnston

The UK’s premier scientific organization, the Royal Society, has released a “new short guide to the science of climate change”.

Entitled Climate Change: a Summary of the Science, the 19-page document can be downloaded here.

The guide was produced in part because of pressure from 43 members of the society, who had complained that a 2007 report from the organization did not acknowledge fully areas of uncertainty in climate science.

As a result, the report has a more measured tone, but still asserts “There is strong evidence that the warming of the Earth over the last half-century has been caused largely by human activity.”

Georges Charpak: 1924–2010

The Polish-French physicist Georges Charpak, who won the Nobel Prize for Physics in 1992 for his work on particle detectors, died yesterday at the age of 86.

Charpak spent most of his career at CERN and it was there in 1968 that he developed a new approach to detecting charged particles. His multiwire proportional chamber increased the data collection speed by a factor of 1000 compared with previous techniques. The chamber quickly became a standard tool in particle physics and won Charpak the 1992 prize.

Charpak went on to develop a number of different particle detectors, some of which are used in biophysics and medical physics. More recently, he developed a radon detector that could help predict earthquakes.

Born in Poland in 1924, Charpak became a French citizen in 1946. After studying engineering at the Ecole des Mines in Paris, Charpak did a PhD in nuclear physics at the prestigious College de France. He spent his early years as a physicist at CNRS before joining CERN in 1959, from which he retired in 1991. Charpak was also an honorary fellow of the Institute of Physics, which publishes physicsworld.com.

Is the Canadian Government muzzling its scientists?

By Hamish Johnston

Back in April, Scott Dallimore of the Geological Survey of Canada did what most scientists can only dream of – he published a paper in the journal Nature.

The work describes a massive flood that occurred about 13,000 years ago when water from an immense glacial lake broke out and hurled towards the Arctic Ocean.

The work was covered in media outlets around the world and Dallimore’s co-authors were quoted widely. Sadly, Dallimore was denied his moment in the Sun because he was effectively prevented from speaking to reporters by his employer, the Canadian Government.

This apparent censorship in Canada is described in a comment piece in today’s edition of Nature by Kathryn O’Hara (pictured above), president of the Canadian Science Writers’ Association.

I say “effectively prevented”, because Dallimore could have spoken if the journalist’s questions and his answers were first vetted by the government. However, this can take several days or even months according to science writer Glen Blouin. When combined with Nature‘s embargo policy (which gives journalists only a few days to write their articles), it is unlikely that Dallimore could have been quoted when the story broke.

A quick survey of blogs and comments on this topic suggests that muzzling is not new. What seems to have changed is that scientists are now a target of the government’s information machine.

Why? It could have something to do with the fact that the current prime minister Stephen Harper and his Conservative Party have strong connections to the province of Alberta – a major oil producer and home to the controversial oil sands.

Years ago when I was in high school we were taught that Alberta is sitting on top of the world’s largest oil reserve – and we only had to wait until the price of oil was high enough to make extraction from the oil sands viable.

30 years on and we have reached that price point, but concerns about vast carbon dioxide emissions and other environmental issues have made the oil sands a political hot potato.

I’m guessing that there are some in Alberta and in Ottawa who want to make sure that government scientists don’t spoil the long-awaited bonanza.

Astronomers find 'potentially' habitable exoplanet

By Matin Durrani

I’ve never done any astronomy but I imagine that looking for extrasolar planets must be fun. Given that researchers have so far discovered more than 400 of these distant beasts, tracking them down them can’t be all that hard, making the “reward/effort ratio” pretty high.

Of course, what we all want to know – from our puny, self-absorbed human perspective – is when will we spot the first truly Earth-like planet.

Well, a couple of weeks ago I was intrigued by a paper on arXiv by Samuel Arbesman from Harvard University and Gregory Laughlin from the University of California, Santa Cruz, who looked at the rate at which the first 370 extrasolar planets were discovered, did some jiggery-pokery in the form of a “bootstrap analysis”, and then worked out exactly when “the first potentially habitable planet with a mass similar to Earth” will be found.

The pair weren’t talking about vague dates in the future but had a very specific time in mind – with the likeliest date being, wait for it, “early May 2011”. Now that’s what I call having confidence in your data.

Today, though, astronomers in the US, who are part of the Lick-Carnegie Exoplanet Survey, report finding a new – and what they say is “potentially habitable” – Earth-sized planet, which may prove that Arbesman and Laughlin were, if anything, a bit too pessimistic.

The new planet, dubbed Gliese 581g, is one of two new planets discovered around the star Gliese 581 – the red object pictured above. Gliese 581 lies some 20 light years away from Earth and is now known to have at least six planets around it, one of which is the grey object above.

The newly observed planet has got a mass of between 3.1 and 4.3 that of the Earth. Its radius is between 1.2 and 1.5 that of the Earth, while its surface gravity is 1.1 to 1.7 times that of the Earth.

The results were obtained by tracking 11 years of data on the star’s radial velocity and looking for tiny movements in response to the gravitational tug from orbiting objects.

The temperature’s a bit on the chilly side though – between about –31 °C and –12 °C. Still, the authors say Gliese 581g is in the “habitable zone” – defined as being far enough from the system’s star so that a planet gets just enough energy to keep water on the surface in liquid form.

You can read more about the finding in the original paper, which is due to be published in The Astrophysical Journal

So is this finding a big deal? Or just yet another, slightly dull exoplanet to add to the mix?

