Unemployment rates among new STEM graduates are higher than average. (Courtesy: iStock/geopaul)
Why, at a time when we hear so much about the UK’s shortage of scientific and technical skills, do unemployment rates among new science graduates remain stubbornly higher than average? This question has been bugging me for some time. Back in 2012, I wrote a blog post about it, suggesting that the answer might be a mismatch between what universities teach and what employers need. But that answer never really satisfied me, so for the graduate careers section in this month’s Physics World, I’ve examined the subject more carefully.
A coin-sized detector might observe gravitational waves before the giant LIGO interferometers, according to two Australian physicists who have built the device. The detector is designed to register very high frequency gravitational waves via the exceptionally weak vibrations they would induce. Other scientists caution that the astrophysical objects thought to emit such radiation may do so very weakly or might not actually exist.
Predicted by Einstein’s general theory of relativity but yet to be directly observed, gravitational waves are ripples in space–time generated by accelerating massive objects. The tiny detector has been made by Maxim Goryachev and Michael Tobar of the University of Western Australia in Perth and is based on the decades-old technology of resonant-mass detection.
Tiny vibrations
Pioneered by Joseph Weber of the University of Maryland in the US in the late 1950s, resonant-mass detectors have traditionally employed metal bars about a metre long and around a tonne in weight, which makes them sensitive to gravitational waves with frequencies up to about a few kilohertz. It turned out, however, that the tiny vibrations that would be induced by gravitational waves are extremely difficult to detect above the thermal noise in the bar – even when it was chilled to cryogenic temperatures.
Goryachev and Tobar overcame this problem by targeting gravitational radiation in the 1–1000 MHz range. Tobar initially thought that the kind of gram-scale detector suited to these frequencies would be far too light to produce any kind of measurable signal. But he then realized that they could achieve the necessary sensitivities by cooling down a quartz bulk-acoustic-wave (BAW) cavity and boosting its output using extremely low-noise “SQUID” amplifiers. “Our technology has actually been around for decades,” he says, “but at room temperatures.”
Trapping phonons
Their device consists of a quartz disc about 2.5 cm in diameter hinged to another piece of quartz and placed in a vacuum chamber. A passing high-frequency gravitational wave would cause the disc to vibrate, setting up standing waves of sound across the 2 mm thickness of the disc. The upper surface of the disc is slightly curved to trap sound quanta (phonons), which improves the signal-to-noise ratio. The piezoelectric nature of quartz allows the tiny vibrations to be converted into an electrical signal that is amplified by the SQUIDs.
The researchers are currently operating their device at 4 K, and hope to obtain the dedicated cryostat and sensitive SQUIDs needed to reach the design temperature of 10 mK within the next year. The device costs about $500,000 to make and the physicists say that its compactness and ease of manufacture lends it to being scaled up into arrays that would improve sensitivity and help filter out spurious events.
Having accounted for all known sources of noise, Goryachev and Tobar reckon that their detector would be sensitive to strains in space–time as low as 10–22, the figure that Advanced LIGO is set to achieve. Advanced LIGO is an upgrade of two existing LIGO detectors in the US, which are searching for gravitational waves using huge masses located at the ends of optical interferometers with arms that are 4 km long. The huge detectors are expected to detect signals between about 0.1–1 kHz, from sources such as binary neutron stars or colliding black holes by the end of 2018.
Cosmic strings and axions
Goryachev and Tobar say that their device should detect low-mass black holes encircled by dark matter, with the latter giving off gravitational waves just as bound electrons in an atom emit electromagnetic radiation. Other possible sources, they add, include plasma flows and exotic cosmological entities such as cosmic strings or clouds of axions. Tobar says that they could detect gravitational waves before Advanced LIGO, adding “We can at least put the first serious upper limits on these sources.”
Mike Cruise, an astrophysicist at the University of Birmingham in the UK, praises the “very sophisticated but believable” proposal, but cautions that many high-frequency sources “are very speculative and may well not exist” and may also be far weaker than those probed by interferometers. “The gravitational energy available is likely to go down by the cube of the wavelength,” he says, “which is very punishing when wavelengths decrease by factors of a thousand or a million.”
Omid Kokabee, an Iranian physicist who has been in jail in Tehran for almost four years, has been granted a retrial by the Iranian Supreme Court of Justice. The decision follows an open letter signed in September by 18 Nobel-prize-winning physicists that called for Kokabee’s to be set free. Since then, the number of laureates who have endorsed the letter calling for his freedom has reached 28. The laureates’ demand came after a separate request for a retrial had been filed by Kokabee’s lawyer, Saeed Khalili, earlier this year. “The Supreme Court has confirmed that there are major faults in [the first] verdict, and has overturned it,” Khalili told Physics World, adding that another court will now have to consider the case anew.
The letter’s release was timed to coincide with a visit by the Iranian president Hassan Rouhani to the United Nations, when he addressed its general assembly on 25 September. The letter – a joint initiative of Amnesty International, the Committee of Concerned Scientists (CCS) and the American Physical Society (APS) – deemed the charges levied against Kokabee as “spurious” and asked Iran’s supreme leader Ali Khamenei to “allow him to return to his studies”.
