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The energy puzzle: yours for free

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<a href="http://physicsworld.com/cws/download/oct2009

“>The energy puzzle: download yours for free

By Matin Durrani

The new-look physicsworld.com has now been live for a couple of weeks. The relaunch went pretty smoothly from a technical point of view and we’ve snared most of the inevitable glitches, of which there were thankfully few.

Apart from a fresh new look, we’ve now got a multimedia channel, which kicked off with an exclusive video interview with the CERN director-general Rolf-Dieter Heuer. Watch out for more videos like that and keep an eye out for our webinar series, which we’ll be expanding too in the coming months.

One question we have been asked is: where is Physics World magazine? The short answer is that you can find it by following this link.

However, user testing that we carried out before relaunching the site told us that most people didn’t actually go to the website to find magazine content on a month-by-month basis. That’s hardly surprising: a website that’s updated daily is very different in tone and feel from a monthly magazine

So what we’ve done is change the focus of physicsworld.com away from being the website of a monthly magazine and, instead, onto breaking news, multimedia content, and our regularly updated blog.

All of which explains why physicsworld.com is no longer dominated — as it used to be — by a large photo of the cover of the latest issue.

But don’t worry if you love the magazine as much we do. Selected articles from each issue of Physics World magazine continue to appear in our in-depth section, which you can, by the way, cleverly filter according to different fields of interest, should you so wish.

And don’t forget that if you’re a member of the Institute of Physics, you can get free access to a full digital version of the latest issue as well as to a searchable archive of the first 20 years of the magazine. Check out the latest issue by following this link

As an added bonus just for this month, you can, whether you’re a member of the Institute of Physics or not, download a free PDF of the October issue of Physics World by following this link.

The focus of the issue is energy and climate change, with some great articles by the likes of the physicist and former BP chief executive Lord Browne, who argues that the biggest barriers to a low-carbon economy are not scientific or technological but political. Other articles look at progress in climate modelling, the materials-science challenges standing between us and clean, long-lasting energy, as well as how in the future we could all be connected to a hydrogen SuperGrid.

Download the free October issue here.

What to expect when your spouse wins the Nobel prize

By Michael Banks

With only one day left until the Nobel Prize for Physics is announced everyone, of course, will have their eyes on the eventual winners.

Yet what about the winner’s family and in particular their spouse: how will winning the prize affect their daily lives?

Anita Laughlin, the wife of the Nobel-prize-winning physicist Robert Laughlin from Stanford University who shared the 1998 Nobel Prize for the discovery of the fractional quantum-Hall effect, has written a behind-the-scenes account of what winning the prize can do to a family.

In Reindeer with King Gustav, Anita Laughlin describes the months after her husband won the prize and the mad rush to sort everything out for the big day in Stockholm.

I haven’t read the book yet, but if it is anything like the video posted on Anita Laughlin’s website to promote it then the account will make for an hilarious read.

“Dad, some guy is calling from Sweden,” is how the video starts, when the youngest son in the Laughlin household answers the phone at 02:30 on 13 October 1998.

Then in true Laurel and Hardy style, with Henry Mancini’s Shades of Sennett playing, the Laughlins rush around their bedroom already dressed in their evening attire  to pack (or at least Anita Laughlin seems to be doing most of the packing, with Robert sitting on the bed holding a bottle of bubbly).

If you believe the video then the Laughlins seem to have got some sleep that evening, I just wonder how many physicists will instead be sat patiently by the phone tonight.

Developing-world research hub unveils new director

Fernando Quevedo of Cambridge University in the UK has been appointed as the new director of the Abdus Salam International Centre for Theoretical Physics (ICTP) in Trieste, Italy. He replaces Katepalli Sreenivasan, the India-born physicist who has led the institute since 2003.

Founded in 1964, the ICTP was the inspiration of the Pakistani Nobel-prize-winning theorist Abdus Salam who wanted to establish an international research centre where young scientists from the developing world could gather to encourage their intellectual development.

More than 5000 researchers from over 100 countries now visit the ICTP each year. Although its focus is still on physics and mathematics, the centre has expanded its activities to cover more areas of the physical sciences including Earth systems and multidisciplinary research. The ICTP is jointly funded by the Italian government, UNESCO and the International Atomic Energy Agency.

