While most solids expand when heated, some defy this thermodynamic trend and shrink instead. Now, an international team of researchers has combined two heat-expanding materials to fabricate a heat-contracting composite metamaterial. The team, led by Nicholas Fang at the Massachusetts Institute of Technology in the US, has created tiny, star-shaped structures out of interconnected beams. The sugar-cube-sized structures quickly contract in all three dimensions when heated to about 282 °C – previous such structures only shrunk in two dimensions. While each of the beams in the stars are made of materials that typically expand when heated, the team realized that when the beams were arranged in certain architectures, they pull inward when heated, causing the whole structure to effectively shrink and collapse much like a Hoberman sphere. The team also found that it could control the amount of contraction by changing the amount of copper nanoparticles added to one of the two materials used to build the structures. Such materials could have a wide variety of applications – they could be used in computer chips (which deform over time due to heat). They could also be used together with conventional materials to build objects that are subject to varying temperatures, including window frames, water pipes and space technologies. The research is published in Physical Review Letters.
New sensor is both laser and detector
A microscopic sensor that can be used to identify different gases simultaneously has been developed by researchers at the University of Vienna, Austria. The team uses quantum-cascade lasers, which emit light in the infrared range, to study gas samples. “Our quantum cascade lasers are circular, with a diameter of less than half a millimetre,” says team-member Gottfried Strasser, head of the University’s Center for Micro- and Nanostructures. “Their geometric properties help to ensure that the laser only emits light at a very specific wavelength.” This is particularly useful in carrying out chemical analyses of various gases, each of which only absorb very specific amounts of infrared light. Indeed, gases can be reliably detected using their own individual infrared “fingerprint”. Doing so requires a laser with the correct wavelength and a detector that measures the amount of infrared radiation swallowed up by the gas. The researchers’ device is both a laser and detector – they use two concentric quantum-cascade rings, which can both emit and detect light at varying wavelengths. One ring emits the laser light, which passes through the gas before being reflected by a mirror. The second ring receives and then measures the intensity of the reflected light. The two rings then immediately switch their roles, allowing the next measurement to be carried out. The sensor could have many applications in everything from environmental observations to medicine. The research is published in ACS Photonics.
Tracking solar waves from sunspots
Sunspot mosaic: scientists used data from NASA’s Solar Dynamics Observatory, NASA’s Interface Region Imaging Spectrograph and the Big Bear Solar Observatory to track a solar wave as it channelled upwards from the Sun’s surface into the atmosphere. (Courtesy: Zhao et al./NASA/SDO/IRIS/BBSO)
An international team of astronomers has tracked a particular kind of solar wave for the first time, as it swept upward from the Sun’s surface through its atmosphere. Plasma and other material courses through the Sun and its atmosphere, and understanding the movement of such charged gas reveals more about our star, including how it heats up its atmosphere, how it creates a steady flow of solar wind streaming outward in all directions, and the dynamics of the star’s magnetic fields. Tracking solar waves in particular helps researchers to study the solar atmosphere, and by imaging the flow of the material the researchers hope to determine how and why the Sun’s upper atmosphere or corona is so hot. “We see certain kinds of solar seismic waves channelling upwards into the lower atmosphere, called the chromosphere, and from there, into the corona,” says lead-author Junwei Zhao at Stanford University in the US. “This research gives us a new viewpoint to look at waves that can contribute to the energy of the atmosphere.” The team made used of data and imagery from NASA’s Solar Dynamics Observatory, NASA’s Interface Region Imaging Spectrograph and the Big Bear Solar Observatory in Big Bear Lake, California. Together, these observatories watch the Sun in 16 wavelengths of light that show its surface and lower atmosphere. Although it has long been predicted that waves on the Sun’s surface (photosphere), are linked to those in its lower atmosphere (chromosphere), the new analysis is the first time that scientists have managed to actually watch the wave travel up through the various layers into the Sun’s atmosphere. The research is published in Astrophysical Journal Letters.
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on Russia terminating its co-operation with the US on moving away from using highly enriched uranium in its research reactors.
Research accounts for about 6% of the global helium market, yet the amount of helium available worldwide is limited. That shortage could worsen, owing to the impending closure of the US Federal Helium Reserve, which the Helium Stewardship Act of 2013 insists must shut by September 2021. Market forces will then control the element’s price, to the likely disadvantage of research customers. “It was clear there was going to be a problem down the road because of depletion of the helium reserve,” says low-temperature physicist William Halperin of Northwestern University, US, who sat on the 11 strong committee that wrote the report.
We want other federal agencies to realize that helium is non-renewable and has an uncertain future
Simon Bare, SLAC National Accelerator Laboratory
While the report by the three societies comes at a time when the price of crude helium has dropped slightly, that fall is not enough to offset the huge increases that have occurred in recent years. These rises have been worsened by the lack of bargaining power that small research institutions have. “By requiring scientists to pay such exorbitant prices for helium, funding is being diverted from other crucial priorities, such as training the next generation of American scientists,” the report asserts.