“Extremely cautious”
“This letter is an opportunity to help him get better treatment,” says John Mather, one of the Nobel laureates who signed it. “[Kokabee] does not deserve to be in jail. I expect Iranian students [studying abroad] would be extremely cautious abouting visiting home. I personally would be afraid to go.”
Kokabee, who was born in Iran in 1982, began a PhD at the Institute of Photonic Sciences in Spain in 2007, before continuing his studies at the University of Texas at Austin in 2010. He was arrested in January 2011 in Iran and in May 2012 was given a 10-year jail sentence for “communicating with a hostile government”.
Worsening conditions
In an open letter that he penned from jail in April 2013, Kokabee denied all charges and claimed that he had been jailed to pressure him to participate in a military nuclear project. Kokabee worked on high-power lasers, which can be used in nuclear enrichment. The CCS claims that his health and jailing conditions have worsened since he entered prison and that Kokabee has been denied medical care.
Despite his incarceration, Kokabee still appears to be keeping up with his work – he posted a paper on the arXiv preprint server this year, penned from his Evin jail. He also sent another open letter thanking the Nobel laureates for their support. Last September, Kokabee was awarded the APS’s 2014 Andrei Sakharov Prize, which recognizes scientists who promote human rights. He was cited for “his courage in refusing to use his physics knowledge to work on projects that he deemed harmful to humanity, in the face of extreme physical and psychological pressure”.
It is a truth almost universally acknowledged that businesses in the UK are facing major skills shortages in science, technology, engineering and maths. In March the Daily Telegraph newspaper reported that the country’s manufacturing industry is being “starved of highly skilled workers” in these so-called STEM disciplines. Later that month, the Financial Times picked up the theme, repeating the UK business secretary Vince Cable’s claim that the shortage of technology workers is “a massively serious problem” that could harm the country’s economic recovery. In May it was the Independent’s turn to call scientific subjects “vital for the economy”. And in June the BBC joined in, reporting on its website that technology firms are finding “too few graduates with digital skills…for the jobs available”.
Reports like these – all of which were based on studies by respected organizations – usually focus on areas that are big employers of physics graduates. The engineering, IT and scientific sectors, for example, collectively attract around a third of physics graduates who enter the workforce within six months of completing their degrees. From the tenor of reports on the STEM skills shortage, then, it seems like employers ought to be falling over themselves to employ people with a physicist’s numerical and technical nous.
Absence of evidence
Unfortunately, the economic data tell a more complex story, one that calls into question the nature of the UK’s STEM skills shortage, and perhaps even its existence. Although there is no universally agreed definition of what constitutes a skills shortage, in 2005 the economists Chandravadan Shah and Gerald Burke articulated a useful rule of thumb, writing that a shortage exists when “the demand for workers for a particular occupation is greater than the supply of workers who are qualified, available and willing to work under existing market conditions”. So if a shortage does exist, economists generally expect to see low and falling unemployment, high and rising wages, and a large number of unfilled posts as employers compete (and struggle) to attract workers with scarce and desirable skills.
On these three measures, the evidence for a broad, UK-wide STEM skills shortage is patchy. Take unemployment. Overall, prospects for UK graduates are good: according to the UK Higher Education Statistics Agency (HESA), which surveys thousands of graduates each year, only 8% of students who obtained their undergraduate degrees in the 2012/2013 academic year were unemployed six months after graduation. For recent graduates in the physical sciences, however, the picture is not quite so rosy: their unemployment rate was a shade higher than the average, at 9%, and graduates in the mathematical sciences, engineering and technology fared no better. Computer science graduates actually had the highest unemployment rate of any degree listed in the HESA survey: fully 13% of the 2012/13 cohort said they were still seeking work six months after graduation.
On salaries, the news for physics graduates and their STEM cousins is better, but only in a relative sense. After analysing HESA data, the Complete University Guide (a consultancy firm) found that starting salaries for graduates in nearly all subjects fell during the recent economic recession. Physics graduates were no exception: between 2007 and 2012, their average starting salaries fell by 6%. Mechanical engineers did a little bit better, down by 5%, but chemists were worse off, with a drop of 9%. These figures exclude the sizeable fraction of STEM graduates who enter occupations that do not require degrees, so the true overall decline is likely to be higher. They are also not adjusted for inflation, meaning that salaries have fallen even further in real terms. However, as bad as these figures are, they are generally better than comparable data for non-scientific fields: graduates with English degrees saw their starting salaries fall by 16%.
Finally, there is the question of job openings. Data on vacancy rates can be tricky to interpret (see “Hard to fill, but not always a shortage” below). Nonetheless, in November 2013 the UK Commission on Employment and Skills (UKCES) published a detailed analysis entitled The Supply and Demand for High-Level STEM Skills that included estimates of skill-shortage vacancies in STEM and non-STEM jobs. The report’s authors found that the available data “do not suggest a higher vacancy rate” for jobs that require workers with STEM skills. What is more, the authors found that this was unlikely to change much in the future: even under fairly optimistic economic scenarios, their model predicts an overall surplus of STEM graduates in 2020, not a shortage.