Nobel supervision

Born in Costa Rica in 1956, Quevedo is a theoretical physicist best known for his work on superstring theory for which he was awarded the ICTP’s annual research prize in 1998. After studying in Guatemala, Quevedo went on to complete his PhD at the University of Texas in 1986 under the supervision of Nobel Laureate Steven Weinberg.

In 1998, following in the footsteps of Salam himself, Quevedo joined the Department of Applied Mathematics and Theoretical Physics at the University of Cambridge, where he is currently professor of theoretical physics. “I am deeply honoured to have been selected for this highly prestigious position at an institution that is very close to my heart,” says Quededo. He added that Salam has always been a role model.

Quevedo will officially begin his new role on 5 November and he told physicsworld.com that he plans to focus on “quality over quantity”. He said that he has no short-term plans to further expand the variety of research carried out at ICTP but would like to “maintain the excellent standard” already in place.

People must start talking

Quevedo also wants to strengthen existing links with other international research centres and to encourage more collaboration between developing nations. “The developing world has changed a lot in the past 40 years. Some of the larger countries like Mexico, Brazil, China and India are now offering a significant contribution to international science. But there are smaller countries, particularly in South America and Africa that people still don’t like to talk about.”

Quevedo believes that countries like Mexico and Brazil have a responsibility to work with their less developed neighbours to stimulate scientific development. He revealed that he will focus on trying to improve the internet connectivity in these less developed nations, which he cites as a key tool in the development of research capacity.

Herschel opens its eye on the universe

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Space chill (credit: ESA/PACS/SPIRE)

By Michael Banks

The European Space Agency (ESA) has released the first images taken by its Herschel space telescope during a calibration run last month.

The awe-inspiring images show cold gas clouds lying near the Milky Way — thousands of light-years from Earth. Five infrared wavelengths have been colour-coded in the image to differentiate very cold material (shown in red) from the surrounding, slightly warmer stuff in blue.

Herschel — named after the German-born astronomer who in 1781 discovered Uranus — is a far-infrared and submillimetre telescope that will study star formation in our galaxy and galaxy formation across the universe.

Herschel was launched in April together with ESA’s Planck mission — a microwave observatory that will study the geometry and contents of the universe by finely measuring the comic microwave background (CMB) radiation, which is a remnant of the Big Bang.

The both occupy a place in space called the Lagrange point L2 — where a probe can usefully hover, little disturbed by stray signals from home and without having to use much fuel to keep it in position.

Herschel will investigate light with wavelengths of 55-670 μm and the satellite will look back to the early universe to see galaxy formations that are invisible to the likes of the Hubble Space Telescope because of gas and dust.

Larger areas of the Milky Way will now be surveyed by Herschel so look out for more cool images soon.

Ig Nobel prize for physics falls flat on its face

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The 2008 Ig Nobel award

By Michael Banks

Maybe physicists are not doing enough research that “first makes people laugh, then think”.

Last night was the annual bash at Harvard University for the Ig Nobel awards, which are given by the humour magazine The Annals of Improbable Research and celebrates research that “cannot, or should not, be repeated”.

Each year the awards have an overall theme. Last year it was redundancy, and in 2007 it was, bizarrely, chickens which involved keynote speaker Doug Zonker repeating the word “chicken” for two minutes.

This year’s theme was risk and mathematician Benoît Mandelbrot gave a keynote address. But fitting in with the eccentricity of the event, every winner of an award had only 60 seconds to give a speech before an eight-year-old girl went up to that stage saying she was ‘bored’.

This year’s ‘physics’ prize went to three anthropologists: Katherine Whitcome from the University of Cincinnati, Daniel Lieberman from Harvard University and Liza Shapiro from the University of Texas won the award for determining why pregnant women do not tip over.

The work, published in Nature, found a difference in the spines of women and men, which allowed a pregnant woman to lean backward and counterbalance the weight of the developing fetus.

I didn’t find the work particularly hilarious and probably represents rather bona fide research.

The chemistry prize lived up more to the suggestion of making you laugh then think. This year’s prize went to Javier Morales, Miguel Apátiga, and Victor M. Castaño at the Universidad Nacional Autónoma de México, for creating diamond films from tequila.

Other 2009 winners include Gideon Gono, governor of Zimbabwe’s Reserve Bank, who won the prize for mathematics for “giving people a simple, everyday way to cope with a wide range of numbers”. Gono ordered bank notes in Zimbabwe to be printed with denominations ranging from one cent to one hundred trillion dollars.