Helium broker
The panel recommends that the US government should provide guidance to agencies about conserving helium and build on an existing collaboration in which the Defense Logistics Agency acts as a “broker” to help academic institutions negotiate lower prices and tighter delivery schedules for helium. The report also calls on Congress to use some revenues from the Federal Helium Reserve to help researchers pay for equipment to cut helium consumption and for scientific societies to help academic researchers to transition to such equipment too.
In addition, the report also takes aim at the Bureau of Land Management (BLM), saying that it should develop regulations for selling helium to researchers who receive government grants. Indeed, the BLM has already been directed by the House of Representatives Committee on Natural Resources to fulfil the report’s relevant recommendations. “We want other federal agencies to realize that helium is non-renewable and has an uncertain future,” says Simon Bare, from the SLAC National Accelerator Laboratory, who co-chaired the panel that wrote the report. “If more groups at all sorts of institutions in the US reduce their use of helium by recapturing and recycling, it’s a good thing.”
The report, Responding to the U.S. Research Community’s Liquid Helium Crisis, can be found on the APS website.
Oldest planet-forming disc spotted around red-dwarf star
A star surrounded by the oldest-known circumstellar disc – a primordial ring of gas and dust that usually orbits around a young star, from which planets can form as the material aggregates – has been discovered by an international team of researchers, together with a group of citizen scientists. Led by Steven Silverberg at the University of Oklahoma in the US, the team found that the newly identified red-dwarf star “AWI0005x3s” has a circumstellar disc (a rarity in itself for such a star), which seems to have lasted for an exceptionally long time. “Most discs of this kind fade away in less than 30 million years,” says Silverberg. “This particular red dwarf is a candidate member of the Carina stellar association, which would make it around 45 million years old [like the rest of the stars in that group]. It’s the oldest red-dwarf system with a disc we’ve seen in one of these associations.” Knowing that this star and its disc are so old may help scientists to understand why M-dwarf discs appear to be so rare. The discovery was made possible thanks to members of a NASA-led citizen-scientist programme “Disk Detective” – the project’s users were listed as authors on the research paper, which is published in the Astrophysical Journal Letters.
Greek researcher wins 2016 Farinella Prize for planetary dynamics
The 2016 Paolo Farinella Prize has been awarded to Greek physicist Kleomenis Tsiganis at the Aristotle University of Thessaloniki, for his work on the applications of celestial mechanics to the dynamics of planetary systems, including the development of the “Nice model”, which describes the migration of Jupiter, Saturn, Uranus and Neptune during the early phases of the solar-system’s evolution. It also explains how the interaction of the giant planets with a disc of left-over debris caused a temporary dynamical instability, which led to the outer planets moving to their currently observed orbital configuration. The annual prize, which was established in 2010 to honour the memory of the Italian scientist Paolo Farinella (1953–2000), acknowledges an outstanding researcher not older than 47 years who has achieved important results in one of Farinella’s fields of work. Each year focuses on a different area or research, and the 2016 prize focussed on applications of celestial mechanics in the solar system. “Tsiganis has produced impressive results in modelling the solar system. In particular, he contributed to a deep understanding of the early dynamical phases and architecture of our planetary system,” says prize-committee chair Alessandra Celletti.
Nanoantennas produce fast optical switches
Gold antennas: an artists’ impression of gold antennas on vanadium-dioxide thin film, with antenna-assisted phase transition (red). (Courtesy: University of Southampton)
A fast nanoscale optical transistor that uses gold nanoantenna-assisted phase transition has been created by an international team of researchers. The researchers say the study will help develop antenna-assisted switches and optical memory. Small nanostructures that can interact strongly with light are of interest for many novel upcoming devices such as small optical circuits and metasurface flat optics. Nanoantennas are usually designed to function far below the diffraction limit via strong optical resonances. “If we are able to actively tune a nanoantenna using an electrical or optical signal, we could achieve transistor-type switches for light with nanometre-scale footprints for data communication,” says lead author Otto Muskens from the University of Southampton, UK. He adds that such active devices could also be used “to tune the antenna’s light-concentration effects leading to new applications in switchable and tuneable antenna-assisted processes”. The team used the properties of the antenna itself to achieve low-energy optical switching of vanadium dioxide – a phase-change material, which is a functional material and switches from an insulator to a metal above 68 °C. Gold nanoantennas were fabricated on top of a vanadium-dioxide thin film and were used to locally drive its phase transition. The research is published in the journal Light, Science and Applications.
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on a plan to deal with the rising price of helium.
A new statistical analysis of type 1a supernovae observations has failed to find substantial statistical evidence that the rate of expansion of the universe has been increasing over time. Instead, the calculations are consistent with a universe that is expanding at a mostly constant rate – something that could be at odds with the popular lambda-cold dark matter (ΛCDM) model of cosmology.