The idea that would not die
Some scholars have taken data like these as evidence that the STEM skills shortage is simply a myth. In March the economics Nobel laureate (and New York Times columnist) Paul Krugman called skills shortages a “zombie idea – an idea that should have been killed off by the evidence, but refuses to die”. The reason it doesn’t, Krugman suggested, is that “everyone important knows [it] must be true, because everyone they know says it’s true”. The American demographer and labour-market scholar Michael Teitelbaum takes a similar stance, arguing in his recent bookFalling Behind? Boom, Bust and the Global Race for Scientific Talent that the US is not experiencing a shortage of scientists or engineers (August pp38–39). Conventional wisdom to the contrary is, he writes, “just the same claims ricocheting in an echo chamber”.
On the other side of the Atlantic, the debate about skills shortages also has a certain echo-chamber quality. In 2012, for example, the Royal Academy of Engineering (RAEng) predicted that the UK economy will require 830,000 additional scientists, engineers and technologists by 2020. At current graduation rates, the RAEng report noted, this equates to a shortfall of about 10,000 STEM graduates per year. Since then, similar figures have cropped up elsewhere. In 2013, for example, the government’s Department for Business and Skills (BIS) cited the RAEng data in its report on “The future of manufacturing”, but claimed that the manufacturing sector alone would need around 800,000 more skilled employees by 2020, including 80,000 managers and other professionals. In April 2014 a report by the manufacturers’ organization, EEF, gave the BIS figure an upgrade, turning “around 800,000” into “almost one million”. And in July this year, the chief executive of the Institution of Engineering and Technology (IET), Nigel Fine, went even further, claiming that “we need to find 87,000 new engineers each year for the next decade”. Based on today’s student numbers, this figure implies that nearly 30% of university students ought to be earning engineering degrees – more than five times the current fraction.
The echo-chamber effect tends to distort claims about skills shortages as well as amplifying them. One source of distortion is that definitions of “STEM” vary, with some groups limiting it to graduates in STEM disciplines while others expand it to anyone who uses scientific or technical skills at work – including plumbers and auto mechanics as well as skilled manufacturing technicians and apprentices. Naturally, the magnitude of predicted shortages depends on which definition is being used. “STEM is a very broad church,” agrees John Perkins, the chief scientific adviser to the BIS and the author of a separate 2013 review of engineering skills. “If you look at different parts of the spectrum, you come to different conclusions about whether there is a shortage, or indeed whether there are too many graduates emerging with those particular skills for employment purposes.”
Saying that the UK’s STEM skills shortage isn’t uniform is not, however, the same as dismissing it as a “zombie idea”. While Perkins acknowledges that the higher-than-average unemployment rate for STEM graduates is a “counterfactual” that merits further study, he is adamant that the shortage is real, and that data on unemployment, salaries and vacancies are not telling the whole story. Surveys of STEM employers tend to support his view. For example, the IET’s “87,000 more engineers per year” figure comes from a press release announcing their own survey of 400 IT and engineering employers in the UK. Around a fifth of these employers said they were having problems in recruiting engineering graduates. A separate survey of 160 employers conducted by the EEF found evidence of rising demand for graduates in technology and computer sciences as well as engineering, with more companies planning to recruit in the next three years than have done in the previous three. Even the UKCES report, which found no evidence for a shortage of STEM graduates per se, admitted that “there appears to be a shortage of the right candidates to fill specific roles”.
The leaky pipeline
The contrast between employer perceptions and economic data suggests that something more complex than either a zombie attack or an echo chamber is at work. One important complication is that the fraction of STEM degree holders who take jobs in STEM fields is actually rather small. In 2011, for example, data from the UK Labour Force Survey cited in the UKCES report indicated that only 45% of all people with “core STEM” degrees were working in sectors that required scientific and technical knowledge (as opposed to general numeracy and problem-solving skills). As for recent graduates, HESA figures show that among students who earned degrees in engineering, physical, biological, mathematical or computer sciences in 2012/13, only about 12% of those entering the workforce found jobs that involved “professional, scientific and technical activities” within six months of graduation, while fewer than 10% went into manufacturing. By comparison, 14% are working in retail. And while those figures leave out graduates who did higher degrees before seeking work, the pull of non-science careers remains strong even at the PhD level: a 2010 report by the Royal Society found that more than half of the UK’s PhD scientists pursue careers outside science.
The fact that relatively few STEM graduates go into STEM jobs is something of a double-edged sword for proponents of the shortage theory. On the one hand, it could explain why employers are struggling to find people with the right skills even though the number of people studying for STEM degrees in the UK has been rising in recent years – up 18% since 2002, according to figures published this year by the Higher Education Funding Council. But on the other hand, it could also indicate that shortages, where they exist, are not severe enough for employers to offer salaries and benefits that would tempt STEM graduates away from alternative careers. The fact that many STEM graduates do something else might even be a sign of an oversupply – for example, graduates might be turning to other fields after struggling to find jobs related to their degrees. Lack of interest does not seem to be a factor: a survey of final-year STEM students conducted by the BIS in 2011 found that seven out of eight wanted to work in related fields after they graduated. So what is keeping them out?