Catherine Douglas and Peter Rowlinson from Newcastle University’s school of agriculture were awarded the veterinary medicine prize for discovering that giving cows names increases their milk yield compared to unnamed cows.

The last few years have seen rather dubious awards given for physics. Last year was for understanding why knots form spontaneously in lengths of “agitated” string, while in 2007 the prize was won for the “physics of wrinkling” — providing insight into why drapes hang a certain way.

It was much better when the prize for physics was given for such things as levitating frogs, calculating that beer froth decays exponentially and finding the best way to dunk a biscuit in a cup of tea.

‘Supermicroscope’ shrunk down to lab-size

Physicists in the UK and Germany have created a powerful yet highly compact X-ray source, which they claim could come to replace some of the world’s major research facilities.

X-ray beams have become a valuable tool for scientists because they can “see” deep inside matter, illuminating its internal structure at the atomic scale. Indeed, the technique is now applied across a wide range of science, from revealing the structure of viruses to tracking chemical reactions as they happen.

As scientists have begun to realize the full potential of X-rays, they have come to require much more advanced X-ray sources than those available at their academic institutions. This has led to the formation of a number of specialist facilities that provide the international research community with a centralized source of high-quality X-rays.

Shake it like a synchrotron

These centres, like ESRF in France and Diamond Light Source in the UK, generate X-rays as a form of “synchrotron” radiation. In the standard process, high-energy beams of charged particles are accelerated using electric and magnetic fields around loops that can be hundreds of metres in size. As the particles veer around the circle, they constantly shed energy in the form of X-rays tangential to the beamline.

In most modern synchrotrons, the particles are also passed through a periodic magnetic structure, known as an undulator, which forces the electrons to “wiggle” and emit X-rays each they change direction.

While these synchrotron facilities have proved very popular and provide researchers with an opportunity to mix with their international peers, they are not without their critics. Some feel that the high set-up and running costs are unnecessary, and it is notoriously difficult to provide all research applicants with sufficient time on the beam line. Moreover, the large size of the accelerators and the air-miles accumulated by all the international visits means that these facilities have a number of sustainability issues.

Determined to overcome these problems, Stefan Karsch of the Max Planck Institute for Quantum Optics and his colleagues have realized an alternative method for generating X-rays. They have developed a technique that has gained recognition in the last few years known as “laser wakefield acceleration”.

Ride the wave

The physicists begin by firing a 37 fs laser pulse at a cell of hydrogen atoms, energizing the electrons and causing some of them to try to break free. However, the positive attraction of the nucleus acts to cling onto the electrons and they end up oscillating back-and-forth about the nucleus – resulting in a form of plasma wave in the cell. Some of the other electrons then “ride” down this wave at relativistic speeds, generating X-rays as they change direction.

Laser wakefield acceleration has been demonstrated previously but never before to generate soft X-rays – that is, electromagnetic radiation that can resolve the structure of matter on the atomic scale. One of the important developments in this latest research was to introduce a miniature version of the undulator present in synchrotrons. The combination of a 1.5 cm accelerator and a 30 cm magnetic undulator enabled the physicists to accelerate electrons up to energies of 210 MeV.

The energy of these electrons is comparable with those in synchrotron facilities, producing X-rays with the same brilliance, but the generator is 10,000 times more compact. “In the long run we aim to replace large, costly synchrotron and linear accelerator facilities with something small and affordable, namely a high-power laser-driven plasma accelerator of cm-size,” Karsch told physicsworld.com.

The researchers now intend to develop their technique to generate X-rays with an even higher brilliance than those in synchrotrons. “Through an ongoing laser upgrade, we first aim at increasing the electron energy to 1–1.5 GeV to reach keV photon energies, which could serve as a first ultrashort X-ray source for application experiments on solids,” he said.

100 years of cosmic-ray experiments

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By Hamish Johnston

It seems that ASPERA has declared that the ‘European Week of Astroparticle Physics’ will begin on Saturday 10 October.