Superconducting trio get entangled

Two independent teams of physicists in the US have entangled three superconducting quantum bits (qubits) for the first time. Entangled trios are of particular interest to those building quantum computers because three is the minimum number needed to do quantum error correction – which is needed to keep quantum computers running.

Despite the promise of outperforming conventional computers on certain tasks, quantum computers can only be useful if physicists can work out how to entangle a relatively large number of qubits. So far researchers have managed to entangle as many as eight ion qubits and 10 photon qubits. But when it comes to entangling superconducting qubits, the limit so far has been just two.

Although they are difficult to entangle, superconducting qubits could have several advantages. In particular, they are completely solid state, which means that they are robust and can be implemented much like conventional electronic devices.

The new trios of entangled superconducting qubits were created by John Martinis and colleagues at the University of California, Santa Barbara, and by Robert Schoelkopf and his team at Yale University. The Santa Barbara team had previously devised a way of entangling two superconducting qubits back in 2006, while last year the Yale researchers had executed several quantum-computing algorithms using two entangled superconducting qubits.

Entangled transmons

The Yale physicists used qubits called “transmons”. Each transmon is made from two tiny pieces of superconductor connected by two tunnel junctions. The superconductors contain a large numbers of “Cooper pairs” of electrons that can move through the material without any electrical resistance.

The energy levels of the qubit are defined by the precise distribution of Cooper pairs between the two pieces of superconductor. One such energy state is denoted a logical “0” and another state “1”. Transitions between these two states occur by absorbing or emitting a microwave photon.

The Yale team made a chip containing four transmons that are coupled to a microwave waveguide. The four transmons are arranged as two two-qubit controlled-phase (C-phase) logic gates.

How it’s done at Yale

Making a GHZ state

The gates are used to entangle three of the qubits and create a Greenberger–Horne–Zeilinger (GHZ) state. This is a superposition of the state in which all three qubits are “0” and the state in which all three qubits are “1”. The GHZ state is made by first entangling two qubits using one C-phase gate. The other gate is then used to entangle the third qubit with the entangled pair.

The team verified the entanglement using quantum-state tomography. This involves creating the GHZ state, measuring the values of the qubits – and then repeating the entire process many times over. This is necessary because an individual measurement of the qubits puts the system into one of many possible states. Multiple measurements are needed to map out the probability that the system is in a certain state.

Oscillating phase

Meanwhile in Santa Barbara, Martinis, Matthew Neeley and colleagues used superconducting phase qubits to achieve three-qubit entanglement. A phase qubit is a single Josephson junction, which comprises two pieces of superconducting metal separated by a very thin insulating barrier. The two logic levels are defined by quantum oscillations of the phase difference between the electrodes of the junction.

The team created its GHZ state using a similar technique to the Yale group – except that it configured the microwave circuit to form two controlled NOT (CNOT) gates rather than C-phase gates.

The Santa Barbara group then reconfigured its circuit to create another type of entangled state called the “W” state. This is a superposition of the three states in which one of the three qubits is “1” and the other two qubits are “0”. “To create this state we excite just one qubit, putting a single quantum of energy into the system,” explains Neeley. “We then turn on a coupling interaction between all the pairs of qubits, which spreads that one excitation out among the three qubits.”

This interaction is created by connecting the qubits together using a network of capacitors. If the interaction is left on for just the right amount of time there is an equal probability of finding the excitation in any of the three qubits, Neeley told physicsworld.com.

Useful in different ways

Both the GHZ and W states are expected to play important roles in quantum computing. According to Neeley, W states are relatively robust compared to other entangled states. This is because the destruction of the quantum nature of one qubit does not necessarily destroy the entanglement of the other two qubits

GHZ could be particularly useful for quantum error correction, which protects a quantum computation from the destructive effects of noise. If one of the three qubits is inadvertently flipped, for example, this can be corrected by determining the value of the other two qubits.

“Error correction is one of the holy grails in quantum computing today,” explains Robert Schoelkopf. “It takes at least three qubits to be able to start doing it, so this is an exciting step.”

Predicting Nobel winners

By Hamish Johnston

Over the last week or so we have been scratching our heads trying to come up with a new and exciting way of hyping up the impending physics Nobel prize announcement (one of the few things that we do hype here at Physics World).

In the past we have published our (ultimately wrong) predictions and invited readers to share their views on who will win the prize.

This year, I’m going to defer to the cartoon residents of Springfield, who have come up with predictions of their own.

There could be a distinguished physicist called Oliver Williamson, but I think Martin may have recycled his economics pick for 2009.

Energy, power, who cares?

By Matin Durrani

Here at Physics World HQ we’re more than happy with the concept of energy conservation.

So we have nothing against energy company E.ON’s attempt to get the public to reduce the amount of electricity they use by giving certain of their customers “energy monitors”.

These are small electronic gadgets that measure electricity consumption around the home in real time, allowing homeowners to keep close tabs on how much they are using.

But I was shocked to get an e-mail today from physicist Steve Bolter, alerting me to the fact that E.ON’s “Energy Fit” energy monitors indicate “Energy Now” measured in – wait for it – kilowatts.

If you don’t believe me, take a look at the picture on the right.

Even worse, click on the video above, which shows a smiling Kevin Bryant from E.ON showing the Fiddis family how the unit works. At about 3.27 minutes, you’ll see our Kev tell the unsuspecting Fiddises that “you are using 580 watts of energy at the moment”.

It’s enough to make you scream – particularly from a company that should know better.

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Nuclear power – the road ahead