In Perkins’ view, part of the problem is that STEM employers “aren’t being as cunning as they might be” at attracting graduates. At careers fairs, he says, students say that representatives of banks and accounting firms are “all over you like a rash, trying to convince you to come into their world” whereas more traditional STEM employers are “shy and retiring and not as effective at persuading you that life could be exciting with them, too”. Many smaller firms avoid careers fairs altogether, and they are also less likely to advertise on “one stop shop” websites for graduate jobs, says Kirsten Roche, a careers consultant at the University of Edinburgh who advises physics and mathematics students. But the problem is not only on the employers’ side. “Sometimes there can be issues around what students want and what’s realistically available,” Roche says, noting that while geology students often want to work in renewable energy, a significant number of graduate geoscience jobs are in the oil and gas industry.
Not everyone, however, is convinced that the leaky pipeline is responsible for the “STEM shortage paradox” of relatively high graduate unemployment at a time when industry is crying out for more people with technical skills. Tom McLeish, a physicist and pro-vice-chancellor for research at Durham University, points out that it has always been common for physics graduates to leave STEM, and “there would need to have been a change in that flow” for it to explain the current situation. The tendency for graduates to leave STEM has actually become somewhat more pronounced over the past decade or so, but McLeish, who is also the vice-president for science and innovation at the Institute of Physics (IOP), which publishes Physics World, isn’t sure that’s a bad thing. The fact that STEM degrees open doors in many occupations is, he says, “one of the ways we advertise STEM to potential students. We say, look, it’ll leave you numerate, it’ll leave you articulate, it’ll give you group working skills and interdisciplinary skills and an ability to solve problems.” STEM graduates going into other fields, he argues, “cannot be both a bad thing and a good thing at the same time”.
Mind the gaps
Another possible explanation for the STEM shortage paradox is that universities are not giving students the skills they need. This explanation is popular among employers and it appears prominently in a recent report by the New Economics Foundation (NEF), a London-based innovation charity. In the report, NEF chief executive Sa’ad Medhat notes that “there is a profound disconnect between what STEM-based companies require in terms of skills; the technological changes that they see on the horizon and what many further and higher education institutions currently provide”. For some employers, it is “soft skills” such as communication and problem solving that are lacking. One software entrepreneur quoted in the NEF report, for example, complains that “students are too frequently ‘spoon-fed’ with information and are unable to break down problems into manageable chunks and solve them on their own”. Other employers focus on gaps in technical skills. Jo Lopes, the head of technical excellence at Jaguar Land Rover, told the NEF that she sees a growing demand for employees who can work with virtual reality software to create prototypes, something that requires “a strong grounding in maths and physics along with data modelling and analytical skills”.
For universities, comments like these are a challenge, and some are working with industry representatives to adapt their courses accordingly. Kate Lancaster, a physicist and industry liaison officer at the York Plasma Institute, says that York and Sheffield universities are setting up a new industrial physics academy to address both the “leaky pipeline” and employer concerns about specific skills, such as computer programming. While undergraduates in theoretical physics are usually required to take a programming module, for experimentalists it is frequently treated as an optional “extra”. That is a problem, Lancaster says, because “unless it’s credited and part of your course, students won’t really engage with it.”
McLeish agrees that universities can and often should do more to equip graduates with industrially relevant skills. While developing plans for a new doctoral training centre in soft-matter physics, he and his collaborators at the universities of Leeds and Edinburgh asked employers to list the attributes they’d like to see in the centre’s graduates (see box opposite). Communication skills were seen as the most important. “Employers want graduates who can walk into a boardroom one day and explain the science to executives, and then go straight away to the production plant and explain to an experienced technician why they need to change the cherished settings on the equipment,” McLeish says.
If you think that sounds like a lot to expect of a brand-new PhD graduate (never mind someone with a BSc or MSc), McLeish is sympathetic. “Some employers want the Archangel Gabriel on a good day,” he agrees. Small businesses can be particularly demanding, adds Steve Wood, project manager of Graduate to Merseyside, a careers programme based at the University of Liverpool. “A lot more is expected of individuals, particularly in terms of flexibility and general work experience,” Wood explains. Sometimes those high expectations are fair, he says, but “we do see some organizations that think, ‘Oh, we’re going to bring in a graduate and pay them 16 grand a year and they’re going to turn us around’. They’re the ones that generally we can’t help”.
When applicants do fall short of requirements, employers are increasingly reluctant to train them up to a higher level. In the UK as a whole, UKCES figures show that investment in employer-provided training fell by 17% between 2011 and 2013. In essence, McLeish argues, employers are asking universities to provide skills that companies used to take care of themselves.