ASPERA is network of national government agencies responsible for coordinating and funding national research efforts in astroparticle physics. According to their press release:

“From 10 to 17 October 2009, in France, Italy, Spain and many other countries, astroparticle physicists will meet the public to reveal some of the most exciting mysteries of the Universe. Within the first European Week of Astroparticle Physics, they will organise about 50 events all over Europe: open days, talks for the general public, exhibitions…

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Victor Hess and his prize-winning balloon

Sounds great, but “all over Europe” is a bit of an exageration. You can see a map of all the events here. There seems to be nothing going on in the UK, Portugal and Belgium, for example, which are all ASPERA members.

According to ASPERA it all began in 1909, when Theodor Wulf set out to measure radiation levels in the Netherlands, on top of the Eiffel Tower and in Swiss mountains — trying to detect a change in the levels with altitude.

The in 1912, Victor Hess ascended 5200 m in a balloon and demonstrated the
existence of radiation coming from the sky. He was awarded the Nobel Prize in 1936 for his discovery of cosmic rays.

Other Nobel Prizes associated with astroparticle physics include the 1995 award to Frederick Reines for the discovery of the neutrino — and Raymond Davis and Masatoshi Koshiba, who won in 2002 for detecting cosmic neutrinos from the Sun and from SN 1987A.

So what kind of festivities can we expect?

“Paris will honour astroparticle physics pioneers at the Montparnasse Tower – the highest building in Paris – which will become a real cosmic rays detector during the entire week,” accoding to ASPERA.

Meanwhile in the Czech Republic, the Netherlands, Poland, Romania and elsewhere, laboratories will put on special events for the public.

The festivities will begin a bit later in Rome, which will celebrate astroparticle physics with the opening on 27 October of a large exhibition dedicated to astroparticle physics called Astri e particelle. Le parole dell’ Universo. Held at the in Palazzo delle Esposizioni, it will highlight the challenges and techniques of astroparticle physics.

You can find out about more events here.

Fixing bones with dissolvable glass

Doctoring broken bones in the future could be easier and simpler – thanks to a metallic glass material that can be used to make dissolvable screws, pins or plates. Bone fractures or breaks are routinely fixed in place with metal implants to encourage healing. These are usually made from corrosion-resistant steel or titanium, but have to be removed in a second operation once the bones have mended.

In an effort to make this extra surgery a thing of the past, materials scientists led by Jörg Löffler at ETH Zurich in Switzerland have designed a metallic glass that dissolves harmlessly in the body. The idea is to make small supporting objects from this material, such as pins or nails, which would disappear over time.

Strength without the bubbles

The biggest challenge has been finding a suitable material. Requirements include strength, flexibility and durability, coupled with the ability to be absorbed without toxic side-effects. The best candidates for the job are magnesium alloys – but when these dissolve in the body they produce bubbles of hydrogen gas, which hinder bone growth.

To get around this problem, the Swiss team adjusted the components of the alloy to 60% magnesium, 35% zinc and 5% calcium, moulded in the form of metallic glass. This is made by rapid cooling of the combined mixture of molten metals – a process that prevents the conventional metallic structure from forming. Instead, the metals have an amorphous glass-like structure that is brittle but strong.

In animal studies, there was no sign that hydrogen bubbles were forming. “By changing the composition of the alloy, we believe that we are changing the corrosion reaction that takes place,” explains Bruno Zberg, lead author on the paper, which is published this week in Nature Materials. The researchers also found that they could adjust the speed of corrosion by varying the zinc content of the alloy, which may prove useful when designing different types of implant.

Slow dissolution

“The glasses usually dissolve at a rate of around one millimetre per month – although it depends on the size of the implant and location in the body,” Zberg told physicsworld.com. “Either way, the number of metal ions being released into the bloodstream is relatively low and they are diluted in the blood quite quickly.”

“This is certainly a novel approach and an interesting concept, but there are still issues to address,” says Robert Hill at Barts and the London School of Medicine and Dentistry, UK. “Early steel implants suffered from fatigue failure after they corroded – so it is important to ensure that this new material does not become critically weakened in the same way.” Another danger, Hill notes, is that threading on screws could corrode, or fibrous tissue could form around shrinking implants, making them come loose.

A further question remains over whether the dissolving metals will help or hinder the growth of new bone in their vicinity. Zberg notes that this also depends on the quantity being released – but acknowledges that these questions will all need further investigation in the future.

Scheme removes entropy from ultracold atoms

Physicists in Italy have shown how to transfer entropy from one ultracold gas to another using a laser beam. They say that the resulting low-entropy gas could be the ideal system for investigating quantum phenomena that can only exist in highly ordered environments.