Type 1a supernovae are exploding stars that play an important role in astronomy as “standard candles” that emit the same type and quantity of light. This means that the distance to a supernova can be worked out simply from its brightness in the sky.
Prior to the late 1990s, cosmologists had assumed that the expansion of the universe should either be constant over time, or slowing down. But then a team led by Saul Perlmutter and another team led by Adam Riess and Brian Schmidt noticed that the rate of expansion of the universe has been increasing. The teams found that more than 50 distant type 1a supernovae are fainter than expected for their measured redshift.
The expansion of the universe causes the light from a supernova to be shifted to longer wavelengths when observed on Earth. This redshift tells astronomers how quickly the supernova was moving away from us when the explosion occurred – which gives us the rate of the expansion of the universe at that time.
Surprise discovery
The surprise discovery was evidence that the expansion of the universe has been accelerating. It earned Perlmutter, Riess and Schmidt the 2011 Nobel Prize for Physics and led physicists to speculate that this acceleration was driven by an unseen entity called dark energy.
The evidence for accelerated expansion is marginal
Subir Sarkar, University of Oxford
Since then, further independent evidence for the accelerating expansion has come to light in measurements of the cosmic microwave background (CMB) and observations of galaxies. Indeed, the accelerating expansion of the universe has become a pillar of the most popular theory of cosmology, ΛCDM, where Λ is the cosmological constant that describes the acceleration.
Hundreds of other type 1a supernovae have been observed since the 1990s, but now some physicists are beginning to doubt whether these observations support an accelerating expansion. Subir Sarkar of the University of Oxford in the UK, Jeppe Nielsen of the Niels Bohr International Academy in Denmark and Alberto Guffanti of Italy’s University of Turin have done a statistical analysis of data from 740 type 1a supernovae and concluded “that the data are still quite consistent with a constant rate of expansion”.
Overly simple
The difference between the trio’s study and previous analyses is how variations in supernovae light are dealt with. While all type 1a supernovae are nearly identical, astrophysicists know that there are important differences that must be accounted for. Sarkar and colleagues argue that the statistical techniques adopted for previous studies are too simple and not appropriate for the growing set of observational data.
Using a technique that Sarkar describes as “industry standard statistics,” the trio took a different approach to dealing with variations in the supernovae. They concluded that the deviation from a constantly expanding universe is less than about 3σ, which is a relatively poor statistical significance. “The evidence for accelerated expansion is marginal,” says Sarkar, who believes that the ΛCDM model needs rethinking.
Roberto Trotta of Imperial College London does not go that far, pointing out that there is other independent and strong evidence for the accelerating expansion. However, he acknowledges that the evidence for acceleration in type 1a observations does not appear to be as robust as previously thought. Trotta – who has developed a new statistical method for analysing type 1a data that is different than Sarkar’s – says that astronomers are poised to observe thousands of new type 1a supernovae and must be prepared to adopt more rigorous statistical techniques to analyse them.
There are still 10 days to go until Halloween, but some physicists can’t resist getting into the spirit a bit early. Over at Symmetry, Kathryn Jepsen suggests a few scary physics films that would make for a spooky movie night on 31 October. They’re not actually real films, but rather a series of posters dreamt up at Chicago’s Sandbox Studio in collaboration with the illustrator Ana Kova. My favourite is Poltergauss (right), because trying to understand magnetism is terrifying.
The €2bn European Spallation Source (ESS), currently under construction in Lund in southern Sweden, will be the world’s most powerful source of neutrons when it fires up in the early 2020s. With an average beam power of 5 MW, the ESS’s main focus is generating copious amounts of neutrons for a range of experiments from biology to condensed-matter physics. Yet there are plans afoot to also make the ESS a leading particle-physics lab and produce the world’s most intense beam of neutrinos.
The ESS Neutrino Super Beam (ESSnuSB) consortium – a team of 50 physicists in 11 European countries, led by Tord Ekelöf at Uppsala University, Sweden, and Marcos Dracos from Strasbourg University, France – say that an intense neutrino beam could be created by doubling the beam power of the ESS to 10 MW. The cost is estimated at €500m (plus €700m for a neutrino detector) – a sum just less than the actual cost of the ESS itself.
Neutrons will be generated at the ESS via a 2 GeV superconducting linear proton accelerator. Those protons are sent to a tungsten target and, in the process of spallation, produce neutrons. The proton beam at the ESS is delivered in 14 pulses every second. Each pulse is 3 ms long, meaning that the linear accelerator is only active about 4% of the time. The facility’s radiofrequency power generators deliver 125 MW of power during each pulse.
Ekelöf and colleagues say that by doubling the number of pulses in the ESS’s linac to 28 per second, thereby increasing the average beam power to 10 MW, half of this beam could be used to generate neutrinos. “In this way the accelerator will be used 8% of the time, which is still quite feasible technically,” says Ekelöf. “Linear superconducting accelerators currently exist that are used 100% of the time.”