For Perkins, the BIS science adviser, there is a drawback to asking universities to fill that gap on their own. A university education is, he says, just that – an education – and it cannot possibly meet the needs of every graduate employer. “There’s a responsibility of employers to enhance the skills of people they take on and train them in the specifics of their particular organizations,” he says. “It’s always going to be the case that graduates are not fit for particular employers immediately on day one. That’s just a fact of life.” Perkins also downplays the idea that ill-prepared graduates are a major contributor to the STEM shortage paradox. Criticisms of employee preparedness have been “a constant observation by some employers ever since I was a lad”, he says, and universities are getting better at providing training in soft skills.
Data from a much wider survey of employers tend to support the view that in terms of preparation, the kids are, in general, alright. A 2013 UKCES report on skills found that in England, 84% of the 17,770 employers who had taken on graduates in the past year regarded their recruits as “well” or “very well” prepared for their roles. Employers in Wales, Scotland and Northern Ireland reported similar levels of satisfaction, and throughout the UK, only 5% said that graduates lacked “required skills or competencies”. Poor literacy or numeracy skills were cited by just 1%.
The wrong kind of STEM
For physics students, the STEM shortage paradox is personal in a way that raw numbers cannot capture. Earlier this year, the IOP asked current physics undergraduates to answer questions about their future employment plans, including the companies and sectors that interest them. More than 300 students responded and the full results of the survey are still being analysed. A section for “free-form” responses, however, yielded some illuminating comments about challenges that physics students are facing in the current job market.
One common concern was that many of the jobs on offer are not suitable for new graduates. “The roles [I see on websites] look far more advanced than the level that I feel I will be when finishing university, which makes them seem unappealing,” one student wrote. Another student expressed frustration at being misled by claims of skills shortages. “When we go into physics, we are told that there are loads of jobs that want our skills,” they wrote. “We are not told that these will probably require a postgraduate qualification.”
The IET’s survey of employers provides some backing for the impression that senior vacancies are indeed more common than graduate-level ones. While almost 80% of employers surveyed said they had struggled to recruit senior engineers, only around 40% had experienced difficulties finding new graduates. However, HESA data suggest that if higher-level shortages exist on more than an anecdotal level, they take some time to materialize. In June 2014 the agency reported that unemployment rates among those who had graduated in 2008/9 had fallen to 3.4% by the winter of 2012/13, well below the UK’s overall rate of around 7%. But while physical science graduates were doing a little bit better than average, with 3.1% reporting that they were unemployed, computer scientists and engineers had some of the highest unemployment rates in the study, with 5.4% and 5%, respectively, seeking work at the time of the survey.
Levels of unemployment in other STEM disciplines might surprise some of the physics students in the IOP survey, several of whom seemed envious of their counterparts in other fields. “Most graduate schemes have few details on how they apply to physicists specifically, with many seeming to focus on engineering and materials,” one wrote. “It isn’t always clear what roles a physicist could adopt within the scheme.” In part, this is due to the relative rarity of physics graduates, but there is also some evidence that employer demand skews towards engineering and technology – more of a sTEm shortage, if you will.
The UK Migration Advisory Committee, which advises the government on whether foreign workers with in-demand skills should be allowed to enter the country, includes a large number of “engineering” jobs in its 2013 list of “shortage” occupations. In the physical sciences, though, only a handful of occupations made the cut. Among them are specialists in radiotherapy and nuclear safety, geophysicists working in the oil and gas industry, and secondary-school teachers in physics and chemistry – all important professions, but fairly specific ones, and hardly an indication of an across-the-board shortage.
Squaring the circle
So far, this article has considered four distinct explanations for the STEM shortage paradox. One is that the UK’s shortage of STEM skills is not as severe or as widespread as the conventional wisdom suggests. Another is that the shortage exists among STEM workers in general rather than graduates in particular. The third theory posits a mismatch between what employers demand and what graduates offer. And the fourth suggests that the shortage is tilted towards experienced workers or specific areas within the “broad church” that is STEM. The true explanation is likely to be a combination of the four, but it is also worth noting that much of the rhetoric on this subject is actually referring to future shortages – ones that will materialize a few years or decades down the line, unless we do something about them now.
Concerns about the future are nebulous by nature, and for what it’s worth, a July 2014 report by the UKCES on Skills for the Future reiterated that the UK is not predicted to experience shortages of higher-level STEM skills between now and 2022. Among industry leaders, though, such assurances do little to allay concern. “Inevitably, when you look to the future you have to make a guess about what it’s going to look like,” Perkins says. “One guess is, well, the future’s going to look like today. But I think a more sophisticated guess would be that technology is becoming more and more important, the world is becoming a more global place, and therefore the skills requirements of the future are going to look different from the skills requirements of today.”
Another important consideration is that the job market is not static. Because STEM graduates take a long time to train, the authors of Skills for the Future concede that it would be hard for universities and employers to react quickly to a sudden uptick in demand. After all, if the number of STEM graduates continues to grow, the economy may adapt by creating new jobs and even new industries to take advantage of their skills. On that basis, efforts to prevent a “STEM skills shortage” may not be in vain. But that is little comfort to today’s physics graduates, who must seek work in the economy we have, and not the economy we’d like to have in the future.