Studying the quantum properties of gases requires cooling them down to a fraction of a Kelvin using various laser-based and magnetic techniques. Creating Bose–Einstein condensates (BECs), for example, means reaching just a few tens or hundreds of nanoKelvin. At this point an atom’s de Broglie wavelength, which is inversely proportional to its momentum, becomes long enough so that it is comparable to the spacing between atoms, which causes all the atoms to condense into the quantum ground state.

In addition to cooling atoms, however, physicists also want to minimize their entropy. One principal aim is to create “quantum simulators”, in which the atoms exhibit similar quantum phenomena to that in superconductors and other “real-life” materials.

Ease of control

A simulator could consist of a lattice of ultracold atoms held in place by laser beams in which the properties of the atoms are easily tunable. For example, the probability of an atom tunnelling from one lattice site to another or the interaction between the particles could be easily controlled, something that is extremely difficult to do in condensed-matter systems such as crystals.

Moreover, unlike crystals, in which impurities or defects could mask some basic quantum properties, atoms in optical lattices represent almost ideal systems with virtually no impurities. The challenge in building such a simulator, however, is ensuring that the atoms have a low enough entropy – a quantity related to disorder – that they can exist in precise lattice arrangements.

Now, Massimo Inguscio, Francesco Minardi and colleagues at the University of Florence, together with Sandro Stringari at the University of Trento, have demonstrated a new scheme that makes it easier to reach such low entropies. This involves putting a mixture of potassium and rubidium atoms into a magnetic trap and then cooling the mixture. Directing a laser beam with just the right wavelength into the trap compresses the potassium at the focal point of the beam while leaving the rubidium virtually unchanged.

Classical explanation

The result is that entropy is transferred from the potassium to the rubidium atoms in a process that can be understood using classical thermodynamics. Filling an isolated box with one gas and compressing the gas with a piston would raise the temperature of that gas. But mixing it with a second gas that can flow through the piston will result in a transfer of heat and therefore entropy from the first to the second gas when the first gas is compressed.

Commenting on the work, Dan Stamper-Kurn of the University of California Berkeley writes that the Florence team is not the first to use one quantum gas to cool another. But, he says, unlike previous groups, it has managed to transfer this entropy reversibly, in other words it has been able to shuttle the entropy back and forth between the refrigerator and target gases. This was shown by repeatedly moving the potassium into and out of the BEC state. This is important because it shows that the process is not irreversible and introducing heat into the system that cannot be removed.

Stamper-Kurn adds that the system can also be used to identify phase transitions of poorly understood target gases with exotic quantum properties. This, he says, can be achieved by measuring the state variables, such as temperature, pressure or magnetization, of the well known refrigerator gas at two different points in the experiment since these reveal how the entropy and temperature of the target gas change.

‘Textbook thermodynamics’

“It is also really nice to see how textbook thermodynamics can be applied to a quantum system” Jacopo Catani, University of Florence

Other groups, such as that of Wolfgang Ketterle of the Massachusetts Institute of Technology in the US, have transferred entropy not between two distinct gases but between one region of a gas and another. However, Florence team member Jacopo Catani points out that Ketterle’s research was aimed more at producing BECs reversibly, whereas the work of his group is a more versatile way of reducing entropy since the target and refrigerator gases can be easily isolated. He estimates that this research might lead to the creation of a quantum simulator within the next three years, but adds that it is not just the potential applications of the work that he finds satisfying. “It is also really nice to see how textbook thermodynamics can be applied to a quantum system,” he says.

The research is reported in Physical Review Letters.

Profiles of genius and persecution

It is no secret that Jewish scholars have made enormous contributions to science, achieving far more than one might expect given their relatively small numbers. They have also faced a staggering array of obstacles, culminating in the near-total destruction of European Jewry under the Nazis in the Second World War. These two themes – genius and persecution – are the twin currents that flow through Ioan James’ compelling Driven to Innovate, uniting a series of profiles that might otherwise be of interest primarily to a more specialized audience.

The book profiles 35 physicists and mathematicians whose lives span the period from the mid-1800s to about 1950. Many of those featured, like Max Born and Albert Michelson, are relatively well known, while Albert Einstein is, of course, a household name. Many others, however, are more obscure: the Prussian mathematician Gottfried Eisenstein, for example, whose intellect was described by Carl Friedrich Gauss as being on a par with that of Archimedes and Newton; or the German physicist Franz Simon, whose stellar career at Oxford in the 1930s and 1940s made the university’s Clarendon Laboratories into the leading centre for low-temperature physics.