There are, however, several technical challenges in doubling the ESS’s beam power. One is to work out the details of how to add more accelerator pulses to double the average power of what will already be the most powerful accelerator in the world. The doubling of the ESS accelerator power will require an increased cooling capacity in the power generators and in the accelerating cavities to compensate for the increased heat dissipation. And the capacity to operate at a higher frequency will also require some modifications to the power generators, such as increasing the power of their capacitor-charging current sources.
The ESSnuSB consortium is now looking to complete a design study via an EU COST Action – a way to co-operate and co-ordinate nationally funded research activities. When a design study and technical design have been carried out – a process that could take five years – the consortium will then look for funding. “It is clear that the additional cost that ESSnuSB represents will require strong political backing,” Ekelöf admits. “Yet it will be the only project to continue frontline experimental neutrino physics in Europe, a field in which Europe has a long tradition.”
Neutrinos oscillate between three different kinds of “flavours” – electron, muon and tau. To generate the neutrino beam, the protons would be made to hit a titanium target to produce pions that decay into muons and muon neutrinos. The neutrinos would be detected using a huge underground water-based Cherenkov detector located in the Swedish Dalarna region about 540 km north of Lund. There are two other planned projects pursuing the same goals as the ESS neutrino idea: the Deep Underground Neutrino Experiment in the US and Hyper-Kamiokande in Japan. These two projects are more advanced in their planning, yet the ESS neutrino project will be unique, thanks to the intense neutrino beam created by the ESS accelerator. It is this high intensity that will allow researchers to place the neutrino detector three times further away than is usual, something that will reduce systematic errors.
However, before the neutrino project at the ESS can get off the ground, the issue of who will pay for the upgrade to the ESS’s accelerator will need to be ironed out. According to Ekelöf, such an investment can only be achieved by an international agreement similar to that made between the 11 countries behind the ESS. Ekelöf claims that the ESS management are broadly supportive of the proposal, adding that they have agreed “to provide information and general support for the ESSnuSB collaboration’s ongoing studies”.
Allen Weeks, head of communications at the ESS, says that while they are focused on delivering neutrons for the foreseeable future, “the science [behind the consortium’s proposal] is very interesting and exciting for the neutron and particle physics communities”.
Physicists call for UK food-manufacturing strategy
The UK should create a national industrial strategy for food manufacturing, according to a report by the Institute of Physics (IOP), which publishes physicsworld.com. The publication – The Health of Physics in Food Manufacturing – looks at the role that physics can play in what is one of the biggest manufacturing sectors in the country. The report, which was launched today at an event at PepsiCo in Leicester, sets out the contribution that physics can make given that the manufacturing side has become more high-tech. It lists a number of recommendations, including that the government establish an industrial strategy committee for food manufacturing chaired by a government minister. This committee would provide a “co-ordinated, strategic, raised level of investment” in scientific research and development in food manufacturing, support collaborations between academia and industry, and spread awareness of the food sector’s reliance on technological innovation. It would also inspire physics students to move into the area.
Higgs-detector trio bag particle-physics prize
Jim Virdee, Michel Della Negra and Peter Jenni have been awarded the 2017 W K H Panofsky Prize in Experimental Particle Physics by the American Physical Society. The trio share the $10,000 award “For distinguished leadership in the conception, design and construction of the ATLAS and CMS detectors, which were instrumental in the discovery of the Higgs boson.” Virdee is professor of physics at Imperial College London and Della Negra splits his time between Imperial and CERN. Both physicists played key roles in the design, construction and operation of the CMS experiment at the Large Hadron Collider (LHC). Jenni is based at the University of Freiburg in Germany and played a crucial role in the design, construction and operation of the ATLAS experiment at the LHC. Data taken by ATLAS and CMS led to the discovery of the Higgs Boson in 2012.
Cosmic rays get past Earth’s magnetic field
A burst of cosmic rays spotted by astrophysicists working on the GRAPES-3 telescope in India has been linked to a short-lived weakening of the Earth’s magnetic field caused by an eruption of matter from the surface of the Sun. The event happened on 22 June 2015 and involved GRAPES-3 detecting a burst of atmospheric muons that lasted about 2 hours. These muons are created when cosmic rays collide with nuclei in the atmosphere and the muon detection rate is a measure of the intensity of cosmic rays that reach the atmosphere. Most cosmic rays are deflected by the Earth’s magnetic field before they reach the atmosphere – which protects us from harmful radiation. However, the Earth’s magnetic field can be deformed by the huge streams of charged particles that are produced in solar eruptions. This reduces the field’s ability to deflect cosmic rays. Writing in Physical Review Letters, Sunil Gupta of the Tata Institute of Fundamental research in Mumbai and GRAPES-3 researchers in India and Japan analyse the burst using numerical simulations of how the solar eruption affects the Earth’s magnetic field. They conclude that the cosmic-ray burst is related to a solar eruption that occurred on 21 June. The discovery could lead to better forecasts of radiation levels on the International Space Station as well as a better understanding of how solar activity affects the Earth’s magnetic field.