Hard to fill, but not always a shortage
When employers struggle to fill posts that require a high degree of knowledge or technical ability, skills shortages are a natural suspect. However, other explanations are possible. For example, a small firm might not have the resources to advertise widely. A brand-new start-up might not be able to pay a competitive salary. Geography can also be a factor, with companies in certain locations straining to convince highly skilled people to move there, while in areas such as central London, posts may go unfilled if the pay and working conditions are not good enough to balance out the high local cost of living. For employers, an abundance of these “hard to fill” vacancies may well feel like a skills shortage even when the labour market as a whole contains enough people with the right skills.
Hard to fill, but not always a shortage The proportion of employers whose vacancies are hard to fill.
This graph – based on data from a 2013 UKCES survey of 91,000 employers across the UK – shows how the different types of vacancies relate to each other. Of the 15% of employers who had vacancies at the time of the survey, one in three reported that their vacancies were “hard-to-fill”. Within this group, around four in five cited problems with applicants’ skills as a reason why the posts were vacant.
Five 'soft' skills in demand
(Courtesy: iStock/akindo)
When Tom McLeish and his colleagues at Leeds and Edinburgh universities asked employers of soft-matter physicists about the non-technical skills they would like job applicants to have, the requests coalesced around five basic skills:
1. Communication. This was seen as the most important skill. 2. Breaking a complex problem into simple parts. 3. Working in an interdisciplinary environment. Employees need to understand how people from different technical backgrounds can contribute to a solution. 4. Working at multiple sites with non-local collaborators. This is something that larger companies, in particular, are demanding of their employees. 5. Being aware of the business context. While scientific answers are important, in an industrial setting they are only one part of the picture.
A Bose–Einstein condensate (BEC) of ultracold atoms has been used to create a laboratory analogue of laser emission from a black hole. The work was done by Jeff Steinhauer at Technion in Israel, and could also provide strong evidence for the existence of “Hawking radiation”. However, multiple definitions of this term are in use, and the most theoretically revolutionary type has not been observed.
When astronomical black holes were first proposed, they were thought to be completely dark and featureless. However, in 1974 Stephen Hawking showed that quantum field theory predicts that pairs of photons are created on either side of a black-hole event horizon – the point at which even light cannot escape the gravitational pull of the black hole. The photon inside the horizon carries “negative energy” and falls in. The other photon, which carries positive energy, escapes. Therefore, black holes should emit radiation.
Such a proposal is astounding, explains James Anglin of the University of Kaiserslautern in Germany, because it suggests that black holes behave as black bodies with well-defined temperatures. Hawking also showed that, in space–time geometry, black holes can be entirely defined by three properties. These two results seem to imply that the founding principles of thermodynamics, in which temperature is defined as the average energy in a large number of degrees of freedom, need revision. “It was very hard to imagine how something that only had three numbers to its name could possibly have a temperature,” explains Anglin. “It was a matter of potentially redefining thermodynamics by bringing it together with general relativity and quantum mechanics – and that made everybody really excited!” The catch, however, is that the “temperature” of all known black holes would be lower than the cosmic-microwave-background temperature, making the radiation effectively undetectable.
Flowing fluids
In 1981 William Unruh of the University of British Columbia showed that the equations predicting Hawking radiation should also apply to sound waves in fluid flow. Now, Jeff Steinhauer has used a BEC to simulate a black hole with two horizons – the main event horizon and a second “inner horizon”. In cosmology, this could occur if the black hole was either rotating or charged. The photons falling into the black hole would be unable to cross the inner horizon and so would reflect back towards the event horizon – although this is a controversial suggestion because they would have to travel faster than the speed of light to do so.
Unable to escape the event horizon, the photons would bounce between the two horizons, thus forming a standing wave. As they bounced back and forth, their energy would become increasingly negative. To preserve the total energy at zero, positive energy would be emitted outside the event horizon in the form of light at a single frequency and an ever-increasing intensity, forming a “black-hole laser”.
Steinhauer’s simulation of this scenario relies on the fact that for relatively long-wavelength waves, the speed of sound in a BEC is less than 1 mm s–1. Sound with short wavelengths, however, can travel faster than this speed. He confined the BEC – rubidium atoms chilled to well below a temperature of 1 K so they are all in the same quantum state – in a long tube using a focused laser beam. The BEC is then allowed to flow in one direction and the flow rate is controlled such that, in a specified region of the tube, the condensate travels faster than the local speed of sound, while on either side of this region the flow rate is subsonic.
Supersonic region
In the supersonic region, only sound waves of very short wavelength can propagate against the flow, creating negative-energy modes that are unable to exit the supersonic region. These modes bounce back and forth, creating a standing-wave pattern in the BEC that gradually increases in amplitude. On one side of the supersonic region, low-frequency sound waves are emitted, and the amplitude of these gradually increases. According to Steinhauer, these waves are analogous to the radiation produced outside the event horizon of a black hole. Although the system is not a real black hole, the experiment “shows that the Hawking mechanism works”, explains Steinhaeuer. “If the same mechanism works in one system, it should probably work in the other system too,” he says.