Yet obscure or otherwise, none of the 35 had an easy life. Many had to flee the countries of their birth to escape persecution. One of the most tragic figures is German mathematician Felix Hausdorff, who, together with his wife, committed suicide in 1942 to avoid the inevitability of capture by the Nazis. But the hardships began long before Hitler came to power. Five decades earlier, Tsar Alexander III instigated waves of persecution, known as pogroms, against Russia’s Jews; in the 1930s and 1940s Jews faced the horror of Stalin’s “purges”. The fascists who seized power in Hungary in 1919 were also rabidly antisemitic. The list goes on.

Even in Britain and the US – surely safe havens by comparison – antisemitism was never far below the surface, as highlighted by the plight of mathematician James Joseph Sylvester. As a student in Liverpool in the 1820s, a classmate recalled, he was “hunted by his schoolfellows, in the open street, for no worse reason than that he was a Jew, and very much cleverer, especially in mathematics, than they were”. Sylvester left England for the US in 1841, at one point attempting to secure a position at Columbia College (now Columbia University) in New York, an institution with a charter explicitly forbidding religious discrimination. Even so, James writes, he was told that “the election of a Jew would be repugnant to the feelings of every member of the board”. A college spokesman pointed out that the sentiment “was not at all on the grounds of him being a foreigner; it would have been the same had he been born of Jewish parentage in the United States”.

Women, of course, faced obstacles of their own. James has included three Jewish women in the collection: Hertha Ayrton (born Phoebe Sarah Marks), who studied maths at Cambridge University and was the first woman to read a paper before the Royal Society; Emmy Noether, described by Einstein as “the most significant mathematical genius since the higher education of women began”; and Lise Meitner, whose work on nuclear fission, many historians believe, ought to have earned her a Nobel prize.

Meitner’s case illustrates just how formidable were the obstacles facing a scholar who was not only Jewish but also a woman. When she earned her doctorate from the University of Vienna in 1905, she was only the second woman to do so; at that time a female student was “regarded as a freak”, James writes bluntly. Later, Meitner was told she could not work in the lab run by Nobel laureate Emil Fischer; women were banned because “they might set fire to their hair”. (She was later permitted to work in an old carpenter’s workshop.) Years later, when she was working at the Kaiser Wilhelm Institute in Berlin, a talk she gave on “cosmic physics” was reported in the press as “cosmetic physics”. Though raised as a Protestant, Meitner was too honest to keep her Jewish ancestry a secret. When Germany annexed Austria, the country of her birth, in 1938, she fled to Sweden.

James does not try to find the root causes of the seemingly endless tide of hostility directed at Jewish thinkers. He does, however, do an admirable job of outlining the recent history of European Jewry in a thoroughly researched introductory chapter. He also reminds us just how important Jews once were to the intellectual life of Europe. Before the Second World War, some European cities were as much as one-quarter Jewish. Many Jews were doctors, lawyers, businesspeople or professors. In Germany, well-educated Jewish families established salons in the capital. “Poised precariously between the nobility and the bourgeoisie,” James writes, “they succeeded in transforming Berlin into a major cultural centre.” He also adds that, in Vienna “Jews began first to enter and then dominate intellectual cultural life”.

In the early decades of the 20th century, many Jews left Europe for the US, and their influence on culture and society came with them. Their role was felt particularly during the Second World War, when Jewish scientists played a significant role in the Allied war effort. And it continues today. As James points out, currently more than 40% of the members of the physics division of the National Academy of Sciences are Jewish.

One thing is clear: when barriers to their success are removed, Jews do very well indeed, particularly in the sciences. In a thoughtful analysis that runs for about a dozen pages, James attempts – bravely, perhaps – to address the question of why this is the case. In this section (which would make a compelling essay in its own right), James, who is not Jewish, points to a variety of factors. “[It is] reasonable to suppose that there may be genetic factors,” he concludes. However, cultural factors along with “certain traditions and values which are distinctively Jewish” may also play a role. No wonder people are squeamish about such matters. After all, one might argue that it is the notion of “being different” that has fed so much hatred over the years.

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