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics. Tune in to physicsworld.com later today to read today’s extensive news story on dark energy.
Electrical currents in the oceans have a small but measureable effect on the Earth’s magnetic field and can be used to peer deep below the lithosphere. That’s the conclusion of geophysicists who have used three Swarm satellites operated by the European Space Agency (ESA) to make an extremely detailed map of the Earth’s magnetic field. Writing in Science Advances, the team explains that small electrical currents are generated when salty seawater is pushed by tidal forces. This induces a weak current in the Earth’s crust, which contributes to the overall magnetic field of the Earth. The team used measurements of the tidal magnetic fields to generate images of the electrical structure of the lithosphere and upper mantle down to a depth of about 250 km below the oceans. The study reveals a sharp increase in electrical conductivity at about 72 km depth, which could signify a boundary between the colder lithosphere on top and the hotter asthenosphere beneath. “These new results are important for understanding plate tectonics, the theory which argues that Earth’s lithosphere consists of rigid plates that glide on the hotter and less rigid asthenosphere that serves as a lubricant, enabling plate motion,” explains team-member Alexander Grayver from the Swiss Federal Institute of Technology in Zurich.
Laser-driven electrons break speed record
Speedy electrons: illustration of how an intense laser pulse (orange wave) causes electrons to oscillate at 8 PHz. (Courtesy: Research Group Attoelectronics/MPQ)
Electrons have been set oscillating at 8 PHz by Eleftherios Goulielmakis and colleagues at the Max Planck Institute of Quantum Optics in Garching, Germany. This smashes the previous speed record for the fastest human control of electrons by a factor of 100. Writing in Nature, the team describes how it created the oscillations by firing intense laser pulses at a piece of silicon dioxide. This material is normally an insulator, but when exposed to the pulses its electrical conductivity is boosted by a factor of about 10 billion billion. The rapid oscillation of the electrons caused the material to emit very short bursts of extreme-ultraviolet light, which were detected by the researchers. The research could someday lead to the development of computers that can run much faster than conventional electronic devices used today. “The idea of using lasers for guiding the motion of electrons inside solids such as to create high-frequency electronic currents is rapidly gaining momentum,” Goulielmakis explains.
New millimetre-wavelength eye on the sky
Perfect pixels: TolTEC is part of the Large Millimeter Telescope. It’s located on the summit of Sierra Negra, an extinct volcano in Mexico. (Courtesy: James Lowenthal)
Astronomers have unveiled a next-generation millimetre-wavelength polarimetric camera that will become part of the Large Millimeter Telescope (LMT) in Sierra Negra, Mexico. The device has been built by a team of astronomers led by Grant Wilson at the University of Massachusetts Amherst. It is the most sensitive polarimetric camera to date and will be used to conduct a series of surveys in star formation and galaxy evolution. Dubbed TolTEC, the camera will be operational by late 2018 and will offer a mapping speed that’s 100 times faster than LMT’s current capability. Observations that today take five years to complete will be done by TolTEC in a little more than one week, say the researchers. Another benefit of the camera is that it is capable of surveying the sky simultaneously in three frequency bands, compared with the current instrument’s single band. It is also sensitive to polarization as well as intensity. The researchers say that their camera will improve our understanding of star formation and galaxy-cluster physics. It will also carry out ultra-deep galactic exploration and magnetic-field surveys of the universe.
You can find all our daily Flash Physics posts in the website’s news section, as well as on Twitter and Facebook using #FlashPhysics.
To truly immerse oneself in Roger Penrose’s Fashion, Faith and Fantasy in the New Physics of the Universe is to fully experience the agony and joy of the theoretical physicist’s quest to reckon with the problem of quantum gravity. The search for a way to unite quantum mechanics and relativity drives the work of many physicists, especially ambitious and optimistic young PhD students. Indeed, there is something romantic about the effort, like a hero’s quest to make a lasting mark on the field by thinking deeply and then riding home triumphantly with the answer in hand.
The problem of course is that after nearly a century, the task has not only proved theoretically and experimentally insurmountable (so far), but it has also come with difficult sociological challenges. The story of quantum gravity is therefore not only about the joys of mastering difficult calculations, asking deep questions and exploring fantastical possibilities. It is also about wrestling for resources; taking unpopular and sometimes career-ending risks; and struggling to understand independence in the midst of a herd.