Renaud Parentani, an expert on black-hole analogue systems at Université de Paris-Sud, is impressed. “Observing the lasing effect is an indirect – but almost direct – observation of the Hawking effect,” he explains, “because the latter is necessary for the lasing to take place.”
However, Steinhauer’s model would lead to an unstable, exploding black hole, rather than the steadily radiating black body predicted by Hawking. Anglin is hopeful that further experiments could either reproduce Hawking’s black-body radiation or provide important insights into why it cannot be simulated. “In that sense, this is one of the biggest advances in Hawking-radiation studies that there has been since the beginning,” he says.
In less than 100 seconds, Carola-Bibiane Schönlieb of the University of Cambridge in the UK provides a basic definition of a Fourier transform. She explains how this mathematical tool was introduced in the early 19th century by Joseph Fourier while he was searching for solutions to the heat equation. It is a way of taking a signal or a function and deconstructing it into a series of sines and cosines.
Today, Fourier transforms are prevalent in many areas of science and engineering. They are used in processing many of the signals we encounter in our everyday lives, such as phone and TV signals, and even in the evolution of the Stock Market. Schönlieb gives an example of how Fourier transforms are used in her own area of mathematics, a field called inverse problems. She explains how images generated using magnetic resonance tomography are derived from a partial knowledge of a Fourier transform.
A vast upgrade to the XENON dark-matter experiment at the Gran Sasso National Laboratory in Italy is set to provide a significant increase in sensitivity by being able to better spot cosmic rays masquerading as dark-matter particles. Costing $11m and expected to start taking data in 2015, XENON1T will contain one tonne of xenon to hunt for weakly interacting massive particles (WIMPs) – a leading dark-matter contender.
The XENON detector contains 100 kg of xenon and has provided the world’s best limits on the collisional cross-sections between WIMPs and xenon atoms within the detector. But despite the laboratory being situated deep underground to block out most other particles, stray neutrons produced by the decay of cosmic-ray muons can still enter the detector and produce “false positives”. Because the signal from the WIMPs, if they exist, will be weak, these false positives could obscure the real signal.
In a conceptual design report published earlier this year, the XENON team has laid out the design of its new Cerenkov detector, half of which will be funded by the US. To eliminate unwanted neutrons and improve sensitivity, XENON1T will be housed in a 10.5 m-high cylindrical water tank, the construction of which has now been completed. Whenever a relativistic neutron passes though, it will produce Cerenkov radiation that will be detected by photomultipliers.
Should a signal be recorded at the same time as one from a neutron, it will be a false positive that can be ignored, because WIMPs do not interact with the electromagnetic force and so cannot produce light of their own. XENON1T could be followed by an even bigger detector in around 2021, dubbed XENONnT, which will have more than seven tonnes of xenon. This would increase the opportunities for scattering events resulting in a stronger WIMP signal, possibly to the point where firm conclusions about the nature of dark matter can be made.
When the first pulsar signal was detected in the 1960s, for a short time it was referred to as “little green man 1”, because the regular pulsing appeared to be a message from aliens. This regularity of pulsar signals means that these rapidly rotating neutron stars can be thought of as the most reliable clocks in the heavens. In this short film, we meet astronomers at the Jodrell Bank Observatory near Manchester in the UK to learn about an exciting application for these cosmic clocks – studying pulsar signals in the hunt for gravitational waves.
Gravitational waves are often referred to as ripples in space–time. “It’s something that’s most easily detected when you have massive objects, for example orbiting each other,” explains Ben Stappers of Manchester University. “That generates a so-called ripple in space–time; a bit like if I threw a stone into a pond, you see the water ripples.” Stappers is involved in a new project called the European Pulsar Timing Array (EPTA) that is looking for subtle variations in the arrival times of pulsar signals that could be the result of gravitational waves between the pulsar source and the receiver on Earth. The international project combines pulsar signals collected at radio-telescope facilities in the UK, the Netherlands, Germany, France and Italy.
The EPTA is not alone in looking for gravitational waves, as others are pursuing the same goal. One such experimental collaboration, who use the Background Imaging of Cosmic Extragalactic Polarization (BICEP2) telescope, claimed in March this year that it had found evidence for primordial gravitational waves because it had seen the polarization signal within the cosmic microwave background (CMB). Stappers comments on these results, saying that it encourages radio-astronomy community to speed things up and make a detection for itself. However, since the making of our film, which was recorded in April, significant doubt has been cast on the BICEP2 results because of inconsistencies with results collected by the Planck satellite, a space telescope that measures the CMB in detail.
If nothing else comes from the BICEP2 commotion, it has at least raised the public profile of the hunt for gravitational waves. You can find out more about how pulsars can help in this pursuit by reading the October issue of Physics World. Details of how to access the issue are here.