The decision by Princeton University Press to publish this work is an interesting one. The text lacks a natural audience, but for those who come to it and are willing to do the hard work of reading it, there are potential rewards. The book is offered as an overview of the boundaries of what we know in high-energy and gravitational physics, with a scientific critique and commentary on the sociological dynamics around these ideas. Penrose takes the view that getting beyond the boundary will require making sure that we are actually at the right one. To that end, he offers protracted semi-technical introductions to string theory, quantum mechanics, modern cosmology and his own pet programme, twistor theory.
Each of these introductions is very evidently biased by Penrose’s own perspective, and by what other practitioners in the field might call his misunderstandings. Fashion is based on a lecture Penrose gave in the early 2000s in which he expressed views that have since been challenged repeatedly by fellow physicists. Unfortunately, the book does not really wrestle with any of those challenges. Instead, Penrose sets up the “fashion”, “faith” and “fantasy” entirely from his perspective, knocks them down and ignores any factors that might upend his logic.
As an elder statesman of the field who has already left a lasting impression, it is possible that Penrose has earned the right to do this. When I was a young and optimistic student of loop quantum gravity who was excited to be seated near him at a dinner, I asked Penrose how he had come up with his majestic space–time diagrams, known as Penrose diagrams. He told me that he needed to draw space–time in order to understand it – that was all. Indeed, the book is replete with phenomenal visual representations of the physics under discussion, a reminder of Penrose’s ability to see and describe physics in a unique way.
A great strength of these discussions is that they include some of the best introductions to difficult topics that can be found in the semi-technical or amateur-oriented literature. For example, Penrose’s discussion of Feynman diagrams is very intuitive. He offers a historic perspective that can only come with having spent decades in the theoretical physics trenches, and his holistic views on the ties between the various branches of physics may help senior undergraduates or beginning graduate students gain some perspective on what they know.
Ultimately, what is most valuable about the book is the excellent example he offers in how to ask questions. He certainly raises more questions than he answers, and I found the answers he provides to be inadequate more than once. For example, Penrose believes that modern cosmology’s reliance on inflationary theory as a building block of our cosmic timeline is overly fantastical. He portrays us cosmologists as uniformly and simply invested in inflation, untroubled by open problems related to it, even though we are all troubled by many of the issues he raises. Despite this, I found that even as I disagreed with Penrose, he forced to me to think, and think deeply, about the fundamental assumptions I have relied upon as a researcher and the axioms I was taught as a student.
While the text has supposedly been made accessible by avoiding the use of differential calculus, in reality, one cannot follow it without knowing the material in a lengthy appendix. Within a few pages, this appendix introduces the concept of fibre bundles, which can be difficult for even a PhD-level physicist to fully wrap their mind around. Penrose’s optimism and expressed desire that the interested amateur will be able to navigate the text is admirable, but on reading, it seems unrealistic. An open admission that this text is intended for readers with a background in physics would have strengthened it. Certainly, such an admission would have shrunk the number of potential purchasers, but it would also have given the author more freedom to make his point.
Readers who struggle to follow the technical prose may, however, still appreciate the sociological commentary. Penrose is right to question the significant impact that the hyper focus on fashionable string theory has had on the physics community. He notes that the pressure to publish or perish and the feedback loop between this pressure and receiving funding is made all the worse by what may have been an excessive emphasis on one approach.
Similarly, questions raised about the faith we have in quantum mechanics are worth thinking through, even though here, again, Penrose refuses to grapple with critiques of his viewpoint. The one-sidedness in the author’s thinking is a general weakness of the book, and this makes it difficult to suggest that a non-expert or student read it without guidance. If one is not expert on the topics discussed, it is possible to be misled by Penrose’s biases. On the other hand, in some sense, this is exactly the phenomenon the text was meant to warn us about.
2016 Princeton University Press £19.95/$29.95hb 520pp
If you are studying a science subject, you have probably read that industries that recruit science, technology, engineering and maths (STEM) students are experiencing skills shortages. In the UK, both the government and employers have described these shortages as reaching “crisis” levels, claiming that a lack of suitably skilled workers is harming the country’s economy and making it less competitive internationally.
However, such “crisis” reports are not new or confined to the UK. Similar accounts have been regularly published here since the end of the Second World War, and they have also appeared in the US, Australia and several European countries. The common theme is that a current or imminent shortage of highly skilled science workers – often blamed on poor science teaching in school – is a threat to the economic and technological development of the nation.
One reading of these reports is that the recruitment of highly skilled science workers has always been a problem that is difficult to solve. This would be a straightforward explanation of the situation – except for the fact that not everybody agrees there is, or ever has been, a shortage. Working out what we mean by a “shortage” can be challenging and, unfortunately, we don’t always have the data available to find out how many STEM workers a country needs.
A problem of supply and demand
Despite the dearth of good data, governments have generally responded to reports of skills shortages with new and expensive policy initiatives. Because employers are most concerned about the numbers of applicants to highly skilled STEM jobs, the ultimate aim of many of these interventions has been to increase the number of graduates with science degrees. However, there are two big problems with trying to match the supply of STEM workers with demand.
The first problem is on the supply side. Producing highly skilled STEM graduates is a long-term process. Students can opt out of science subjects at various points and increasing the number of STEM graduates means persuading young people to continue studying the sciences throughout their education. Those who have already dropped the sciences are unlikely (and often unable) to pick them up later. This means that increasing the STEM workforce has to start in the early stages of education. We cannot drastically increase the number of STEM students over the course of just one or two years: plans must be made decades, rather than years, in advance.
The other problem concerns demand. As we have seen recently, future changes such as those promised by the UK’s vote to leave the EU can have immediate and considerable impact on the economy and, in turn, on the labour market. Among physicists, the decision to renew the Trident nuclear programme will have an effect on future demand for those in certain sub-specialities, as would a decision to scrap it. Whether the proposed Hinkley Point C nuclear power station is built – and perhaps which countries might be involved in funding it – will also have implications for demand. These and countless other developments all affect the demand for highly skilled STEM workers, and they do so on a timescale that is much quicker than the process of producing STEM graduates. This makes matching the supply of STEM workers to the likely demand for them very difficult indeed.
Even if we could predict an increase or decrease in the demand for STEM workers, we really need to know which kind of STEM workers are needed, and what STEM subjects students should study. Lumping all STEM graduates together isn’t actually that useful: we need to know what subject specialists are needed most urgently. To take the previous nuclear example, a surge in the number of biology graduates isn’t going to help meet increased demand for radiation physicists or nuclear engineers.
Where the money goes A report by the Institute for Fiscal Studies on UK graduate earnings compared median annual earnings for STEM graduates (green); graduates in law, economics and management (LEM, yellow); and other graduates (blue). Box plots show earnings in 2012/13 for women who graduated from UK institutions in 1999. The line in each box represents the median of institution medians, while the top and bottom indicate the 1st and 3rd quartiles and the whiskers are a rough measure of scatter in the data. In general, LEM graduates have the highest earnings, while the difference between STEM and other subjects (primarily humanities) is not as pronounced. The area of the black dots indicates the number of students in each subject. An equivalent graph for men showed earnings approximately 5–10% higher in most subjects. (Adapted from: How English Domiciled Graduate Earnings Vary With Gender, Institution Attended, Subject and Socioeconomic Background (Institute for Fiscal Studies Working Paper W16/06))
First jobs after graduation
In our study, which was funded by a grant from the Nuffield Foundation, we aimed to find out whether there really is a shortage of highly skilled STEM workers (and if so, in which areas) by bringing together analyses of the best available data in the area. We first looked at data collected by the UK’s Higher Education Statistics Agency (HESA) on the destinations of all graduates six months after they have finished their degrees. Every UK graduate is sent questions on their employment status and response rates are very high, at around 80%. Although HESA also collects data on the longer-term career outcomes, these data are based on only a sample of graduates and have very low response rates (22% in 2012), so here we have only used the data on immediate destinations.
We looked at HESA data from 1994/5 to 2010/11 because it was the best data for making long-term comparisons (the survey changed after 2011). Although the number of students going to university doubled during this period, we found that the patterns of early graduate destinations did not change very much. In general terms, STEM graduates (excluding those studying medicine or dentistry) didn’t have any real labour market advantage over those taking other kinds of degrees, and similar proportions of both groups entered “graduate” jobs (a term that, in essence, denotes jobs that involve some form of managerial, associate/professional or technical expertise). STEM graduates in general were also just as likely as non-STEM graduates to find themselves in positions at the lower end of the occupational scale, working in jobs such as routine sale assistants, caring roles and other elementary functions.
There were some differences between STEM subjects. Graduates in engineering, for example, were more likely than average to find themselves in highly skilled STEM jobs immediately after graduating, while those with degrees the biological sciences were actually less likely to be employed in such positions than those with degrees in some non-STEM subjects. Physicists were somewhere between the two. In every year we studied, between 5 and 10% of STEM graduates were unemployed six months after they graduated.
A relatively high proportion (around a quarter for all disciplines) of graduates in the biological, mathematical and physical sciences stayed on for postgraduate study. This could suggest that some of them were unable – or at least felt unable – to get the kind of job they wanted with just an undergraduate degree. In 2010/11, some 37% of physics graduates stayed on in full-time postgraduate study. If we include those who carried on studying part-time, balancing their studies with work, this figure rises to 46%.
In the same year, less than 5% of physics graduates who found employment were working as “science professionals” six months after graduating. Another 8% worked as “engineering professionals”, and the same proportion were teachers. A much larger proportion (19%), worked in business, finance and statistics, but the largest proportion (26%) were in non-graduate jobs, with 14% working in sales, customer services or other elementary occupations.