A large metallic mirror previously used as a prototype for a cosmic-ray observatory will be reused by physicists in Germany to hunt for “hidden photons”. These exotic and hitherto unseen cousins of normal photons could account for some dark matter – the mysterious and invisible substance that appears to account for about 85% of the matter in the universe.
Most dark-matter experiments try to detect weakly interacting massive particles (WIMPs), which are predicted by the theory of supersymmetry and interact with other matter only via the weak nuclear force and gravity. WIMP detectors aim to capture the tiny amounts of energy given off in collisions between the putative particles and atomic nuclei – usually in large detectors deep underground. However, about a quarter of a century has passed since the first such experiment started and not a single WIMP has been unambiguously detected.
Hidden photons are predicted in some extensions of the Standard Model of particle physics, and unlike WIMPs they would interact electromagnetically with normal matter. Hidden photons also have a very small mass, and are expected to oscillate into normal photons in a process similar to neutrino oscillation. Observing such oscillations relies on detectors that are sensitive to extremely small electromagnetic signals, and a number of these extremely difficult experiments have been built or proposed.
Many different experiments
“In the last few years, the interest in hidden photons has been growing,” says Jonathan Feng of the University of California, Irvine – partly because searches for other dark-matter candidates have “come up empty”. Also, physicists have realized that many different kinds of experiment can be built to try and detect hidden photons.
Now, Babette Döbrich and colleagues at DESY in Hamburg, the Karlsruhe Institute for Technology and other institutes in Europe are using a portion of a spherical, metallic mirror to look for hidden photons. This was suggested in 2012 by physicists in Germany in a paper called “Searching for WISPy Cold Dark Matter with a Dish Antenna”. The scheme exploits the fact that hidden photons would interact with electrons – albeit feebly – and when they strike a conductor they would set the constituent electrons vibrating. These vibrations would result in normal photons being emitted at right angles to the conductor’s surface.
A spherical mirror is ideal for detecting such light because the emitted photons would be concentrated at the sphere’s centre, whereas any background light bouncing off the mirror would pass through a focus midway between the sphere’s surface and centre. A receiver placed at the centre could then pick up the dark-matter-generated photons, if tuned to their frequency – which is related to the mass of the incoming hidden photons – with mirror and receiver shielded as much as possible from stray electromagnetic waves.
Ideal mirror at hand
Fortunately for the team, an ideal mirror is at hand: a 13 m2 aluminium mirror used in tests during the construction of the Pierre Auger Observatory and located at the Karlsruhe Institute of Technology. Döbrich and co-workers have got together with several researchers from Karlsruhe, and the collaboration is now readying the mirror by adjusting the position of each of its 36 segments to minimize the spot size of the focused waves. They are also measuring background radiation within the shielded room that will house the experiment. As for receivers, the most likely initial option is a set of low-noise photomultiplier tubes for measurements of visible light, which corresponds to hidden-photon masses of about 1 eV/C2. Another obvious choice is a receiver for gigahertz radiation, which corresponds to masses less than 0.001 eV/C2; however, this latter set-up would require more shielding.
The DESY/Karlsruhe experiment – provisionally named FUNK (Finding U(1)’s of a Novel Kind) – will not be the first to search for hidden photons. The CERN Resonant WISP Search (CROWS) at the CERN laboratory in Geneva, which has been running since 2011, looks for both hidden photons and other low-mass dark-matter particles, such as axions. Also looking is the Axion Dark Matter Experiment at the University of Washington in Seattle. Although, as its name suggests, this facility has been set up mainly to detect axions, it can nevertheless probe the existence of hidden photons down to very low interaction strengths. The advantage of FUNK over its rivals, says Döbrich, is that it will be able to operate across quite a broad range of frequencies – just how broad will depend on the availability of suitable electromagnetic detectors and the performance of the mirror.
Fritz Caspers of CERN applauds FUNK’s “very nice” design, but has concerns about how difficult it will be in practice to shield the mirror from electromagnetic interference. “The devil is always in the detail,” he says. He also wonders why Döbrich and colleagues did not “go directly” to look for emitted radio-frequency radiation using a radio telescope, with a dish up to perhaps 100 m across, rather than the smaller version they will use. “You could easily find much bigger mirrors in the world,” he says. Döbrich points out that in terms of optical measurements, their mirror is a very good choice.
Face to face at the interface between physics and biology.
By Michael Bishop
In the 60 years since James Watson and Francis Crick brought physics and biology together to unveil the molecular structure of DNA, the boundary between the two disciplines has continued to become increasingly blurred.
In this post-genomic era, ever more principles from physics have been applied to living systems in an attempt to understand complexity at all levels.
Yet cultural differences still exist between physicists and biologists, as is made clear in a set of excellent perspectives in the journal Physical Biology, published by IOP Publishing, which also publishes Physics World.
In “Perspectives on working at the physics–biology interface”, a group of eminent scientists give their accounts of working at the interface of physics and biology, describing the opportunities that have presented themselves and outlining some of the problems that they continue to face when working across two fields with quite different traditions.