The occupational destination of students varies considerably depending on the type of higher education institution they have attended. STEM graduates from Russell Group institutions (such as the universities of Oxford, Manchester and Cardiff) had similar levels of full-time employment compared to those who attended institutions belonging to the University Alliance or Million Plus (UA/M+) groups – predominantly made up of former polytechnics such as the universities of Coventry, Bolton and Nottingham Trent. But a larger proportion of Russell Group STEM graduates gained graduate-level positions and they were almost three times as likely to enter highly skilled STEM jobs. Russell Group STEM graduates were also more likely than those from UA/M+ institutions to remain in education. However, similar proportions from both types of university found themselves unemployed six months after graduation (see table).
Looking further afield
The other data sets we used in our research were the 1970 British Cohort Study (BCS70) and the 1958 National Child Development Study (NCDS). Both of these “longitudinal” studies have tracked the education and careers of all people born in a particular week of the year these studies started. The 9000 or so participants in the BCS70 are now in their mid-40s and those in the NCDS are in their late 50s. The data collected for these studies allowed us to look at the long-term career trajectories of STEM graduates and to compare them with those of graduates in other subjects and also with non-graduates. This is important because it may take some time for graduates to establish their careers, and people also may move in and out of different kinds of jobs over their lifetimes. Because it is more recent and more complete, we will concentrate on the BCS70 data here, but results for the NCDS study were very similar.
Our analyses showed that the long-term career trajectories of STEM graduates and those with degrees in other subjects weren’t very different. By age 30 similar proportions had graduate jobs (86% of STEM and 84% of non-STEM graduates) and the most common jobs for both groups were teaching and “functional management” (managerial roles in finance, marketing, sales and so on). As they got older, many of those working in scientific jobs moved out of these roles, often into management positions. People were unlikely to move into scientific positions later in their careers, however, meaning that overall, fewer older respondents worked in science. If STEM graduates hadn’t entered highly skilled science jobs in their 20s they weren’t likely to do so later.
In fact, we found that surprisingly few STEM graduates worked in professional scientific, research or engineering positions at any time in their careers. At no point between the ages of 26 and 42 were more than 22% working as engineering, information technology and science-related professions (the three key “shortage” occupations) and by age 42 this figure had fallen to only 14%. A comparable proportion (12%) of 42-year-olds worked as teachers and 13% worked as functional managers. Teaching and management were also common destinations for graduates with degrees in other subjects.
Crisis? What crisis?
Our research shows little evidence of a shortage of STEM graduates of “crisis” proportions. Although most STEM graduates find work, and most of these jobs are graduate-level positions, only a minority of them work in highly skilled STEM positions; many more work in teaching, business or management than in science. This situation isn’t new, as our analysis of cohort data shows, and looks unlikely to change in the near future.
If employers are really having trouble filling essential jobs in their science industries, then why are so many STEM graduates working in jobs outside of science? One common explanation is that universities are not providing students with the skills that employers need. But as we have seen, it is nearly impossible to predict what skills will be needed in the future. In any case, universities have to provide a broad, general education; they offer more than just vocational training for particular positions.
Another possibility is that professions outside of science are regarded as more attractive by science graduates, either because they pay more or are seen as more interesting. There are rarely reports of a shortage of bankers, for example, even though the sector relies on recruiting graduates with the kind of mathematical skills that are common among STEM students. Is it actually the case, as many economists argue, that while there is no shortage of STEM graduates, there is a shortage of those who are willing to work for the pay and conditions that are currently on offer?
We would certainly not want to discourage any students from studying science. One of us (ES) is a former secondary school chemistry teacher and the other has taught undergraduates in the sociology of science. We both support science education, and we think that having graduates with science degrees is important for the economy but also for society more widely. Having more politicians with scientific backgrounds, for example, would almost certainly lead to better policy decisions in many areas.
STEM graduates have at least as good career outcomes as those studying other subjects and in some cases slightly better. But we are concerned that the regular scare stories about supposed shortages of scientists may unrealistically raise the expectations of students studying, or planning to study, STEM subjects at university. Science graduates have very promising career prospects – but so do graduates in general. Our research shows that differences in career prospects between degree subjects can easily be exaggerated and that in some respects where you study is as important as the subject on your degree certificate.
For some careers you will certainly need to have a science degree. But bear in mind that most STEM graduates never work in these types of jobs. Having a degree will undoubtedly help your career prospects, but you should study science because you enjoy it, not because you think it will give you a “leg up” in the graduate labour market. Unfortunately, our results show it probably won’t.
What physics graduates really do
(Courtesy: iStock/sorbetto/Mat Ward)
Physics graduates are employed in a wide range of sectors both inside and outside the STEM field. From our research the most likely jobs for physics graduates are (in no particular order) in the following areas:
physical science
IT analysis
software programming and development
business and financial occupations
secondary school teaching
higher education
While there are still many more male physics graduates than female, the types of jobs they do tend to be similar. However, by far the single largest occupational group for female physics graduates is secondary school teaching.
